Your post got me reading this:
https://www.aopa.org/news-and-media/all-news/2000/may/pilot/loops-spins-and-rolls
particularly this part:
"This unit consists of a discussion of wake turbulence—its cause and effects—with briefing on recovery procedures. The half-slow-roll (crossed-control initially) recovery is not taught. Instead, the aileron-and-rudder-together method of rolling is taught, as would likely be used by a pilot in an inverted position to get back upright—and damn the resulting heading. (Few would have the presence of mind to cross-control under the stress of a real upset unless they were experienced acro pilots.)"
Is this the non-intuitive action you were speaking of? This is somewhat confusing to me, because isn't the 2nd half of a slow roll (from inverted to upright) done with aileron and rudder in the same direction(both left or right)? And the second half would be the upset recovery portion right? I'm not an acrobatic pilot btw. Just curious. Maybe the author was just saying they don't teach the first half of the slow roll I guess.
Thanks.
Well, as a quick review of aerobatic technique, there are 2 methods of rolling (3 if you count the barrel roll, which isn't a roll, but I digress). First is the aileron roll, which is not a competition maneuver. This is a roll performed using aileron only. Elevator and rudder remain neutral. Because no control inputs are used to counteract reduced lift during knife edge and inverted flight, the nose drops and results in a dive at the end. To avoid finishing in a steep dive, the maneuver is commonly flown by pitching the nose up to 20 or 30 degrees. The slower the roll rate, the more you need to pitch up.
The other type of roll is a slow roll, which is a competition maneuver and has standard judging criteria. Note the name has nothing to do with the speed or roll rate at which the maneuver is performed. In a slow roll, the objective is to draw a straight line through the sky, eg level flight with no deviation in heading. To do so, you must constantly vary the rudder and elevator inputs to counteract for the effects of reduced lift and adverse yaw.
The diagram below will help explain the sequence of control inputs, though the description is a bit wonky because the picture depicts a roll to the right instead of the more common left roll in western aircraft.
From position 1, you start with slight right rudder to counteract adverse yaw, then increasing amounts of left rudder. At position 2 you will have a large amount of left rudder deflection to generate lift using the side of the fuselage in knife edge flight. From 2 to 3 you continue with left rudder and add forward stick to generate lift in inverted flight. From 3 to 4 you would reduce stick input to neutral and transition to a large amount of right rudder to generate lift in knife edge flight. From 4 to 5 you add some back stick and reduced right rudder. I'm skipping some of the nuances of the timing to focus on the gross inputs.
One difference between normal and aerobatic aircraft factors into this discussion. Most normal aircraft have flat bottom airfoils. That means they require a substantially greater nose high attitude to generate lift than a typical aerobatic aircraft with symmetrical airfoils would. Your nose will need to be WELL above the horizon.
If you roll inverted with some altitude, say 1000 feet like the Cirrus reportedly was, a simple half aileron roll should be sufficient to get you upright. Your nose is going to fall through and you will lose some altitude, but the roll only takes a few seconds and you should be able to cut power and recover from the dive. IMO almost any pilot should be able to do this, as long as you react quickly with full aileron and neutral elevator.
If you rolled inverted at
low altitude in a GA aircraft, you would need to fly a slow roll to avoid altitude loss. So your immediate action would be a decisive amount of forward stick to get the nose up and generate lift while inverted. When you do that, you will experience negative G force, at least -1 and probably -2 G. You will be hanging upside down in your seatbelt, which is disorienting the first time you experience it, especially in a crappy 3 point belt that probably wasn't that tight because you weren't expecting to fly inverted.
The rudder is less important. You aren't going to generate a whole lot of lift in knife edge flight at approach airspeed, and adverse yaw is not relevant. Every bit helps, but the rudder is probably not what determines success unless you are right at ground level. But the aggressive forward stick while inverted would be essential, and very non-intuitive if you have not done it before.
Here is a video of a 720 degree roll I filmed in my Decathlon last week. I am by no means a skilled competitor so it is quite rough. However, it is useful to illustrate because my aircraft has a very slow roll rate, probably comparable to most normal category aircraft. Watch how the tip of the spinner inscribes a circle around a point on the horizon, and note how high the nose is when fully inverted. Also notice the half roll from inverted to upright only takes about 3 seconds.
