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Altitude performance question

Discussion in 'Phantom 2 Vision + Discussion' started by mrh, Aug 16, 2014.

  1. mrh

    mrh

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    Hi All,

    Considering a phantom 2+ but I live at 5175 feet at the base of the rockies one of the reasons I have not considered a cheaper solution.

    Today at my home we have 95F, 16% humidity and pressure of 30.12. This calculates to a density altitude of around 8000 feet.

    How does the bird perform at this density altitude? What is affected? Flight time shorter? Less maneuverable?

    What about wind? We have a lot of nice days here. We also have some "typical" days where the wind is 10-15 knots. Is the bird able to handle this or based on density altitude and wind would I be grounded?

    I used to fly both R/C planes and hell and used to fly commercially for many years both fixed and rotorcraft so I'm aware of weather and environmental limitations. I would not expect the phantom to perform like at sea level but if its a real dog at this altitude then perhaps I need something a little beefier.

    Thanks to all who reply! Looks like a fun bird!
     
  2. paulsluxmd

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    You have to be very mindful of a condition called "Vortex Ring State" when descending.
    I crashed 2 copters in Aspen this summer as i descended through my own prop wash.
    Aspen is at 8000 ft and the air density, especially as the day heats up is low. Also, it is worse if there is no wind to move the dead air from under the prop.
    This is what it looks like:

    https://www.youtube.com/watch?v=Xm4sTVueyl0

    If you start falling, the natural response is to give full up throttle, which only makes it worse.
    If this happens, push the right stick to the right/left/front/back to steer the craft into good air and it will stabilize.

    Good luck!!
     
  3. mrh

    mrh

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    Thanks for the reply! Ya "settling with power" a condition where you can be at max power and still going down because you are unable to generate the right flow through the rotors. The right recovery (at least in a hell) is ANY lateral flight.

    I guess in the phantom when it gets in that state can you even get lateral flight going?

    Scary video. I think in general with most rotary wing aircraft descending straight down is problematic unless you control it very carefully.

    Good to know people are flying at altitude. I went to our local hobby store and took out their $150 quad and it could get up about 12 feet today but that was it.

    Thanks for the reply and info.
     
  4. DBS

    DBS

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    Location:
    Ft. Pierce, Florida
    And don't use prop guards... another thing that makes high altitude flying more sketchy... I knew I was gonna see those in the video posted above :oops:
     
  5. mrh

    mrh

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    Ok I was gonna order some but you are the second person to say they contribute to VRS. Thanks for the info.
     
  6. cahutch

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    Location:
    Sonoma County, CA
    The Phantom has a typical max speed of ~35mph in GPS mode (~30 knots) so if the wind is faster, she won't be able to hold position.
    In any case, I wouldn't fly in wind speeds half of that.

    I've read several accounts of owners flying at high altitude and crashing due to decreased lift or updrafts and downdrafts in the mountains, but those accounts were over 10 thousand feet I think.
    I've only ever flown within a few hundred feet from sea level so I can't speak from experience but I would think you'll have shorter battery life and decreased agility due to having less lift, but I don't know if that would have any noticeable effect at 8,000ft.

    My thoughts on Prop Guards. Even if they have no effect on flight, they still aren't much use. Not worth the extra weight and drag.
    I bought some myself and took them off after three flights. You can't put the phantom in the box or any case with the guards attached so you have to take them on and off all the time.
    If you're like me and you don't fly low, near people, trees or buildings, then they don't do anything and have no value being attached.
     
  7. mrh

    mrh

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    Thanks sir!

    I don't know the altitude I will fly until I've tried it. I can think of three reasons to get a quad:

    1) fun.. Just flying about
    2) Inspecting my property. Only an acre but would be nice to fly to various places and look at stuff including my roof (hail damage etc)
    3) Prairie. We have a huge prairie next to us with lots of deer, snakes, prairie dogs, etc. I can see some fun hovering out over parts of that to check out whats going on.

    I'm curious about the range. On a day when I did that I'd like to sit in my back yard, on a slight hill and head out to the prairie (call it 400 feet away perhaps a little more) and hover about.

    On this last part I'm thinking I'd like to be 50 feet or less looking down to see whats happening wildlife-wise but perhaps the thing will scare everything away. Who knows. But at say 500 feet and 50 feet up that seems kinda low and far. Will I have that kind of range? It will be line-of-sight.

    I would expect at my altitude to have less performance and probably less batt life for sure. So I could see doing something for 10-15 mins max and heading back.

    Yes on wind. I think most days we have less than 10 mph. But on the really windy days, no way. I've clocked 65+ here at the house.
     
  8. cahutch

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    Location:
    Sonoma County, CA
    If you have LOS, you should have no problem getting 500ft range. I get 600-700feet typical in open ground.
    But that range will decrease if you have trees in the way, even if the trees don't break LOS to the phantom, if they come close, they'll affect the radio signal.

    Also, the P2V+ has a typical 15 minute battery life, so you should expect to come down from there.
    Some get 18-20 minutes depending on how they fly but 15 is more common due to the added weight of the gimbal and camera

    A couple of accounts I could find of flying at high altitude
    viewtopic.php?f=27&t=21405
    viewtopic.php?f=27&t=22669
     
  9. ToThePoint

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    Location:
    Antwerp, Belgium
    Don't use propguards due to its contribution to VRS even @ sea level and watch out on descend on a low or no wind day. Even when descending and the direction the bird moves in is the same as the wind blows.
    I've seem the wobbling today for the first time as it was coming in and it was following the wind direction, stupid me but no harm done, it was not that harsh and it was only 3m above ground but i quickly released the sticks and moved back so just before it touched ground it bounced back up.