Constant Speed Props

[gripen]

Straiga,
Well, you don't have to teach me on this. Basicly all planes with neutral or positive lateral stability need a bit of ailerons (to the bank side) in the level turn. In the case of the laterally unstable plane aileron direction and amount varies depending on case.

gripen

[GScholz]

Originally posted by hitech
So why do they put the twist in the wings if not to counter engine torque?

I was thought that the wing twist was for giving the pilot some advance stall warning. The inner part of the wing would stall first, but since the wing is twisted the outer part (with the ailerons) still has normal airflow. Engine torque is countered by mounting the vertical stabiliser at an angle, usually set to cruising speed.

[HoHun]

Hi Straiga,

>I think computers pilots would be worse to teach. They already know everything and they wanna be a pilot, but the only way they will know how to fly is from the computer, which most airplane sims are about 60 percent accurate from the way an real airplane flys.

Gripen knows his stuff, and while he might be wrong, you should be able to point out exactly why. CFIing an internet discussion platform requires a rather different approach than CFIing in an aircraft.

And be prepared to be precise - inaccurate statements like those you made on constant speed propellers won't score you any credibility points with us wannabes.

Regards,

Henning (HoHun)

[Batz]

lol HoHun

[hitech]

Straiga: You are incorect about teaching computer pilots. Especialy those coming from somthing like AH. The instincts of how the plane reacts, especialy at departure time, are already all built in.  They just need to be translated to a different enviorment.
And being one of those guys who first flew RC's and computers, then when on to flying the real stuff. I was cleared to solo at 3.5 hours.

When I started my areobatic training, instructor was amazed how easy it was for me to fly only looking out the side of the plane, this was simple for me, because ive spent lots of hours with that same sight picture in combat sims.

In general i've found that most pilots and CFI's have only a very limited understanding of the physics of flight. The only exceptions ive seen to this are when they have an engerining back ground, and study the physics of flight. Generaly they recite what they have been taught, and don't think about why it works that way, hence come to incorect conclusions.

GScholz: Your refering to washout. wingtwist is more or less incidence on left or right wing.

The rudder incidence is primarly for slipstream effects. Hence why I said early on in this disccusion, if your talking the general term "Torque" you can't have a physics discussion. You need to referer to which 1 of the 4 components your speeking of. And while rudder is used to correct the left turning tendency of a prop plane, that effect is not caused by engine torque, but by the 3 other effects.


HiTech

[GScholz]

Ok, I kind of knew it couldn't be that simple.

[Straiga]

What I have been saying all along is I find that AH and there aerodynamic modeling is close but when it comes to use of ailerons and aileron trim for torgue controll is totally inaccurate.  You shouldnt have to trim aileron on an airplane trough all airspeed changes this is incorrect I dont do that in the real world, except for pitch trim, for every power change and pitch change you need trim change. I have flown alot of different airplanes in my 30 years of flying singles, multis, turbo props, jets, helicopters

 We all know the left turning tendancies Torgue, Prop slip stream, P-Factor, Gyro-procession but there are others to force we have to tend to adverse yaw, preverse yaw, cross wind take off, asymmetrical power, and spin recovery. In addition to directional stability, the airplane must have adequate directional control to cordinate turns, balance power effects, create sideslip, balance unsymmetrical power, etc. The principal source of directional control is is the rudder and the rudder must be capable of producing sufficient yawing moment for the critical conditions of flight.

Gripen,
 If you know airplanes, it would roll more into a turn than roll out of a turn by itself, its called over banking.
 As you enter a turn and increase the angle of bank, you notice the tendancy of the airplane to continue rolling into a steeper bank, even though you neutralized the ailerons. This overbanking tendency is caused by additional lift on the outside, or raised wing. Since the outside wing is traveling faster than the inside wing, it produces more lift and the airplane tends to roll beyond the desired bank angle. To correct for overbanking for overbanking tendency, you can use small amount of opposite aileron, away from the turn , to maintain your desired bank angle.

GScholz,
 You are correct about the vertical stab countering torgue. Wing twist is because of airleron deflection or excessive airspeed. This does nothing to counter togue. Some planes move the airlerons inboard to prevent twist. In excessive speed cituation the plane will roll opposite in the direction of the airleron deflection. The B-2 bomber uses wing  twist and drag flap to stabilize about the yaw moment.

[Pyro]

To isolate torque from P-factor, slipstream, and gyroscopic effects, remove the prop from the plane and have the shaft terminate into a brake.  Without the prop and therefore those other effects, you will see what direction the effect of torque has on a plane.  Do you think a plane in that test configuration would try to yaw left or try to roll left?  Or put another way, when you're driving screws with a drill, what does the drill do?  Rotate or yaw?

