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It's the exact same principle for planes and helicopters. If a plane isn't producing more lift than weight it will fall, just like a helicopter. Planes work by
by Cogito 5y ago
It's the exact same principle for planes and helicopters.
If a plane isn't producing more lift than weight it will fall, just like a helicopter. Planes work by pushing a wing through the air, helicopters by spinning it. In both cases the wing has to push down enough air to keep the aircraft in flight.
- hamilyon2 5y agoSo, people answering on quora for example, are wrong? https://www.quora.com/Can-a-helicopter-having-a-power-to-weight-ratio-of-less-than-1-fly https://www.quora.com/Can-a-helicopter-having-a-power-to-wei... I am even more confused now.
- DangitBobby 5y agoNo, I have to conclude that the previous commenter didn't understand your point, which was the observation that heavy aircraft with very low sustained forward thrust (thrust that would not be sufficient for a helicopter to hover) results in sufficient upward lift to suspend the aircraft indefinitely, which is very surprising.
- afterburner 5y agoA helicopter doesn't rely on the forward thrust of the chassis, it relies on the forward thrust of the helicopter blades in rotation. Those blades are wings.
- DangitBobby 5y agoThe way the thrust is generated is mostly irrelevant to this observation. The observation is about the mechanics of lift, which is some function of thrust combined with the wings, rotors, balloons, etc. You'd observe the same bizarre mechanics if the thrust were generated by releasing highly compressed air from a tank.
- Cogito 5y agoI'm not sure how you're connecting that quora discussion to what we were saying above, but I think the confusion comes from what 'thrust to weight ratio' means. Helicopters and planes are both pushing down on air to generate lift. The lift generated has to be equal or greater to the weight for the aircraft to fly. Thrust can mean many things (at least colloquially). As discussed in the quora you linked, a helicopter will have a defined power to weight ratio that allows it to fly (maintain level flight) in its 'normal' flight envelope. There are a number of things the pilot can do that causes the aircraft to 'push down harder' on the air. One of these is flying close to the ground (the ground effect) which is sort of like pushing against the ground as well as the air, and another is by moving horizontally (usually forwards, like a plane, causing transational lift). Both of these allow the aircraft to maintain height while using less power than if it was hovering, but to do so it is still generating enough lift to counteract gravity.
- marvin 5y agoI didn't read your link, but the "thrust" in thrust to weight ratio generally refers to the force that the engine produces. Therefore, it isn't a brilliant analogy to compare the thrust of a helicopter rotor (which does get all its power from the engine) to the thrust of an airplane propeller. The propeller doesn't contribute materially to the lifting force on an aircraft, while the rotor of the helicopter provides practically all the lifting force on the helicopter. Both machines need to (somehow) generate lift equal to their weight to stay airborne. The airplane just does this by moving a static wing through the air, which is a much more efficient way of doing it. Its engine/propeller isn't even immediately required to move the wing through the air; once airborne, the aircraft can fly downwards at an angle without engine power to maintain its speed. You'd say that a helicopter uses "powered lift" while an aircraft does not.