# Is there a difference in the Helicopter power needed to stay on different altitudes?

I heard that what can make a helicopter go higher is the presence of "Air" to power its engine.

Let's assume that the amount air would be exactly the same at different altitudes, would the power needed by the helicopter to stay stationary at 50 meters high be less than the power needed to be stationary at 200 meters (or even higher), or would it be the same?

• What do you think, seriously what assumptions would you make.? Hint: helicopters cannot rescue climbers stuck on the top of Mount Everest , 29,000 feet....why is that?
– user108787
Oct 26, 2016 at 23:25
• And contemplate if there is a difference between 500 feet and 50 feet (much less 5 feet). Oct 26, 2016 at 23:30
• Sorry I don't understand at all what both of you mean. Or maybe I just added an extra zero to the "feets"? I am used to think in terms of meters, not feets, and I have no clue how high a helicopter can go. I just want to know if it has to spend more energy to <u>stay</u> at different altitudes, not to flight from one altitude to another. I don't know if I am being clear now. Oct 26, 2016 at 23:58
• @CountTo10 ok, I got it now. I will just edit the question Oct 27, 2016 at 0:01
• Use meters, always metres or km or any SI unit, I just used feet because you did:)
– user108787
Oct 27, 2016 at 0:04

This is just an educated guess from an occasional pilot. Let's forget about less engine air by making it an electric motor. Then the question is, is more power (wattage, horsepower) required at higher altitude? My sense is, it should be about the same, because the lift/drag ratio should be about the same. The rotor blades would have to spin faster to move the same amount of air, just as a high-altitude airplane flies faster to get the same lift. Then you come up against the speed of sound, but that's a different issue.

I heard that what can make a helicopter go higher is the presence of "Air" to power its engine.

The helicopter's engine is powered by burning fuel together with oxygen from the air, then its propeller forces air (not necessarily the same air which is burnt with the fuel) downwards to lift the helicopter upwards.

Let's assume that the amount air would be exactly the same at different altitudes, would the power needed by the helicopter to stay stationary at 50 meters high be less than the power needed to be stationary at 200 meters (or even higher), or would it be the same?

Yes, it should be basically the same if the air density is the same. Air density is not the same at high altitudes like one or two kilometres, but it's approximately the same from 50 metres to 200 metres above ground.

Something called "ground effect", an improvement in performance, occurs within one radius of the blades from the ground. However, helicopter blades don't come as large as fifty metres. Apparently (from searching the web), the largest helicopter in the world is the Mil V-12, which has blades of radius only seventeen metres.