Welcome to InspirePilots.com

Join the leading DJI Inspire community for free!

Flight Times at High Altitude

Discussion in 'General Discussion' started by andreweio1, Mar 2, 2016.

  1. andreweio1

    Joined:
    May 14, 2015
    Messages:
    53
    Likes Received:
    13
    Location:
    Amersham, Bucks
    Hi Folks,

    We have a potential client who is in Santiago in Chile and he is asking how the performance is affected by altitude. His altitude is typically about 3000m, therefore can anyone on this forum who lives or has had experience of flying at higher altitude please advise on the typical percentage flight time loss, and confirm what altitude, and the typical temperature. I can then go back and advise on the expected flight times based upon normal altitude flight.

    Many thanks in advance
     
  2. The Editor

    The Editor Moderator
    Staff Member

    Joined:
    Aug 7, 2013
    Messages:
    6,705
    Likes Received:
    3,861
    Might want to get yourself a set of two of the high altitude props as well.
    Official DJI Store
     
    Orchard, dopeytree and damoncooper like this.
  3. damoncooper

    Joined:
    Mar 20, 2014
    Messages:
    3,451
    Likes Received:
    1,620
    Location:
    Boston, MA
    Also warm the batteries before flight to 25C if at all possible and try to keep them in the 20C - 40C optimal discharge temp during flight. Especially if ambient air temp is < 10C.
     
    The Editor likes this.
  4. dogear

    Joined:
    Mar 4, 2016
    Messages:
    11
    Likes Received:
    2
    I am operating at 1800 meters above sea level and have noticed significantly lower flight times than normal. My theory is the motors are having to work harder in the thin air to produce the lift needed to operate the drone. I'm also a helicopter pilot and the performance of the machine is significantly reduced at high altitude reducing the useful loads the aircraft can maintain especially when the ambient temperature is high.
     
  5. damoncooper

    Joined:
    Mar 20, 2014
    Messages:
    3,451
    Likes Received:
    1,620
    Location:
    Boston, MA
    Yes. Makes sense. Use increased pitch props if you can.
     
  6. dogear

    Joined:
    Mar 4, 2016
    Messages:
    11
    Likes Received:
    2
    Yup ordered some last thx for the advice.
     
    damoncooper likes this.
  7. dopeytree

    Joined:
    Oct 8, 2015
    Messages:
    103
    Likes Received:
    22
    Location:
    Somerset, UK
    Learn something new every day - I had no idea you could get those high altitude props! I've just flown the inspire pro on Sakran Mountain (Iraq) at 3587m. Flew fine but not for long as it was so windy I brought it down for safety. Probably 17-25mph winds. We were very lucky and able to drive 2 jeeps up so I used those as a wind break for takeoff. Also I used the DJI battery heater http://store.dji.com/product/inspire-battery-heater
     
  8. dogear

    Joined:
    Mar 4, 2016
    Messages:
    11
    Likes Received:
    2
    I do have the heater. As I said in an earlier post I think that there are a number of factors going on with high altitude ops. Firstly the props must turn faster in order to generate the lift in the thinner air therefore using more power from the batteries. Wind would definitely be a factor as well, and lastly the cold would also factor into shorter battery life. I think the service ceiling on the Inspire 1 is something like 14,000ft which isn't too shabby. I am not sure that the high alt props are going to extend the battery life. I think that they might just make the drone more responsive in the thinner air. Will be interesting to see. Cheers
     
    #8 dogear, Mar 5, 2016
    Last edited: Mar 5, 2016
  9. dopeytree

    Joined:
    Oct 8, 2015
    Messages:
    103
    Likes Received:
    22
    Location:
    Somerset, UK
    I wasn't flying very far away or high from take off point. Just circling our protagonist on the mountains tops. To show the guy & his surroundings (as much as you can while hiding the crew & 2 jeeps) It wasn't the biggest flying time as I wait until the ground camera filming was done so my flying time was limited to about the last 10 minutes of sunset. But we nailed it! It rained the day before & after too.

    How many batteries have you got?
     
  10. dogear

    Joined:
    Mar 4, 2016
    Messages:
    11
    Likes Received:
    2
    Got 4, two regulars and 2 of the "high capacities". As I said we will have to see what kind of flight times I get here at 1800 meters (6100ft). I ordered the high altitude props so I am looking forward to seeing what kind of performance I get. I am a retired helicopter pilot and have worked out of this area a lot. In the summer I had room in the machine for me (no pax) and very little fuel, just to be able to get the machine off the ground and down to where we could take on fuel, and we are talking an Augusta 109 (twin engine) which seats 6 including the pilot. It's very interesting to see what kind of performance the Inspire 1 gets at the same altitude. I am fascinated with the technology that they cram into such a small space. The Augusta that I flew was certified single pilot IFR which required it to have 2 "Heliflight" systems on board. Basically a stability augmentation system. These DJI drones have 20 times the sophistication of the Augusta at just a fraction of the cost!!! Now I've heard that they have added an anti collision system to the Phantom 4, unbelievable!
     
    dopeytree likes this.
  11. damoncooper

    Joined:
    Mar 20, 2014
    Messages:
    3,451
    Likes Received:
    1,620
    Location:
    Boston, MA
    4500m ASL actually, according to specs
     
  12. Bryan Conover

    Joined:
    May 27, 2015
    Messages:
    146
    Likes Received:
    32
    So what's the result if used at sea level?
     
    Terry Lowe likes this.
  13. The Editor

    The Editor Moderator
    Staff Member

    Joined:
    Aug 7, 2013
    Messages:
    6,705
    Likes Received:
    3,861
    Using s steeper pitch at sea level will draw more current from your battery and so you will get shorter flight times although the DJI offerings are not hugely different from stock.
    The side affect of drawing more current means everything will work harder and heat up. In extreme cases using a very steep pitch prop at low altitude can cause the motors to cavitate.
     
    dopeytree likes this.
  14. Bryan Conover

    Joined:
    May 27, 2015
    Messages:
    146
    Likes Received:
    32
    Thank You !
     
  15. Orchard

    Joined:
    Jan 30, 2016
    Messages:
    13
    Likes Received:
    5
    Editor: Are the high altitude props for the Inspire also compatible with the Matrice?
     
  16. The Editor

    The Editor Moderator
    Staff Member

    Joined:
    Aug 7, 2013
    Messages:
    6,705
    Likes Received:
    3,861
    Providing your Inspire has the 1345s attachments then yes, the steeper pitch of 1360 should be fine to use at higher altitudes.