Backpacker - that seems pretty clear. Max roll rate to 60 degrees of bank, pull to get 2g, as soon as you're in the white arc dump full flap, keep pulling whilst letting the airspeed bleed until you're in the buffet and/or stall warner, then keep pulling to JUST stay on the edge of the buffet.
Actually I would say "max roll rate to at least 60 degrees of bank, then pull to the buffet." 2g is very hard to measure without a g meter and without aerobatics experience. But in addition to that, why would you limit yourself to 2g when the aircraft might be capable of pulling more G's, thus making the turn radius smaller?
Furthermore, why full flaps? As you rightly say, most aircraft will not have the excess thrust available to sustain these kinds of max rate turns, and they will bleed speed quickly despite full power. By using full flaps you are just adding to the drag, making the problem worse. I would personally use half flaps, to augment the lift and reduce the stall speed without a heavy drag penalty.
But to be honest, in a 60-degree plus banked turn everything happens so incredibly quickly that you will not have time to monitor the ASI and pick the right moment to select the proper amount of flaps. By the time you are actually pulling to the buffet you've probably already done the first 90 degree of your turn, and your focus should be on maintaining the buffet, and thinking about rolling out at the right moment.
Back to the subject.
The turn radius of a 172 at 70kt with 2 stages of flap is quite tight. A good plan is to practice this at a safe level and form a view of what you can, and can't do. The idea of an average pilot/rental aircraft combination performing any other kind of manoevre in a canyon is in my view fantasy.
In real life, many canyons climb faster than the aircraft and it will be reducing terrain clearance, rather than a sheer end wall which will most likely trigger a turn back. The temptation to climb out 633 squadron style can lead to surprisingly close encounters with the rim, partly because of sinking air but mostly to do with the false perspective. As you approach the end of a canyon you have no horizon reference and are probably already in a climb attitude as you inadvertantly raise the nose to make the picture look right. So your facility for an improved rate of climb is already diminished. Always try to visualise where the horizon would be projected against the walls as you fly into a canyon.
When you do turn back, there may be plenty of room but beware falling air. The shadowed side of the canyon will be cooler and air will be descending, which is why it's always better to fly up the shadowed side and have the option of turning into rising air. But an even bigger reason not to turn toward the shadowed side of a canyon is the way that pinnacles can hide in the shadows, because your vision has limited depth perception in the lower light.
Of course canyons hold other hazards, including cables and cabins with livestock. And great big birds that can attack you (Yes, really, in a Cessna!). There are far less unpopulated canyons in the SW USA than when I started flying there in the '70s. In those days, we were allowed into the Canyon of the Little Colorado at Cameron, Arizona and could follow it almost to rim of the big one. Not any more, but what you can do is to land in the Grand Canyon at the Marble Canyon airstrip South of Page, Arizona. Don't let me or anyone else put you off the exhilaration of canyon flying. Just do it downhill and watch out for National Park and similar land where there are 'requested' or mandatory restrictions.
The temptation to climb out 633 squadron style ...
End even they get it wrong sometimes. Like the German Tornado that crashed into the "Lauterbrunnen Wall" in Switzterland in 2007 while trying to climb out the steep slope (http://en.wikipedia.org/wiki/Lauterbrunnen_Wall).
As you approach the end of a canyon you have no horizon reference ...
But also bear in mind that you will have no horizon reference when doing your steep turn inside the valley! Without instrument flying experience it is almost impossible to fly a level 60° banked turn with only sloping valley sides as reference. And even on instruments it is demanding as 60° of bank is far inside the "unusual attitudes" range that normal pilots never see - even the steep turns flown during checkrides don't exceed 45 degrees.
I was directly involved with the modification, testing and training for a Cessna 207 used for atmospheric research. The pilot who flew this aircraft "on the job" got it wrong. The accident investigation does not tell us much that we don't already know, but is interesting reading.
Oh, and chandelles in a 182RG!!! 'Been there, done that, should not have... It flies them beautifully, but it sure speeds up fast coming out the other side.
Pilot DAR, what happened in the 182? I can't see how you would end up nose down at high speed exiting a chandelle? Or did you mean wingover or stall turn?
Perhaps uncautiously aggressive chandelle.....
At normal cruise speed, pull up until you get close to stall speed, then full rudder and aileron in the desired direction
Isn't that how to do a flick roll?
These Youtube videos all have a non-emergency turn in a valley, usually using half the valley. When going close to the side, it's important to be aware a downdraft could turn you into the wall.
It almost looks like he is doing descending turns there, but I can't tell...
Regarding the use of flaps to facilitate the turn – flaps of course reduce the stall speed but the secondary effect is they reduce the Va (nothing to do with strength of flaps or supporting structure)
