If a wing is severed due to structural damage or from a mid-air collision, what is the best control input to make?
I would think opposite aileron and rudder, i.e. if right wing falls off, input full left aileron and left rudder.
We know from previous events that it is possible to come out of such an event safely.
This one:
Yes, an F-15 has once landed with a lost wing. However, the landing was a close call - 20 more feet and the plane would've overrun the runway. That landing took both skill and luck, as well as a very capable aircraft.
In this case, the pilot applied afterburners to stabilize the aircraft, then performed a carrier-style landing - which isn't a normal flared landing, more like a CFIT (controlled flight into terrain) with a hook and cables arresting you while you're crashing.
What made that landing possible is:
The engines and large all-moving tailplanes were able to overpower the asymmetric lift. It might not have worked, were the damage slightly different. The other necessary control input is using roll to compensate for asymmetric lift - on a fighter, it moves both the ailerons and the tailplanes, and the latter were working.
What makes such a feat impossible in most aircraft is:
Jet fighters are uniquely equipped to handle this kind of emergency. Their thin supersonic airfoils work almost linearly across a wide range of AoA, and they have especially large control surfaces. Basically, their controls are more powerful than their wings.
The only planes without ejection seats or ballistic parachutes which have any chance to survive this might be high-end aerobatic or racing aircraft, some of which have stabilators (and some also have ejection seats). The input is essentially the same: go full throttle, counteract roll and spin, counteract whatever else is going on.
In any other aircraft, a crash is inevitable. It's impossible to make a versatile recommendation, but if you can't bail out, and still have any control, bleed energy while you can, and brace for impact.
Yes, it is indeed possible to come out of such an event safely..... if you happen to be in an aircraft where some of the lift is generated by the body, have an excess amount of thrust available by way of afterburners, and unknown (but probably decades) of flight experience under your belt.
Any other situation... not so much.
If you lose an entire wing, or the majority thereof I would hazard a guess that there is absolutely no control inputs that you can make that will cause you to regain any form of control. A violent crash is inevitable.
There is one class of light aircraft where you have a very high chance of walking away from a catastrophic structural loss, that is one fitted with a Ballistic parachute. The control input in this case is pull the chute!
That said, not all mid-air collisions cause unrecoverable loss of control. Even what looks like major damage might allow you to remain in control. The first rule of aviation still applies - fly the plane. For example, If you notice a roll to one side, adjust with opposing aileron. The same with the use of elevator and rudder. Most importantly, keep the speed up, there's no point having marginal control if you stall it into the ground.
If a wing is severed or suffers severe damage, and the airplane isn't an F-15 with a lifting body for a fuselage, all-flying tail surfaces can can compensate for much of the lost wing area, and a thrust-to-weight of better than one, there is no control input that will save you.
Maybe, some minor damage out at the wing tip that doesn't compromise the wing spar's bending strength or make it collapse backwards, say from the tip getting struck by a propeller that mangles a couple of feet of tip, you can save it by aileron and rudder inputs to stop the resulting roll, but if that doesn't work, you are done.
Worrying about structural failure is like worrying about a ball joint letting go in your car and sending you careening into oncoming traffic. It can happen at any time, but you put it out of your mind, because the world's full of dangers and you have to live.
If the airplane is aerobatic enough to sustain knife-edge flight without descending rapidly, roll 90 degrees, fly down to a landing, and roll level just before touchdown. Large radio-control models have demonstrated this often, although I don't know of a full-scale occurrence.
If a wing becomes detached you must make sufficient control inputs to counteract the roll moment generated by the still-attached wing. This means that you must:
So you would want to roll hard into the remaining wing by turning the control wheel or pushing the stick hard to the side of the remaining wing. This will not, however, be sufficient, as the ailerons on an aircraft can reduce but cannot eliminate all of the lift generated by that wing.
The downside to the above is that you're essentially trying to remove all lift generated by the wings from the aircraft. In a fighter such as the F-15 where the body produces significant lift there may be enough lift to allow the aircraft to fly if you fly fast enough, but in almost any other type of aircraft the lift removed by the control inputs (if sufficient control inputs were possible) would turn the airplane into a brick, which has well-established glide characteristics.
In general, if a wing detaches the aircraft is not going to land safely, and no control inputs you might apply will be sufficient to make it land safely. This leaves you with three options:
Those are your options. Plan accordingly.
