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1. enopod+(OP)[view] [source] 2026-02-03 20:30:43
Sounds like a helicopter is not very efficient?
replies(2): >>Anothe+j7 >>kingst+PB4
2. Anothe+j7[view] [source] 2026-02-03 21:07:21
>>enopod+(OP)
Less efficient than an aircrafts wings over a long distance but very efficient for an aircraft with engines pointing straight down.

The blades are massive, push a lot of air relatively slowing compared to smaller engines. There's a reason most planes will stall when pointing straight up, despite in theory having more power to weight. Their prop efficiency is worse than a helicopters rotors.

3. kingst+PB4[view] [source] 2026-02-05 01:47:17
>>enopod+(OP)
Not for moving sideways at a constant altitude.

If you think about what a plane does to keep itself up, it sweeps through a curtain of air which ends up blowing downwards.

In a second it must blow down a large volume of air with enough speed to equal the impulse created by gravity in a second.

Basically m_air × v_down = m_plane × gravity × time

The energy you need to do this is the same quadratic, 1/2 m_air × v_down^2

A larger volume of air with a smaller v_down (a huge curtain of air of a fast plane with very wide wings) is more efficient then the smaller disk of air with high velocity of a helicopter.

But if the plane isn't moving forward the curtain has no volume and the plane stalls and falls. But helicopters have no trouble lifting off vertically.

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