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Jul 06, 2012, 09:46 PM
Registered User
Discussion

high altitude


i live at 8600 feet altitude, and have purchased 2 different small remote control helicopters. there wasn't enough air pressure for either of them to get more than a few inches off the ground. does anyone have any experience of what would fly at high altitude?
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Jul 06, 2012, 10:06 PM
Registered User
wlee1017's Avatar
Quote:
Originally Posted by stevef24 View Post
i live at 8600 feet altitude, and have purchased 2 different small remote control helicopters. there wasn't enough air pressure for either of them to get more than a few inches off the ground. does anyone have any experience of what would fly at high altitude?
what 2 small rc heli you have?
Jul 07, 2012, 05:03 AM
mutski
Make sure your batteries are good. It wouldn't hurt to try a new battery.
Jul 07, 2012, 10:35 AM
Rocket Programmer
jasmine2501's Avatar
The Walmart toys won't fly at this altitude, but hobby quality helicopters will be ok. High performance helicopters do very well. So like, your Trex 450 and so on. But, those are hard to fly and require training or you will crash it and they don't crash well.
Jul 09, 2012, 03:11 AM
Registered User
Three factors influence the performance of helicopters at high altitudes.
1) Thinner Air
2) Decreased Power
3) High Winds
Jul 09, 2012, 03:14 AM
Registered User
I can tell you from experience that not all cheap micro helis are the same, not even the same model! I have flown 4 different V911's, and they all flew a LOT differently. My first one I was lucky to get a 2 minute flight out of. I too chalked this up to the high altitude I'm at (6,600'). My second V911 though was a different story. I easily got 5 minute flights out of it and it flew much better as well. The third one came with what I assume was a defective board as it was almost uncontrollable, while the fourth flew as good as the second one.

Needless to say, I was happy to know that the altitude was not the problem, just bad quality helis. I should also mention that my 450 heli flies great at this altitude and I easily get 7 minute flights out of it. My advice is to try a V911. Actually, try at least two!
Jul 09, 2012, 04:52 AM
A man with too many toys
Quote:
Originally Posted by stevef24 View Post
i live at 8600 feet altitude, and have purchased 2 different small remote control helicopters. there wasn't enough air pressure for either of them to get more than a few inches off the ground. does anyone have any experience of what would fly at high altitude?
Since the air presser is lower the blades need to turn faster to have the same lift and motor load. Usually a 1 tooth larger pinion will do the trick on most helicopters.

The alternative solution is a higher voltage battery but make sure that the electronics can handle that before you try more voltage.

Jul 16, 2012, 02:32 AM
Registered User
I have known a lot of folks having problems flying small helis at greater than 6000 ft, the helis just won't get off the ground or out of ground effect mode. The basic problem is lift. There are a few basic factors in generating lift, in simple terms: speed (or rpm), angle of attack (pitch), surface area, and air density. Air density changes with the altitude. If everything stays the same except the altitude, at 8600 ft ASL you will have about 77% of the lift as at sea level.

Quick table of altitude ASL and % of lift compared to sea level:
500 ft = 98.6%
1000 = 97.1%
1500 = 95.7%
2000 = 94.3%
2500 = 92.9%
3000 = 91.5%
3500 = 90.2%
4000 = 88.8%
4500 = 87.5%
5000 = 86.2%
5500 = 84.9%
6000 = 83.6%
6500 = 82.3%
7000 = 81.0%
7500 = 79.8%
8000 = 78.6%
8500 = 77.4%

The only ways to compensate for the decrease in air density is to increase pitch, increase speed (rpm), or increase surface area.


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