Yes, sort of. If you reversed nothing but the engines, it may still be able to fly. But it’s designed to fly forwards, of course - the shape of the wings assumes airflow in one direction.
So I suppose the real answer is that your scenario doesn’t violate any laws of physics, and wings may still generate some lift even if the airflow is reversed. Whether it would be enough to get the thing flying, I dunno.
This is a different scenario from the OP, though, where the airflow doesn’t change direction.
If you don’t take into account control, sure. The wings provide almost all of the lift, ideally, but if you point the engines away from the ground, they would be able to provide the lift.
IIRC, a quote from the designers of the F-117 (or it may have been the B-2, I forget) said that you could make -anything- fly if you put a large enough engine on it. So, they designed the plane to be stealth, and -then- they designed around that to make it flyable.
Picture a swimmer in one of those small pools where you just swim against the artificial current and go no where. You’re speed is essentially zero, but if you were in a regular olympic-size pool doing the free-style stroke you would probably go about 3-5 miles per hour.
Picture that if you have trouble with the concept of a plane going nowhere into a strong headwind.
If you even get to the beach and watch those banner planes (towing banner ads), there are times when the shore breeze picks up rapidly and the banner planes head back home into a headwind, and at full power they are going no faster than someone taking a brisk walk. At times their ground speed drops to almost zero, and ocassionaly they are forced to land because of it. It is unlikely to see the ground speed drop to zero, because it is hard to find a constant relentless wind of 60+ mph.
To make things clear and succint, yes, it means a ground speed reduction of 100 mph, but not instantaneusly.
The aerodynamic design of the plane in level flight at a certain speed means that the drag/thrust ratio is at an equilibrium. If a plane suddenly gets hit by a 100 mph wind initially the airspeed would be +100 mph, but the increased speed means more drag that will bleed off the excess speed until the previous equilibrium is restored and the airspeed goes back to its original value.
In real life the effect, on a level flying aircraft, of a sudden head wind is that the plane gains height (more airspeed = more lift) if there are no counteracting measures. Conversely a sudden tail wind means a momentary loss of airspeed and lift, making the plane drop. You can get that double whammy if you luck (out) into a microburst.
So… going back to this. What happens is that the plane will initially gain airspeed and altitude, the airspeed will go back to the one you started with (provided you don’t monkey with the controls) On the other hand, the ground speed will initially be the same, and as the extra airspeed bleeds off it will end up being 100 mph lower.
A wind isn’t the entirety of the surrounding air, though. No natural force moves a solid block of the atmosphere at a given speed; some moves, some doesn’t.
Everyone seems to be approaching this as if the plane was in a gigantic swimming pool, and a 100mph headwind meant somebody picked up the swimming pool and moved it toward the plane’s point of origin at 100mph. That isn’t the case here, though; AFAIK, a 100mph means maximum the maximum sustained speed of any given molecule within the windy area is 100mph. The rest may be moving more slowly or not at all.
Well, he meant “average” when he said “maximum”, although I’d love for him to propose how he intends to do a molecule by molecule analysis of a fluid phenomenon. Hell, if we could do that, our equations wouldn’t be mostly empirically derived.
Anyway, my point still holds, I think - if we allow for differing speeds within this gust or whatever of 100mph, then we can’t assume that the headwing will exert a universal force of -100mph on the medium as a whole, meaning the net effect on the speed of the plane may be less (or possibly even more) than -100mph.
I think what you’re trying to conceptualize is Eddy currents, which would be taken into account once we realize that 100mph would be far into the turbulent flow regime. If that’s the case, then the answer to your question is that any time we enter the turbulent regime, the flow is going to behave similarly. We speak of the “bulk” air temperature, bulk pressure, bulk speed of sound; the (mostly empirically derived) equations take these small perturbations into account.
I think that’s what I’m trying to conceptualize too, and your explanation makes sense; presumably, though, those “bulk” calculations are based on a fixed volume of air moving into a fixed space, rather than over the surface of an irregular object.
IOW, if you had an aircraft sitting on the ground with a takeoff speed of 200mph, and then a 200mph wind came along, the aircraft wouldn’t take off, would it?
*I know, we’re getting perilously close to the whole treadmill thing now.
ETA:
The tailwind would increase the forward speed of the aircraft, meaning it would still be traveling at some given speed greater than 100mph. The part I don’t get is how the tailwind would impart an additional 100mph to the plane, rather than a portion of its own speed.
That is called vertical wind shear. When a thunderstorm creates strong downwash, the air flows outward near the ground in all directions. If an aircraft flies through this, it encounters first a strong headwind (of the sort the OP asks about) then, almost instantly, this becomes a strong tailwind…it is a Bad Thing ™
