Helicopter Stability & Control Flight Testing

2004-03-25T11:27:00.000-08:00

The University of Tennessee Space Institute

UTSI Aviation Systems department Hosts one and two week short cources desined for graduate study and continuing education.
The flight test series includes Fixed-Wing preformance, Fixed-wing Stability & Control, Rotary-Wing Preformance, and Rotary-Wing Stability and control. The cources are taught by the test pilots on staff at UTSI as well as those guests from naval and army test pilot centers and some industry test pilots.
These cources are not only designed to train up and coming test pilots but to help engineering professionals better understand how and why certian data is collected.
this blog is an assortment of lecture notes taken during some of the Helicopter(rotary wing) stability and control lectures.

If you would like more info or would like to take one of the many short cources, feel free to contact our dept.

UTSI Aviation Systems offers Masters Degree Education designed for industry and military personel through distance education. Classes can be attended through VCR tapes, CD/DVD's, internet streaming, e-mail, or any combination of these technologies depending on student prefrence.
UTSI has excellent facilities to conduct your flight testing needs as well as help with aircraft certification, STC, R&D, and special IFR projects.

2004-03-11T12:38:00.000-08:00

This blog is the work of the flight test pilot in training miller wilder. Please enjoy more of the online empire of miller wilder as you have the time.

flight in the am.
rucie moore with frank couse tom left town.
rucie did the fliying.
then my group came out and pout laird the canadian in the front.
he did some hovering in the retund near the runway.

lectures begun at about 11:00 am. Mr. David Green of:

Starmark Corporation
18640 Greyton Lane
Davidson, NC 28036
Ph (704) 655-7353
Fx (704) 655-7473

naval tps grad, long time in helicopter worlds worked on automatic controls. Dave Green

he appreciates the opprotunity to be here. he has on the screen powerpoint presentation of scanned in notes from

the old school.

going to talk about flying qualities and handleing qualities, but in the "man machine" closed loop sorta

discussion.
-not to put down the ladies.
so inthis open loop the mind is still closed loop. he will equip you all to plan and analyze using the long term

concepts of how to get it right and how to do what he calles"table top siumulation" how to walk through the

flight, and why do you care?
couse we are beign trained to fly to the spec. and he is saying that the automatic control system is suitable

for service use.
if there is somehting wrong then you are supposed to report it.
The Rotorcraft is Typically a Highly Coupled Asymetric Aircraft.
nothing happens twice the same way.,
the stab aux system takes care of all the bad stuff. unless you find the corner of the nevelope.
Power:
Power Avaliable and power required is very important for flying qualities. anything that makes the tast more

difficult is important for the task. (trouble with remote control)
now showing the power required curves for airspeed.
the power required goes down in rearward flight.
it is kinda like amound in the three dimentional rtepresentation.
so the point is that if i am at some high alititude and the power required to turn and then you are coming down.

the "cone of power required" is that representation of the power required integrated over all directions of

flight. ie. foreward sideward rearward, etc.

THe Nav Air reports show how the power and controll runs out.

there are lots of variables and if you attempt to do lateral directional oscilations some roll off up, some down.

Attitude Variation With Airspeed.
with the h-60 in the flight and you decide to yaw left and you were going 90 knots, and then you get a wind shift

to the left then your pitch changed from 10 degrees up to two degrees down.
the pilot dosent get the infor about what to do, or that it is going to change, he can just adjust according to

the compensation necessarry.
the thing flys better to fly with the wing coming over the right hand side. then you learn to do it. and you

learn this over the coffee pot. sikorsky dosent put it in the maunal.

the roof scene is important to hold a hover. really anu visual scene. even at altitude.

so where do you put the money? you can put it in the display or in the control system, or wherever. anywhere on

the line you got common preformance. you can increase the toys in the aircraft, but then you loose out on thea

augmentation flight. so eigher easy to fly with good pilot systems. but really we are moving away from that and

forget displaying stuf to the pilot just make the chopter fly it's self better.

the longer you take to find trim then the longer it is going to stay.,

trim might be a trim or it might just be to turn on some automatic thing.
some say that you got to restrain the aircraft laterally to make the long turn. but when the thing noses over it

it then out of trim in yaw, then the aircraft will nose over and roll.
you do the split axis thing so you can know how the aircraft flies, then you let it go and see how it wants to

fly., how it is coupled. either you need augmentation or higher levels of pilots.

dpending on the community, flight directors are either in or out. flight director is part of the autopilot.
has alot of features in it. the flight director tells the pilot what to do as far as pitch roll and yaw and even

power.
there are times when the pilot will do the tasks manually and forget the autopilots.
the automatic carrier landings. hmmm. we migth get shot to talk about it.

so what if it dosent work. i gotto bring it abord or i get dead or wet.
the people would not practice it in the day time so when they had to do the hard ones, then they had to land

manually.

the limitations tend to keep everything the same. the pilots augmented on over and over flights. and all the

parts and failures are preemptively anticipated.

the world is a function of the enviroment. and the wind conditions, the celieng, visibility, the lighting, the

land or water surface conditons etc.

pilot rating of a 5-5 was a nasty thing. so they call lt green.
so the enviroments were different for the two pilots. a 4-5 guy and a 5-5 guy.
and the airforce paid him a big bag of money to figurethis out, and then they happily ignored the results for the

rest of his life.

no one designs an aircraft to be flown full up. (not sure) oh, they design it so that you can loose some

systems. and the question is how do you fly with what you got left.

if i got a crappy flight display ,i better have good controls.

he now is complaining about flying as a copilot with generals. and those who dont want to go.
the folks who say that they dont want to go talk bad about the aircraft during training.
ie. if you cant fly a broken helicopter then at best all you are is a copilot.

if you want to make an argument and win it, then you need the use these techniques to

lunch at 11:20 and to resume at quarter till one.

japoneese lunch. mmmmm.
and back to the class 1:10

an introduction to rotorcraft automatic flight control systems.
he had some leter from the pentagon from an admiral that said he could fly it if he could touch it.
so he went out and flew all the different machines. shooting rockets and guns and stuff.
then people like bob richards were on staff and they then built the pax river tps. he (david green) wrote the

first manual for the automatic stabilization system. but they said you cann not call itass. so they changed it

to say ase or sas. so stability augmentation system or automatic stabilization equipment.

the had one but did not use it and then they bought it without the system so they asked for more flight

augmetnation systems in 1958 or 59 they were hacing to hover at night.
approach 100 feet at 40 kts. then it took you to 20 feet and hover.
h-34J the first coupled system first viable aircraft was like 1961.
then the H-3 and the H-34 had vaccumn tubes. analog system with gyros that fell over etc.
you could turn peices on and off and select stuff.
now boing had a completely different approach. no attitude hold.
stability system.
then we have a big big big problem if you loose all the hydrolic systems in the helicopter.
the forces are absolutley huge. it happened to david green on the ground.

the force feel system plays in to the system through the hydrolic system and you can feel this. it is either

hydrolic or electromechanical. like on the other side of the extensible link. works good ibn turbulent air,

however you never actually arrived at an airspeed in the smooth air. just oscilated along in the smooth air.

short term response = how many seconds? two to four seconds or so.

long term, anything that is not short is long.

"how high am i above the water" the thought of the navy guy. maybe 150 feet flying ifr.

the f-4 pilot is at 20k feet and with the stars and thinks he is ifr.

People can claim that they have good inherient flight qualities but they cannot demonstrate it. the ones that

have good characteristics are augmented.

the open loop is not adjusting the controls. closed loop is adjusting the controls.

Graceful Degredation is escientally that the dosent degrade so fast that i have a heart attack. it slowly goes

to level of degredation that is really not that bad. ie. i can still complete the mission and then complain upon

return.
insulting degredation, like in the medical world, some thing tricks you it fails and you get the wrong

impression and then it slams you.

the cyclic causes pitch and roll.

the collective spoils flight, if you did not have one then you'd be lot easier off. but you would also not have

hte benefits.

the boeing company tried to stabilize the
href="http://aeroweb.brooklyn.cuny.edu/database/aircraft/getimage.htm?id=4016">h-46. this was designed to

take the mariens to the beach and then pick them up. no one ever said anything about ifr.
itshas a four second oscilation on the 3degrees trying to chase a speed.

the single rotor helicopter that does not have a tail rotor is like the rotar.

the notal is insensitive to ghusts in yaw.

break in the action.
return:

what is a helicopter - asymetrical and highly coupled.

how to prove it to someone. show graphix which say pay attention this is the way it is.

showing the cooper harper scale on the overhead projector.

objectional is if the workload is so high that pilot compensation might not yeild adequate preformance . pilot

would not contiune unless there was no other alternatives.

fifteen knots wind from the left side makes for hard landings in chopters.
there is a video of the H-2 loosing it in hight wind becouse of the left inboudt flow probnlems.

you ask the copilot to watch the coupler (autopilot) by asking him to watch the aircraft. then you just watch

him out of the corner of your eye while you are doing other stuff.

you will be hero's when you get peopleto write down what they see.
ie. huey flies best at some speed.

so what green has done is map the operating envelope of the aircraft with contours of pilot ratings for the

tasks. so then you can put in the desired task and predict the pilot rating for the mission.

it looks cool actually.

it is kinda likethe power required in three dimentional . you can then put this ont the three dimentioanl and

seethe vrs as a ball or it goes away with some side wind with a yaw, then you can get the vortex settling etc.

climbing rearward flight. it was never tested, it was never tested. it was never tested.
there are lots of manuevers that have not been demonstrated, you can easily be a test pilot.

also rearward descent it is not somehting that you do if you know it. but it happens in low visibility at night

situations.

with the average pilot "rodney" there is an enviroment and airship failures etc.

to split up piles. take say twenty and divide the good and the bad into ten piles.
then split the good and the bad of those piles into two piles and you end up with a sorted stack.

roll canceling = positive dihedral effect.
if you roll left then the pilot steps on the upper pedal.
trim into the turn it works great, if not hmmm.

they know all these secrets at these plant and their memory dies, history is not handed down. ie. the new 172.

or the 53 with the upper hydrolic problems.

thanks call if oyu have questions and he is learning about golf.

bob richards and a girl who works a half day man an office for utsi just out side of gate two at pax river.

handing out CEU credits and making everyone a ut alumni.
this status allows you to apply for football tickets.

thanks and good night.

2004-03-10T14:11:00.000-08:00

UTSI worked with this helicopter to complete the FLIGHT TEST PLAN TO ASSESS OF PVFR ROUTES . This Project is important considering how difficult is was to certify the 500e helicopter.

2004-03-10T12:35:00.000-08:00

Order Ralph Kimberlin's book online: Flight Testing of Fixed Wing Aircraftavaliable at AIAA
the flight this morning was in the drizzle.

we did ldo and

also we found that htere is little or no control coupling on this aircraft.

we found some ammount of "efficitve dihedral"

we have a positive lateral stability.

when you introduce a sideforce with the sideslip then you get the low side and the

rotor flaps laterally and you get dihedral effect and theaircraft returns to

level.

the collective with beta was considered fixed.

positive static directinal stability is showed by more right pedal required to

increase a sideslip.
we do have positive static directional stability. it wants to weathercock into

the wind in a sideslip so yuou have to counter with pedal.

the pilot comment from the pilot that the forces were qued to show the frank

lombardi says that he was able to feel the forces while he was flying the test.

this is interesting becouse rodney allison had sweared that he would not let any

of the engineers fly becouse of the 700 foot celings and drizzle.

dampning ratios were like .3 or point 4. this was calculeted by the add seven and

over ten thing.

you are increaswing the oscilations with the one inch input on the pedals.

due to the law of averages, and since the pilot was not so smooth then it is goos

to get about three or more and make an average.

the phe beta ratio was showing that it is more oscilatory in the directional then

in the roll.

looking like a football on the side. tipped kitty corner with the nose down.

ldo is not considered to be distracting to the pilot.

the frequency can be stated in hertz. the radians are hard to think about.
thanks Rucie Moore and Frank Lombardi for the presentation.

1:30

ralph kimberlin

certification of ifr on a small helicopter
single pilot in instruments.

Vy1

best rate of climb speed.
this might not be the exact preformance speed, it might be for handeling

circumstances.
maybe a little higher speed than best rate but it is more stable.

Vne1
maybe a little slower then the fastest possible, but fast enough that you loose

stability.

Vmin1

even so you need to realize that about 50 percent of the incidents the pilot got

into rearward fligtht then the chopter swapped ends and the helicopter then spills

the gyros.

so this is the minimum speed for ifr, and again the hover there is no stability.

so the pilot is the stab aux system in the hover.

***
so these are the new rules and concepts for the instrument flight rules. also in

apendix b or part 23 you got to be able to rtim the forces to zero for all

approved airspeeds.

oh 58? can you do it. no. there is a 206, but it is all automated.
the md500E , which there is a handout in the orange book that talks about it.

md-369e 94-2157

trim in both lateral and longitudinal trim. beeper in longgitudinal.

the flight test manual talks about forces and what not, but in the helicopter it

must posses positive static longitudinal force conditions.
the stick force must have increasing forces as such that the force increase must

be clearly perceptable to the pilot.

ie ? what subjective.
like how many lbs per 10 knoits. two pounds per ten knots. pilot can precieve

it at one pound per ten knots if control has little friction.

they found that the one in ten was enough for the pilot to get good feedback and

know when he/she was off trim.

so in a stick force vs. airspeed you see theat the increase is linear.

the conditions are ...
climb for single pilot the faa wants to be sure that hte chopter is easy to fly

and the workload is not too high.

ad-27.1.b is the circular that describes and gives discussion but it dosent nail

it down.

for single pilot approval the airspeed must return to withing ten percent of trim

when the stick is slowly returned to the trim condition position.

it must be climbed at a speed range plus or minus 20 knots from trim. with the

helicopter trimmed at vy1.

now you see why you define the vy1 to be what you wanted.

ie. if you used the origional Vy sa y 60 vknots. then you got to show positive

stability all the way down to fourty knots and as high as 80 knots.

the stability curve reverses as you get close to hover. so you move it to 70 and

you are not in the reversal region...

cruize is has to be shown from a speed range from point 7 to one point one Vh.

where Vh is max level flight speed.

notice that you will have to be decending during this potrion of the test.
couse it is faster then the max level flight speed.

now you got to show stability from point 9 v minni to 1.3 v min.

as you get slow and into hover or translational lift. he does well when he has

good visual refrences but then when it gets slow youre standard 3 inch instruments

you cannot get real good indications or attitude.

so this doctor installed a basketball sived attitude gyro on the chopter.

the faa in otherthan...whoa

the beech 99 airliner the wheel is moving foreward but you are putting on control

force.
so there is not control position stability, only control force stability.

the feedback to the pilot on instrument flight is mostly thrgouth the force and

not the position.

descent at 1000 fpm which is way faster than would be used.

you must check a 3 degrees approach angle.
if the aircraft is light and slow then you have to go faster then the Vne. but

this is for certificatioin and it it ok.

dynamics are not even applicable to the small helicopter.
welp, there if you are going to fly instruments there is.

less than five second dampned LDO.

must damp to half amplitude in not less than two cycles.

must not achieve double amplitude in less than 20 seconds.

no we take a break and then we will discuss the md 500 e. 2:20 pm.

Retuern to see the worlds only ifr certified mcdonald douglas 369e or 500e grew

from the oh-6 but it has a tee tail with endplates.
fully articulated rotor with four blades.
a tad of hub offset.

