Catastrophic crash tonight - Phantom 3 Pro destroyed!!

[blade strike]

Using the wrench to get the props good and tight is the best way to prevent one being thrown off during braking. If they get too loose from repeated removal after overtightening, just replace them. The new all plastic composite interior props are 1/4 the cost of the old ones that had metal threads inside! Consider periodically replacing them as a regular maintenance item, even if the blades still look like new. The interor cushioning of high end running shoes wear out long before the exterior tread ever shows signs of wear. Same idea.

Please do not use the wrench to tighten the props. It's included to only remove the props if they are difficult to remove.

Spin the prop on and then snug them up by hand. This is all that is required.

 

[GadgetGuy]

Please do not use the wrench to tighten the props. It's included to only remove the props if they are difficult to remove.

Spin the prop on and then snug them up by hand. This is all that is required.

Thanks for the correction. Can you be more specific about the reason?

 

[30secs]

I would like to get a confirmation that active breaking in fact reverses the motors spin. It does not make sense. Perhaps the esc's reverse the motors output so it counter acts the last movement. Can someone confirm?

 

[Marlin009]

Reversing the spin would be ugly. It's breaking, slowing down.

 

[GadgetGuy]

Reversing the spin would be ugly. It's breaking, slowing down.

So there is no way the self tightening props should be coming off in flight, even if not tightened properly? I thought I had read somewhere (doesn't make it true---) that the P3P uses composite prop threads because the metal threads would unscrew during braking. Can anyone corroberate or refute that?

 

[Marlin009]

So there is no way the self tightening props should be coming off in flight, even if not tightened properly? I thought I had read somewhere (doesn't make it true---) that the P3P uses composite prop threads because the metal threads would unscrew during braking. Can anyone corroberate or refute that?

That is the point of the composite hubs, they grip better than bare metal.
Clearly, props should not come off in flight. If a motor stops on either the P2 or P3, the result is the same. The breaking feature on the P3 is not causing props to come off, assuming it is working as designed.

 

[mrburris]

DattaGroover - best of luck to you. I don't look forward to that process.

Upon further inspection this morning, it looks like one of the props came off!. the other 3 props were either sheared off on impact or badly damaged. The 4th rotor had no prop. I looked all over for it around the crash site to no avail. I always give these a nice snug tightening after spinning them on, so I know it had nothing to do with how I put them on (I even double checked in my pre-flight). After reading a bit more on how this could potentially happen, sounds like maybe a motor failure either locking up, changing direction or something similar could spin off a prop?? Sounds rare, but not sure what else it could be.

Since I just received this 3 days ago, bought through Amazon, using my Amex, I am almost inclined to send it back and get a replacement unit this way, after hearing some horror stories about DJI warranty, and the fact that it could take 6+ weeks (unacceptable IMO). I feel like I would be on trial or something - after spending $1300 for a defective unit, to wait weeks, to only have them subjectively determine whether or not to replace it?? Any thoughts?

Here are all of the pics: https://www.dropbox.com/sh/jlrwieleltlqyu1/AADJxWJh_Y4L2RXhCUN1ndRka?dl=0

Is that a gimbal lock I see in the picture? Was it still on the unit when you flew? Could that have been the culprit if so?

 

[30secs]

That is the point of the composite hubs, they grip better than bare metal.
Clearly, props should not come off in flight. If a motor stops on either the P2 or P3, the result is the same. The breaking feature on the P3 is not causing props to come off, assuming it is working as designed.

Help me understand what you are saying. What do you mean by if a motor stops? Due to failure? Due to breaking? Do you know how the motors react in breaking? Do they just stop or apply reverse direction thrust (not reverse spin)? What result for p2 and p3 that is the same are you talking about?

 

[GadgetGuy]

That is the point of the composite hubs, they grip better than bare metal.
Clearly, props should not come off in flight. If a motor stops on either the P2 or P3, the result is the same. The breaking feature on the P3 is not causing props to come off, assuming it is working as designed.

I, too, want to better understand this P3 braking feature, and how it works, and whether it is different than the P2. From what you are saying, it isn't a reverse spinning of the props, as many have incorrectly assumed, or read on the internet, where false information abounds! So, how does braking actually work, as simply slowing down should actually cause it to keep moving more slowly in the original direction, instead of stopping?

