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What are the props actually doing

Discussion in 'General Discussion' started by Bathy, Jul 15, 2014.

  1. Bathy

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    Ok might be a bit of a dumb question but, how do the props and motors actually move the phantom up/down/side etc?
    Coz I can't see any way they actually change angle!
     
  2. ProfessorStein

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    The controllers vary the speed of the motors, spinning the props faster and adding more lift on one side of the Phantom or the other... which pulls (or is it pushes... hmmmmm) it in the desired direction.
     
  3. Bathy

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    So how does it descend if the props are still spinning the same direction as going up?
     
  4. Monte55

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    when the lift of the props by a lower speed can't match the weight of the quad it will come down
     
  5. N017RW

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    Think about how propellors work.
    The faster they spin the more force they apply to fight gravity.
    Reduce speed, reduce force, gravity brings it down.
     
  6. ProfessorStein

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    The motors slow the spin of all four props until there's slightly less lift than is needed to offset the weight of the Phantom... and it literally begins to fall... hopefully in a controlled manner. Pretty simple physics. Though the control algorithms are probably nastily complex.
     
  7. discv

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    As you say hmmmmm! Just to confuse things further---- when the craft rises- it is actually being sucked up :cool:
     
  8. ProfessorStein

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    Lol, discv! Yes... as Amy Pond says... "and this is where it starts to get complicated"
     
  9. chuddly

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    and lets confuse it more than that. Its not actually the thrust down of air that lifts it but also and more the lack of air pressure behind the lead edge of the blade that lifts/sucks its up
     
  10. Monte55

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    WHAT.

    It's not being sucked up. The down thrust of air pushing on air below the quad from the props is what makes it go up providing the thrust can overcome the weight of machine. No air such as in a vacuum....no lift at all.
     
  11. Seawell

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    Professor Stein. Is it like an airplane wing? Lifted up?
     
  12. Judderman

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    Monte55 - You are wrong I'm afraid. 'Lift' is what keeps the craft in the air, not simply downward movement of air.

    http://www.nasa.gov/audience/forstudent ... 8U2cPldV8E

    "Wings are curved on top and flatter on the bottom. This shape is called an airfoil. That shape makes air flow over the top faster than under the bottom. As a result, there is less air pressure on top of the wing; this causes suction and makes the wing move up. A helicopter's rotor blades are wings and create lift. An airplane must fly fast to move enough air over its wings to provide lift. A helicopter moves air over its rotor by spinning its blades."
     
  13. ProfessorStein

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    I think what chuddly and discv are alluding to is what actually happens with regard to an airfoil... which is what the props are. Low pressure is created on the upper surface of an airfoil, and high pressure is created underneath. Since air always moves to stabilize pressure, it's actually the underside that is getting "sucked up" by the low pressure above. That's why they call it "lift", and not "push".

    You can look it up.
     
  14. discv

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    Try it this way then. The air taken to create the pressure below the rotor has been taken from above-

    Creating a vacuum- that 'sucks' the craft up ;)
     
  15. damoncooper

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    I heard that they create an anti-gravity field under each motor and that propels the craft. Warp drive should be coming in Phantom 3, though. No word on whether FPV will work with FTL travel.

    :)
     
  16. ianwood

    ianwood Taco Wrangler
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    Just watch out for the wormhole flyaway. Make sure the Phantom records all the dimensions before you take off otherwise it will end up in the future and it's a total pain to find it.
     
  17. chuddly

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    Nope...wont happen on P3. The FAA says a quad copter is not in LOS if it travels through time :lol:
     
  18. discv

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    That might explain fly aways. DJI are using us as free R & D researchers.
     
  19. ProfessorStein

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    Does GPS work at a quantum level??
     
  20. discv

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    I wonder why the OP has gone AWOL.