130 knot cruise helicopter.

added a sperate pidot static system.
compltely alernate heated system.

the static port is located on the back of the dog house.

one on top of the other.

this helicopter belong to a heart surgeon in springfeild illionois. did sixty

angioplasty or baloon surgery per month.
they cost about 20k per pop.

he also has a single pilot cessna citation biz jet.

in illionis doctors are required to get continuing education.
his company has the contract for sttewide continuing education on heart stuff.

transplant harts and sew them up.

he had a 206 that was instrument certified but he felt that he was just along for

the ride and he liked to fly. so he was actually a pretty good pilot for a

medical doctor.

he tells a story, when he was yound he wanted to be a pilot but ot be a pilot he

had to read all these books, and to be a medical doctor he had all these color

pictures.

ha ha

dave green is coming tomorrow maybe later.

dave and doctor snider were in a meeting with the faa and the faa talking about

certification issues for ifr helicopters.

he had astronautics autopilot and flight director in the cockpit.
has basketball attitude. the instruments are moved over to the left side like an

airplane.

had moving map gps.

there is a good story about him and his friends going to the bahammas, but you'll

have to get that one off the record.

he had moved the collective and had a stepper switch so he could set up most known

frequencies before he even picked up. then steop through the frequencies throught

the flight without letting go the stick.

rules say 45 minutes after a failure. but these guys wanted 1 hour and 30

minutes.

if the electrical system failed then he had two hours on basic instruments with a

second battery.

yaw dampner required for the ifr certifications.
Nr is real powerful so that is why it is important.

FAA did not want to do this. when we sent in the application we did not make

drawings. if he had done drawings then you could buy them and make it just like

this one.

for a one time cert. drawings are not necessarry just take some pictures.

did not have to make too many ifr restrictions to the flight envelope.

above ten thousand then the dampning was not too much.
the tip path plane would do strange things with a cyclic doublet.
we restricted the ifr celing to 8k feet.

rodney interjects that rucie moore will have to take one of these oh-6's to the

15000 feet.

so the doctor would take along a nurse on each flight, preferably a different one

each time.

this plane has a constant LDO. a little lean at the hover too.

so with six months and $40k later. we have the only ifr 500E in the world.

in 1926 the aircraft industry wanted regulations for to get insurance and bank

loans. so they petitioned the govt for rules.

the first rules were to fee to promote and regulate aviation.

hmm. opposites promote and regulate.

early rules:
propellors; must have at least one.

used string pots and hand heald strain gauges. anes gauges etc.

used telemetry reciever from hospital. good for 20 miles.

shot some approaches. used foggles etc.

FAA pilot Tom Archer. ntps grad, naval pilot retired. cheif flight test guy in

seattle now.

he flew at night with three failures. and still flew safley.

tail number of the chopter is: N

test plan have some holes in it. so when they want more you just plug in the

holes.

thrust to weight is .5 on ball jetwing.
top speed 225 indicated mph.

since 1978 or so we give 15-17 hours of graduate credit for either the army or

navy's test pilot school.
on video tape and cds . and it is better than online.

twenty folks might graduate this spring. alot. have had about 25 graduates total

in avSYS.

end kimberlin
rodney's breif 3:27

spiral stability.

see you in the am.

3:36 end if

or anything you want to see again.

turning manuever so visibility important.

dave green tomorrow afternoon for discussion of automatic control systmems.

maybe finish up tomorrow afternoon. might have a short period

2004-03-09T13:38:00.000-08:00

taking dater

taking dater.

flight for tomorrow steady heading sideslips lateral directional oscilations and spiral mode.

2:30 talking about the roll equation and the twomain derivatives are the Lv Lt and Lp.
so Lv but we will use L beta which is the change of the rolling inertia over Ixx and this is like when you are flying alond and take a positive beta and then see how the aircraft will roll after an inducted beta.
we use the rigth hand rule so a positive beta gives a negative roll mode due typically to the dihedral effect.

thisis a big player in the spiral stability.
when you drop a wing and then you rotate the

thrust vector and you are then deficient in the

lift department and so if you drop the wing then

you get a lbeta negative then the rose returns.

like in older model aircraft that have alot of dihedral so that the wings dont roll off. so wit hthes you get a positive dihedral effect with a negative derivative. helicopters. the side velocity increases when the beter begins and the blowback occurs on the side velocity. we will call that "blowside" which causes a negative effect to roll away from the wind. or to roll away from the preterbation.

the next derivative is the Lp. in fixed wing it

is roll dampning.

so how much it dampnens is due to the lag per unit

roll rate which is a functuion of the lock number of 16 times also the offset and the hight of the

rotor over the cg times omega. so the mq and the lp is negative in a hover.
we want a negative numner. something like 3.2 to 4 for the h-60.

switcher peanut shaped helicopter called hmm.

sounded like a gatlinburg. it would be good to

ahve alot of roll dampning.

the typical time constant for the h-60 would be

like a third of a second.

a steady heading sideslip is when all the rates

are zero.

flying along and put in a little pedal and the

aircraft tend to roll so you put in some cyclic.

and then steady it up and then you got a steady

heading sideslip.

so in the steady condituion all the dot terms go

to zero. also all the rates are zero.

right stick is positive left is negative.

the magnatude aand steepness is irrelevant however

the sign is important.

aaah, hard to remain attentive for the derivations

after a mexican lunch..

us system has positive inherent sideslip and the

russian have negative inheriant sideslip.

the trim point is important.

oh yea, yesterday during our flight the handle

fell off of the left rear door on the helicopter.
w
and on friday tom morrissey and bill jr. got in a

car crash. tom had to climb out the window like

bo and luke duke.

break at 3:38

3:49 lat dir, get the nose swinging and let the

thing go back and forth.
now all the derivatives are players.
there is full equations, so the model is all the

equations.
in the big pricture, test the same as for fixed

wing. like 70 knots. and we want to know about

the dutch roll modes. ldo is the same thing as

dutch roll.
normally you are interested couse you are flying

along and you get hit with a ghust and then you

watch the thing ro round and round. ads-33 gives

some s-plane requirements for this mode. page 44

in the red book. s plane imaginary and real

axzis. pilots like it ok when well damnped.

typically and historically there have been lower

measures by pilots on other tasks.
typically an oscilatory mode. it is from a pair

of complex conjugate roots on the s-plane. ads33

gives some hints to desired location.

it is fast enought that it would be good to have

electronic dater recorders for this type flight

test.
so to excite this for testing with a doublet.
ideally you find the natural frequency wit hthe

doublet.
too fast and it dosent excite it and too slow it

goes into backlash and roll off etc.
if ytou hit it at a frequency to close to the

period ytou get a good reaction.
it is rodney's job to make the frequency correct.

picture worth 1000 words on this one...
...

seven minus the overshoots over ten gives the

estimate for zeta.

ie with four over shoots, seven munus four is

three over ten and then point three is zeta.
...

we will do spiral mode, it is a first order. it

is not oscilatory. if the root is in the right

hand plane, then it is unstable, then when you

bank it i t will fall offf.

if it is unstable it will fall off, and to

characterize it oyu find the time to double the

bank angle.

so disturb it and then measure the time to fall

off.

so twenty seconds or longer is A-ok.

neutral it stays banked.

if the root is in the left hand plane, then it is

positive and then it will roll wings level.
bank it , note bank angle, and then note time to

half the bank back to the level.

the four derivatives are called the spiral

descriminate and he will draw a cartoon.

stable and not stable.

Nr Lb on left under stable and Lr and Nbeta on the

right under non stable.

nr and lbeta is yaw damponing and dihedral effect.

also Nr , once the aircratgt rolls ofrf Nr tensts

to stop the yaw rate and roll off. Nr is a good

guy.

if aircraft has large product of Nr and lbeta.

large N beta gacuses the rpiral mode to be

undatble.
it is a battle between these four derivitives, so

the aircraft can be stable in one airspeed and

unstable at another.

so also with the twenty seconds to identidy then

it is a pretty weak areodynamic mode.
you could make it go unstable by having everyone

lean in the cockpit.

fuel slosh story:
the A-4 skyhawk they would get completely

different spiral mode indications. they then

found that if the wing tanks were full or empty

then it was stable, if it was partial fuel then it

was unstable.

so check it out... do some flight tests.

4:30 break and then rodney talks about stuff.
nope no break...

tomorrow.

going to do steady heading side slips.

read pages 7.93 two pages.
then 7.118

center, then data on quarter ball half ball and

full ball

so that we can make a line, does not have to be a

any specific angles.

then we will record ldo on the computer. also

tryto do it looking at the aircraft...

7.119 and 7.94.

spiral stability might do it the fourth day.

the book talks about different attitude changes,

so we will go five to thirty. time to half and

time to double.

always get a trim shot.

group one eight o clock.
ready break...

2004-03-09T11:14:00.000-08:00

our airport for operations isAirNav: Capt Walter Francis Duke Regional Airport at St Mary's

Tuesday morning 8:00 am
we came for a group photo.

then we took to the air for the flight test. the dater was collected manually with pencils and clipboards.

this is actually Lairs digilently collecting the G dater from the accelerometer in the center of the console mounted on the orange backing plate.

the test was for constant airspeed steep turns . our velocity target was 70 knots. rodney allison tried real hard to keep our velocity constant as well as keeping the desired bank angles. he did a good job and it is evident on the excellent data which was collected.

just after lunch we had a flight breifing about the g loading per angle of bank . or loaf factor vs. bank angle. as well as longitudinal oscilations and dynamic stability.

bill miller 1:00

flight in the am,
Helicopter Lateral Directional Equations of Motion

N is the sum of all the moments in the yaw

direction.

at low speeds the q doesnt vary much and there is this spinning thing atop the ah-64 and thatr spins and measures the slight changes of the air so that they get the velocity.'

the dvice is two pidot tubes spinning and the difference between the advancing and retreating you can get the velocity.

called loras invented at calspan.

electronically it measures the velocity by the differental between the pidot tubes at the different sigh .

calspan has the x-22 aircraft four ducted fan engines. it was supposed to do low airspeed research and one also on the horizontal axis to measure w as well (w being vertical velocity)

so if you are flying along and there is a ghust you would like the aircraft to come back to the trim condition.

we will assume that the derivatives for the atability are linear. we will assume that the rotor is a rigit body, or a quasistatic rotor. and we will assume that the rotor is uncoupled to the pedals and other controls.

we would like the nose when preterbed out, that it would return to the desired direction of travel. positive it when it goes back to the desired location, neutral is when the thing remains where it is placed. and think about that, if you are slipping or kitty corner, you dont want to be crusing alond with the nose offset to the wind. if the plane is negative then it will once preterbed contiune out off to the undesired wya,

x-46 or ch47 are both unstable aircraft, and the tandem rotor system would prefer to fly sideways then to fly into the wind,. it is more efficient to fly that way. but the blacl boxes will keep it lined up. if there was not as much side area it would not slow down.

this is also called weather cock stability.

in an arrow, the tail feathers give this stability.

for up and away you want lots of directional stability. for hover you dont want any. you want to be able to hover in a cross wind and not cock into the wind nor run out of peadal.

Nr is the yaw dampning ,

you want the aircraft to have yaw dampning.

we are somewhat concerned that the weather tomorrow will be illin and snow will be chillin.

if this is the M.O. then we will not get to go flying.

going to get a break now at 2:15

2004-03-08T10:36:00.000-08:00

Order your copy right now online!

2004-03-08T09:00:00.000-08:00

working their way up in the flying ladderthe blue angels fly the fa-18 hornet. here at the ntps they have some for flight testing

flight this morning in OH-58-A+
a little windy for flight test however for demonstration we tried to collect the dater.

2004-03-07T20:16:00.000-08:00

tilting the rotor system into a full hover after while

what a cool air vehile

2004-03-06T08:14:00.000-08:00

Where's George? Dollar Bill Tracking Report went to the BQ at the naval base. quite a bit of fun. played some bar games with some test pilot engineers and snuffed. saw some secret innovations on the V-22 and some of the ah1zulu as well as the uh1z which absolutley looked like ass kick incarnate. also saw two x-26a gliders -formerly known as sgs-232.
other things we saw and learned we cannot discuss for reasons of national security.

2004-03-05T08:39:00.000-08:00

Geocaching in the PAX river area
Friday 7:10 am

meeting for collection of dater. assignment of the parameters to the dirrerent seating

arrangement.
the guy in the front gets , Q, Hp, Vo, To . ie. Torque, Altitude, Airpseed, Fuel Count.
the guy in the back gets, Nr, Del

Lecture Bill MIller 8:03 am

recapitulation of yesterday.

FQ metrics from ads-33

undesired occurances in the helicopter, must be measured and controlled.

pitch to roll,
roll to pitch
yaw to collective

handout, sidestep maneuver.
we check for cross coupleing problems in the conteols. the sgressive bank angles checked

and see if pitch and roll problems persist.

also a slolam maneuver. suggested cource detailed in drawings.

mission task elements.

when you pull collective the rate of time constatnt to be less than five seconds. we want

for one test that llthe guys get the same results. so the proceduve is layed out and then

the least squares method is outlined to make sure you get the same result.
toirque overshoots must not go out in two seconds. the overshoot boundary is listed.

lat dir, for monday afternoon. requirments are to be within the S-plane for up and away.

pedal position looking for oscilation and it must fit in there. requiring a natural

frequency of one or better. the page prior... spiral mode. you put hte wings level and

read maps etc. and then see if the aircraft falls off one side or the other. sometimes it

falls off, we'd like to to remain level. if it does fall off, then wwe check for double

amplitude. time to double. should take the same time from 5-10 and from 20-40. so again

we can figure out a half amplitude. Level one is ok for unsatbility and too unstable is

if it doulbles amplitude in twenty seconds .. level 2 = 12 seconds . level 3 is four

seconds.
(handout 4.2.5 sidestep (ss))
****

longitudinal dynamic.
if there is a long term oscilation it can be characterized by a conjugate pair of

cooridinated on the complex plane. or S-plane.

chapter 6.

trim aircraft, say 70 kias, wait for natural excite, or you can provide disturmance.

light up to 75 kias. then you return the controlls and you will get blowback and nose up,

wonce you slow up, blowback works in the opposite direction . Mu is the biggest player in

this gig. And onve you get a pitch oscilation then Mq comes into the picture. Xu is not

so much a player. Looking at Root locust we see that Mu and Mq have the domanant character

of the oscilation.

can be done with a recoring devive, but it is slow enough to get cockpit dater.
you characterize it with zeta and omega n. or zeta and aperant omega.

can be graphed pretty good from cockpit dater, locate the peaks of the instruments and the

times.

one mode is the long term oscilation typically a long period damnped ocscilation.

primarily driven by Mu. so the more you are going faster the more it will pitch up and

down and it will compress the frequency scale at velocity.

we also get the equations q dot, w dot, and u dot. the sum opf all the memonets getves you

the q dot,
then it goes on .

Iyy again and q is pitch rate, so pitch acceleration is q dot.

so we express these are a first order tayler series. list the variales that changed

movments.

eigen plot with s-gris is the "web of despair" tehese are the lines of constants. so it

looks like negative dampnping ratios

gliders tend to have unstable phugoids couse they areso slick.

long dynamics then the first order dynamics are characterized by the Q which is pitch rate.

we test this and call it control response.

