P3S's prop flies off mid flight

[joeb1999]

There are only a few ways this can happen. There is the possibility of a factory defect.

First possible way is you had at least that one prop on in the wrong spot. Probably not. Or you'd have all of them wrong to look right just wouldn't make any sense.


Then there is over tightening. And potentially stripping the threads. It's nylon so it's not hard to do.

Could have cross threaded the prop and maybe it felt tight but was barely on. I'm thinking this the most likely.


They are threaded counter to the rotation so in theory they self tighten. Even so I usually snug it up by about a quarter turn max. Maybe even 1/8.

Its never happened to me yet. Hope it won't.

-Joe

Anyone ever have this happen to them?

My very first flight out of the box, about a minute into it. had it in A-Mode and was headed back to me 6 feet up. Next thing I know it flips and flies straight into the ground for a hard landing(not even a scratch)

Second time happened to today. This time I did auto take off and the second it took off it flipped and crashed into the ground(again not scratch)

Is this some error on my end possibly? Different props and different colors

1st time I had not done an IMU cal yet.
2nd time i took off from a not so level surface. 5-10 degree angle

 

[Jay H]

I have been thinking about this and I think flight would be possible but it would have to rotate continuously.

not possible unless u have a tricopter... 100% cant not fly a quad with 3 props.... one of the motors would be spinning the wrong way....

 

[msinger]

100% cant not fly a quad with 3 props

It's not impossible

 

[Jay H]

It's not impossible

lol i stand corrected.. although a phantom is much heavier... if someone wants to test, good luck! haha

 

[msinger]

That definitely will not work with the Phantom as-is now. Perhaps DJI would be able to implement a similar failsafe in a future Phantom though.

 

[Travis726]

I have been thinking about this and I think flight would be possible but it would have to rotate continuously.

Maybe, I know it is possible with 2 (while spinning). Trying to control it could be interesting though.

 

[TheRealNick]

not possible unless u have a tricopter... 100% cant not fly a quad with 3 props.... one of the motors would be spinning the wrong way....

The video msinger posted is a lot like I pictured, maybe I should have said fail safe instead of flight but that is what I meant when I said continuously rotating....there would be no way to balance out the yaw.

 

[Steven XXIII]

Steven XXIII, were you able to find the missing prop? If so, what does the inside of the hub look like?

no, i could not find the missing prop. The aircraft "landed" on a remote hillside thick with bushes. I was lucky to fine anything.

 

[Steven XXIII]

Its not a design flaw, its physics. NO quadcopter can fly with 3 motors/props that I am aware of. Doesnt seem possible.

Well there are pictures of quads flying on 3 props so i respectfully disagree. It is not a smooth flight but there is an algorithm that will take it down in a semi-controlled manner.

On a related topic, DJI should recommend using blue locktite on the props to prevent the "self-tightening" props from coming off.

I will give DJI credit for fixing the aircraft without charge.

 

[Ron Arnson]

I wouldn't want to use Locktite. I have to remove my props after every flying session in order to put it in my case. Also, I would be afraid that the Locktite might soften the plastic hub.

 

[kmaluo]

On this note, should I avoid using a case where the props have to come off everytime?

 

[msinger]

should I avoid using a case where the props have to come off everytime?

It's best to inspect your props closely before each flight to ensure they are not damaged. You want to check for things like cracks around the hub and stripped/worn threads inside the hub. That'll be impossible to do if you store your Phantom with the props attached and never remove them.

 

[stulpin300m]

I always start the drone and let it warm up on the ground spinning for 30 sec then I lift it up about 3 feet and do the same before I take off. You lose over a min a flight time but it lets it warm up and gives you that min to make sure it's good to go.


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[shorttimer]

It's best to inspect your props closely before each flight to ensure they are not damaged. You want to check for things like cracks around the hub and stripped/worn threads inside the hub. That'll be impossible to do if you store your Phantom with the props attached and never remove them.

