Iris+ operations at high altitude 6000ft-10000ft

I have a project that will require my Iris+ to takeoff and fly anywhere from 6000ft to 10000ft above sea level.  The aircraft will only be about 300ft above the ground.  I have run the numbers in ecalc and found that my required throttle will be over 80% just to hover with no payload.  Which has me very concerned that with payload it may not even be able to take off.  Does anyone have first hand experience in operating at these altitudes, and can you share the weight of your aircraft and flight time, or a data log that I could look at?  I contacted 3DR support, and got the response of it should be fine, but I do not think that the response was based in testing / calculations.

Thanks for any help.

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  • Any updates Justin?

    I plan to do some glacier filming between 9 and 11 thousand feet this summer.

    I'm reviewing the linked article now.  Did you successfully get the new props installed?  Were there any glitches to report along the way?

  • All,

    Thanks for the info that you have submitted.  I previously did estimations using ecalc and was worried that there would be issues, which is why I came to all of you.  I planned to go with larger propellers as was suggested, and still do, however on the iris you have very little tip to tip clearance between propellers, which means that a 10" prop is about as large as you can go without the props hitting each other. 

    An additional question, Todd, do you have a recommendation for prop adapters to replace the ones currently on the quad, or can you share what you bought to secure your replacement propellers?


    • Please read Christian Elsen article on Improving lift

      I use his suggestions and have great success.

      Todd H

    • Todd,

      I did read his information before starting this thread, but thanks for providing the link as well.


      You have seen those?
    • I ordered a set of those and just tried them, they do not fit on the iris prop adapters.  It looks like the Iris threaded shafts are a little larger than the phantoms.  I will report back when I find ones that do fit.

      I measured the nuts and they are the same size, and I thought it felt odd that the nuts would try to thread on but would tilt, turns out that the colors do not match between vendors, the silver nuts go on the black shafts, and the black nuts go on the silver shafts!  So those nuts do indeed fit nicely.

    • The article by Christian Elsen also mentions that the colors will be mixed.

  • Hi Justin,

          I live at just over 8,500ft here in Colorado. Needless to say that is the altitude, I more often than not, launch from. In fact most of the time when I go out to film or take pictures its from a higher altitude.

    Recently I launched from an altitude of 10,150ft and held a steady hover aprox, 200ft above that with no issues.

    My flight time that day was 9min, doing smooth maneuvers with several hovers. The IRIS+ was rock solid during the entire flight. No issues to report.

    Again I usually fly from altitudes above 8,500ft and have so for many years now with other UAV's so I am quite accustomed to flying in thin air.

    My IRIS+ set-up is as follows:

    IRIS+ with the latest firmware.

    Stock battery (fully charged)

    HQ Prop 10x4.7 Slow Flyer props.

    Feiyu-Tech 3G Ultra 3 axis gimbal

    GoPro Hero 4 Black Edition.

    FatShark FPV Transmitter with a Mad Mushroom Blue Beam Antenna.

    Total weight is a hair over 3.5pounds.

    Please feel free to ask me any other questions regarding my setup and/or flights.

    Todd H.



  • Hi. I flew an original Iris (non plus) with a mobius camera in Puno Peru at 12,500 ft. It was sluggish and then I had GPS issues before a crash. I found out that my throttle was close to 100% before the crash. I would run the calculations that Martin suggested before flying.

  • No experience here but:

    According to XCopterCalc it would probably help to fit props as large as possible. That gets you more lift and better (lower) RPM in thin air. Theoretically with 11 x 4.7 props you are back to hover @ 60% throttle.

    One mod working and tested is described here:

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