.....

we dont do the long stab too long and control fixtures couse it is not a good idea with the

teetering rotor becouse of the mast bumping.

if the m alpha is tilted 90 degrees, then you get alot more undamnped oscilations.

some have alot of tail volume to get aoa stability.

apachie came along

and is different than the

h-60 vs. the oh-58

the th-55 has the

kitty-corner tail so it's tail volume is pretty much the shadow. or the "divided

ocmponent" of the horizonal of the tail.

if there is no tail at all, then the rotor system is aoa unstable alot.

the rotor tilts back becouse of the dominant lifting change in the advancing side. so the

rotor makes m alpha positive.

get your a1s in gear!

so test you rotor stability at the lock number that is critical.
ie death valley on a cold day.

break 9:25

return 9:42

big tail will cause the short term to be oscilitory and a stabilizing effect on the long

term. somewhat stable like the fixed wings.

home built helicopter with rotor and no tail. m alpha will definatly positive. and you

let mw go positive. then these two will be moving along the axis and it is a wild

divergent ...ie. one oscilation and youre gone.

definatley level three.

the heep mode time constatnt, heave mode. close to mius one over z w. the z w is the

short time constatnt for the deravitald it not bne mnice that if the collective set the

climb rate just like that.

some have a delay between the input and even the collective to take hold eith climb. to

pretect the delay it must be less than 200 milliseconds. the bss adressed this.

make sure the delay is not too large and the instrumentation must be better than baro.

accelerometers etc.

no requirement for short term heave in 8501.

what the chart is supposed to look like vs what the dater actuially ends up looking like.

talking about dater scatter-
"there is a fair ammount of art to this science" - ralph kimberlin.

break atr 9:50

made coffee.

resurme new prof ralph kimberlin. 10:06

we can leave the stuff in here in the weekeind.

going to the base in a bit.

part 27 and part 29

previous lecturer bob miller is the director of acedemics at the test pilot school for a

long time instructor in both fixed and rotatry wing flies both airplanes and helicopters as

a civil cfi.

ralph's background
had airplane ride in 1947 he was seven years old.
grew up in missourri, country. he had a friend who came ot the dfarm feild and then he

took a ride. and now he knew what he wanted to bne fdrom age seven. went to the missorue

school of mines and metalurtgy. kept trying to go to service acabemts. ended up at hte

naval academy graduated 63 cruised shangrala it is not in the muesum in the pensacola (cut

up ) determined that the two thirds of the earth that is water all looks the same .,

switched to aiforce went to moody and took pilot training. the doctors got crossways and

he went ot egland as aflight test engineer then he met a capt. named ron carry. he had an

idea abourt side firing. ended up putting tofether a thing called the AC-47 puff the magic

draggon , the the ac-130 which is still going today. he is the daddy of those two

airplanes and weapon systems. but never could get the sirforce to put huim back on flying

statud. he has meanwhile flew cvile went to cessna and designed did not like it went ot

beech and worked on the kind air 100 ,, then the industry took a nose dive. ghot tired ot

witchitaw. nice town, jsut take a log chain and drag it to a decent climate. dso he went

to albeny ga to work on aerocammander 111 and 112 programs. 111 was great airplane

certified twice got to jump from flutter and the airplane tail came off and the then the

wings. touched the ground less then ten feet for parachute opening . decided he did not

know enought so he went to the utsi to get a masters. then returned to industry and went

ot piper. a friend luynn helms was president. changind image from piper cub to newer so

he helped put tee tails on the airplanes . nasa was saying tee was the way to go as far as

spins. well got to jump out of another. nasa lied about the tail damnping power factor.

nasa has blacked balled him from research monies. after the second jump so he thought

since momma was a teacher all her life so he tried that going back at 1978 . ben there

since. got to fly the jetwing poiwered lift airplane. upper surface powered life blowing

aircraft. dr. peter solies worked with hium on that one., came bac to space institute be

had to have doctorate it is necessarry and german universited dont require residency so he

went there for the odctoragte at aachen. put the mill stone of stufent around ytour neck

so he did the doctorate in aachen . so here he is today getting close to retirment. he is

a flight tetst DER for faa has half a dozen projects as we speek has last night a king air

with higher preformance engines.

going to talk to us today about the far';s

and ads -33 alot of thought went into that specification.
one of the things that wnret onto tis the it is mission oriented.

all those tsassks were missionn related, bob peek over trees, etc. etc. etc. the FAR 's

they are the LAW. THey must be complied with . military spec is not law, you can waive

it. like if the airplane meets the mission.

with far you cannot throw it out.
there are ways toi show an "equivalent level of saftey" which is a process you'd prefre

not to go though couse it requires a "multiple expert team" and they have to vote yes, all

five of them.
they are about saftey of flight and not the mission objectives.

the federal deficates make us going into aircraft from the civilian market. so both of the

machines all faa certified so the mission. talking about the president's new aircraft.

spent 29 years in the airforce reserve. at right patterson they found out that he knew

about the faa regs. and so they came ot him.
so they thought that the FAA certification meant that it was ready to go.

but they would still have to do the flight testing for see if the mission is going to be

met.

as the military you are the customer so they do their own testing.

the faa regs allow you to build an experimental and fly it your self , there is no law

about suicide, but you just cannot take someone with you.

stopping you is a moral thing, not a legal thing.

if you want ot build this thing and kill yourself in it . have at it. put experimental on

the side.

faa-"hmm it kinda looks like it could fly"

but if yuo are going to get on it to fly from here to there and pay money to do that the

regulations are alittle more strenginer
FAR part 27 is for small, and par 29 is for biggret ones.
much like ads-33 which has a bug with an eye.

the advisory circulars are an acceptable way to comply with a regulation, however is it not

the regulation is is kinda a how to. some faa guys like to think they are regulation but

it is not necessarily the only way to comply with the regulation. AC27-1b is for small and

AC29-2B is for large. can be gotten from govyt printing office however getting expencive.
6000 pounds or less is the small chopters. small chopters with two engines cabn e

certified in caterogory A if they meet the requirments, like the bell 407 is probably in

the category A.
large chopters there are catogory A and category b determines buy the number of engines and

the numbers of passengers.

flight characteristics 27.141 must meet the requirments under the range of temperatures and

altitudes in the envelope. things like cg can be adjusted to meet hte complance required.
sometimes you will see aircrtagfty with certified that are not quite usable machines.

someone starts a company up and wants to build aircraft. and then he runs out of monie,

well if he can get a type certificate then the can get more money. and at least be able to

fly.
there is a six seater he knows about that could only have two people in it. this two place

six place airplane.
for example he just di the recent certification of the liberty aircraft, also known as the

europa. contental iof-240 contental with fadec., got the type certificate two weeks ago

exactly. but due to the composite fuselauge and the faa's conservatism regarding

composites, started with life at 25 hours. but prototype has already 300 hours. the firt

production runs will have only 250 hours fatigue life. the way the rules are written they

will not get the fatigue life. and again the rules are always behind the technology. they

had some years back that conventional airplanes were low tails. tee tails required

negotion about rule changes. they got what was called special contitions...
you go with yourt machine and a three view and negotiate wth time about the rules and the

special conditions.
also there are alot of them that were certified under the previus rules,m ie CAR 6 and CAR

7 like the bell 206.
most of those machines except the robisons R-22 and R-44. the flight characteristics there

is not much difference, but preformance there is alot of differences.

power opperations for speed and rotor rops muchs be acceptable in CFAR 27.141 which is

pretty much the same at CFAR 29.141

smooth operation without exceptional skill. thus the "average pilot" does not exist.

well rodney allison maybe. he he he

so what is the average pilot? the recreational pilot certificate holder.

so the faa or the designee gets to decide wether the aircraft is acceptabley controllable

or safe.

there is an appendix B for IFR helicopters.

mc donald doublass said it would take a million dollars to ifr an helicopter, but utsi did

it for about $100k.

it must be asfley controllable and maneuverable etc.

twenty seven and 29 are the same except for the go around from an auto rotation.,

perticuraly to a touchdown.

**recently on tv a swicher 333 that at night they lost the engine and they put it in this

parking lot. wow. probably on the internet now.

you hear them go auto auto and they do a good job of getting it onto this parking lot and

did not get the flair earlie enought. but they can build another helicopter they cannot

make another you.

so in the part 29 ones, a engine failure is still an emergency even in the twin engine

types.

all the faa tests are dont at the critical conditions. and you have to find out what are

the critical contidtions for the perticulat machine.
hmmm. if you dont know how to get the limits.
guess you will loose one or two.

has to hover at 7ooo feet.

dynamics for the helicopters is only required for the ifr. the dynamics at altitude were

not too much fun . so they lowered the max altitude.

talks about time delays from the engine failure. one two three react.

it is not less then three tenths of a second. usually about two seconds.

the 707 has six seconds for a reaction time to engine failure.

some can have Vne power on and a Vne power off.

some of the part 29's covuld possibly be operated by individuals witout alot of experience

just a lot of money. dale earnhardt drove a bell 206.

breakout force and preload, must not be excessive. no number there. all up to the DER or

test pilot. alot of judgement left to the flight test crew.

even if the AC gives some guidance it is not regulatory , so many pounds per inch. etc.

but you can argue if you feel that it is not excessive. free play must be smooth., etc.

highly subjective.

thereis a push force limit for speeds below trim and a pull force for those above trim.

that is a centering spring fix. he he he

stability general stuff, again without undue pilot fatigue or strain. this is determined

by the test pilot without demanded guidance for what it too low or too high.

if you got hydrolics and augmentation both on and off for the flight tests. higher

workload for the off condition etc. then go to the AC and see if the workload is going to

be thought of as excessive.

they do not use the HQR scale, they have not defined this at the moment. again these are

minimum standards of saftey. so then you getthe lawers and they say, ahhh, you just

designed it to a minimum level of saftey. then they take all your money.

airbus is trying to get in a cooper harper thing with a three scale type thing. but not

all inplace yet.

they would liketo take some of the ambuiguity out of the regs, but not yet.

cooper harper is too top heavy for this type approach. the faa dosent want to say that

"this airplane is better than this airplane"

they would like one but ahve not come up with a good one as of yet.

static longitudinal stability, requires that stick foreward makes faster than trim, and

stick aft makes slower than trim. testes at sea level and at altitude.

then is 27.173 the term negative is not defined and they are thinking that mathermatically

positive is waht would be considered negative. but it is to like hover but at 17 knots

which is really almost a translational airspeed.

must be stable in climb between 0.85 Vy and 1.2 Vy
cruise stability .y Vne to 1.1 Vne or Vh whichever is less.

mostly control positon vs. speed and not stick force like that in the aiplane. unless for

ifr then it includes stick forces .

you have to test autorotations at Vne, coming down like gangbusters.

27.177 far for sideslip limits, liekten percent.

29.181 does only mention the short period. couse the rotor dominates it is usually

deadbeat. probably couse the airplane dosent include long period stability couse the

pilot is in the loop and he is the damnpner. it might ought to be in the IFR type.

then the catchall 27.231 says on ground and water no uncontroillable tendencies . whoa.

no spray characteristic that obscures the pilots vision.
no tenedency for ground resonance.

27.251 free from excessive vibration. ??? what is excessive.

so thinking about it... who is going to pay the test pilot? so who's subjective opinions

to be used.

recently for all stc's the DER can do the flight test and approve it. as a designee a DER

cannot approve a flight manual. he can reccoment it, but FAA has to finally approve the

flight manual. so if they dont like the report they caqn come look at it themselves and

then approve or disaprove it.

since aircraft costs are so high there are lots and lots of STC's being produced. and the

FAA is really more worried about the transport type. and that "Aunt Minnie" is safe.

11:06 break, then pax breifing...
11:16
now steve potter who works with jon o conner and he is a utsi graudate.
goinna talk about flight control systems
and intro what to see at the lab.
solies and kimberlin were on his thesis committie.
he has aero degree from u or collorado.
first job in 89 was at johnson space center training astronauts. then worked for navy 95 on super hoirnt then is now here as an instructor at tps.

teaches mechanics and what not...

now about flight control systems.
like how much force is required to push a button etc.
how to evaluate a systme.
there is reversable control systems which the pilots is ":directly linked" ot the control surface.

there is an infinate resivour of strength on the attach point.

pilot has to actually overcome the airload with his forces. can be significant at the control sticks.

in the 20's and thirties the forces began to get stron becouse of airloads and higher airspeeds.

can add belcrank for "graring ratio"

can also ass a bob weight. this helps in different g loadings.

in the thirties we began to see hydrolic assists.bob weights and hydrolics. etc. etc. etc.

feel springs.

manual reverson for failed systems. makes for lots of complexity in the systems.

p-3 has a g limit of 3 g's

the stability augmrntation system can damnp out the dutch rtolls.

the pilot is a voting member and the computer has a vote too.

2004-03-04T14:00:00.000-08:00

getting in the mood

jim lewis 8:00 am thursday
talking about eigen values. and eigen vecotrs.

the aircraft is a linear system and it is a sum of first and second order systems.
the first place to start is the forst order tesponse tywps
if you put in a step on on flighret then you get a dsortt oderd reaction.

on the complex plane (flaps and prop) the real root and the "imaginary" or complex root.

so on this plane there is the real value and this is the real root or igen value.

wil be one over tao.

if i want to see this in flight to get it started is with a step input.
take whatever the control of interest and input the ideal step and gold it.
helicopters use fixteures. to set the throw. maybe not fill throw art first.,

sp then what is the output? poitch rate, roll rtate or the first order output.
this then goes to some steady state value.

the time response tells us that x sub t . call ithat x is the steady state or a tiumes one

muinus e to the - one over tao times t.
of you get a bigger input then there is a bigger steady state. if smaller input then

smaller steady state.

so what does the input look like.
so if you remember what the sxponental looks like then ... and eto the muinus one is like

.368 whis is about a third. and this exponentially decays down to zero.

so put these together, and thne the response in the first orser and like .632 is the

corresponding value for tao.

(this is like the time to steady as discussed yesterday.)

for human perception it wakes three tao's or three time constants to get to the steady

state. so like a second and ahalf. this charasteristic root location tells us th tao.

if you takje the input out how fast will it stop. so what is that relation. and the

things decays with the same exponential and then if you are flying aroudn with the same

conplex plane, take how long you think, then divide it by htree.

_puit in input take it out, tim it and divide by three. -- approximation

if there is a specification then you can take time histories and then you can actually

calculate it.

mathc maticallu it never actually gets to zero.

other creatures can detect the residual motion, like the border collie that attacks the

lawn mower that has not been run in two weeks. she then sences the residual motion and

asttacks the wheels on it.

handout passes out ...

imaginarry world, to get all the candy and wax lips you want and you dont have to fo to

school." - jim lewis

but really there is a slight ammount if wiggly in the graph so we have to assume it

contaminated and then use the "displaced axis methos.

a good tangent to ta good curve gives you the point intersection and that is the ..well it

can showthe time constant.

there are methods to find it woult the stewayd state, and we will use it .. if you take

our the input then you can assume that it will roll out at the same time constant.

the thing you really are interested in is what charesteric of the vehicle that sets that

time constant .. like on a an airplane the roll mode time constant is the roll dampning ..

this is detreminant of things like speed. if change the monenets. or change tihing s on

ghe rotor suystem.

the root will stack it wis the ":root locust:" (can get hte box woods if you dont get in

the seven dust early" so as the toot tracks off to the left, then the time caonstant is

gatting fdaster and fgaster. and as it goes rtight slower and sloerw.

that was first order system, so also there are second order systems,. some in ldo - short

rterm and long term response all second order.

ldo = larteral directional oscilations.

:second order has two roots. so must be twice as complicated. there ahte roots exist in

the comlex plane. the real part is the smae but the imaginaty parts are cogfnates. so it

might be sigma puls or minuts i omega.
if they are not congigates you cannot multiply then and get real numbers....

so here we begin with the spring mass damnpner again. the is is a second orfert. some

things are like springs and some things like dampners.

fingamentally the things taht act like a spring = force proportinal to the dispalcement,

and dampner force dependant of the rate.

so we will then get this this ging and get out of the way. ..
input, doublet, stick rap, (rap = hit and get out of the way)

we will analuyais to the thing and then that will tell is what kind of input to put in.

what is the time response going to look like? the characteristic response is going to the

a damnped sine wave. the real root defines that.
and it is like x(t)=e^sigmat times sin( omega t)

so we will draw the envelope where the sine wave will be oscilating. the real past of the

exponential shows the roots envelope.

so do this like the perf testing, "draw the line, then put in the points"

the period is like whice the cycle and then omega is like two pi over period. and period

is two pui over omega.

so when you got this decal and a dampning onvelope and it is like in three time constants

then this is where you will see negligable motion persisiting.

you mayu not see the entire motion expically if you close down on it quickly.

ifg the roots are complex thie is what we will look at. it is possible to get a pair of

real roots, but this would ne a really damnped oscilation. and then the two roots that are

the same. but we dont get that. the two real roots would be a dampned system with a value

of like one. heavilty damnped.

how od the physical prarameters of the system relate to the syestem to how it is goiung to

react with respect to the time response.

teh samping will come from fdifferent thigns.

one way to get there is to look at the characteristic equation ...

s ^2+beter /m,*s+k/m=o this is the laplacian and the s is an laplacian variable. and the

troot of this things are what we have been talking abou as roots.

the quadratic to this one and we get toots. ouch(fast formula)

the real paet of the roots is the part of the physical damnpning in the system.,

the spring is set(frequency of it)_ is the part under the rooot.

