Bf 109 rudder physics explained

[Anatta]

A while ago we had a thread about the rudder of the Bf 109 and how left rudder had to be constantly applied in combat. To do a short summary for those who don't know: The Bf 109 doesn't have a rudder trim. It is set up in a way so that it flies straight without rudder input at about 400 km/h. Under that you need to apply right, above you need to apply left rudder to go straight.

 

Now, in the thread I mentioned, I wrongly claimed that I think I don't feel much of this in combat. This weekend it turns out I just was overcorrecting to the left with the stick (which made aiming harder than using rudder btw), but only when pulling it back. And this goes for speed under 400 km/h, where I usually have to apply right instead of left rudder. So here is the question I cannot answer myself:

 

Why is it that under 400 km/h (or lets say even lower like 250) I usually have to apply right rudder (which I understand), but as soon as I pull the stick back, the plane rotates to the right, makeing me apply constant left rudder (how it supposedly was in RL).

 

I tested this extensively and am pretty shure it behaves likes this, or is it in my mind after all? If no, a physical explanation would be great.

[HansHansen]

Gyroscopic precession is the word you are looking for.

 

The propeller basically acts as a big gyroscope. If you pull on the stick, the gyroscopic precession pushes the nose to the right, so you have to compensate with left rudder.

Edited December 16, 2013 by HansHansen

[216th_Jordan]

you mean as you pull up?

 

that has something to do with centripetal force and inertia, i cannot exactely describe it to you so that it is understandable, but with some research and graphics it will become evident.

 

it is about your propeller spinning in front of the airplane and your change of attitude of the plane. if the propeller spins right and you pull the plane up the plane should move right a little (if i didn't confuse directons here..)

 

 

look at this video and think that the weight would be your prop.

https://www.youtube.com/watch?v=lz5Wy3FCEsE

Edited December 16, 2013 by Jordan

[Georgio]

Get hold of a decent toy gyroscope, spin it up and try moving it up/down and left/right, multiply that by about a thousand and there's your problem... :D

[216th_Jordan]

Umm...well the effects described above are not the only force that apply in that process, there is also the "p-factor" http://en.wikipedia.org/wiki/P-factor