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Mountain flying
1621 25 2017-3-5
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Jmarker
lvl.2
Flight distance : 67310 ft

United States
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If i take the phantom with me to colorado and fly it at 14000ft will the drone have enough lift since the air is so thin up there? Without drastically reducing fly time?
2017-3-5
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piowoc73
lvl.4
United States
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Check post #18 in this thread: http://forum.dji.com/forum.php?m ... mp;page=1#pid697333
You may want to ask blackcrusader for more details, but he definitely has some experience on this.
2017-3-5
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jpferman
lvl.2
Flight distance : 1775 ft
United States
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I took my Phantom 4 with me to Colorado and flew it up in the mountains around Ouray and the drone flew flawlessly.  The altitude might cause higher battery use, but it really wasn't notiiceable.
2017-3-5
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Nigel_
Captain
Flight distance : 388642 ft
United Kingdom
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jpferman Posted at 2017-3-5 09:35
The altitude might cause higher battery use, but it really wasn't notiiceable.


Although the altitude means less dense air, the amount of energy required to overcome gravity is the same, the only reason for shorter battery life would be that the propellers/motors need to spin faster and they may be a little less efficient at higher speeds, more likely it just reduces the top speed.

There is also less gravity up in the mountains around Colorado than average which will help a very small amount.  
2017-3-5
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Jmarker
lvl.2
Flight distance : 67310 ft

United States
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jpferman Posted at 2017-3-5 09:35
I took my Phantom 4 with me to Colorado and flew it up in the mountains around Ouray and the drone flew flawlessly.  The altitude might cause higher battery use, but it really wasn't notiiceable.

Lake City is where i would be going which is close the way the crow flys to Ouray. Good to know the drone flew great through.
2017-3-5
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piowoc73
lvl.4
United States
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Nigel_ Posted at 2017-3-5 10:18
Although the altitude means less dense air, the amount of energy required to overcome gravity is the same, the only reason for shorter battery life would be that the propellers/motors need to spin faster and they may be a little less efficient at higher speeds, more likely it just reduces the top speed.

There is also less gravity up in the mountains around Colorado than average which will help a very small amount.

Would the air temperature be a factor here as well? I assume that at very high elevations the temperature drops significantly and as we know any battery will last shorter in lower temperatures.
2017-3-5
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dronist
Captain
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United States
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Just keep an eye on the batteries and when you land check the propeelers for any pressure/crack/smudges and the inside plastic are good. Post some vids!
2017-3-5
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Bullflyer
Second Officer

Spain
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Are there propellers for high altitude flights?
2017-3-5
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Bullflyer
Second Officer

Spain
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In high altitude flights, in your case you only lose performance on the propellers, because of air density, and not in the motors because they are electric. You will need more RPM in your motors to get the same lift than at sea level.
2017-3-5
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Nigel_
Captain
Flight distance : 388642 ft
United Kingdom
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piowoc73 Posted at 2017-3-5 10:27
Would the air temperature be a factor here as well? I assume that at very high elevations the temperature drops significantly and as we know any battery will last shorter in lower temperatures.

You might need to warm the batteries up a little, but it's probably not going to be cold enough to stop them reaching normal working temperature after a couple of minutes flight unless you are going to the very top in the winter.
2017-3-5
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Nigel_
Captain
Flight distance : 388642 ft
United Kingdom
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Bullflyer Posted at 2017-3-5 11:56
In high altitude flights, in your case you only lose performance on the propellers, because of air density, and not in the motors because they are electric. You will need more RPM in your motors to get the same lift than at sea level.

The motors will loose power as they get nearer their maximum RPM, so although you may not loose efficiency, the maximum thrust will be less.
2017-3-5
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Geebax
Captain
Australia
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There is footage of a Phantom being flown at one of the base camps on Everest, so I would not be concerned at 14,000 feet.
2017-3-5
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Bullflyer
Second Officer

Spain
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That is why I asked before if there are  propellers for high altitude flights

2017-3-5
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DJI-Jamie
DJI team
Flight distance : 112405 ft
United States
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Altitude density can potentially be an issue, you do want to be careful when flying that high up.
2017-3-5
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Nigelbrinkmann
First Officer
Flight distance : 577484 ft
Australia
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It will be no worries at all, I have flown my P4 at 4800mtrs (approx 15700 feet) did it no problem.
Ha, it was harder for me than the P4!!
2017-3-5
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fans847e5a8d
lvl.1

United States
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Nigel_ Posted at 2017-3-5 10:18
Although the altitude means less dense air, the amount of energy required to overcome gravity is the same, the only reason for shorter battery life would be that the propellers/motors need to spin faster and they may be a little less efficient at higher speeds, more likely it just reduces the top speed.

