any good links would be appreciated thx
2006-07-27 13:30:38 · 6 answers · asked by limetemple 2 in Science & Mathematics ➔ Engineering
As a helicopter hovers above ground effect, it starts to lose lift due to rotor tip vortexes. The vortex created by one blade reduces the lift of the following blade. Any horizontal air movement, either from the helicopter orbiting (orbiting: flying around a fixed point) or a breeze removes the vortexes and maintains rotor lift.
See below:
At a hover, the rotor tip vortex (air swirling around the blade tip from above to below) reduces the effectiveness of the outer blade portions.
Also, the vortexes of the preceding blade severely affect the lift of the following blades. If the vortex made by one passing blade remains a vicious swirl for some number of seconds, then two blades operating at 350 RPM create 700 long lasting vortex patterns per minute. This continuous creation of new vortexes and ingestion of existing vortexes is a primary cause of high power requirements for hovering.
During hover, the rotor blades move large volumes of air in a downward direction. This pumping process uses lots of horsepower and accelerates the air to relatively high velocities. Air velocity under the helicopter may reach 60 to 100 knots, depending on the size of the rotor and the gross weight of the helicopter.
2006-07-27 17:34:50 · answer #1 · answered by Anonymous · 0⤊ 0⤋
It also saves fuel. Lift on a helicopter is at a minimum when it is hovering. As the helicopter moves faster the lift becomes more efficient and therefore it burns less fuel to stay in the air. Flight time is always a major factor for helicopters since they must lift the weight of the fuel in their least efficient state. Moving forward to have extra momentum in case of engine failure is a factor but flight time is a bigger one.
2006-07-27 21:01:18 · answer #2 · answered by scientia 3 · 0⤊ 0⤋
Well the basic answer would be for safety, in essence if there is an engine failure, a moving object would still have some momentum for the pilot to manuever the helicopter as far away from a crowd or dangerous area as possible.
See the link below for an FAQ answer from one air supply unit site
2006-07-27 20:36:14 · answer #3 · answered by unstable 3 · 0⤊ 0⤋
If it's moving forward, it's generating some lift from the forward motion, helping it to stay up. Hovering would likely require more effort. Also, a hovering helicopter is kinda sketchy.
2006-07-27 20:34:02 · answer #4 · answered by DakkonA 3 · 0⤊ 0⤋
Moving forward takes less fuel than hovering. No other reason. There is an optimum speed at which the fuel consumed is less. Gallons per second is optimized.
2006-07-27 21:50:04 · answer #5 · answered by Dr M 5 · 0⤊ 0⤋
Helicopters hover.
Satellites orbit.
Not vice versa.
2006-07-27 20:34:54 · answer #6 · answered by 2007_Shelby_GT500 7 · 0⤊ 0⤋