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The University of Tennessee Space Institute Hoasts Patuxant River Naval Test Pilot School

Thursday, March 25, 2004

The University of Tennessee Space Institute

aerial photography by test pilots miller wilder and daniel lehman

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.

UTSI tullahoma airport facility

Thursday, March 11, 2004

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.

Wednesday, March 10, 2004

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.
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

Tuesday, March 09, 2004

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...



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

Monday, March 08, 2004

NTPS f4 skyhawk

Dr. Kimberlin with his new book

Order your copy right now online!

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.

Sunday, March 07, 2004


tilting the rotor system into a full hover after while

what a cool air vehile

Saturday, March 06, 2004

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.

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