Constant speed or constant attitude?

Martin,=20

I just can't resist a good argument.

Sorry, but your vector diagram as described gives AOA with sign =
reversed.

On encountering a rising airmass from stabilized flight, the =
instantaneous effect is an increase in AOA - the relative wind that was =
flowing from straight ahead is now flowing from ahead and below. This =
increase in AOA gives added lift at the wing and reduced pushdown at the =
tail. Since the CG is ahead of both CL and tail, both give a nosedown =
moment. The aircraft attitude is disturbed and it pitches nosedown.

Now the inherent stability starts to work through a series of =
transients. The pitch down reduces the AOA and the aircraft accelerates =
because the gravity vector is closer to where the nose is now pointing. =
The reduced AOA and the increased drag gradually restore the aircraft to =
its original stable attitude [maybe after a few oscillations, it is far =
from a deadbeat system] and sink rate through the airmass. The final =
result is an aircraft flying at exactly the same attitude, speed, L/D =
etc in the new airmass, but with a sink rate relative to the ground =
equal to the old value less the upward velocity of the new airmass.

Agree with your conclusion, just can't help nitpicking the argument..

Going back to the original question, whether to fly constant speed or =
constant attitude, both are difficult to achieve when hit by a gust. =
But if you are skilful enough to stop the nose drop then your attitude =
will remain constant and your speed will also be constant if the gust is =
vertical. If the gust is horizontal, there wil be relatively little =
change in AOA but an increase/decrease in total energy will be reflected =
in the vario and your airspeed will change. Holding attitude will let =
the aircraft stabilize itself, but trying to regain airspeed is a better =
bet. If the gust gives a speed increase, a little nose up will turn =
your inertia into more altitude sooner, and if the gust gives a speed =
decrease you might want to nose down a little to avoid a wind-shear =
stall situation.

In my case, gusts are always some unknown combination of vertical and =
horizontal, and my reactions are too slow to hold anything truly =
constant...

Ian