There is also less gravity up in the mountains around Colorado than average which will help a very small amount.

I DON'T think so...
2017-3-8
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fans847e5a8d
lvl.1

United States
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I have flown my P4P+ many times up in the sierra's over 10K altitude.. Flys great but battery life is shorter.  Higher Density Altitude requires more power / less time in the air.
2017-3-8
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Nigel_
Captain
Flight distance : 388642 ft
United Kingdom
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fans847e5a8d Posted at 2017-3-8 06:14
I have flown my P4P+ many times up in the sierra's over 10K altitude.. Flys great but battery life is shorter.  Higher Density Altitude requires more power / less time in the air.

There is extra gravity in those mountains, but it's quite likely that the shorter flight time has more to do with extra wind at higher altitudes and it having to do a lot of extra work just to keep still.
2017-3-8
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Kneepuck
Captain
Flight distance : 275102 ft
United States
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Phantom has a service ceiling of 6000 meters (19,685 feet ).  So it is well within the limits.
2017-3-8
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piowoc73
lvl.4
United States
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Nigel_ Posted at 2017-3-8 08:45
There is extra gravity in those mountains, but it's quite likely that the shorter flight time has more to do with extra wind at higher altitudes and it having to do a lot of extra work just to keep still.

Gravity does indeed change with altitude. The gravitational force above the Earth's surface is proportional to 1/R2, where R is your distance from the center of the Earth. The radius of the Earth at the equator is 6,378 kilometers, so let's say you were on a mountain at the equator that was 5 kilometers high (around 16,400 feet). You would then be 6,383 kilometers from the Earth's center, and the gravitational force would have decreased by a factor of (6,378 / 6,383)2 = 0.9984. So the difference is less than 0.2%.
2017-3-8
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Bullflyer
Second Officer

Spain
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The most important is air density, decreasing with altitud and affecting propellers performance.
2017-3-8
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Nigel_
Captain
Flight distance : 388642 ft
United Kingdom
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piowoc73 Posted at 2017-3-8 10:36
Gravity does indeed change with altitude. The gravitational force above the Earth's surface is proportional to 1/R2, where R is your distance from the center of the Earth. The radius of the Earth at the equator is 6,378 kilometers, so let's say you were on a mountain at the equator that was 5 kilometers high (around 16,400 feet). You would then be 6,383 kilometers from the Earth's center, and the gravitational force would have decreased by a factor of (6,378 / 6,383)2 = 0.9984. So the difference is less than 0.2%.

Don't forget that mountains are heavy and generate their own gravity, those particular mountains generate more than normal.  It is only a small difference but these things can add up.
2017-3-8
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Makirichi
lvl.1
Flight distance : 274199 ft
Canada
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I flew last week with P4P in my Rockies. Wind factor is important to consider, so down/dusk better (best for pics) Also, choke air intake by 80%, temp was -2 C and Alt. about 8000 ft. https://www.facebook.com/rsrc.php/v3/y4/r/-PAXP-deijE.gif
2017-3-9
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blackcrusader
First Officer
Flight distance : 689774 ft
Taiwan
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First read your manual. I know my P3S is rated to 6000m or 19685 ft.

No issues. Someone said there is less gravity up at that height.  Made me laugh.
You don't need bigger props but you will need to consider temperatures for the batteries.

I'll be doing a flight up to 11,000 feet altitude next week.  The drone flies just the same as anywhere else. Do watch out for wind speeds.  The drone can handle a lot though.  

I needed to fly 380m just to break cloud cover.  But it was worth it.

2017-3-9
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Airmunn
lvl.1

United States
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I keep reading comments on GRAVITATIONAL pull up in the mountains... Maybe at a very, unmeasureable amount of performance ,  There is NO aircraft manual that I have ever seen that had anything about differences in GRAVITY in its performance section. NO A FACTOR.   What you need to know are the factors that contribute to DENSITY ALTITUDE.  read up on it.......
2017-3-10
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piowoc73
lvl.4
United States
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Airmunn Posted at 2017-3-10 06:40
I keep reading comments on GRAVITATIONAL pull up in the mountains... Maybe at a very, unmeasureable amount of performance ,  There is NO aircraft manual that I have ever seen that had anything about differences in GRAVITY in its performance section. NO A FACTOR.   What you need to know are the factors that contribute to DENSITY ALTITUDE.  read up on it.......

The gravitational force is proportional to the distance from the Earth's center, so the higher you fly, the weaker the gravity, but it is estimated to be less than 0.2% variation for it in the attitudes reachable by drones. As far as the geological factor of the rocks is concerned it is estimated to be even less important, something around 0.01%, so totally unimportant.
2017-3-10
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