"Julian Scarfe" wrote:
There's a great deal of debate in this part of the world at least on the
issue of which control to use to pick up a dropped wing.

http://www.pprune.org/forums/showthr...threadid=75116

"Roy Smith" wrote in message
...
To be honest, I don't see much debate in that thread. Sounds like
pretty much everybody is saying the same thing I am -- that rudder is
the right thing to use to recover from a wing drop during a stall.

Really?

"As for rudders - I teach - rudder to STOP yaw. Not to pick the wing up...."

"I taught stall recoveries as:
Centralise aileron
Rudder to stop *further* yaw (NOT raise the wing NOR prevent further wing
drop)
Reduce AoA eg to ~ glide attitude
...."

"I have found that teaching the stude to use rudder at the stall to 'limit
further wingdrop' can actually lead to 'EXCESSIVE AND OVER ENTHUSIASTIC'
opposite rudder.......leading to SPIN!"

All three of those correspondents seem to oppose the idea of the use of
rudder for roll control.

I've not really thought fully through the arguments.
Is yours simply about control authority or is there more to it than
that?
Perhaps we should take this one out of .ifr?

Yup, control authority. That's pretty much it. The rudder has control
authority over a much wider range of conditions than the ailerons do.
When things are happening fast, you want to have a plan that always
works, without having to put any thought into it. Hence, my
recommendation to use the rudder to maintain heading.

I'm not convinced by that. I can see two arguments against it:

1) The use of rudder for roll control works as a secondary effect of yaw.
At speeds approaching stall, that yaw can make the difference between
spinning or not. (Of course, so can an abrupt aileron input :-))

2) In any control loop the timing of the effect of control inputs has a
significant impact and an unhelpful lag can lead to divergence. Thomas wrote
in his original post:

"Now using the rudder to turn, the airplane takes a while
to respond. With the constant upsetting influence of the thermals, the
plane is always wanting to turn. You see it on the GPS, and by the time
you get some rudder pressure on, you are maybe 10 to the right. Now
you hold the rudder and wait for the plane to respond, and slowly you
come back on course, but overshoot. I try to adjust my inputs to smooth
things out but the TB makes it pointless. I resign myself to the fact that
at best we will make constant small s-turns all the way."

That wouldn't happen with the ailerons.

Julian Scarfe