****QQQ if you set the doublet and you are way off from the desired frequncy how much will

the reaction be dampned at your frequencyor will you notice it trying to go to the desired

frequency, ie what you had under the root in the quadratic of the laplacian...

omega n = un dampned natural frequecny
and then there zeta is the dampning ratio.

zeta is the ratio of the actually dampner to the "critical damning.

if it is oscilating and if you put in a big enough dampner it owuld just settle and not

over shoot. thisis critical damning.

so as such a dampning ratio of zero woudl oscilate forever.
damponing of one it dosent overshoot. so between thise two there must be oscillatory

responses, so then zeta is between zero and one.

if higher then two real roots on and we woill dicsuss later....

if oyu know the ratio then you can kinda preducti it, "here is a chart its is official ,

it is typed" -lewis

this function of the ratio the nyou can scetch this what it looks like, not the frequency

or amplitude, but you can get an idea of the reponsed.
ie. relating to the number of times it will overshoot. zet is roughly seven times the

number of overshoots. over ten.

so ifyou get like two overshoots then then this is like .5 damnpnign.

if you see seven it doent mean one, then at about .7 damnpning the human operatoir cannot

detect the overshoot . ie threshhold of percieved dampning. this is called a "dead beat

rsponse"
QQeach over shoot is not a cycle, ie. up and down and up is three.

omega n is the natural frequency . def: if i could magicaly pull out the dampner this

thenis is the case where it would oscialte for eer with no change.

it is really the square root of k over n. the pure spring stiffness.

the damnping ratio sorta quantifies what it will looks like.

the tighter the spring the higher the natural frequency and the faster this ghting is going

to go.

we are trying to take the abstract idea and transfer it into somethign that we see in

flight.

time for a break : 8:45

dampning in flight test, is dampning ratio. in mechanics those guys arethinking physical

damnpner.

the charasteric root moving left collapses the envelope.

if you say im gonna increase the dampnpin, do they mean the damnpning ratio or the

physical damnpning.

in termn of root locations,. where is zeta and omega?

if we do this ,and take all the root location, how to rtranslate the zeta nd omegna.
s ^2+ 2 zeta omega n s +omega n ^2 = 0

-zetaomegan+-omegan sqrt(1-zeta^2)i

we know thay are complex congate pairs, so we will only really look artthe real one. and

jsut know that the imaginary one is down there.

so the omega observed is the distance from origion to the root on the vertical.
and then the ed is the angle back from the origion. omega n is the pathagrian distance to

the point.
and the angle ed is the zeta sin ed.

there then is a circle that says that the natural frequency is on the path that makes a

circle back over the

"you see much that is hidden o' tim" - "quite" - monty pyton.

bob will bring in later in excrusiating detail (his boss)

to here is all this absstrat engineering stuff, what about a time history.

how about of the time histor and what is the roots.

either from handheald dater or on board instrumentation.

what is the long term response, trim, slow it and release.

so looking at like the airspeed plotyou can figure out that the zeta and omega n are.

if you do your math (or maths for the british) then yuou can find out how fast the thing

decays.

half cycle is amp one over amp two, and full cycle is ampone over amp 3 .
(amp one is one over shoot of the airspeed and two the next overshoot. etc. x being the

distanceA(amplitudeA)
from peak to peak is the freaquency.

the natural frequency is in there but not obvious.

(wallis collie = wallis.collie@navy.mil)

w obs /sqrt(1-zetasqd) = wn
and w obs = 2 pi over T and T is the first period.

ok, so what about the augmentated aircraft. well this is all based on the normal god

fearing aircraft , but these non god fearing aircraft like the comanchie. now rules.

f-18 is fourty eights order. normal aircraft is about fourth order.

so if you do a doublet input to the f-18 you thinkg you got sdomething that looks like the

right response but it might now be.

ads 33 if thething gets so complicated, what happoens if you drivethis thing.

so lets have another technique to test this thing. so we have frequency response

tresting...

so we input a nice frecuency sin wave. then how big an aoutput do i get for a given input.

how many is that to how manny is that.

we trick it up a little bit by defining the amplitude ratio to AR(DB)=20 log 10 (ar)

zero gives same
+6 db is twice output and
-6 is half output.

what is the fidelity to this things, how closely is the output trracking the input?

time delay ie phase shitft. ? how close in phase . so we defien a phase angle.

=(t*/P)...
this is the ammount of a perios that it is then times 360 for degrees, and this is a

negative number, ie, quarter cycle is 90 degrees of fase lag.

how is it tracking in time. (positive is possible)

increasing the frequency from slow to fast over about nintey minutes till you have covered

all of it.
get two plots , ie amplitude ratio and phase angle plot.

this is a bode plot= from bell labs he did not anme ti that byt someone else did.,

if the input system is not linear to the output of the system then you got some non

linearities and problems.

so... we want to kjnow what happend when ew are in the things and we try to drive it at

some frequency?

you want to be able to sontrol up to about five or six radians.

needs to be reasonalbe in phast. 180 out makes for like PIO;s

so how did we get away wtih all this zeta and omega stuff for all thise years.
credit Savant call sign"idiot" ??

there are frequencies that can give large output and some not so it is not exactly

predictable.

the natural frequency sets the bandwith and dampning ratio tells the predictability.

most people dont fly airfract with oscilation inputs.
****QQQQ comments glider pilots in thermals "churning butter"

ads 33 135 degrees fase lag begins trouble.

the db is decibels. hmmmm.. sounds ok to me i guess.

you have people out feeling around looking for the maximum output, and thik this is the

natural frequency ... but no you are finding the resonant frequency which is off from

natural by dampning. same at zero damnponing .

so for first orer, and it is like 1/(s+10) then go pup by
a factor of ten it begins to roll off and then it rolls off in phase l.
ok, to sum, the first order 1/t you cant track for amplistude, and .1/t then you begin

to get phast lag, and 10/t begins 90 deg. lag. ouch.

that is t being log (w)

resonant frequency is always less than the natural frequcncy...

end discussion 9:35

enter bob miller 9:55
welcomed us to pax river,
said usually cource taught at the univ. of tenn space institute. utsi (www.utsi.edu)
handed out a quiz. lat dir is going to fly tuesday.

right now we are going to begin longitudnial dynamics.

statics before dynamics., probably the way to test also.

fq metrics, there is an s-plane which is some imaginary dynamics. ads-33 is the info i

guess.

had flight on monday, saw the coupling. pitch to roll and yaw to pitch soupling

requirments.

s - plane survey also called root locust plot.

gonna get the equations of motion also.

so the quiz to answer all the topics on ads 33.
flying qualities area.
new words:
response types uce, divided attention operation, addidtude caommand attitude hols
transitional command. transitional rate command,. rate command height hold...
some others went qucikly.

he askes ,about 1/3 already familliar with ads-33 so he said he will work from there.

aircraft design standard thirty three.
if you want to built a helicopter 8501 is the old standard. now the 33.

new spec develiped over a decade. still being adjusted.

ads-33d comanche but it went away, ads-33e is the current one.

the d version specifically for the comanche but the e is for all.

who has input. army aero synamics flight lab. they lead activity who contracted with sti

and roger hoe . and chris blanken were primary govt guys. wkring over ten years. every

so often ipr and industry would "murder board it" and the team would then give time to the

comments. ten times from 1980-1990 so the contractors and test agencies all had input.

army aero flight dynamics.

if you become a seriuous student of ads 33 get a BUIG background user info guide. this is

like three inches thick. has all the back ground and apology for the manuyal.

also supporting dater in the BUIG or buig no electronic version exist and dis is limited.
we can have a little of it in handouts but copies are limited.

ads-33d, july 1994.
BUIG,dec.1989 also the most recent: ads-33e-prf dec 1999 avaliable as a .pdf file.

when the spec was being designed they were looking at testability issues and they put the

apachie through the ads33 and they did it in the h-60 also so in 1991 there is this book

that reviews the acceptance in an anry report. this report shows the flight test results.

blue book is the e version. this is avaliable electronically. will try to get it.

**the if remote for the powerpoint did not work, and he complains about the "fly-by-light"

system. he he he - or could be fly by wireless.

you have a vested intrest that the avr flight qualities are good, it is hard togo back

after the fact. so good guidance up front is importent.

8785 is for fixed wing. late fifties for helicopter 8701 not changed after 1960's.

ads -33 progression:
sti-calspan
they fly in in the learjet and do other stuff.
funded a program to develop the new spec. had fly-off(as such) systems technology

incorporated dave mitchel and roger hoe. govt, dave keef and chris blankenship.
begin 1980-
sti - new struct

draft spec & buig

govt & industry rev

ads 33b spec & buig

ads 33

ah-64 refine

mil-std XXXX

ads33d &ads33d prf

cargo/load hq

flt test guide

jssg format

now 2000

this standard is a "new aircraft" if you wantto meet these thay are strenginet. you

hannot paint the h-60 and meet this. ah1-z series not to spec.

v-22 siapan when mogo had the pio then they looked at this buig and bodie plot. mongo came

to the school and said he hand fisted it. the bodie showed that it was in level three.

took the focus off "pilot ham fisted it" and said it was a handling issue.

it is possible that the spec is too striengient such that it is prohibitive for new

manufacturers. he wont accept that. said get this in on the ground floor and they will

have to do a good job.

bandwith is equal to the damnpning derivative. etc. if the size of Mq is equal to

bandwith then you know how much offstet you will need.

Prior to first flight must have full manned simulator with feel system , SAS. then take

the flight test.

if the comanche was different to the comanchie then you would change the comanchie.

_software issues some like RLN and the horizontal tail was unnaceptable for stab ctrl.

section four in red book, has MTE of Mission Task Elements.
usaavscom Technical Report 89-a-008

the phugoid is called long term in chopter and it is usually unstable. from that you can

get zeta and omega n and plot it on imaginary axis.
damnped.
the buig explains who and how you go do this. on page 228 you then determing the level.

Level 1 handleing qualities are damnped. level 2 is lightly damnped. and pilots dont like

the undamnped level 3. make it live over in level 1. Level one is ok to have a divergent

if the frequency is long then you can have a divergent long term.

point five radians. this is in rad per second, and this in seconds is 12. so less than

tweleve second phugoid , it ok.

this is also in the "fully attended operations " hich i assume to be stick fixed and also i

figure that there is not an y requirments for chopters on stick free.

legacy aircraft like the h-60 dont evaluate so well sometimes.

0h-5 no dsas and no ascs and designed in the 1940

Conclusion, the buig and acs-33 might could be met by a non augmented aircraft, however

they have have to be within spec for all characteristics and the likely hood is way down.

Also all those legacy aircraft weretoo lightly damnped. It is not likely that an aircraft

can be designed that meets the spec without a SAS or SCAS system.

so this then concludes that the us military has determined that they will no longer

purchase an aircraft that is not flight control system augmented.

the Wright FLyer was an HQR of ten. in the fifties they weresmiling that helicoptes fluew

and not they are tightning down. Back then it was pilot compensation and they were real

heroes back then.

**in our design class we mostly addressed preformance issues. not too much about the

handleing qualities.

missioin task, precision hover. come to a point and keep it within adecuate and desired

tolerances. then there is a hovering turn. landing defined in detainl. these are all

mission task elements. so if you can do all the mission elements, then you can do the

mission. ie they all ahve to be HQR able. also, bob up, bob down, sidestep, slolam, dash,

high yo-yo low yo-yo , hovering turn, ie. page 54 on sectoion 4 hovering turn. to check

for undesirable handeling ualiities and moderaleys off axis hovering turns. altitude less

than 20 feet. the cources are there on the base, and they are also on the sim.

we might getto fly the sim. makes sence. couse otherwise we could have had the cource at

utsi. tullahoma.

rate command attitude hold (rcah) that is a resopnse time

attitude command and attitude hold. stick position determines attitude. (weird)

question is what does the pilot decides which is more better.????

11:10 break till 11:24

TRC is rtranslational rate command. this is the prefered command during visual command.

acah is a dericative command then the space shuttle has acceleration command. second

derivative.

TRC is like one inch is ten feet per second. and then two inches is 20 feet per second.

return the stick and it stopps.

hmmm,

also there is a UCE or usable cueing enviroment rating.

afcs aircraft flight control system.

there is a listing of the mission rewuitements and then they experiemented with the

different flight control suystems. uce one = perfect visual ie. more than ten miles.

rate command height hold could be used on the collective.

in really poor visual cues, then thisis UCE-3 so the trc is desired. this is simply stick

foreward move across the ground and then back is back up. etc.

(great discussion of things like transition from control types, and emergencies, and modes

of visual refrence, etc. etc. etc.
to me it depends on how dumb you want the pilot to be.)

solies asks about non pilots about desired types of controls.

lunch at 12:00

looked at pickup truck.
301-481-4438 the guy who said he would sell it for 900 bucks.

resume: 1:20
OFE operational flight envelope.

specified by procurement accuracy.

SFE service flight envelope.

based on aircraft limits.

pilot opinion in section four requires that 3 pilots must go out and give it level one.
thisis based on the cooper harper testing schema. level one is 123, level 2 is 234, and

level three is 789

again there are requirements in visual cueing.
UCE scale is for visual cueing.

visuonics. like a head mounted hud.
comanchie had no flight instruments in the cockpit. it has a moving map on one side and a

crt on the other. you attitude stuff was in the helmet mounted display.

bandwith = how fast can the pilot movethe stick and the nose still stays in phase.
bandwidth also can mean if you get not too far (135 degrees out of phase.)

if the pilot's only job is to fluy the aircraft then we can put up with poorer handling

qualities. but if he dosent have a gunner/navigator. then the aircraft must be able to fly

it's self.

spectrum in matlab is the tool to get the bodie plots.
break for fifteen:3:30
awknowledgement of online

documentation of ads-33e
resume:3:45

they filled their shotguns with HQR's and then shot the graph and drew these lines to

delimit the level one two and three for attitude quickness etc.

if there are bobbles in the attitude response, then this amplitude of the bobble is

considered adverse and the min of the bobble is the value and the top is the max. can be

faired for discussion but gets counted into the HQR.

pretty good correlation with pilots using one two three(pull) four five six seven, and no

more than .25 of achieved pitch in adverse axis.
ie pull to 12 degrees and 3 degrees left is all that is acceptable.

desired levels of avaliable attitude quickness:
level one: 30 deg/ sec in pitch
50 deg/sec in roll
and 60 deg/sec in yaw.

they do bias the spin direction and have less determination for the spin the wrong way.

could be a "thesis topic" woudl the us govt give varianceto the other direction for a

contractor proposing a heliopter with a retreating blade chopter.
-discussion of the hover collective addition yaw rate induced.

time constants for collective addition must be less than five seconds. ie. 12 seconds till

climb is maximum

break 3:35

resume 4:00

they are interested in indicated torque and then not really care about the transmission.

in ads-33d&e is the fixed wing roll to sideslip coupling requirements that are directly

placed into the document. even the typographical errors are in there.

ldo is the same as LDO which is lateral directional oscilations is also called dutch rolls

in fixed wing.

some flight testing was done by a pilot and then the observer would determing wether the

aircraft was ok HQR rodney confirmed that the mission was acceptably good or done well

enough.

pax river ch-53 chopped up by collective oscilations and it looks like it ate it'self.

all of them got out. frequency sweeps one, helicopter zero.
oh-58D for saftey they will have TM hawking that and with gentle buildups and then the

pilots were aware of the natural frequencies also there was a chase plane. (obvioulsy) and

they were doing the sweep, all in tm room happy , good traces, helicopter all happy,

chase plane gave a Knock it off. ball on top almost flopping out the rotor.
apachie lost a sheep pin, and it crashed. the pilots lived.

sweeps in oh6 with instrumentation tuned sim to represent aircraft. in the school we

concern doing them over and over fatigue can build up.
mosher just arrived 4:35

it makes senceto try it with a new aircraft, but not over and over. respect the plane and

build up .

program for ps called CIFER maybe 2k can get the bodies from matlab. also conduit and vss

(variable stability systems)

done 5:42

rodney now telling us what will happen on monday.
page 66.

says tomorrow is the pax river base excursion.
on monday 6.86 -6.9
thisis the goal of the first event wewill divide it up to the five groups.
going to do a 30-50 do a 60-70 do a 80-100 and four and five will do 50-60 five 70-80
so goup one does
page 6.68
page 6.84 tells the dater required.
pedal position
airspeed,
control position
power

all this goes on a data card.
come up with one for the group. need to know the parameter numbering . make it quick as

we can.