 

[Akrosfer]

I would like to get a confirmation that active breaking in fact reverses the motors spin. It does not make sense. Perhaps the esc's reverse the motors output so it counter acts the last movement. Can someone confirm?

Let me tell you my opinion:
Motors never stop and no motor change its turning direction during brakes.
Brake can only mean that 2 front (flying direction) motors are taken into standby mode (as seen before beginning to fly) and the other 2 rear motors begin to turn faster.
We already have 2 groups of motors turning in opposite directions and positioned in opposite directions. Why should they change their direction of turn?

 

[Wayne Parris]

Using the wrench to get the props good and tight is the best way to prevent one being thrown off during braking.

I usually spin my props on until they stop, then slightly tighten them hand tight. I've never used a wrench. Do you know exactly how tight they are supposed to be? I was afraid to over tighten them due to stripping out the threads.

 

[Australis5]

Is that a gimbal lock I see in the picture? Was it still on the unit when you flew? Could that have been the culprit if so?

No. Gimbal guard was not on the unit when flown. Was just gathering all pieces of the kit.

I'm also curious on the braking issue. Just received my replacement unit, and am cautiously excited to fly again after this crash. I put the props on, and used the wrench to snug them, and had planned to leave them on based on earlier advice. I think I need to go back, and re-do this only by hand - possibly with a new prop set. Curious for more opinions - do you guys leave your props on? I can certainly see the case for doing so.

In my case which started this crash thread, it was deemed an ESC or motor failure that brought it down. I can't even guess what an ESC failure would do. But, assuming it was a motor failure - hypothetically, what exactly could that mean that would bring it down in an instant like that? Did the motor locked up and spun off the prop? Did it power down? Did it reverse direction? I do plan on turning down braking slightly, but am interested in making sure I'm doing everything I can to have this one stay in the sky and land softly at home. I get that rare mechanical failures can happen, but again, interested in hearing more about prop tightening and/or removal as well as braking that I can have a potential impact on.

 

[Wayne Parris]

I would like to get a confirmation that active breaking in fact reverses the motors spin. It does not make sense. Perhaps the esc's reverse the motors output so it counter acts the last movement. Can someone confirm?

Rotor blades only produce lift while rotating in one direction. The breaking action incorporated in the Phantom is where two motors next to each other slow down or speed up their rpm. For example, when you advance the right stick to go forward, the rear motors speed up. This causes the entire aircraft to tilt forward. Then, at some point, the front motors speed up as you push the stick further forward and allows for more speed. When you slow down or come to a hover, everything I just described happens in reverse order. The same thing happens when you slide left or right, except instead of the rear motors speeding up, it's two on the same side that do.

You have two props turning in one direction and two turning in the opposite direction at all times. Counter-rotating props counteract the torque produced from each motor. If they weren't counter-rotating, we'd have to have a tail rotor like a helicopter. Our props are self-locking, meaning that the motor head is turning in a direction that continues to apply pressure in the tightening direction to the prop. Example, a Chinook helicopter has two main rotor heads that turn in opposite directions. All single-head helicopters have a tail rotor to counteract the torque produced by the main rotor. Otherwise, the body would just spin in the opposite direction from the main rotor.

Short answer---if the motors reversed their direction, this thing would flip over out of control. The props would unscrew themselves and depart the aircraft. The threat to injury to people below would be so great that it would never be available for sale due to the liability.

I hope this helps in finding the answers in which you seek.

 

[Marlin009]

Help me understand what you are saying. What do you mean by if a motor stops? Due to failure? Due to breaking? Do you know how the motors react in breaking? Do they just stop or apply reverse direction thrust (not reverse spin)? What result for p2 and p3 that is the same are you talking about?

Disclaimer - I am not a P3 expert by any means. I do not own one. I have not RTFM.

My opinion is based on logic alone. I don't know how DJI implements the dynamic braking, but it cannot stop or reverse the motor. The result I'm referring to is that both a P2 or P3 would crash if a motor stopped or reversed. It would drop that corner violently and gravity would take over. The only reason a motor would stop is a failure of some sort.

I assume that the braking feature is a more efficient ? way to change the speed of the motor to affect the attitude of the quad and change its direction. There may be something in the DJI Wiki pages that describes how it actually works. The reason for the composite hubs would be to provide a tighter fit so that they will not loosen when the braking is applied.

