Cracking the P3 crack

want to upload other pictures, but It seems I am not allowed :confused:
(oops my bad... it works now)
 
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pic1: the carbon on the base of p3's motor
pic2: the alu on the outside to reinforce the plate. (discarded this idea - but actually seems good for the visual :D )
 

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I was thinking (being in manufacturing myself) there could be a few reasons for the cracking problem on the P3.

- Flight fatigue and stress over time
- Off Balance motor due to rotor damage

But look at this, a FLIR image of a P3 after about 1 minute of hovering

View attachment 30029

Heat buildup from the motor is NOT good for the plastic. Combine that with vibration and over a period of time you get brittle arms. I saw a number of 3d printed re-inforcing plates - this could in fact increase the heat issue What we actually need is machined aluminium plates, those will acted as a heatsink as well..

Any thoughts?
If that's from 1 minute of hovering I can only imagine what 3-4 batteries right in a row would do.
 
pic1: the carbon on the base of p3's motor
pic2: the alu on the outside to reinforce the plate. (discarded this idea - but actually seems good for the visual :D )
Interesting idea. Certainly better than the stock situation. The only issue is that you are still supporting the motor in that small area of thin plastic. The ideal solution (short of DJI actually engineering a real solution) would be to reinforce that plastic and spread the load towards the center of the bird. The engineer in me likes the fact that the Strong Arms connect to the other two body screws thus spreading the load.

I'm not convinced that heat is a significant problem. The motors themselves have built in heatsinks and the plastic seems to be heat resistant enough as the batteries get much hotter than the motors without a problem. I think the main problem is how the motors attach to such thin plastic mounts with the vibration and other forces involved with the more powerful P3 motors.
 
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If that's from 1 minute of hovering I can only imagine what 3-4 batteries right in a row would do.

I Imagine there is a point where it hits an operating temperature and stays there. My experience with RC anything is it eventually maxes out at a temp at some point.
 
What about a new body design. Something that you can take out the guts of the P3 and just attach to a new undercarriage that is made of aluminum and /or carbon fiber. Have a plastic shell to cover the bits and pieces like it is now, but the undercarriage provides all the support and rigidity needed. You can use round or square tubes to hide the wires going to the motors. And could even come up with some cool toppers that can allow for customization and styling. The P3 as a whole is solid and a good product, but it would be nice to allow for customization a bit more and to have a more solid and stylish foundation like the Inspire 1.

Just some food for thought.

If someone out there has some mad engineering skills that could design a new frame and topper, I'm in. I'd buy one to move my guts to.
 
It's very unlikely that the motor just ripped itself out during normal flight. It had to have been involved in a crash or very hard landing. Just my opinion.
I had to send mine back a couple weeks ago due to symmetrical fractures on two of the arms, all of which were around the four motor mount screws. Almost exactly the same on both arms. With just a little force I could have easily separated the motor from the shell, that's how bad these were. I had never crashed, had hard landings or anything. For all intents and purposes my P3P is a 400 ft tripod. I didn't fly it aggressively, had the gains/ breaking adjusted to ensure smooth footage and yet it still exhibited the same cracks as the guy who actually had the motor fly off mid flight. My arms look almost the same besides my motor still being intact. This is obviously a real issue and I believe we will see more and more of these as more time passes, regardless of whether the craft has crashed or not. The shell doesn't seem like it's built to last. When it returns I'll install the UAV bits kit from Gary and pray for the best lol
 
It's very unlikely that the motor just ripped itself out during normal flight. It had to have been involved in a crash or very hard landing. Just my opinion.
I had a minor crash a few weeks into owning my P3 back in June. I checked it closely for damage at the time and found nothing (that I could visually see). I flew my P3 long distances (up to 5km) and in heat as high as 38C (100F) over the next 3 months without a sign of a problem. I had checked for cracks about a month and a half ago and saw nothing. Then during a easy test flight at the park doing simple hovering and gentle maneuvers the motor literally came right out of the bird with no warning sending it spinning into the ground. I am just so grateful nobody was around to get hurt and that it happened 30 feet in front of me so I could recover it.

If I did something outside of "normal flight" I'd like to know what it was. I used my P3 as it was intended. I wasn't afraid to use it and sent it on some epic adventures, but never did I hit anything or crash hard.

This is simply a design flaw. Now that I know about it I can reinforce where it is needed and hope that if I lose my bird again it will be because of a much more exciting story than the motor flying out of the air frame.
 
Reply 2 Brian
Wait til a battery is cooled. 10-20 min cool area, stone floor. Avoid storing at full charge ( for long). Never charge hot. Keep in fireproof bag/metal box, not in p3. Gentle with them - air = combustion + carcino' gasses.
 
Reply 2 Brian
Wait til a battery is cooled. 10-20 min cool area, stone floor. Avoid storing at full charge ( for long). Never charge hot. Keep in fireproof bag/metal box, not in p3. Gentle with them - air = combustion + carcino' gasses.

