An Immelmann in a situation where turbulence is possible, and accuracy is essential? I’ve little aerobatic experience, and none at low level, nor in turbulence. Not something I’d try.
I’ve often done turns in glacial valleys, often encountering turbulence.
Climb close to chosen side, allow speed to reduce, bank and let nose drop. Pull out as speed increases, not pulling much G. As Adam said earlier.
What’s wrong with an Immelmann in a sunny valley with orographic turbulence, high density altitude and not enough engine power to pull you from straight & level up through the top of the loop… yeah I really don’t see what could go wrong there in fact. @LeSving maybe you want to post a video of you doing it to illustrate?
You are thinking too much Mk2. It’s not engine power that pulls you up in a loop, it’s speed. Orographic turbulence – the aircraft has no idea what kind of turbulence it is, and doesn’t care. I don’t have a GoPro, and never have, but maybe I can find some glider videos with loops from ENOP. No engine power at all and doing loops in the middle of “orographic turbulence”.
Seems to me everybody are thinking too much. The main “rule” of mountain flying is don’t hit the mountains. Otherwise it is simply business as usual, only energy and wind management is more important than in the flatlands. You make turns in the usual way, just remember the main rule. If you happen to bump into a situation where you cannot make a normal turn, but need to make a turn nonetheless, and this isn’t planned up front, then this is an emergency situation. You are in deep shit in fact, caused by bad planning and poor airmanship, some call it bad luck though. Anyway, in such situations you do whatever the aircraft is capable of doing to get you out. If that is an immelmann or a hammerhead or whatever, who cares? If the aircraft has a BRS, then this is the time to use it, if you have the alt.
We have to distinguish between solid aerobatic pilots in RV-8s and the regular guy who flies his family in his C-172.
In the RV-8 you could do a „half reverse cuban eight“ to reverse the course … or one of those extreme bush flying maneuvers, the most extreme one being a box canyon turn where you simply turn the plane around on the spot: full flaps before the stall, full left rudder and full power. Was shiwn to me by a professional bush pilot in a 300 hp Cub. But you don‘t recommend that stuff to „normal“ pilots.
Fly on the safer side of the valley, do not wait too long and until the valley gets too narrow to turn. Slow down, 10 flaps and fly a safe steep turn. If more bank is necessary lower the wing loading by descending in the turn. This will work for any but the most narrow valley.
When i was 12 yo my father flew into a dangerous box canyon in Austria, too narrow to turn and made an unannounced emergency landing on a military grass strip. He was greeted by soldiers who only relaxed when they found out that the base commander was some distant Austrian relative. He got some fuel from them and he took of in the other direction. Guess how many times i had to listen to that story :-) But that was the Seventies …