 

[GadgetGuy]

Rotor blades only produce lift while rotating in one direction. The breaking action incorporated in the Phantom is where two motors next to each other slow down or speed up their rpm. For example, when you advance the right stick to go forward, the rear motors speed up. This causes the entire aircraft to tilt forward. Then, at some point, the front motors speed up as you push the stick further forward and allows for more speed. When you slow down or come to a hover, everything I just described happens in reverse order. The same thing happens when you slide left or right, except instead of the rear motors speeding up, it's two on the same side that do.

You have two props turning in one direction and two turning in the opposite direction at all times. Counter-rotating props counteract the torque produced from each motor. If they weren't counter-rotating, we'd have to have a tail rotor like a helicopter. Our props are self-locking, meaning that the motor head is turning in a direction that continues to apply pressure in the tightening direction to the prop. Example, a Chinook helicopter has two main rotor heads that turn in opposite directions. All single-head helicopters have a tail rotor to counteract the torque produced by the main rotor. Otherwise, the body would just spin in the opposite direction from the main rotor.

Short answer---if the motors reversed their direction, this thing would flip over out of control. The props would unscrew themselves and depart the aircraft. The threat to injury to people below would be so great that it would never be available for sale due to the liability.

I hope this helps in finding the answers in which you seek.

Very helpful! Thank you! I'll now be much more comfortable removing props for transport and only hand tightening them upon installation, without worry that braking can spin them off, if not cranked down!

 

[Farmer]

All these random crashes with no reasons to them are making me nervous! I know I won't be upgrading to the latest firmware once I receive mine. Sorry for your loss and hopefully DJI pulls through! From what I've seen, it certainly looks like something failed on the unit and not pilot error.

I usually spin my props on until they stop, then slightly tighten them hand tight. I've never used a wrench. Do you know exactly how tight they are supposed to be? I was afraid to over tighten them due to stripping out the threads.

There is no way, I am not going to use my wrench to tighten these Props - given the anecdotal evidence that crashes have occured as a result of loose props.
And I bought a case that allows me to keep my props on for thiat very reason.

 

[Meta4]

There is no way, I am not going to use my wrench to tighten these Props - given the anecdotal evidence that crashes have occurred as a result of loose props.

It's amusing when conservative users make up their own rules to make their flying even "safer" and often it has the opposite effect.
Using your wrench is not necessary at all and the anecdotal evidence you mention isn't very reliableif they used genuine P3 props with composite hubs.
Using the wrench puts too much pressure on the soft plastic threads and will weaken them prematurely.
They are only supplied to loosed stuck props after a crash - not for putting props on.
Do you fancy having a prop thread fail in flight because you've over-tightened?
Check the manual - DJI say tighten the props by HAND.
When you start the P3 you notice the motors rev up twice.
That is the P3 tightening the props itself.
Put your props on properly and they will not come off in flight.

 

[Automattic]

Very helpful! Thank you! I'll now be much more comfortable removing props for transport and only hand tightening them upon installation, without worry that braking can spin them off, if not cranked down!

By the look of the video I would say that one of the blades had a defect in it. The high speed spinning caused it to break itself apart. Missing one blade would cause what was seen in the video.
I have seen this happen before.
New Blade looked fine and spontaneously exploded in flight.

I think a blade spinning off would be much less likely by design.

Most defects are going to show up in the first 15 flights or so. As others have mentioned you want to do lower flying until your Sure everything is functioning as it should.

Hope the next one turn out better for you.

 

[Australis5]

By the look of the video I would say that one of the blades had a defect in it. The high speed spinning caused it to break itself apart. Missing one blade would cause what was seen in the video.
I have seen this happen before.
New Blade looked fine and spontaneously exploded in flight.

I think a blade spinning off would be much less likely by design.

Most defects are going to show up in the first 15 flights or so. As others have mentioned you want to do lower flying until your Sure everything is functioning as it should.

Hope the next one turn out better for you.

If you mean the video in this thread of my P3 going down...I actually found the prop that spun off on the roof of the neighbors house a few days ago, fully intact in new condition

 

[Automattic]

Oh wow, that is bizarre.
Nevermind then.