FT, GP not that much a factor, torque not much a factor, difference in lift of wings is why plane rolls, its about the amount of each ailerons deflection rate.

Rama, what do you mean by " heavy aileron " ?

Reasons why you need rudder in an established turn:

1. Even when banked over and ailerons neutralised*, the outer wing will be going faster than the inner one because of it's larger radius of curvature. It will therefore generate more lift and more drag. This will tend to i) further increase the angle of bank as the outer wing generates more lift than the inner one, and ii) simultaneously tend to yaw the nose out of the turn because of the extra drag on the outer wing. At high angles of bank, the yaw will increasingly have the effect of raising the nose because of the bank. In the extreme case of a 90 degree bank, yawing will only raise of lower the nose above the horizon. The tendency to increase the bank, tightening the turn, generating even more unequal lift and so further tightening the turn is know as spiral instability. It means that without corrective action the turn will evolve into a spiral dive.

2. The "long tail" effect, where in a tight turn, the airflow will hit the fin at a slight angle, even though the wings are aligned with their long axis pointing to the centre of the turn. Because of the geometry, this "push" on the fin also acts to yaw the nose out of the turn.

The result is that into-turn rudder is required to compensate, even when established in a turn. These effects are particularly noticeable with gliders because they can make very tight turns and have long wing spans compared to the possible radius of the turn. In a tight thermalling turn, a glider can often be in a 45 degree bank. The pilot will be applying into-turn rudder to stop the nose yawing outwards, back elevator to hold the turn and slight opposite aileron to oppose the spiral instability. The turn is thus flown with the controls slightly crossed (ailerons and rudder in opposite direction). The effects are reduced for powered aircraft because the wingspan is usually much smaller and the tail much shorter in comparison to the radius of the turn.

In RoF, I often find myself flying the Dolphin with crossed controls in steep, slow turns. I'm not sure if it's just habit from glider flying, or if the FM really rewards that type of turn.

Cheers,

RD.

* A very stable aircraft may require continual into-turn aileron input to overcome its natural tendency to self right, e.g., model aircraft with a lot of dihedral are very stable. If ailerons were fitted to such a wing, it would require continual aileron deflection to maintain a constant angle of bank.

Ailerons you need strong muscles to move...

@Rocketdog
There are also other reasons (as the one I raised for after-CoG airplanes)

Sorry, not sure I agree. The CoG position impacts required elevator trim and susceptibility to spinning. I don't see why it would have any effect on the rudder inputs required in coordinated turns. Always open to being corrected!

Cheers,

RD.

The only plane I need strong muscles to move was the Lockheed 12A Electra Junior I flew. That one you needed both hands on the wheel to roll. In the Dr.1 and D.vIII I flew, one hand, with a like touch. .... maybe a Gotha?

Hello Womenfly2,

you wrote:



But i thought all ailerons are differential ? I mean pushing the stick to the right lifts the right, and pushes down the left aileron (and vice versa) ?

There comes a second question to my mind - i am still researching the Otto pusher biplane in german East-Africa in 1914/15, and on the photos i have, both ailerons (only the upper wings have them) are hanging down, when the plane is not in flight. Are they uncoupled from the stick for keeping the control cables from lengthening while on ground, or is there some strange other reason ? Can it be they also "hang" in flight, and are only upheld by the wind ? But how would you bank with this kind of arrangement ? I would really like to solve this

Thanks and greetings,
Catfish

CF, look up the difference between the two, differential & non-differential.

Hello WF2,
thanks, for anyone else who wants to know it:

http://en.wikipedia.org/wiki/Aileron#Differential_Ailerons
and
http://en.wikipedia.org/wiki/Adverse_yaw

Still remains the Otto/Pfalz biplane hanging ailerons. I have seen this with a lot of early planes though ..

Greetings,
Catfish

Some ailerons are rigged trailing edge down to increase camber and maximum lift, and also to enhance initial response to deflection. The downside is increased adverse yaw.

differential ailerons mean that they are cammed or set so they will go up more than down...I use them on all my rc planes,,give much better control. Non diff means they go up and down equally.

Up aileron is like a spoiler on a glider, spoils the air, down aileron is drag. The P-61 Black Widow did not use ailerons at first, just spoilers to to turn but test pilots were nervous about this so production models had small ailerons fitted to the wing ends.