terminal velocity of a phantom
- Thread starter turbodronepilot
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There's not enough mass for the surface area of the Phantom in free-fall to ever get to 125 mph, which is the terminal velocity of a sky diver. Take off the floppy dive suit and point straight down and you would go faster. Mythbusters actually took on the question of "can you kill someone with a penny dropped from the Empire State Building"? They did wind tunnel tests to calculate the wind resistance of a penny falling flat and edge-on and determined that falling flat, it would reach about 35 mph, and face down about 65 mph, but since it would tumble they estimated that the terminal velocity of a penny is 45 mph.PhantomFanatic said:
I started this post after one I was interested in about a phantom with a kill switch and parachute. .was wondering if a parachute would be effective in slowing down a phantom to a velocity that would be less likely to cause injury to someone or property damage. Im glad some of you found the post to be amusing. .. it's the least I could do..
turbodronepilot said:
Absolutely, if the chute is big enough and the rotors aren't spinning! Add a beeping sound and everyone will be sure to look it!!
PhantomFanatic said:
You're not serious, correct? The terminal velocity depends on several factors including the objects mass, the drag coefficient of the object, and the projected area of the falling object. Unless a man shares all these variables with a Phantom, it's unlikely they will share the same terminal velocity. Meta4 provided the correct answer earlier: experiment with your drone to determine the terminal velocity or figure out the surface area and drag coefficient and calculate the terminal velocity. I can tell you from personal experience that the terminal velocity exceeds the shear strength of the gimbal system.
There is a video somewhere of a phantom where the pilot put it into freefall and IIRC the altitude data is also shown - simple time - distance calculation will reveal its velocity.
I have seen several videos of Phantoms dropping from a high altitude where the first the Phantom drops, then the quad will right itself at speed and the props will start to autorotate. At this point the props will act to slow the fall, much like the prop on a gyrocopter or a helicopter autorotating. The machine will still crash hard but at much less than freefall speed. This effect will only happen in a fall from several hundred meters or more.
Found it
https://www.youtube.com/watch?v=bMbvA2xyPL8#t=789
At about 12:30 motor are shut off and decent speed is about 5MPH - props will be in autorotation.
Surprisingly slow.
https://www.youtube.com/watch?v=bMbvA2xyPL8#t=789
At about 12:30 motor are shut off and decent speed is about 5MPH - props will be in autorotation.
Surprisingly slow.
paulajayne said:
Something wrong with that flytrex data. At 15:00 minutes in the video, the decent rate jumps to around 30 MPH which is closer to what I would expect Phantom terminal velocity to be.
:shock:
I've seen this video before, smh.
You really didn't think we could let a straight line like this go without snark, do you?turbodronepilot said:
The idea of the parachute is to protect the drone, not what's on the ground under it. If you drop a Phantom into a crowd of people, the odds are that you won't have a direct hit on anyone because if you look down on a crowd of people, even at a football game, there's an awful lot of empty space between them*. A glancing blow is much more likely. Considering a three pound mass moving at probably 30 mph, there's not a lot of energy there to do a lot of damage. Sure, if it hits someone, there will be bruises and maybe even a laceration. If it hits a car there might be some paint scratches. There will not be the blood and mayhem that some people, even on this forum, think is inevitable from a Phantom dropping out of the air.
If you were flying a hexacopter with a $5000 camera, a parachute might save the camera.
*Ever watch the T-Shirt cannons at public events where a tightly folded T-shirt is blasted into the crowd from a compressed air cannon? Most of those shirts land between people and they dive to the ground to grab one. And these are people who are trying to catch a falling object.
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N017RW
Premium Pilot
Skydronik said:
How is that possible with fixed pitch blades and no way to 'disconnect' them from the drag of the motor(s)?
If you want to actually do some measurements without destroying a Phantom, you just need a tall bridge that you can walk to the edge of, one Phantom, and a good length of sturdy string. And a stopwatch. To be really accurate, I'd suggest painting the string at various intervals, and filming it as it unwinds. To avoid friction from unwinding, it should unwind from the middle of a spool-less bundle.
A couple of important points: The length of the string should be less than the height of the bridge, and the other end should be tied to something solid at the top. Using some bungee cord at the end may also be a good idea to prevent the string from snapping.
A couple of important points: The length of the string should be less than the height of the bridge, and the other end should be tied to something solid at the top. Using some bungee cord at the end may also be a good idea to prevent the string from snapping.
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N017RW said:
Hi. All this thread is a joke.... Dont take it too seriously. The fact of not being able to engage/disengage rotors is not an excuse to not trying it. We all know what is going to happen with the bird, but we want to see funny videos of this happening on someone else's bird.
N017RW said:
I was wondering when someone would pick up on this. Good job man. No pitch adjust, not enough mass to do any good. The best to hope for is IF the props will spin and and slow decent and that's only if the quad falls flat which it won't.
I just saw Intersteller and I would really watch out for black holes that change your time in space to say 1754. You're gonna freak some Spanish King out big time. Also, keep the FatShark gogs on really tight as you reach light speed. And, do not...do not, turn off the Auto RTH.
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