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.
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.
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.
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.