I just leave both of my P3As on my desk with the props on. I do inspect the props each day. Two days ago I went for my first long flight with my P3A with old shell and motors and went 6600' Yesterday I was going to take my P3A with new motors and shell for a long run. Props looked fine but when I looked at them running, idle, on the ground I saw the smallest wobble in one of the hubs. So I shut it down and just replaced it with a prop from my other P3A and it didn't wobble any more. Again, it was very small but it was noticeable. I don't have a prop balancer so either I will get one or just toss it. I just didn't want to chance it.

 

[buford]

I'm of the opinion that if a prop falls off during flight, it wasn't the drone or braking or anything other than the prop. I'm reminded of a kid who wrote in, having had a not too bad crash, and he wanted to know if he should replace his prop, since it did hit the ground and had some damage showing. Everyone told him they would change them. He disagreed, and said he was going to fly it anyway. Props do not just fly off in flight. The motors don't switch rotation when braking, for that matter, there are only a few conditions that can make a prop fly off, and they are screwed up theads in the hub, propellers installed incorrectly (silver to black/black to silver), loose propellers, propellers left on for 50 flights with no checking, you get my drift....LOL

 

[TheRealNick]

Well there are pictures of quads flying on 3 props so i respectfully disagree. It is not a smooth flight but there is an algorithm that will take it down in a semi-controlled manner.

On a related topic, DJI should recommend using blue locktite on the props to prevent the "self-tightening" props from coming off.

I will give DJI credit for fixing the aircraft without charge.

That is cool that DJI fixed it, do you happen to have the .dat file? Since they fixed it perhaps yours was a case where the motor seized because of the esc or another reason....would love to see a data file for that....

 

[N017RW]

Well there are pictures of quads flying on 3 props so i respectfully disagree. It is not a smooth flight but there is an algorithm that will take it down in a semi-controlled manner.

On a related topic, DJI should recommend using blue locktite on the props to prevent the "self-tightening" props from coming off.

I will give DJI credit for fixing the aircraft without charge.

I too have seen a video of the so-called flight on three motors. (same one as you ???)
It's more of a highspeed spin which is the only way to obtain any type of relative stability and was using a more or less symmetrically balanced quad which would seemingly not be feasible with a Phantom nor would it offer any better outcome once the gear/camera/gimbal struck the ground or an object spinning like that. I believed it also requires quite a bit of computing power which the Phantoms lack.

As far as LocTite is concerned the Blue and Red types are not compatible with plastics so this may be risky with the props..

 

[TheRealNick]

There is another thread where a propeller came off and the poster confirmed he would just spin the props on until they stopped. It seems like he had several flights that went ok with that method as well, it made me feel a ton better about what I do. I spin them down and then turn the props about 1/10 of a turn. To remove them I do not have to use the wrench, but I also do need to use both hands. I have been playing around with different degrees after the prop touches the motor and I am really thinking 1/10 of a turn is about perfect....

As a result, I do not think lock tight is required...and would never us it myself.

 

[syotr]

I'm of the opinion that if a prop falls off during flight, it wasn't the drone or braking or anything other than the prop. I'm reminded of a kid who wrote in, having had a not too bad crash, and he wanted to know if he should replace his prop, since it did hit the ground and had some damage showing. Everyone told him they would change them. He disagreed, and said he was going to fly it anyway. Props do not just fly off in flight. The motors don't switch rotation when braking, for that matter, there are only a few conditions that can make a prop fly off, and they are screwed up theads in the hub, propellers installed incorrectly (silver to black/black to silver), loose propellers, propellers left on for 50 flights with no checking, you get my drift....LOL

Props can and do come off in flight. That's why DJI added prop locks to the Inspire props and changed to the composite hubs on P3 props. DJI claimed that active braking could make a prop come off. The other possibility is a glitch in the ESC. If one of the three motor wires is disconnected the motor will lock up and the prop will fly off unless it was really tight.
Here is a video of trying to make a prop fly off by manually stopping the motor. It was difficult but possible. At the end, you can see what happens if you disconnect a motor wire.

 

[movius]

Always install the props, spin them, then grasp the motor & turn them by hand a 1/8 turn or so until you are certain the prop is fully seated & snug. You don't have to use the wrench you just have to make sure they are completely seated.

My approach exactly. So far so good.


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