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Never been a math scholar so I need some formulas

Discussion in 'General Discussion' started by lawman0210, Oct 28, 2015.

  1. lawman0210

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    I know the Phantoms software calculates speed and Rth times etc but I'm looking to know it for myself. It will also help if I'm looking on a map.

    I want to be able to calculate how far I can fly and make it back home if I am flying at 1 mph, 10 mph, 30 mph etc and translate that into feet. I measure how far I am by feet. I know my quad can go an estimated 30mph and has say 15 mins of fly time. If you guys can throw a few formulas in there for different calculations that would be great.

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  2. rockhoundrob

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    (# miles per hour) X 5,280 feet X (flying time in % of 1 hour) NOTE: if you fly for 30 minutes, then 30 / 60 =.5 (see first example below)

    Examples:

    30 MPH X 5280 X 30 mins = 30 x 5280 x .5 = 79,200 feet
    10 MPH X 5280 X 10 mins = 10 x 5280 X 0.1666 = 8,800 feet

    then divide by 2 for round trip! sorry I misread the question...

    so 79200 / 2 is 39600 feet out and back ( or 79,200 total feet)
     
    #2 rockhoundrob, Oct 28, 2015
    Last edited: Oct 28, 2015
  3. witold

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    If you're getting 20 minutes down to 15%, it means you can fly 20 minutes.

    10 minutes one way, 10 minutes the other way. 10 minutes in a circle. Doesn't matter.

    At that point, it depends on winds, how often you hover, how often you change elevation, etc. There is no easy formula.
     
  4. lawman0210

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    Awesome ty

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  5. RoyVa

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    You'll get pretty good at it the more you fly and calculate flight time. I know from slack wind conditions I can fly out and make it back in 18 minutes if I don't go over 15,480 ft one way. That give me a buffer if the wind comes up during flight. I could go further may be a half mile but that would be pushing it..
     
  6. lawman0210

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    I have only gone 1000 ft with P2 vision and vision plus. Now with my P3 I went 1100.00 but that was just playing around getting the feel of it. I will need to start at other end of my field and head the other direction I am very close to the blimps Jlens. Speaking of which they are suppose to be able to track small hobby drones but they actually lost one of them for a short time today. The tether broke and it ended up in Pennsylvania

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    #6 lawman0210, Oct 28, 2015
    Last edited: Oct 28, 2015
  7. PilotHarry

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    Actually, wouldn't it be 20 minutes in a circle? ;)
     
    witold likes this.
  8. lawman0210

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    What is the formula knowing your battery time? What I mean if I know I can fly 15 minutes at 30mph what what be my total distance one way I can fly taking into account a return flight. That way I can plot a course on a paper map. Put it to scale and know what my ability is.

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  9. PilotHarry

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    15 minutes x 30 miles in 60 minutes= 7.5 miles :)
     
  10. lawman0210

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    I realize I can just go balls to the wall and know my total distance which won't change much until battery starts getting old. I also realize that winds play a factor and probably more math then I care to get into.

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  11. lawman0210

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    Last question. When trying to estimate range on a map is flight time or speed most important? Is faster going to yield longer range or slow? What I am trying to say is, Does going faster get you farther since time is a factor or does going faster drain battery more so your flight time might be less and thus having to turn back sooner

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  12. rockhoundrob

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    Flight time is more important to me. As for speed, the faster you go, the faster the battery will drain.

    Bottom line...I think the battery time is related to distance regardless of speed. You fly slow, the battery lasts longer, but takes longer to get there.
    If you fly fast, the battery drains faster, but you get there faster.

    I would think the total distance is almost the same either way.
     
  13. lawman0210

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    That's what I was thinking

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  14. Mark The Droner

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    Well, I guess to be sure somebody needs to run some tests ;)

    My thinking is, there is probably a reason RTH speed is what it is. It's probably the most efficient speed. Flying top speed home on a weak battery will probably get less distance.

    What is RTH speed? According to this thread, it's around 17 mph.

    Lost! B/c RTH speed? | DJI Phantom Forum

    But that would be relative to the wind, of course. The phantom would not be programmed to RTH faster in a head wind because that would be counter-productive.

    So seems to me, if we're gonna do a distance test and there is some wind, we must be sure we are heading into the wind, and we have to be sure to turn around with no less than about 60% battery.
     
  15. lawman0210

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    Agreed

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  16. Meta4

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    DJI have done the hard work and put a lot of programming into the app's timeline.
    Look at the green, yellow, red line at the top of the screen.
    [​IMG]
    The yellow H (for Home) slides along the line to indicate the bingo point at which you must come back if you want to see your Phantom again.
    If you come back closer to home, the yellow H slides back out.

    The Phantom uses most of it's power just to stay in the air and travelling at speed uses very little more.
    Climbing uses much more power than level flight.
    As for RTH speed, I can't find any reason for it being only 10 m/sec.
    If you are battling a strong headwind to come home, there's nothing efficient about it at all.
     
  17. R2-D2

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    I study where I'm going to fly using google maps. If you right click on the their map screen you can select measure distance. Then you can plot how far out you plan to fly and know exactly how far it is. From past flying trips I notice 1 mile uses about 12% battery, so rule of thumb is turn around and fly back when your battery is 65% or so. So you should be able to fly out 2-3 miles and turn around and fly back if you use a windsurfer. Take baby steps.
     
  18. lawman0210

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    That would be open area I assume?

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