Just out playing--no canyons..up high...I know get a qualified CFI.....read POH-Ha!!!
there all disclaimers out of the way
mxt-180 0-360
flying along--slow cruise--say70-80kias--I tried to have20' flaps in,begin steep ,up to60degrees,turn,add power--seemed to be a pretty tight turn--actually it felt like I was almost standing still, but the ground I referenced looked to use less than about 2000 feet "canyon width" Would full flaps be better/worse? I think I'll have a CFI along for any steeper turn, atleast the first few times
thanks
mark

Generally speaking, the slower the airspeed at the same bank angle will yield a tighter turn radius. Just be careful of an accelerated stall.

MAF (Mission Aviation Fellowship) used to demonstrate a box-canyon turn in a C-185 that looked like they just stopped the plane and reversed directions in less than 200 feet. From the ground, their technique look like it was this:
1. Cruising along at about 120 mph (like up the canyon looking for a way thru...
2. Chop the throttle simultaneously then...
3. 30 deg of flaps followed immediately by...
4. Turn like hell, then...
5. Full throttle at the 3/4 way point around
6. Then clean-up the airplane..
7. If this was a real condition, clean out your shorts.

Whole maneuver took less than 7 seconds to got from 120, turn, and back to 120 and it was pretty violent.

I have never tried this technique, but it looks like fun... In someone else's airplane.

CHEERS!

I had an opportunity to spend several hours with Amy Hoover in my plane several years ago. She emphasized the conditions and demonstrated how to do it. We spent quite a bit of time on it. The first one she did and it was a very un-natural manuver for your plane to make. Your discription is pretty much on, violent, standing still, reversed direction.
In the Peril it was one notch of flaps at about 70mph, roll the airleron and full rudder and pull full flaps and full power, clean the plane up. Done right, you won't lose any altitude and you'll regain your speed almost immediately. I belive it to be much safer than some other manuvers suggested in the past. 120mph seems pretty fast though, there's a lot of stress in doing this. It's been a while since I've practiced it, haven't had a need to really.

what about a simple wingover?

pull up, slow down, about 90 degree bank, drop nose, accel back to cruise

Wasn't the chandelle the design maneuver for this?
I was taught the same one YELLOWMAULE describes. It's basically a modified chandelle, anyway.

At OSH last year, the chief pilot for MAF (he runs the transition course in Idaho for new MAF pilots) taught a seminar on this exact subject. MAF does not support wing-overs, chandelles, etc. because of past bad experiences with things like this.

MAF teaches the following techniques:
1. All exit maneuvers are flown level.
2. When flying up a box canyon, always give yourself a 100% margin to turn around. That is, don't fly up a box canyon that will require more than one-half the width of the canyon to reverse course.
3. Go into a box canyon configured to turn around. Thus, 80 knots for a C-206, departure flaps. Speed has a geometric effect on turn radius, so don't fly box canyons at cruise speeds.
4. Test the canyon. Make a turn-around and see if less than half the canyon width was used. If so, continue on further. If more than one-half the canyon width was used, go home and come back another day.
5. Make all turns with 45 degrees bank, level, and full throttle in the turn.
6. Only fly on one side of the canyon--always the upslope side.
7. Never go thru a pass while climbing, for you can't see what's on the other side. Always climb first, then approach the pass level.

MAF's preference is, weather permitting, to fly to a strip above the peaks, then spiral down to land. Flying up box canyons is done only when clouds force it.

I'm a flatlander, but found these to be "rules to live by." MAF has developed these techniques from decades of bad experiences, crashes and lost lives. He said deviate from them at your own peril.

TK & Rocketman - for us lowlanders the chandelle or wingover works just fine but the the issue with the chandelle or wingover is that you have to be able to climb or lose altitude in order for execute the manuvers. In the real mountains out west you may not have the altitude available to lose and you may not have the power left with which to climb...if you could out climb the terrain then there would be no reason for the course reversal. Take your Maule up to between 8,000 and 10,000 feet and see how well that chandelle works.

With the canyon or box turn as described above it can be done without the gain or loss of altitude and with a minimum use of real estate.

Good point Bob, Especially #7.
Amy stressed level manuevers and keeping to the one side (usually the right) side of the canyon wall. If wind was a consideration, you shouldn't be there anyway.
When she first decribed what the manuever was, I was dubious, demonstrated, I was amazed that I could turn in such a tight area with such control.

The way people usually get into trouble in box canyons is something along these lines, the floor is increasing in altitude faster than you can climb and the walls are narrowing.
By the time most realize that something other than continuing straight ahead must be done, they are almost always at full power, best rate or angle climb speed and that does not give them a climb gradient that will get them over the top of the end of the canyon.
There is no increasing power, they are already there, and high airspeeds like 120 isn't happening either.
You either make the turn before most realize they are in trouble, or you smite the ground.
There is nothing at all wrong with making the turn early, continuing to climb and turning to go back up the canyon when you have enough altitude to make it.

A64 is absolutely right, and a lot of times by the time the turn in initiated, the airspeed is well below best angle while trying to clear terrain, the turn is initiated just above stall, and now you're in big trouble. Bottom line is do not fly up unknown canyons or mountain terrain low level unless you are very familiar with the particular canyon. Also remember that lots of canyons references look different with low overcast then VFR as the clouds are now covering your waypoints. There have been an awful lot of very good high time pilots up here in this area who missed the opportunity to turn back or didn't properly identify the canyon they were turning up due to limited VIS and......