Fight control systems with respect to adverse yaw

[Zhuntar]

Hi I am writing a paper on the phenomenon of adverse yaw and different methods of yountering it. I know that the wright flyer had a wing morphing flight control system mechanically linked to the rudder to counter act the yawing motion, any more information on how the system worked?
Also if possible I was told that the Cessna 152's and the de Havilland Tiger Moth also have a mechansim to counter adverse yaw would you have any more info about the effect and the methods used to counter act it would be very helpful.
Thanks in advance
Alex

[supermunk]

Gliders are more susceptable to adverse yaw by virtue of long wingspans and ailerons well out on the wing. Adverse yaw is mainly produced by the fact that if you have more lift, you have more drag. One way to get around this is to have differential ailerons where the upgoing aileron goes up more than the downgoing aileron thus producing more drag and hopefully equalising the excess drag produced by more lift produced by the downgoing one. Glider pilots have to use their feet wheras in most powered aircraft the rudder bar is mainly for steering on the ground and resting your feet on

[HPSOV]

As stated in the previous response adverse yaw is caused by the downgoing aileron creating more drag than the upgoing one, causing you to yaw away from the direction of the turn.
The C152 has what are known as frise ailerons. The ailerons are hinged so that the leading egde of the upgoing one will protrude into the airflow on the bottom surface of the wing, thus creating drag to counter the drag created by the downgoing aileron.
The Tiger Moth has a system (dont know what it is called) where the downgoing aileron reaches its most displaced point at about 3/4 of control stick travel. If you move the control stick more the upgoing one keeps going up, but the downgoing one will also start to come back up. The theory here is to limit the adverse yaw when it would be at its worst, that is at full control deflection.
Hope that helps!

[mustafagander]

The system on the beloved Tiger is called differential ailerons. It's beautifully simple - the aileron control rod from wing to aileron is mounted on a plate that rotates in the horizontal plane with stick deflection. It can be easily imagined that where the rod attaches to the plate controls deflection and, yes, it does reverse the downgoing aileron at large stick deflections. Still need feet though!!!

BTW One of the reasons big jets tend to use spoilers for roll control is to counter this effect.

[This message has been edited by mustafagander (edited 02 October 2000).]

[Checkboard]

Some aircraft, such as the Piper Navajo also have an aileron - rudder spring interconect.

[Genghis the Engineer]

Go and read Darrol Stinton's "flying qualities and flight testing of the aeroplane". If there's a possibly aerodynamic fudge available that Dr Stinton hasn't documented I should be surprised.

G

[This message has been edited by Genghis the Engineer (edited 02 October 2000).]

[Dan Winterland]

Some autopilot systems have a small rudder input with ailerons. For example, my jet, the VC10 does. The Tristar doesn't. When we are taking fuel from a Tristar, on rolling into a turn we appear to move out to the outside of the turn. The effort of getting back onto the centreline isn't worth it, as when established in the turn, we appear to move out to the other side. We don't have this problem when taking fuel from the VC10.

I don't know about more modern systems. I should think that Airbus have programmed something into the electronic trickery of their Fly By Wire systems. Anyone else know?

[This message has been edited by Dan Winterland (edited 02 October 2000).]