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Phantom flying and the theory of relativity

Discussion in 'Pro/Adv Discussion' started by MILLER4PRESIDENT2020, Jun 24, 2016.

  1. MILLER4PRESIDENT2020

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    I was in an RV the other day with my phantom and got to thinking with my friends what would happen with the Phantom if I tried to fly it within the RV on the highway? I was drinking and so decided not to do it however we all had a discussion. Now my theories are as follows, not sure if they are correct or not.

    If the RV was in a perfect cruise control at 55, and not accelerating/decelerating or weaving about within lanes then I could launch the phantom and it would hover there in the RV in the same spot and not appear to move to us. To the passengers the Phantom is moving 0 mph. To an outsider standing on the side of the highway, if the RV was made of invisible material, it would appear the the Phantom is moving forward at 55 mph, despite the fact that the physical speed limit on it as about 30 mph.

    My friend believed that as soon as I launched it, it would fly backwards and hit the back of the RV because the forward capability of it is around 30 but we are actually going 55 meaning it doesnt have enough forward mobility on its own to keep up. I dont think this is correct, what would it look like if this was the case? Would it just be sitting on the floors rotors spun up, and the split second its landing gear leaves the ground it would instantaneous acceleration backwards at 20mph? This doesnt seem right as nothing is instantaneous. But another way of thinking about this is what if this happened in the back of a pickup truck that is more exposed? I can definetely envision trying to launch from the back of a pickup on the highway and as soon as you lift off you are out of the bed and then the phantom is dancing like crazy sorting itself out.

    I believe that if the RV was at zero, I launched and went into a hover, and then accelerated the RV, the phantom would slam into the back of the RV. Kind of like if I was wearing roller skates and did nothing to add friction then I would go sliding backwards.

    A lot of interesting hypothetical here.
     
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  2. konidair

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    why don't you buy a $10 copter and try it ;)
     
  3. fantom69

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    Very interesting question, My guess is that the bird would hover in the RV without going backwards. I may well be wrong but a similar thing I noticed when I was a kid made me tonder... I was sitting on a bus travelling at about 50mph and a fly was flying around trying to get out of the front window, I wondered why the fly wasn't splatted up the rear window?

    I still don't really know why this happens.

    Fascinating anyhow.
     
  4. bbfpv

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    Assuming you have disabled GPS, if you take off and hover while the RV is at a constant speed, the quad (and you, and everything in the RV) is moving at the same speed as the RV, ie, the physics of everything is relative to the RV, so the quad will hover in place while actually traveling at the speed of the RV relative to the earth. However, if you take off while the RV is accelerating/decelerating, your quad may crash into the back/front of the RV due to the acceleration forces of the RV being applied to the bird on take-off. See Newton's First Law
     
  5. N017RW

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    +1 bbfpv
     
  6. Bigalpdx

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    The whole mass of air inside an enclosed vehicle is traveling at he same speed of the vehicle. That allows a "bee" to move inside the vehicle without having to reach the speed of the vehicle first. Open some Windows, cause some turbulence... Then there goes the bee and his power to move around. I would think a drone inside a close vehicle starts at the same 55mph and will continue to be at this speed since the air around is traveling at the same speed.
     
    Pharm likes this.
  7. BigAl07

    BigAl07 Moderator
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    Two words for everyone..


    ROAD TRIP!!

    Although I would be interested to know what kind of funky GPS errors you'd get with GPS on.
     
  8. N017RW

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    GPS would surely qualify as an 'external force' in terms of Newton's law. ;)
     
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  9. Pharm

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    As long as there was no air moving in the RV and GPS was off, it would hover. Try it with a lightweight object (a piece of paper, etc.). Other than air deflecting it as it falls (just like it would outside with no wind), it will fall straight down. The only issue might be the turbulence created by the downwash from the rotors. Think of it like this (concerning relativity): the RV isn't moving at all, the highway is moving.
     
  10. Pharm

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    This brings up another question I'm currently testing. According to Einstein, a fast moving observer measures the passage of time slower than a stationary observer (time dilation). Does that mean if I drive really fast that I'll age slower? Unfortunately he also stated that a fast moving object also has increased mass. So, I could end up younger, but larger. Hmmm...
     
  11. N017RW

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    Yes. Neil D-Tyson once calculated this effect on Indy 500 drivers.
    Sorry, no link at this time.
     
  12. bbfpv

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    But time dilation is relative to the speed of light. You need to accumulate the distance traveled by light in your lifetime. So for example, if you drove your car to the moon and back, you would be 3 seconds younger than someone on earth when you returned because it takes light 3 seconds to travel to the moon and back.
     
  13. drm

    drm

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    As long as GPS is disabled and the RV travels in a straight line, it should hover in place with respect to the RV just as well as it would if you were flying indoors (ie. with no wind effects). It's no different than hovering on Earth and having the Earth rotating ( at up to 1000 mph surface speed). Good luck, let us know how it turns out. (I'm sure someone will eventually try this)
     
  14. rhexis

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    time is also affected by gravity not just speed. hang out next to the great pyramid in giza for 50 years with a very precise clock and you would probably see a few miliseconds difference with another clock not near the pyramid. now do the same but hang out near a black hole. the larger the gravitational force the slower time.
     
  15. Multicoptertec

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    Easier to demonstrate with a ball, or any object. Throw the object into the air, it won't go backwards in an RV, car, jetliner, whatever.
     
  16. K9DAVE

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    Thats why I love this forum, where else would you get a question like that knowing that somewhere down the line you will get the answer BRAVO! :)
     
  17. WetDog

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    Here, hold my beer.....
     
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  18. Newgmole

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    "It's good to be king"
    Michael Badnarik
     
  19. Newgmole

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    Too deep for me right now! I've had a couple blue moons…


    "It's good to be king"
    Michael Badnarik
     
  20. Wibble

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    This is all crap.
    By rights we shouldn't even be here. We are obviously all figments of someone's warped mind!