TFCP
group one 30-40-50 three dater points.
two 60-65-70

he wants up to sit down as a group and pick the airspeeds

combine all the dater onto one dater card.
then present all the dater onto one excel spread sheet ,
and then together breif the one graph.
tuesday morning debrief the dater, and go fly that day's flight.
eight o' clock and then go to the airplane at 8:30

we will also do static longitudinal stability.

one leader per group.

sixty point, seventy , and eighty for a trim speed.

all the position indicators, get it all stable fixthe collective , a couple of knotxs

above the speed.

speed vs. longitudinal position.

thirty minute flights. read these two sections.

the groups are:
group one, Kacie Fleck, William McCartney, Eric Rodzankas.
Group two; Rebeca Nixon, Douglas Mousseau, Wallis Collie.
group three; Rucie "baby love" Moore, Frank "helicop" Lombardi, Tom "bobby hill" Morrissey.
group four: John Nelson, Georg Contag, Bill McCandless.
group five: Laird McKinnon, Catherine Kelly, Miller Wilder.

this dater sould be collected by hand. nine items to collect.

man stab later, lat dir, this other stuff we will do with the computer?

we will not do the sideways and hover turns couse of saftey issues.

we dont have the fixtures yet for the controll response tests. also the coupling tests.
no engine failure stuff.
no autorotation dater (hopefully)
rotor rpm and airspeed maintenence.
rodney gets all excited while talking about this stuff.
his eyebrows get all pointy tall when he does too!

see you in the morning
end if: 4:59

2004-03-04T11:24:00.000-08:00

something a little different and also interesting is Peter solies discussion of the dynamic soaring as preformed in australia by a team of test pilots.

2004-03-04T11:22:00.000-08:00

the specificatiuon for helicopter stability and required pilot opinions is detailed in The BUIG report whic is not avaliable but the ADS-33 is and here you can get it HQR values must be in level one for all the new chopters. the comanchie rah-66 uses ads-33d but now we are on ads-33e

2004-03-03T11:57:00.000-08:00

lockhead Lockheed C-840 AH-56 Cheyenne this one has a prop from behind so it can go faster

2004-03-03T11:16:00.000-08:00

Rotary-Wing Flight:Piasecki Piasecki helicopter
good morning, wednessday the 3rd or march.
8:04 am.
mike moser., begins announcing that he won six dollars in the night before's poker game.

ok so new we have that model of the tip path plane. mostly we spoke of longitudinal.

the rotor dosent lknow about pitch and roll. it should be east to paste this onto the vehicle.
and refrence any axis.

so we will begin with the longitudinal equations of motion. :
knowing what columns to hae in the test plan. (code table)
do i need to do it at a bunch of altitudes? or does this not matter.
do i need to do it at a bunchof airspeeds or does it matter.
figuring what you got to do helps you be more efficient.
again -- to make a simple and effective test plan.

either in newtonian or lagrangian.
newtonian f=ma have to have axis and sum the forces each way.

we will creat a "stability axis" system which looks like the aircraft (helocopter) x out the nose, z = down, and y out the door.

ie, the axis is refrence to the aircraft and as it manuevers the axises move with the aircraft.

and the x axis is aligned with the relative wind, (at time = 0)

+there are axises in some peoples stuff where the earth is the refrence frame-

back to our convention, the x axis is aligned to the relative wind, so the alpha shaft moves somewhat to accomodate to arangement for the specific instance. once you begin wifferdills then these maneuvers beome non zero.

"it is changed from trim is what we will be tracking" - mosher

jonny o' is late and he has the notes, they have a line drawing of a helicopter on them,.

up until now we have had Vf to be the forewward flight speed. this vector can be broken into three components. the vector inbound on the x axis is small u
right ear wind, ie inbound on the y axis is positive v. and up from below is w and it is positive.
this is the cockpit perspective as opposed to the airshow perspective.

at time = 0 becouse we line it up with the x then there will not be any v or w.
cap x cap y and capz will be the motion vectors.

we can break the angular velocity vectors into any direction we want. we will choose, p q r, p is left roll. r is right yaw, and the nose up is plus r
moment about the z axis is cap L , M out the door and N moment from below (z axisZ)
up collective is up, but it gives you a negative w.

this is alphabet soup., dont get lost in the alphabet soup. there is method ot the madness, just remember the z axis and then you can work to the others.

we have three angular motions and three linear. six degrees of freedom.
we will break them into in plane motion and out of plane motion. out of plane motion is "lat/dir" (in plane is longgitudinal stability)

solies calls for the aircraft world where thre is a plane of symetry.

EFx=max , EFz=maz , EMy = Iyyalphay

sum of the forces means all of them.
spoken: "some of the forces means all of them", ha ha

acceleratuon is the derivative of velocity . can be weither change of direction of the velocity or the change in length of the velocity.

wdot = Uoq ie you got to have either changing velocity or accelteration to make a g force.

if q is the pitch, then q dot is the pitch rate.

* it all kinda makes sence however there is a little bit of obfscouration due to inability for me to recognize the letters and the overusage of letters in abstract though.,

like x sub zero is the trim condition.

the trim position is both the stick location in the cockpit where there are no any pilot forces. in the classroom the trim is where all six degrees of freedom occur and the sum oif all is zero.
the issues are "how easy is it to get the aircraft to a desited trim condition? how easy is it for the aircraft to trim.
flight characterestic ,and aerodynamic conditions. could be real stable, but if could not get the stick home then that is a different issuse.

we are only tracking disturbances, so disturbed x. and this if from a trim condition (asylum)

like airspeed, if we are going 100 knots, and now we speed up to 105. hmm airspeed causes changes in the x force. \different to angle of attack we will use the W as the similar parameter.

we will confine it to the motion in the board. ie. "you cannot come into my yard couse my mom said so."

ah-56 is chyanne. pieseckie aircraft will probably have the hand out the window?

time check 8:35 and the coffee is ready, but he is still talking .

mosher is saying about the size of the preterbations ie. distrubances. thes will be like five knots. or so. this is small enoguth that we can approximate the real world with a straight line.

now he lost me with a bunch of partial differentials, representing the slopes nad how they change and then some thing abotu has the mas in it. so it is a balence of accelerations in say the x direction. can do it for all otehr axises.
these are the "stability derivatives"

im not going to scribble these equatuoins, some fourty characters long across the board, and there are six lines up there. eeww.

ok interesting thought, that the gravity is the x theta and we all use the 32.2. regardless of airplane submarine car whatever . (admission of the secret submarine base, i think so) and unless you use a differing euler angle then this is the value: 32.2

euler angles resolve the gravity vector into the body system.

now he has given out those equations with color coding and the digfferent colors give the different variable types. good actually.
to descroibe the state of the aircraft .
blue = stability derivatives.
red = control derivatives, we have cyclic and collective. lateral cyclic not there, and neither pedals. these are considered lat/dir but if the aircfat is ouf of rig,,, hmmm.
we will assume a perfect world and purosfully leave this axis out for the time being.

we assume a quazi static rotor. ther are no state vairiables that apply tothe rotor. we are pretty macro. (there are four degrees of freedom in the rotor anyaya(stated yesterday) ie. this is kinda a point mass look at hte problem.

oh all that four seconds for a rotor revolution of two, it is four a second or four per second.

jonny'o arrives. he forgot the notes. 9:48.

now we look at a matrix , ,there matrix multiplication . the point of all ahtat is to throw in a"fourth dimention:" ie. if you are banked 90 degrees then pull (elevator)pitch you actually yaw. ie to "pitch " you got to step top rudder.

this is going to be pitched couse we are only necessarily intered for understanding linear quadratic regulators. and the control system is only as good as the assumptions you use. can include rotor states, or maybe 8 x 8 and take in all the degrees of freedom.
what ever you assume can realy make an ass out of you and me.

control designers, coming out of college, know exactly how to plug in the matrix and get equations. but to them it is just a set of numbers. like an elevator cannot be at 90 degrees. etc.

now on to eigenvectors ??? what

also pilots are instrumented for accelerations., we dont feel moments we feel accelerations. pilots might have moments but they dont feel them. poor mans accelerometer in the ear, or maybe rich mans.
now we will take a break and see what we will be able to use thse.

the reason we cannot use the clasic equations from fixed wing becouse all the forces arecoming from q but on the chopter gets alot from all over.

you never crashed couse you ran out of Cm, it is couse you ran out of Realm.

you might could do it all as a function of tip path tilt, and then non dimentionalsice. but still this only works for in a specific state.
you get into that when you have like swashplate trims. and with the tandem rotors, trimming the swashplate. trim for speed and it adjusts to keep the airframe level.

break 8:59

now jonny o foreward flight longitudinal stability: 9:14

chapter objectives to have a though understanfing of engineering test techniques.

handling qualities are the aircraft's response to gusts ets.
workload is are you able to preforma task gicen a certan input.
with automatic flight controls like on the tandem rotors they have a stick position corresponds to a certian speeed till you get slow enough to it to be an attitude controller, so faster it is just a speed controller.

workload is also to shape the mind to make the input to what you need to get the predictable outsome.

closed loop. watching changging input and change in state of theworl;d.

closed loop, sensing processing reacting, sensing processing reacting.

open loop, put in input see what the output is.

might pitch down and accel, might roll etc. there are controls fixed and there are also controls free.

mixing, like to not migrate the stick then wyou can mix the controls maybe becouse of design or offset etc. you can rig it or add mechanical mixing. mixing can be aperant and or unapperant mixing. like the stick moved and the pedal moves a little. or maybe it dosent make the pedal move, but there is an antitorque thing hack behind that makes it change. possibly seen from out sid.e

then coupling - aerodynamic or rate, like asymetric tails. "canted tails"
also inertia coupling, not exactly a concern.

-rodney talks about 100 degrees per second all the way around in the comanchie.

now talking about input shapes.

the impule input it a step or a square and the real world dosent like that. step , ramp, pulse, doublet, rap, (kinda a pointy doublet)

doubleet is good couse it is kinda like the helicopters natural sinusoidal modes.
doublt is a smooth fluid ramp in and ramp out.

you could havea pulse doublet and or ..
the doublet is to "excite the mode" and should be entered with sinusoidal like smoothness.

rap is sometimes just banging the stick, can be used called a spike".

reversible and irreversible, pretty much it has to do with does the pilot feel the response from the input. hydrolic might be irreversible, manual conected linkage usually reversable.

as you gain speed you get migration of the controls. derivatives, like the speed stability, mb1s. control sensitivity, b1s moment, pitch dampning.

HQR this is the tolerance for the airspped or so. the VAR is the desired velocity or so. - talking about trimmed flight control positions.

fuel count is important for weight.

static stability, might wantto be at the bucket speed of sixty or sevently and then you hold speed and try a few different power increments and see what climb rate youget.

static trabilitu in level flight:
looking at the restoring moments you are fighting. if if you otthem at all.
m alp[ha or m q.
positive static stability to golds it avbobe trom and neagtive to hold slower than trim.
open look to see you ifg yert a restored moment to the trim after input.

histeresis. so take the thing from trim and hold it and measurethe displacement, all the engine dater required too.

stabilize for about ten second prior to recorfing the dater.

s-92 is supposed to be all waxed and slick.

there is a region right around the trim that is breakout forces. it could be a prtonbelem with the slop in the linkages, escoteric to tlakt abouti ti . we want a positive gradiant . wit airspeed going up we require more force.

looking at steady turnd man stabl. more g more aft and more and more with more and more. steady g steady airspeed,. ytou dont want something that digs in.
\target g and target inputs. for pull up and push overs we will demonstrate and not collect dater.

you want to associate the g with some coresponding aft stick as well as force.
and due to blow back characteristics do you have nough tail to not blow back.

s-76 will dig in, no requirememts for positive stability in civillian.

clack hawk has alot of stabilator. due to tails on each side and not necessarily even in both directions.

thisis done collective fixed so you will be descengind while turning . falling out of the sky fast, so ge the dater quickly.

**^^ man stab-steady turns ^^**

now man stab-pull up.
want the vector to be straight through the earth.
have the g on level so the weight is going through me at the target airspeed.
can do pull up and push over to accomplish.

you getthe grady wilson - "standby, standby, mark, passing through stable." not exactly a stable g.
ralph kimberlin says he has a good grady wilson story too.

it can be a yeee-haa too is the tail breaks loose. watch the g loading limits on the airframe.

testing fixing fixture, bring extra rubber bands. testing complete, failure of rubber band.

pushover, acceleratefirst, then raise nose up and slow down and right before the airspeed stuff it ,and try to fly the g level on theta through the airspeed.
not real comfortable in teetering rotor. more problems in negative g than positive g.

time to take break 10:20
books here, mosher went and got them.

back at it with mosher 10:42

the pilot dosent really care what the flight controlls are doing, what is the moemnt of the blaced change, and really the pilot just is interestg in what he is feeling oand where the stick is.

five minute thing on Xu. this is a derivative,
it is dfined as one over mass times change in x forces over the change isn u. velocity dampning.

which means that it is a dampner opposing the rate. ie. a force becouse of a rate in the same axis.

if im in hover and ibegin to drift, holding all constant, and thne...

hobver? fwd flt? it would be good if the chopter began a force into the opposite direction and then returns it to trim. if the thing went awway from trim would be positive. ie. for a foreward drift i would like a backward force.

you got to have it negative but not so much" gust rejection" (0) value is perfect gust rejection. smooth ride or stable aircraft. it is a balence between negative and zeor.

what are the controbutions? we have a rotor and also a fuselauge.

page 25

looking at the fuselauge restoring force. and the rotor forces, ie. blow on fuselauge the drag goes up.

D=1/2e^U20f like the equivalent flat plate drag like front area of a car.

small squared at TPS is zero. point one is zero.

in a hover no drag change by small preterbation.
but at velocity it is much worser
u0 rho etc. are constants.

then the rotor tips back due to a ghust that the blow back is not a function of velocity, it is about the same at all speeds.

in page 9 you can determione from the notes that by the foreward flight table is the in the center column the rotor paritals.

flat pitch on surface no blowback couse not pitch to work on.

becouse the Xu and the 1/over and the numbers get small., also from nasa time ago and not from flight testing. some negative value in hover and decreasing linearly with speed. and boom you got it.

the blackhawk data is good, but not as good the windtunnel dater.

four real "dater"

five would be to change it....

** blow back goes up with higher collective setting.s more xu so make a heavy aircraft that is always close to blade stall. or to increase the flat plate area of the aircraft.

black box. the cadence is the same, when you go look at hte derivative. measure the denomanator. have computer tha feets to the actuator and changes the numberator.
so device that measures the airspeed. (loras for low speed) feed it to the computer that makes x force change. but there is no x force generator except on the piesecki or chyanne. then pusher prop. or throw out some drag device.

to make some theta you got to go through two integrations of the del c m.
dzam. however almost all controls tasks are a pitch attitude control thing. controlling attitude. ie. attitude is everything.

in the z equation Zw is important.

***vertical dampning.
the trim solution and if it it soo negative then the gust will cauze huge z forces. almost nz/alpha.
so again - for stability - and 0 = gust rej. and + for "suck down"

so until someone invents negative drag, then the fuselage is going to help me.
the tip path plane will cause negative z and the blates will tilt back and cone so that is restoring. it will help me.

looking at real dater page 32. the advancing side always wins. the ammount of q you get is more bigger than this is less"

when you honk the collective it should appear that it is becoming more stable.. most of the 60's have a limiter to not let you overtorque the dude.

measure inertial height. and feed it to the collective through the black box.
what authority does the inner loop of the vcs have, and the answers is why do you ask to the lawyers and then admit complete authority. on a v-22

speed stability

ok hit with foreward ghust if nose drop back up and then goes foreward.
zero wins for ghust rejection. - is static instability. + is stability

contributions/; rotor and fuse.
blowback is the positive part.

