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So, you're saying I should try it? I'm gassing up the truck right now. Moon, here I come!
Phantom flying and the theory of relativity
- Thread starter MILLER4PRESIDENT2020
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N017RW
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Inside the RV with windows closed, GPS off, and the RV holding a constant speed and direction (and not going over or down a hill), it should just hover. Open a window or launch it from outside the RV (on the roof) and you're in trouble. 
As mentioned, it's the same as if you drop a ball inside the RV: it'll just drop straight down to the floor of the RV. Objects in motion tend to stay in motion unless affected by an outside force (like air). When you block off the rushing air by being inside the RV, you've sort of made your own relative environment.
Mike
As mentioned, it's the same as if you drop a ball inside the RV: it'll just drop straight down to the floor of the RV. Objects in motion tend to stay in motion unless affected by an outside force (like air). When you block off the rushing air by being inside the RV, you've sort of made your own relative environment.Mike
Hover in the RV with RV stationary. Accelerate RV. Assuming no gps, and no rotor wash effects, the phantom will initially "move" back but once the RV speed becomes constant, eventually the air in the RV will settle and the phantom will stay still again. At least that's my theory B-)
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N017RW
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I think it will either go nuts or be fine. If it cuts off gps mode fast enough it will hover fine in p-opti mode. Like others said, cabin pressure will cause the craft to also be moving at 55mph and the motors will just hover. If it trusts the GPS readings it will crash. It will try moving toward the back of the van at max speed, to maintain it's position in space.
If it cuts off gps mode fast enough it will hover fine in p-opti mode. Like others said, cabin pressure will cause the craft to also be moving at 55mph and the motors will just hover. If it trusts the GPS readings it will crash. It will try moving toward the back of the van at max speed, to maintain it's position in space.
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Well... it's been officially resurrected, so I read it all. And now I have to ask:
Since virtually everyone has said "with GPS off"... blah blah blah.
What's the expectation with GPS ON?
And I'm not asking "will it struggle with orientation, will it feed back errors", I'm asking "will it suddenly slam against the back of the RV, trying to hold hover on a static GPS coordinate?
Since virtually everyone has said "with GPS off"... blah blah blah.
What's the expectation with GPS ON?
And I'm not asking "will it struggle with orientation, will it feed back errors", I'm asking "will it suddenly slam against the back of the RV, trying to hold hover on a static GPS coordinate?
As Einstein would say "Its all relative!". Just depends on your frame of reference. Inside the RV, is the RV moving around the world or is the world moving around the RV? The answer is "Yes!" That's why when you are in an airplane going 450 MPH and drop your peanuts, they don't shoot to the back of the plane like a rifle bullet! I substitute teach in the local middle and high schools and despite the general feeling about how dismally kids are being taught nowadays, I just sat in with a group of 9th graders who would have gotten this right, too!
Yes... but the peanuts are not trying to orient themselves with a sophisticated built-in GPS receiver system... at least not the peanuts I get on the plane...
The consensus on this thread is correct. All non-accelerating frames of reference are equivalent in terms of the laws of motion, and so without an external reference (GPS) the Phantom would be perfectly stable in a vehicle moving at constant velocity. The complication is the addition of GPS - in GPS mode the FC will attempt to hold position which, in a moving vehicle, would result in a prompt and rapid collision with the rear window.
This reminds me of a more interesting vehicle physics question - if you are driving with a helium balloon in your vehicle and brake suddenly then what does the balloon do?
Hit me in the back of the head, like it did last week.
However I'm assuming that's because of the mass of the foil ballon skin and not the gas contained within.
Interesting - if the balloon, in total, is lighter than the air that it displaces then the mass of the foil is not really relevant to the problem. It will move backwards in the vehicle, not forwards, because the direction of the overall acceleration vector (dv/dt + g) is back and up. Are you sure that it didn't hit you when you were accelerating?
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