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Old Jun 01, 2012, 09:34 AM
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Joined Jun 2012
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High altitude guys, are you having any problems?

Dear High Flyers,

We are working with some of the DJI equipment, and we are looking for some parameters from flyers in the +5000ft MSL area. Are you having any issues taking off or operating? Have you had to make any prop changes or are you noticing during high temperature operating that you are experiencing reduced lifting capability? What have you done to overcome these issues? Bigger prop? Bigger pitch?

Thanks for your help guys. Were located at about 20ft MSL, so testing a system at 5000+ft msl is not too easy. Just looking for some info before we conduct our testing. Thanks!
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Old Jun 01, 2012, 09:52 AM
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United States, CA, San Bernardino
Joined Feb 2012
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i live at 4500ft and have taken it to areas of 5000+ ft about 2-3 times.. flying a Bumble bee, with a naza clone controler.. ive had no such issues..
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Old Jun 01, 2012, 11:02 AM
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United States, CA, Big Bear
Joined Jan 2006
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Quote:
Originally Posted by TBMcustservice View Post
Dear High Flyers,

We are working with some of the DJI equipment, and we are looking for some parameters from flyers in the +5000ft MSL area. Are you having any issues taking off or operating? Have you had to make any prop changes or are you noticing during high temperature operating that you are experiencing reduced lifting capability? What have you done to overcome these issues? Bigger prop? Bigger pitch?

Thanks for your help guys. Were located at about 20ft MSL, so testing a system at 5000+ft msl is not too easy. Just looking for some info before we conduct our testing. Thanks!
I'm at 6900', stock setup is fine but I would suggest running 4s if you want the same punch.

You will find this to be the same with heli's you never want to increase pitch for altitude, just up the head speed, you're doing the same with 4s on mutli's!
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Old Jun 01, 2012, 11:16 AM
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United States, CA, San Bernardino
Joined Feb 2012
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ya you are pretty close to me blade strike. good advice too thanks
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Old Jun 01, 2012, 11:53 AM
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blade strike's Avatar
United States, CA, Big Bear
Joined Jan 2006
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Originally Posted by ddoltar View Post
ya you are pretty close to me blade strike. good advice too thanks
Yeah I saw that, no problem man! Enjoy this nice weather we are having

Just to think we got some snow last weekend
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Old Jun 01, 2012, 03:24 PM
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Joined Feb 2011
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hi,
i life at 7000ft+, the problem I have only reduce of lift capacity, around 15%

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Old Jul 16, 2012, 02:26 AM
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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 say 6000 ft ASL you will have about 83.6 % 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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Old Jul 16, 2012, 03:02 AM
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United States, CA, Fresno
Joined Mar 2011
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I noticed a drastic drop in flight times flying for a month at 6000' above sea level.

I was getting 7-8mins with high disk loading and at altitude I was getting 4:30-6mins.

I didn't bring bigger props to test
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Old Jul 16, 2012, 07:21 AM
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Las Vegas/Lake Tahoe
Joined Feb 2010
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I fly a lot at 6500' and have never had a problem. My maiden for my S800 was at that altitude and I got 20min on 2x6S 5000 packs at 50 degrees F. That was pressing the limits of the lipos. I have since backed off that number and fly 16-18 min at 2500' but now in 100 temps.
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Old Jul 16, 2012, 12:00 PM
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United States, CA, Fresno
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Have you flown @ sea level with it?

Your rig is light (relatively) sans z15 right?
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Old Jul 17, 2012, 01:12 AM
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Joined Feb 2010
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Not at sea level. Yes it is light, no gimbal, but it has Vtx and Data Link. I fly with 2 6S 5000 lipos which are not light.
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