[Widewing]

Originally posted by Pyro
To isolate torque from P-factor, slipstream, and gyroscopic effects, remove the prop from the plane and have the shaft terminate into a brake.  Without the prop and therefore those other effects, you will see what direction the effect of torque has on a plane.  Do you think a plane in that test configuration would try to yaw left or try to roll left?  Or put another way, when you're driving screws with a drill, what does the drill do?  Rotate or yaw?

Newton's third law of motion....


My regards,

Widewing

[Straiga]

Hitech,
 I do have an engineering degree in aeronautics. I soloed in 3.5 hrs too in a airplane and also in a helicopter I recieved my RotorCraft rating at 40 hrs. I started flying when I was 14 I wasnt legal when I was soloed but when your dads own the airport with no feds around I didnt care. I had 376 hrs by the time I recieved my private pilot certificate this was because of my age, at the same time I took my Instrument and Commercial licences at 17. My CFI at 19 and ATP at 21.
 You ask one time who my flight instructors where My first instructor was my dad a retired two star general USAF with 105 missions over north vietnam in the F-105D ThunderChief. Every aircraft he flew in the air force, he was an instructor in. He flew T-6, P-51,T-33, F-86, F-84, F-100, F-105, F-111 and F-16, my next flight instructor was mys dads partner in the airport he was a retired Col USAF he had 100 missions over vietnam he flew the F-4 Phantom II. I have also had about 20 different flight instructors between the military and civialian flying for different ratings and type training.
 If you were  wondering were the airport was it was KRKR  Robert S. Kerr airport in Poteau OK about 30 miles south west of Ft.Smith Arkansas, we moved there from Las Vegas when my dad retired from Nellis.
 I been flying for 30 yrs, I probabley have more logged instructor time then most pilots have total time. I have over 7,000 hrs rotor time  alone 1/3 of that as an instructor. The only ratings I dont have is float plane, glider, tiltrotor, hot air baloon, but there next when I get time.
 So I think I may know something about aerodynamics not just in theory but in practical military and commercial flying, but talking in general about a subject matter I shouldnt have done, I should be more on the point. My wife says I talk over peoples heads because Im so technical when I talk, so I try not to do that anymore.
 
I also fly RC helicopters and airplanes and computer sims PC and military and FAA approve class sims.

 I cant think that you use ailerons to counter torgue in your RV-8 on takeoff or in any other flight manuever. I have RV-8 time too I just use rudder.

HoHun,
 Sorry I didnt want to talk over you head.

[hitech]

Ill tell ya what straiga how about you stop draging other things in to the basic question at hand, and try to describe how a rudder counteracts torque. Wrather than just continuing to state that it does. Because the more you say on the subject, things like

I cant think that you use ailerons to counter torgue in your RV-8 on takeoff or in any other flight manuever. I have RV-8 time too I just use rudder

makes me think you can't seperate the forces in your mind. Because you do NOT use rudder to counter engine torque. When the plane is on the ground the wheels do a fine and dandy job of opposing engine torque.

The yaw forces at take off are NOT produced by engine torque. Engine torque produces a roll , and what plane control is best for makeing a plane roll.


HiTech

[RTR]

WhooHoo!
sign me up for the Free Office Tour!

I have $20.00 (although Canadian) burning a hole in me pocket!

As for the rest of the discussion, us real Peelots buzz around in Helicopters

RTR

[gripen]

Straiga,
The speed difference between wingtips in the WWII fighters is not really a factor . As an example the Spitfire I (real plane in the real world test by RAE) could do continous 2,65g level turn (angle of bank 68deg) with 696ft turning radius. Due to angle of bank the speed difference between wing tips is very very small if compared to rolling moment due to turning. Basicly if we assume correct piloting technique ie the rudder is just used to keep "the ball in the middle", then "overbanking" (or what ever) can't happen in the laterally neutral or positively stable  WWII fighter (that covers probably more than 90%of them) . In practice I have seen this phenomena (in sailplanes) only in very slow speed turns which are in yaw due to wrong piloting technique (too much rudder).

gripen

[HoHun]

Hi Straiga,

>Sorry I didnt want to talk over you head.

Don't worry, my head might be a bit low but I can still follow fine.

I'm sure this is not over your head, but you seem to have missed it anyhow: The Spitfire manual puts a limitation on the boost to be used for the constant speed propeller to function in the way you described, while you maintained a constant speed propeller would be able to regulate speed under all circumstances.

A bit more attention to detail, both with regard to technology and with regard to the posts you're referring to, and you will do great on this forum.

Regards,

Henning (HoHun)

[gripen]

Because here seems to be a lot people with RC background then a good way to demonstrate engine tourque is to hover plane and make it to roll using tourque.  During hovering the only way to counter tourque is ailerons.

gripen