(1/Iyy)*(TH+(ebmsomega^2)/2) 2a1s/2u this h-58 does not have this moment generating capability so it has to have a tal high mast to get some.

e is offset in feet.
b is number of blades
ms is first mass moment of one blade. it is the intergral of rdm.

people tend to work outside the bracket, ie work on the 2a1s(which is really a partial not a 2)

this offset is more plus becouse of the offset. and anythinging that the rotor does that you like will be amplified by offset, and anything the rotor does you dont like will be increased with offset.

in the axis of no flapping they are not flapping on the axis not that one, but the effective one, and lead lagthen gos through the hooks joint. the axis system makes the blades out of the things. flapping in position rate and acceleration. so that sheer force due to the tip plane path tilted from the flapping at the offset and there is in the prior equation this resolved as the ebmsomegasqd over 2 .. and this is with respect to the mast axis and perpundicular at the flap hinge axis.

** so looking at the tilting rotor you get a tilting along the fuselauge and there is a del moment on the tail . so depending if you have a down load of an up load then the restoring and stabilizing forces on the tail can be either negative or positive contributer.

tail volume is given in cubic feet back there.

the blackhawk hasto have a profile, at 7o to 80 fps and moving but the tail is still hanging down. the tail is there and slower ted so aligned with the flow from the propulsive disk.

to change mu, measure the denominator, either movethe tail back or make it bigger.
different incidence angle.

or black box... measure airspeed and feed it to somethign that causes pitching moments. then

well we have a sikorsky hand out and the black box is slow and does not control the full authority and can be trimmed out even after failure.

lunch at 12:02

return at 1:15 due to a crashed car blocking the airport drivway.
mosher already in progress.

the thrust vector grown and tilts back when disturbed and we call this "growback" which is almost like a nose up moment squared. this is the rotor contribution to m alpha in foreward flight. the rotot by tiself largely contributes to instability. offset, and tilt ,and growback.

if we assume that the tail angle of attack sees the same angle of attack at is the wind from uunderneath and less down is like more up. so track the change in moment and it is minus the change in lift on the tail and minus the aoa on the tail, and...
so a ghust from below in foreward flight creates a down pitching trend.
then mw is a regular power and the m alpha is for fixed wing and it is squared.

ooooh no the tail IS stabilizing. couse if the gust then less nose up and which brings it down.s so we need to have enought tail to counter act the instability of the rotor. deign case is one g flight.

the destabilizing effect of the rotor is not liinear so the tail will loose when you increase the load factor. so in flight testing the positivity or negativity is a function if they put enough tail on it.

the programing tail like on the blackhawk goes with angle of attack only
the angle of attack stability negative.

maneuver diagrams, the marines teach to compare the turn rate diagram and overlay the threats. power required often.

interesting , if 10,000 lb, then the coresponding table for 1,400 corresponds to 1.4 g and then you can keep pulling it and you do the point turn radius.
you might not be able to keep the g level, but you "dig in"

you can "pull the collective with the disk behind the schenes" make it grow foreward.

Pitch Dampning:
Mq tail is U0 to the first power or LT squared. and an independant Lt, so you get more for your money again for length of the tail.

it is possible that you can get 50 degrees per second pitch rate on an elevator which means that the stall is possible on the tail.

tuypical is two to one rotor at max speed, and a-typical is blackhawk then it minus 2.1 at 25 fps

if i have enought pitch dampning then i know i will have enough roll. mq is important derivative.

stab bar huey.
to give free SAS ie poor mans sas. measureing a gyro outside and let it cause pitching moment changes. neither it nor the rotor know the difference in pitch and roll, and things oyu might want in pitch you will get in roll also. may not want it.
some SAS stability augmentatin system. yaw dampning on 707 wasthe first ever in commercial use.

m delta long next, and leave m delta collective to the reader.
m delta long = Mdel = 1/Iyy)*(2M/2del

so how many degrees blade pitch per inch.
like a gearing ratio.

in the rotary wing hallway at tps any thing that has the word sensitivity are going to be units of accelleration per displacement.
other places it is = steady state rate per pound force.
the reason is becouse the cockpit stick forces are so low. in airplanes 8lbs per g possibly. in the copter it can never be moe than 8 pounds. except for breakout and home, the stick location is more impotatn than force. so for chopter degrees per second squared per inch.

the stick moved the tail on only the huey cobra series. no other helicoopter we know where it moves it. it was fly by iron, and it only went a few degrees.

ok time for a break, and see what the big players are and what the test techniques. and what to expect prior to flight.

2:15 try to return at 2:30

2004-03-02T17:51:00.000-08:00

comanchie helicopterthis is the guys who make the fuel cells for the once active comanche / comanchie recononsance helicopter. rodney allison once flew in this helicopter.

speaking of rodney, here are a few test pilot jokes
how do you know if someone is a Test Pilot? : they will tell you
what is a test pilots birth controll? : his attitude
how does a helicopter fly? : aloft becouse of the pilots inflated ego
a helicopter dosent fly, it beats the air into submission
what is a helicopter, it s a thousand parts flying in formation loosley heald together by hydraulic oil.

if you are getting bored in class check out pablo comix.

2004-03-02T13:26:00.000-08:00

H-3 Sea King - Wikipediahas in his hand an elastomeric bearing from a h-53 sea stallion
h stands form helicopter and uh is utility and a is attack.

lock number (gamma) is the rho a c R^4 all over ip

high inertia rotor system is not what is meant in the i p under the equation for lock

numbner. this is the in the flapping direction anyway.

to vary the lock number the only parameter to be varied in is testing is density.,

lock numnber in oh-58 is five.

or half that at 20k feet. where the rho is half.

as far as geometric twist, what is good for hover is bad for foreward flight, and visa

versa.
like on the 60, it is 13 but all the way to the root is 16. which is optomozed for hover.

hughey is about 8.

berp blade has a fancy tip, british experimental rotar program. most of the real schienc

is in the airfoil section. the 101 has the berp blade on it.

so moving on to the spring mass damnped system
x , x dot, x double dot.

EFx=max

f(t)-Kx-cxdot=mxdoubledot

as the bloade flaps up the lift gets reduces and then there is automatic flapping dampning.

the lock number is zero in a vaccumn. this is past of the damnpoing.

the natural frequency is the frequency where you will operate with no damnping.

we can add enough dampning that it does not overshoot the trim after disturbance. this is

critical dampning.

is a function oif the mass and the stiffness. wn=sqrt(k/m)
.25 - .75 dampning ratios on the chopter blades at flappings.

recap: naturl frequency is ewual to the rotor speed and the lock number is lock number over

15.

rotor goes around one time in four seconds and the oscilations usually die out in one

revolution of so.

amplitude ratios can get real big, like the a/b
the phase angle sigh the peak of the input is later in phase then the input is.
90 degrees offset.

now looking at a bodie plot.
intercepting a different shigh, so if you pull the stick back you get pure tip plane path

tilting aft. no transient aleron type response.

strange movements at hight altitudes couse of dampning and then later or earlier in phase.
celing limiting on some., like on our ifr cert.

delta hinge arrangement. normal no change in aoa with flapping
if at angle it goes up lodes aoa down takes a bite.
positive (negative spring)
or flip it over, and have a delta three hinge.
this is used in tail rotors about ten years ago.
only russians use it in the main rotors.

blow back is aft tilt when increasing velocity becouse of the tip path plane increasing the

aoa. or actually the dynamic pressure not aoa.

so when the stick has to be placed foreward and to the right after the foreward velocity is

established.

be 105 lock number of 5 and at 20k feet the lock number is half and the delta sigh is 50

degrees and the stick goes just as much right as to go back.

h-58 tetering rotor can then blowback into the tail.
the big flapping value makes this, the h-6 and h-58 have 30 degrees of delta three.

bell 407 and 427 has gobs of delta three to keep tail rotor to not flap into the fins.

bell 407 it set the vne till fixed.

the russians make some to be really strong and not so menueverable but the ydo last forever

and alot of delta three.
espically in the coaxial rotors, to keep the flapping dampned to keep from "brushing the

blades"

aerodynamic stiffness plus delta three dampning plus mechanical, so then you will talk

about "effective offset" due to the stiffness etc.

lunch at 11:45

resume: 1:25

the convention for air coming down through the rotor is positive.

there are some non dimentional terms that can describe the relative wind and the foreward

flight speeds.

different flight sighs. page 32 or so of the notes has (green book) much better equations

than i can type here in ascii text.

.3 is a high advance ratio.
tip speed in denometer and foreward speed ontop.

advance ratio is symboled with mu to the pilot it is just the airspeed.
lambda (giraffe) it is vifrom v sin dy over omega r. (aoa to the pilot)
and x is the radial station. r/R

i think the advance ratio is also the solidity ratio.nope it isnt, it was solid vs. dashed

line. the page 34 bvchart shos us that hteh dampning is similar at hover and at valocity.

this is a time varying dependant differential equations, however the yare time varying

with sinusodial.
"same stuff different day, equation.

smalles chopter = 485 rpm rotor shpped 4 Hz

eight blades on a mi-26 @ 2 hz or 129 rpm

so beta double dot can give oyu g loading on the blade

"management is where fear and folklore run things, dont confuse me with facts."-mosher

"dont train anymore flight test engineers couse they are going to come up with ways to

test."-johnny o' talking of contractors.

a one s is the aft angle of the tilted tip plane path.

if you increase the b one s, then the a one s goes neagtive.

ok, so if you take one degree on the one side and add a degree on the other of feathering.

then you get 90degrees later in the rotation a one degree tilt of the tip plane path.

53 echo has 5 degrees transmission tilt
uah1-yankee has three degrees of tilt in the transmission.

so that the mast isnt taking the loadfor the tilt moemnt.
so a one s is the tilt angle from the mast of the disk.

"trim condition ie. operating point ie. home - all synomoyous.

q is pitch rate. in the equations.

they put an oh-6 in the wind tunnel to get the a1s 1970 paid for by the navy at nasa aimes.

a1s = change in velocity over time, plus the change in lat plus the change in lon, plus the

change in aoa plus the change in q

question: hpow do they put a chopter in a wind tunnel? under it's own power to spin the

blades? or autorotating? how do you wind tunnel hover?

160 knots even in the wind tunnel which is way faster then it can actually go.

talking about blowing up from below and the chipter cones.
if you add a foreward vlocoiuty
then you get a gust then the tip path plane goes tilting backwoards becouse of the did

symetry of q along the back side of the disk.

the rotor is less stable at angle of attack and it gets worse at velocity.

if we increase colective then we gat more tip path change witch goes back just like the gust

from below.

ie. same reaction when you pull up collective you go aft, and if you push down then the tip

path tilts foreward.

gust from above get pithc change.

ie. also when you adjust the collective you have to adjust cyclic.

some aircraft have mixing to help this .

pitch up and roll right and pitch down and roll laft.

this left and right is due to the fact that delta sigh is not ningthy exactly.
cannot rig this out.
can rig out part of it, the del a1s.

1/3 mrsquared in ertia for a thin rod.
now we are talking about the flapping and the lead/lag
they are damped by centerfugal.

once for three times around is the lead lag.

ground resinance can be effected by changing the resonance mode.
if a fully articulated head and chain it down and then ytou get 4/3 omega or -2/3 omega

which is not good modes. and self destruct.

4.3 Hz rotation in the blackhawk so 2 omega over 3 gives 3Hz.
and then in the landing you can excite the mode.

h-66 comanche .667 per rev. then the h6 has .5 per rev. and the -1/2 omega for the fixed,

but the rotor is 8 hz

4/3 omega "advancing"
-2/3 omega "regressive"

ok, and the pilot is the one that is exciting the Hz with input at that frequency.
but it is kinda likethe child in the swing and if you are close or hit each other one she

will still swing.

tomorrow rigid body bandwith. tomorrow discussion.

if the aircraft is too big then the aircraft cannot actually respond at the frequency of the

resonant mode.

solidity ratio is the aera blade/aera disk usuallt .1

brown belts in rotorcraft dont use time they use rotor rpm.

evident in the uh-60 graphed flapping angle which is interconnected with the lead/lag.

for anti ground resinance you need the smallest damnper avaliable which is scarry like in

the air.'

if the mode is "three percent damnped" then zeta is .03

if you are worried about the mode damnpning then t
first flight should be at max gross weight.
this was done with the ah-one

ah-1 is the super cobra.

omega cross omega cross r. so the aircraft is going altitude.
to have a 90 degree tilt becouse of a nose up rate.
sixteen over lock number times omega tells you the nose down rate from the perterburation.
since it is lock number it is then a function of density

so you get more pitch dampning and roll damnpnoing at altitude as well as at airspeed.

so at altitude, it appears sluggish, but uit is not that it is becouse the roll modes are

damnped real good.

2004-03-02T07:27:00.000-08:00

RotorWay News7:58, francesco lombardi the helicopter copper was nervously shaking or something and then there was coffee everywhere. and they were saying that the coffee was strong enough to melt the table.

8:04 am begiun after frank lombardi finished claening his spilled coffee.

mosher, mike.

we need a model of how the aircraft responds to gusts and pilot inpit, how does it do when disturbed from trim.
and importatn to moving to aonother trim condition.

so to approach this model, we looked at alot of helicopter configuration.
and tip plane path tilt is prettu much the biggest deal.

offset and what not does not make much change with collective change.

so tracking the tipplane path tilt is the key tothe model. if we can locate it anyehwre in space, then we aretracking thge moembnets that are made on the machine. this then boils down to the moements and changes in inertia on the machine.

the goal we are after this tip path plane is going to bne a common issue.

ok, now for somethign new. rotott types.
fully articulated and starflew, and teetering and what not.

the naming of htem makes it harder and more confusing.
lets define a rotor head so that we can explain it to anyone.

page six in the little green book shows the six degrees of freedom.

there is an axis of rotation defined in the center of the vertical mast, then we have an axis on the horizontal for flapping and one called lead lag, "in the plane of the rotor allowing the rotor to go up and down. amd then the rotor it's self can feather, or twist. featherin changes the aoa, whether azmuthal or not.

1.rotation.
2.flapping
3.lead / lag
4.feathering

lets make the rotation a constant and call it omega.

the reality os that the blades have some in plane motion as well the fuel control is not completely perfect.

transient group and static group discussions will cover this non constant omega.

omega can be rad/sec or deg / sec or maybe even hertz.

so sigh = omega times time.

to convention zero at the bottom, and nintey on the right from overhead, and 180 on top and 270 goes left, the relative foreward direction is from top.

in usa this is right blade advancing.

of moving on to flapping, positive blade flapping upward, and call it beta. the flapping angle is drawn arrow negative on the diagram in the green book.

the flapping offset is the distance from the axis of rotation to the flapping axis. this is esub beta. if someone just says offset, they usually mean flapping.

then we use foot pounds per degree to talk about the dampning, which we will call k.
and then also beta dot, and beta double dot.
so these are the time derative and then the double derivitive. so it can have an upward flapping velocity and an upward flapping acceleration.

so in the lecture yesterday when he was talking of the five percent offset he meant five percent of the rotor radius.

on to the flapping, we will call it angle zeta, (the squigglie) and then there is zeta dot and zeta double dot.

there is lead lag offset as well and this is e-y or the "vertical hinge" likewise the flapping can be the horizontal hinge.

usually the lead lag axis is outbound of the flapping. some chopters like the blackhawk has a u-joint for a hinge.

the last thing associated with the laead lag is c sub zeta. usually there is some dampning mechanaically in the lead lag axis
flapping dampning is not so common but there is always a lead lag spring or dampner.

xv-15 picture = gimbled head and the hub springs dont roatate. the springs are lowwer pushing the dude back up.
then the LTM lateral translation mode is left on it burns those dudes up.

the last degree of freedom is flapping and we will use trailing edge down and this is theta but we will not talk about theta dot and we dont implement a feathering dampner. and is theis is done by structural twisting ie. flex beam rotor or flex beam twisting.

again leading edge down is negeative.
lead lag = leading into the direction of rotation is positive.

the three degrees of freedom, looking at a bell ah-1 has a flapping by teetering hinge and a flex beam. issues here: teetering hinge ie. teetering rotor. and a virtual hinge for coning and movement of longerons.
one pair of flapping is one up and one down of the tip along rotation.

so five degrees is : five up in the back, zero on one side, five tild town on the front, and zero on the other side, , and that would be five degree tilt "foreward" oncer per reve flapping .

so zero per rev is called coning. thisis like what i would think of as dihedral, this motion is allowed from the flex beam.

roll moments by coning is not an issue.

coning and pre coning = ie. if you have an articulated rotor and the there is a steady coning value and the gross weight changes it a little but only a few degrees while the aircraft is operating either hover or foreward flight. this little bit causes a bending moment on the hub, and we can "pre cone" tje hub then the moemts of bending are lined up. ie. a v shaped hub a little bit say five degrees or less and then the hub can either be smaller or lighter or have a longer life.

flex beam hub made of composites can then be preconed etc.

two per rev flapping. can happen; but it would be a tip path pringle it dosent do that really it is pretty flat.
the tip plane path will be the once per reve flapping
on this bell ah-1 there is no offset and there is also no lead lag on this tetering rotor.

to alleviate the corrolios loads or conserv. of momentum, "ice scater effect"

to controll the vehicle we will neet tip plane tilt maybe five degrees. and as the blade flaps up and down the tip gets longer and and shjorter. or the center of blade mass moves from the center of rotation and the rotational speed increases.
like when the ice scater pulls in the arms.

given that the tip plane has to flapp up and down and it has to tilt. so we either allow it or really restrain it.
the teetering rotor has alot of beef up becouse we will not give it a lead lag hing so we will restrain it.

teetering rotors do not have the third degree by beefing up the root structure.