Awesome! Got it! Thanks for the info!
 
I wonder if heat is such a problem? Plastics tend to crack more with cold than heat - they become more "plastic" when they are warm!
I suspect over tightening and maybe prop vibrations are the main culprits.
 
I had a minor crash a few weeks into owning my P3 back in June. I checked it closely for damage at the time and found nothing (that I could visually see). I flew my P3 long distances (up to 5km) and in heat as high as 38C (100F) over the next 3 months without a sign of a problem. I had checked for cracks about a month and a half ago and saw nothing. Then during a easy test flight at the park doing simple hovering and gentle maneuvers the motor literally came right out of the bird with no warning sending it spinning into the ground. I am just so grateful nobody was around to get hurt and that it happened 30 feet in front of me so I could recover it.

If I did something outside of "normal flight" I'd like to know what it was. I used my P3 as it was intended. I wasn't afraid to use it and sent it on some epic adventures, but never did I hit anything or crash hard.

This is simply a design flaw. Now that I know about it I can reinforce where it is needed and hope that if I lose my bird again it will be because of a much more exciting story than the motor flying out of the air frame.

Sorry for your loss. I guess in hindsight the damage was already done after that initial crash but was hidden inside from view. I assume you didn't split the shell apart to see if the motor mounts were cracked. Why would you. People crash or have hard landings and tip overs all the time and never have a motor depart the aircraft. Design flaw, maybe, but you can't expect the drone to be designed to resist damage from a crash. Hope you get back into the air soon.
 
Ahh! Good to know! Thanks for the info guys! How about charging a battery that is still warm? Any issue there?

Battery on P3 won't let you charge it when it's hot. It will wait until it's cool enough and then start charging.
 
I assure you that our birds are made of a thermoplastic, not a thermoset. Epoxy, melamine and Bakelite are three common thermosets. Polystyrene is probably the most common thermoplastic.
Then why are we finding cracks? With Thermoplastics it will soften and bend/warp. With Thermoset Plastics subjected to high heat it cracks.

Another said some used a hair dryer to reshape deformed arms on P1 & P2 birds. Are we absolutely sure we're dealing with Thermoplastics on P3's?

Don't mistake me & I may be wrong but, from what I've researched so far, Thermoset Plastics CRACK when subjected to high heat. Thermoplastics soften/melt/deform.
 
Then why are we finding cracks? With Thermoplastics it will soften and bend/warp. With Thermoset Plastics subjected to high heat it cracks.

Another said some used a hair dryer to reshape deformed arms on P1 & P2 birds. Are we absolutely sure we're dealing with Thermoplastics on P3's?

Don't mistake me & I may be wrong but, from what I've researched so far, Thermoset Plastics CRACK when subjected to high heat. Thermoplastics soften/melt/deform.
I refer you to my post number 34 in this thread.
 
@StumbleBee - I will investigate the temp difference with the screws in more FLIR photo's Good point...
@Chris Vedeler - Thicker support would have made a huge difference - I agree. What the FLIR showed me is that it is not only vibration but a combination of factors.

I need to calibrate the camera and take actual temp readings over time. My hypothesis is that Aluminium support will be a) stronger and b) handle heat dissipation better. It is also a flat area on the bottom so laser cutting a 3mm plate will not be that difficult.

I will hopefully do a drawing and test them with some silicone paste in between. It will be nice if we can get some DJI engineers in on it....

Can you post the original FLIR image? Flir images typically are 12 bit images with tons of data just waiting to be read by FLIR Tools.
 
I refer you to my post number 34 in this thread.
I suspect you meant # 35 post? In any case I wholeheartedly agree and will refrain from further comment on the topic.

Because all we've accomplished so far is no more than speculation. Until we get concrete valid info on the subject, we should wait or contact someone who can validate our speculations. I'll do what I can to find someone. All else should do likewise. Best of luck to all...
 
I suspect you meant # 35 post? In any case I wholeheartedly agree and will refrain from further comment on the topic.

Because all we've accomplished so far is no more than speculation. Until we get concrete valid info on the subject, we should wait or contact someone who can validate our speculations. I'll do what I can to find someone. All else should do likewise. Best of luck to all...
Yes, I did mean to refer you to post 35. I am approaching an age where I can remember fifty years ago like it was yesterday. And I remember yesterday like it was fifty years ago. :)
My gut feel, having been there myself, is that DJI has furiously attacked the problem internally while saying nothing outside the company. The only way to know for sure would require analysis of failed housings vs. intact housings for thickness, radius, and layout changes, and plastic resin composition. All things beyond our abilities. One day we will just notice that there are no longer any posts about structural failures and say to each other "Remember when..." and we will be proud of ourselves for having been there and lived through it.
 

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