** lead lag dampners and the mantinence officers anti-favorite thing** so the reason to not have them is to smaller the numbers of parts.

this makes alot of vibration and small patts heads and it is offposite of an h-3 . the trrade off is nothing to do with te be thnaglind qualities . let it vibrate it is used for training etc. chopter cops.

** dr. peter solies brought up underslinging so you could teeter it so if the blade flaps down and the other up then one wants ot go but they have equally moved with respect to the center of mass vs. rotation distance.

so let there be coning and then the tip path plane tilts then with the coning and this one goes down and hte other up and both were up previously then you do get some movenemnt on one from the axis of rotation and then te is a force onto the rotation and one wants to speed up and the other not to .
so the entire rotation tries to both go the same way then the pilot has to over come the loads, so they put somthing in there, -could not see- restraining of the inboard helps with the lead lag .

in short the lead lag hinge is not there and there is zero offset on the teetering rotor.

bell-222 or (bell 222) is flex beam tetering hub with hub spring, probably had a two degree of motion on the flapping and the feathering is done with an elastomeric bearing.

sikorsky s-58
fully articulated rotor
means that all three degrees of freedom are allowed for by a real mechanical hinge.
has flapping hinge offset two or three percent. real vertical hinge. some feathering thrust bearing. they all exist as hinges no structural beanding.
feathering bearing all others hinges.

** he says fully articulated is same as articulated for all intents and purposes, nothing is actually fully instrumented. **

so there sikorsky s-76 is all fully articulated iwth an elastomeric bearing. kina cool. 4.7% offset both flapping and laging.

bell 412 is a soft in plane head.
it has a flex beam hub. acedimic definition: soft in plane= the natural frequency of rotating plane oscilation is less then one. Wnzlike the baby iun th jumping jack and put in a bigger K spring the oscilation is slower and stiffness slower.
so the lead lag degree of freedom if the blade is displaces. then there is a spring to oppose displacement there is a dampners oppose rates, mass or inertia opposes acceleration this is true in the angular and linear modes.

remember this expecially"":
springs oppose displacement
dampners oppose rates
inertia opposes acceleration

so the pulling it in is a function of the offset ammount. so the restoring is something like a third per radian. stiff in plane the natural frequency is greater than one per rev.

soft in plane the hub structure bends.
you cannot really say where it is actually flapping. in fully articulated you can say it exists exactly at the hub.
so there is an"effective offset" so on the bell 412 is is about 4% effective offset.

virtual flapping hinge and and effective offset, we will computer later.

it does have a real lead lag hinge. then it is soft in plane.

elatromeric bearing looks like agiant slinky dipped in hard rubber. an "elastomer"
the K zeta is stiff but not stiff enought to drive the natural frequency above omega

brantly has a natural frequency above -- a strange beast.

lockheed AH-56 is a
to stop without attitude change it has a high horse power fan.,
it would be crusing at 200 knots too.
so it has a viurtual flapping hinge with a titanium structure. like ten percent offset., big offset numbers. no lead lag hinge. no real hinge for lead lag. the equivalent of replacing the hinge the structure is bengine to allow for leading and laging and it was so stiff in plane its natural frequency is more than omega.
all articulated rotors are soft in plane. if there is no lead lag hinge at all it is probably stiff in plane.

you cannot be ground resonant if you are soft in plane.

most other (like h1z) are soft in plane to havethe not have ability of ground resinance or air resonance.

vibes come from the rotor, the hinge cannot transmit the moemnts but the hinge can transmit some forces.

**track or balence, your choice. cant have both... ha ha ha by chopper guys?

MBB MO-105 virtual flapping hinge fifteeen and virtual lead lag hinge it is a soft in plane and can tailer the material to give whatever the freucencey is desired, so they chose soft in plane.

*** most helicopters have symetric airfoils so that with a change of aoa there is no a change in pitching moments.

alot of them have no hydrolic system so they have to be able to be done by pilot mechanically.

the new ones have hydrolic systems and still they want little pitch moemnt change iwth aoa to have small systme.

you owuld not want (large pitching moment change with aoa) that for like an h-6 and you are already at the edge of having enough power anyway.

Westland Lynx has hingless hub with all of it is plastic.

there is a comanchee md900 h1zulu no hinges all virtual hinges less parts count. and the words are "infinite life"

ah1z has a life of three hundred hours. thery are trying to fix that right now.

if going totally hingeless you can tailer all the stiffness and offset where y ouwant it. but you do need a little more hydrolics couse twisting composite takes alot of more force than a roller bearing.

star flex bearingless hub " causes confusinn,

ten minute break (appreciated ) 9:14- 9:25

to describe the rotor head, you are telling about the degrees of freedom of the blade and the way that they are accomplished.

so we will then think about the importatnt part is that the blade has to flapp and we will then mapp the tip plane path.
lead lag is thought of as a nusiznce thing.

so now we are going to try to put some math on it. the flapping degree of freedom is the one we will look at in a discipline way.

flapping angle is degfined as up is plu and positive measured in a line perpundicluar to the shaft.
so

beta(sigh) = ao - b1s sin sigh - a cossigh.
bunch of math, and a1s is the longitudinal tip plane angle.

we make a tip plane axis to refrence it to the body, except for the v-22 the shaft is fixed to the body.

FTM in chapter four has the discussion of the different axises. somewhat confusing so we will not discuss. read it on a sunday in the library if you like.

truncated fourea series. bater(sigh) = a0 - beta1s sin sigh - a 1s cos sigh. 99% solution of the moments on the aircraft.

alot of collectives are linearly proportional ie. one inch take 2 degrees of bite and two inches up makes four degrees etc. etc...

side to side stick motion changes the fore and aft blade angles.

A1s = lateral cyclic angle
del lat = inches or percent displacemtn.

so if you have one inch of control left, then you dont know what exactly , you could say that you have ten percent of the stick left and that lets people know better.

to plot you must have enought info to convet back and forth to the stick deflection so number of degrees of cyclic angle to stick deflection.
at tge exprema there might be a issue with the linearity of the stick movement to conteol.

aft stick is plus del everywhere but at bell. associated with nose up moments. so then the gearing ratio is minus two degrees per inch.
this will bite us later in the stability derivities.

the theta whitch i think i the lateral control is an exact forea series, the only difference in the equation is plus soghns.

purte mechanical connection to the swatch plane and for the root of the blade it is exact. not so much for the tip.

makes me think of swashbuckle.

higher harmonic control is to move the swash plate to remove or to counter the vides of the chopter.

lots of blade adjustments for a multiple blade system. maybe 5 per rev on a four blade system.
oh-6 that is trying to reduce the vides with the oscilating the swashplaes. or with individual blade controls and the pitch is not connected it has an actualter. like oscilating the swashplate but better and have inflight blade tracking.
bell-430 tries to do it in the transmission.

all that said...
single example:
lets look at the hover.
rigid blade flapping, no offset,
only flapping in hovering.
bunch of math...

the prandle lifting line theory says that in the vertical climb you are losing aoa after motion begins.

tip plane path tilt is beta dot = flapping velocity.
the further out on the tip more velocity,
the l/d of helicopter blade section is like only 10.

gave equation for b double dot.

time for a break.
10:15

2004-03-01T10:22:00.000-08:00

Naval Air Station Patuxent River, MD
mike leigh
electrical engineer.
15 years in coal mining instrumentation,
then transfered to helicopter instrumentation at boeing.
and now at utsi...
at utsi for 5 years.
instrumentation expert
designed the instrumentation on this helicopter n88ut, as well as n89ut.

the best placeto start is on the overhead projector with a block diagram.
two systems operate in parallel, meters "volt meters"
there is a pidot and static
airspeed and altimeter manual gauges .
they have differential pressure transducesr, 0-1 psi., (0-200knots)
then an abolsute pressure transducer for altimeter.
they ahve a meter for five volts with buffer amplifier and no load loss.
so then on the list. avaliable in volts
air speed
alitimeer,
rgt or oat.
turbine outlet temperature, tapped on milivolts from the ship.
torque is measures by the pressure on the engine. then tranduces by four arm srtain gauge

bridge.
side slip vane potentiometer. calibrated in volts.
vertical gyro for pitch
and a yaw gyro (uninstalled right now)
three accelerometers for n (x,y,z)
then for stick positions there are long stick and lat stick and pedal with high level

potentiometers.
the thing that is so negative about this perticl=ualr system is that all the volts have to

be converted into engineering units.
but it is quite intuitive, tjhat is good thing.
the calibration is linear on the voltage swcale which makes for easy conversion.
pitch -45 to +45 degrees.
lots of examples of the data calibrations, most of them are zero equals zero or neutral.
all are within .5 of zero for neutral and the +5 and =5 volts being the extrema.
through out the parameters, the useful range is about -4.5 to +4.5

data aquisition system uses laptop computer connected to instrumentation infrastructure.
now for demonstration by mike leigh.

backview is the program we use.
tab selected data channels windows based , fairly intuitive. oh58.dak is config file to be

run after conected and then it "hooks up"

backview likes to use Hz, and the navy guys know how to use percent speed.
there is a conversion for them.

all the no channels can be removed and we can look only at those parameters we areinterested

in however all data is collected.
we can then export the data as strip chart, or graph, or spreadsheet. etc. powerful stuff.

can trigger data to do aquisition after triggering event, but we will go continious couse of

effective length of our data and our needs.

live data can be observed in flight, 100Hz sample rate. collation of data is avaliable

option to compate multiple flights.

each flight will be preformed by a different team of students.

after the data run, the info is stored in an ascii format.

convienient format for excel or matlab etc.
can be stored in matlab .mat format for smaller file size and less compatability.
if you like.

2004-03-01T09:10:00.000-08:00

john o'c onner
retired navy commander,.
cheif of contuniuning education at test pilot school pax river.

march 1, 2004 9:02 a.m.

why do we do testing.?

assuming we are on the deign side. assumes we are figuring out a prosuct before the flight line.

why test?
requirments analuysis.

looking for the tool for all the tests,
how far, how fast how high.

comboniation of human and machines to preform the functions required.
the function must be easy to do.

developmental test interestedi nlooking at sub elements of the system, and quantifiyng the charasteristics.

we will make a data model and gather date "ogf the aircraft"

in the end we are trying to find out if we can preform a mission or a number of missions or tasks.

flying qualities , preformance, and weapons systems.

opreformance sells the aircraft, all the little children nask how fast will she go?

weapons systems help find fix track target and engage. sensors as well as armambnat.
flying qualities is basted on thestability oand control characteristics. we can build a model and wyatnify but that is not enough...

testing: preformance, flying qwualities, structures, systems, ship interface. reliablility.

designing the test is importat so that you are efficient and to use alloted time avaliable.

Generalized data model. most of the aircraft ate atmospheric sensitive, trying to build a model to see what the aircraft will do under a standard atmosphere or at any givern atmosphere.

powere avbaliable and or power required. weight changes, and atmosphere changes, alitltude, rpm, oat, etc.

the curves then are normalized to a standard, can be done in relevitevly few flights.

using the data and those curves produces, then we check and see if we make the mission preformance or the specification compliance.
inlet recovery is important for these helicopters. not so much it seems for the fixed wing.

missions are like : go and loiter or maybe go and drop bombs or something like that.
checking to these mission profiles is called unreffering the dater.

helo preformance tests.
airpseed cal, engine gover, flight climbs and descents.

joe walsh's mazarati goes 185, how does he know? calibrated poliece radar. (1970?)

the industry uses standard day. the army likes hot day as well.

minimum is endurance and tangesnt is range, and the max vs. the requd is top spees, ie. hedid a quickie pref calss with the eshp vs. power required with velocity.
excess power at an airspeed can give you a climb.
hover celing is a function of the power avaliable refered to the altitude.
engine shaft hp can be refered from a different altitude and you get a different top speed etc.

range and endurance is mostly related to what the fixed wings call the drag polar. this polar is similar however it breaks down in the really low airspeeds. a little motion is helpful for the chpter.
speed power polar is somewhat easy in only turbo prop aircraft.
the others takes alot of dater points.
interfaces and sensors anre tested in the lab, abnd then must be retestesin the chopter.
this is the "as installed" charasteristics of the sensor.

if we change the state of the machine it changes the state of the world. ie. configuration changes makes lots of changes in the device. predictabability within the devices in changes is important. the sensors and avionics and displays might be inedaquate as installed, etc.

flying qualities testing . these qualities and charastics thatdetermine the ease of operrtation for the pilot to precicely preform the tast or missions.

including the cockpit interface,
the stability and control of the aircraft,
the enviorment,
and the stress levels.

quantatative pilot opinions oftern obtained from data and controll test too.
function heirarchy:
flight management
a/c management of sub systems.
mission system management.,.
application of *** and qualitative tasks.

we use the cooper harper model to characterize the quantatified .
this also helps us decide if the stability derivitives have to change.

we will talk about the mechanical charestics of the controlls them selves, then either feel the aircraft move by direct observation of by instrumentationm.
this is also called, changing the state of the world.

interface and unpredictability makes for non precision.
then you have to also impose an enviorment. ie. turbulence and forrest fires and anything that crates extra stress.

we can quantify the force per displacement and all the mechanical charestics of the controls, but we need a pilot to tell us if that is of for the mission, ie. i can make it precise, or it aint no good.

we want the pilot to behave like an expert, and you know that people behaviors control the,m
so wehat we do is train them and give them expeience to manipulate their behavior.
things like sleep requirements and stuff helps for predictability , 12 hours of sleep 8 from bottle. etc.

controls and displays kinesthetic they instill to believe the visual display when the body gets all confused.

aicraft weight, configuration,s ac/.state, failures, all this can cause deviation from the models.

flying qualities is alot relied on pilot opinion.

v-22 an ads 43 approach?? something ab out failures on the carrier deck.

complexity can be due to multiple interacting factors, it is maybe the tail shapee, canopy, control, display or it is all these not dancing together.

meeting the spec does not mean good flying qualities. but the spec may call for rewuired workload.

prespective:
fleet pilot?: the task is difficult i must work harder,
the test pilot, : the task is difficult there is something wrong with the airplane.
the test pilot is a winer.

utsi has some navions that can vary the stability and tps has two rotory wings that can vary the stability, so what you do is go out and see what the derivitives you want to make the aircraft desirable.
some of this can be done with software, but when the gain is all the way up, you run out of gas and you got to go and bend metal... and change shape.

flying in a tunnel, got to maintain rotor tip path plane.
so what about the aircraft needs to be changed to be able to preform the mission.
if i am mixing the soup, then will i get desirable response.
what is the highest frequency
to get a response? ie. im trying to do a task , can i do it with adecuate precision/
you can put it in bank and see wow long to roll off or whatever.

then you think about this and extrapolate into the missioin.
like the tunnel, or the train at 120 knots and you have to hover wtiht a foot so the cops can go down the rope and catch the bad guys...

evaluating the controls
does the control control attitude, or rate, or heaven forbiud an acceleration controller.

PIO pilot induced ocilation scale or the cooper harper scale

the cooper harper scale has a chart, 1-10. it is worthless if you just go hmmm, give it a five.
we can do time traces with video and see how much work is done, but what does th epilot think?

"stirring the soup" this means to be working the control stick at like 60 herts, also to be moving the stick around, also sweeping out the cockpit, also churning butter"
lots of cutsy ways of saying the same stuff.

at some point the stirring makes the pilot tired and cannot be done forever.

the five: adecuate preformance required considerable pilot compensation.

the engineers need to know what the descrapance, maybe a minor or annoying deficiancy . mauybe tghe pilot is putting in a little, maybe an inch here, and then and inch here, and then an inch here. could be the lateral direction , negative stabilit, etc. what is it that is abhorant that is causing frank all the trouble in the challenger..??
so you figure it out and then repair it. or placard it. he he he.

the PIO test is for if the controls and displays are not matched to the task to be done.

is the task preformance compromises? and do desired or undesired aircraft motions occur.?
divergent oscilations = crash and die. that is a six. (6)
a pio of 1= plane tenst to be real stable.
smooth as bananna daquaries here, this plane gets a one (1)

vibration rtating scale is 0-10 more appropriate to helicopters then foixed wings.
over ship decks you get translation lift and all , and this makes for some undesirable modes and virbartuons.

maybe air off the tail rotor, or air from the ship deck, and there might be a speed where the vibrations is unnacceptable.

problem:
the helicopter was easy to fly sideways to the right, bowever it was hard to hold a steady heading, and the aircraft response ot pedal inputs was slow and large awkward movements were needed to maintain desired control.

this includes positive neutral and negative stability. go figure it out(duh)

well, positive, = dampned neutral not and negative it is divergent.

whoa lots of tests to be preformed, cant typp them too manuy.
phuogoid, is the last one. sounds cool.

vertical fin is there foir the speed stability this might be something that gets changed, simon's strength..
to be a test pilot :
knowledge of the aircraft,
technical training
observation skills.
adaptability,
communications skills.
flight discipline - mitigate risks.

this is all it takes, hmmmm. military can do it.

more info at the:

Cooper-Harper Handouts.
USNTPS flight test manuals
FTM-103 fixed wing s&C
FTM-107 rotary wing s&c
Mil-Std 1797a
USAF FQ textbook
BOQ bar.

the gain on the persons skills can be reset to the gain required for the pilots usual use.
the kiowa 57 needs more gain than the 60's /
it is not som important that it is super easy, but it is the guy who goes over the cliuff that screws it up.

dont get wrapped around the statistically sanmple, the figures should colapse to somehting around one or two in ten but it sould be the trend thatis important.
the whole power is important, and some have hundreds or pilots over many many years. but you cannt have this luxury in the test pilot regime and with new aircraft.
superhornet wing drop was a thing where the test pilots are squawking and then are saing i get one wing drop in the cource of a 7 g wind up turn. and the fleet pilot is just like whatever and can do it, but the test pilot is all like waa waa. rodney allison is a winey test pilot. thinks the world revolves around his rotor blades.

then there is the real test pilot who can fly anything (ralph kimberlin = mr. golden arm) and then when joe fleet pilot gets ahold of it he cant cut the musterd.

the preformance can be easy or it can be hard, and if the guy is supposed to try to exrtapolate, and at what point are you going to drop from desired to adecuate. maybe the skipper only gets 100 hours a year he is alwyas on the back side of the power curve. "send out a JO so to help me get this started and lets get into the air.

end:
10:11 a.m.

mike moser
he is instructor in the ntps pax river.

10:30 a.m.

mike is a 87 graduate of ntps, georgia tech prior.
been here for fourteen years.

engineer and helicopter his whole career.

he teaches pidot static and helicopter structual flight testing.

he says he has 15 hours of material and he will try to fit it in in five ohour.
so me might not stick to the agenda, but he wants to not miss out on the good stuff.

so the starting point:
intro to rotorcraft stability and control.

rotorcraft is a helicopter

the ultimate goal is to come up with a simple and effecitice model of the aircraft which describes the response of the aircraft to gusts and disturbances and pilot inputs.

ie. flying along at 100-knots and then a gust now the pilot has to move the controls to replace the desired speed.

the control inputs are to conange the state of the aircraft.
you have to traverse the modes of the aircraft to get the sesired mode.
the 90% solution is what we want, if the real high frequency and all like once or twice per second are not importat. if it occurs less often then we will consider that handling qualities.

it needs to be simple and effective, like to decide wether it is to go on to the next point. dont need be able to have to run matlab and what not.
be prepared to make the decisions on the fly as to go on the the next point ...

(white guy, maybe 35 short brown hair, tie, ~210lbs, somewhat muddles voice kinda muddles(not crisp or articulate))

ok, so he uses some overhead slids. move the stick and the aleroons move, and then a roll model.

pedals times the pressure times the tail arm. ...
the point is that in the fixed wing there are direct relation to axises exvept that the vertical axis.

but the helicopter can make a vertical force, can go up. that is why she can be low and over the trees .

this calles six degrees of freesom. the helicoter has direct lift, the aircraft has directed thrust.

the direct lift makes the biggest difference in the two vehicles.

example, when landing the helicopter guys slow down and the airplane guys and climbing the walls.

-this i experience teaching captain chris mills to fly fixed wing.
it was taking a little time to break him of the habbit of deceleration in the foreward direction on landing.-

ther is a thing in the cingle main rotor design called:
penny and farthings, has to do with the british monetray units.

pitching moments are made by lifting the rotor cyclic.
this we will call raising the tip path plane.

-what we will do is model the blades as a plane of blades. this model is pretty good.
if the blades moved alot, then we would have a tip path pringe, but we dont. it is a plane so this is a good model.

the thrust vector is buy definition perpundiclular to this plane. ie. normal to the disk.

the helicopter guys resolver the vector into the two forces or three as the thrust in the up direction and one in the x and y direction. ....

so back to the chart, the pilot makes the motion on the cyclic and then the tip path plane changes, and the line of action of the thrust vector is aft of the cg, and then the aircraft makes a translation.

lateral, the aircraft is flying straight, and the stick moves left, and the tip path plane moves left and the cg then is moves right relative to and then the aircraft makes a translation o the left.

point is that laterral and longitudinal is in the same design and implementaion.
however the yaw axis is different, and the petals change the moment of the blades from drag by increasing and decreasing the horoizontal thrust, ie. anti torque.

the engineers would make this two different functuons, how to balence the rotor torque, and then how to i make desired directional control.

so then the story gets kinda foggy in the low g. (gravity force accel)
do the thrust is a functuion of the down load on the fuselauge, and when the huey and what not , the thrust vector is 4% but in a V-22 it is 11-12% becouse alot of the fow makes forces on the horizontal wing.
t = w, but this approx should be the T= W*Nz. couse in a turn the W is load factor really.

so if the g is 0 in the cocppit then the thrust vector must be zero. so to take this away this makes the controls in the cockpit still makes motion, but there is not a thrust to make the moments, so it needs twice the tip plane motion.
so then if you go to the minus g then the forces go backwards.
ie. no g, stick right = left roll.
also 1/2 g stick must move twice distance for 1 g, and tip moves twice as much.
(mast bump can occur, eeeouch)

so lets talk about the flapping and put the flaps out board of the axis of rotation and this is "offset" so if you move the flapping hinge outboard, and you will have the centripital forces that is really really big, and the moment on the rotor head becomes offset to the axis of the mast, and then there is a giant moment (mh) that makes the head want to tilt.

lets call the offset small e. and is is something like 5% of the overall radius.
enstrum or brantley, i think brantley is not at all.
but again he is militaty so the smallest thing he knows about is a bell 206 or the little bird. maybe a hughes th-55 but he is not that old probably.,

so back to the hub, we can install a hub spring in the tetering rotor craft and you get some resztoring force.

or we can have a rigit rotor system and then we will need the blades themselves to bend.
typical the atwin-zule yankee the comanche etc.
they calle these flex beam rotors. gives rise to the idea of effective offset.

so for effective, if we tilt hte path 1degree, how much offset will i get and how much moment, and what would i have had to have had to get the same offset.

so we will consider geometric offset, smallest number is like 2%, 5% is like h-64 whci is alot, and the biggest is 6.4% which is the h-64E anyhting above the 5 is big.

the v-22 is a gimble with a reasonable stronb hub and it is like capable of 8%/ but usually 1.2% offset.

h-66 is capable of 11% h-66 = comanche

bl-105 = 15% german engineering...

.....
so in one g flight there is some component of the lift that we made what ther eis and if we add offset there is some moient in the tilt vecotr and some from the offset.

rolling moment on the ah-64 apache = 33% is from the lift vector and 67% is from the offset,

kimberlin brings up the brantley now. he says he know nothing except that it has alot of lead lag....

so back to topic... the forces trying to straighten the hub is what translates the aircraft.
if we can do somethign that increases the offset, then we just multiplied (trippled) the controllablity of the aircraft....
pulling up still works as advertised, at all g levels, mashing on the petals blades take a bigger bite, and then .... it works at all g levels.

but the latitudinal control is what reverses at 0 g.

now the twin rotors. ...

they still when collective pulled and then they take the load, neither spin up or down couse of the sync shart, so there is differential collective and cyclic.

so there is two ways to change pitch:
either with varying collective control, or cyclic .
differential collective , when push foreward in cyclic increast thrust on the back and less on the fron. or lift rotor cyclic, and then the thruist vector becomes aft of the cg at trim. and the cg goes foreward then the aircraft will incur a nose down.
(frog and toad h-46 and h-47).

there is a man behind the curtain, ie computer that makes simultaniusly adjust both tip path plane and differential collective.

so then the lateral, well it is the same story as the single rotor ecectpt there are two.
so the torque is the same anyway couse same rpm.

so to make lateral we need differential tip plane path deflection.
step on right pedal back tilts left and fron tilts right.
if you draw it from above and think of moments on the cg then you can see the yawing moment.

so what ARe the chances that the torques are exactly the same, well cource tuning and then there is differential scyclic to balcnce the meonerts.

*** how about low g on the twin rotor.

verticl works, longitudial vbut the cuclic will not work becouse the tilt of trhust would not work but hte lifting collective will make the corrections.
so using the cyclic you can tilt and manuever well at zero g longitudianlly.

so in the lateral direction same problem as the single rotor.

differential cyclic and zero g hmmmmm,.. for yawing . not vecor relying on the tilt, no vector no yaw. so offset?? no couse this is just going to twist the fuselauge.

hold airspeed at zero g, but cannot roll.

ka-50 warewolf has a tradoff design coaxial flight.
big attraction is vertical flight., it is kinda like a two stage compreesor.
if you move alot of mass through a small velocity change you get alot more efficiency.
like harrior = ionnefficent hover, helicopter relatively more effficient.

ka-50 and havock and what not, makes good hover and time to climb and logging and what not. like 0-30kfeet in less than ten minutes.

counter roating always has advanciing blades, but the russian blades does increase and the blade will stall and then if you did have a smart control system then you click out the aoa on the retreating blade, the "ABC sikorsky" and it has jet engines for direct lift, but it lost to the xv-15 couse it was political demonistrator and it only had 45 minutes of gas. so then they guys thought that is used alot of fuel.

note to self: carry alot of gas for demonstrations.

worst thing in coax is blades hitting each other., either make them real strong and stiff. or make then far apart. russian are like 10% of the disk area. but the abc 1970's sikorsky was really really stiff.

so if you pull on sollective on this thing then the blades on the "entire rotor" increase aoa and you get more thrust vector.

same with the cyclic side ot side, the tip lanes tilt and you get a rolling movmebnt...

the ones that are marketed have a couple of precent offset. couse we cannot put them up the middle couse of the other. three blades is just enough offset to getit outboard of the axis of rotation.

ojk directional in coax, ie. yaw. the torque of upper and lower are exual. when you step on the pedals it is rigged to the collectives of both rotors, and in one g flight both rotors power is that the one rotor increases and the other decreases and the torque of the aircraft makes the torque do the turning.
so in zero g, then the average aoa the aoa is zero,m and the pedals are stupid so they do what they are told and the ....
say step left, increase top rotor aoa, and decrease the aoa so they both increase torque due to drag and there is no net torque and there is no control. and at negative g, then the the pedals will reverse the command desired. so control reveral in zero and negative g situations, this is bad couse like in the helix, the tail plane is huge couse when the torque balence speed and in a descenting flight or autorotation there is no torque so the only control you have is a fixed wing rudder.
so there is real problems in engien failures or low power situations. they end up with huge rudders.

******
side by side.
like the v-22 and xv-15 counter rotating and the inboard ones toward you is the direction. the vx-15 has collective just like helicopter "fly by iron" mechanical
v-22 "fly by wire" fadec, the bloddle after harry blot.
so the aero refuling is critical so what you do is do it like an airplane.
do push foreward the fuel dumps in and the collective at same time.

so the they haveissues in engine losss. but whatever.

nr controll all thgouth gas, and the inertia of the blades makes a differenct, the v-22 has much less inertia.

so v-22 push foreward to go up, and increase gas. hard to teach, not so intuitive.

some propoganda to attract the best aviators. hhmmmm. (army guys have issues with "squid")

so the gyroscopioc problems are that they tent to cancel out the stability. and the lateral goes , and when in high gain revert to helicopter training and do the famous crash.

so with this in mind, it takes minimum 20 hours to be able to land the thing vertical.
they train in sims and allmost all crash the first times.

--- lifting rotor cyclic, will increasr the tip lane path and it can be the ((((8% for longitudinal cyclic on v-22 and most the stuff have alot more.

oooww- lets talk about mast bumpin..
that is where the hub hits the mast, 12-14 DEGREES.
there are flapping stops and droop stops, this gives you a little more flexibility and still like 10-12 degrees of tip path. but the hub on the v-22 you get only 8.
bell-222 airwolf has really strong huib spring and it is a teeter,k and it can handle -.5 g's .
alot of effective offset.

so on v-22 to roll, increase collective and or change tip path plane.
the A model had both , LTM and could use the cyclic to tilt tip path, so you could strafe, and go sideways witouth attitude change. and a little sick and get roll movmebnts.
STS system could hold attitude. good for manuevering around the ship, crosswinds etc.
ir suppressors and what not get banged all the time couse of that

so once a guys forgot and compressed hub springs doing it wrong and it burned up the parts and there was no replacement, so the commanding officer said take out the feature.

and they still met hte mission requirments and they never have again returned the strafe ability. and they thing of perf figures, not the stability or control.

"preformance sells aircraft, handling qualities make them classics" -ralph kimberlin

they should have just added spring returns or something but no.
so now some blen of both occur, _roll on deck program official present and saying still adjusting. buzz words DCP and LSG differential collective plates, and Longitudinal slosh grating..
they are still wanign the little jolt when the cyclic moves, not happy again yet....

so lifting rotor if differential tilting cyclic and you get the longitudinal mothing... hmmm, could do differential nacells. (nacelle tilt) if ever tilted wrong it would be bad. so only for manitinence ... so it is possible and it could be bad.

ok the cay-max or and it has angles twin tilting overhead rotors and one transmission. allows the pilot to look out and down. functions as firefighting and logginds.

kaman k-max

has two two teetering rotors and (25degrees off of vertical so loosing 9%) and less transmission makes it ok.
so you can transfer axle and it had alot of change from normal, and it we... lacey has distracted me a little, but there is a poster of the k-max inthe office and it is cool i agree.

some trolley in the transmission and a trolley thing with weight so they had to fix that issue to be fixed.,

so directinal is differential translational for the cyclic, so stepping on the pedals one rotor takes more collective, and at 11% collective and 100 on pull uip, the differental torque reverses and the blades reverse. like when the blades are being driven by the air. the device for the switchover is "liek a hog looking at a wristwatch" all mechanical switchover.

all mechanical. wow. super patented....

11:46
go to lunch and expect instrumentatin at 1:00p.m.

"blade brush and mast bump. misnomer for the plural couse it will only happen once" - rucie "baby love" moore

2004-03-01T07:28:00.000-08:00