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Stress Cracks WTF
- Thread starter bkushner
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Yeah, I get your point, but the 30mph wind speed is much less than your plane analogy, and weight mass of these craft is way less. I can understand a little extra stress, but I think the sudden jerks and turns that we put these craft through with regular and expected navigation maneuvers is way more stressful to the shell. Adding wind turbulence isn't much more, given the ratios. I think even letting off the sticks when a full speed, suddenly stopping, as you suggested, is more stressful than a turbulence from a 25mph wind. I may be wrong, as I'm not an expert, but logically I think the notion that wind turbulence crack craft these, I just think it's less of an issue versus the root problem. These should be designed to fly in 20mph winds
I blame the cracks on DJI's lack of quality control, or lack of monitoring their shell vendor adequately. I personally think that's the root problem, but I may be wrong. Plastics is a delicate science to produce consistently good quality and durability. The difference of only a few degrees can ruin the "crosslink" process in certain plastics, and for this hard shell plastic, I perceive it's even more difficult to optimize durability, IMO. It's probably not easy to optimize a design for light weight, and pick the exact formula (thickness, materials) to optimize durability. I'm sure DJI has spent weeks trying to figure out this formula to minimize their liability in the P5, as they have likely replaced thousands of P4 craft, with brand new craft (like they did for me), only because of a shell crack. They changed the materials from P3 to P4, and that didn't seem to solve the cracking problem. I think we can expect another change in plastics for the P5, anyway I hope so, maybe carbon fiber!! I can only hope.
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Hard plastic is going to be more brittle which is one of the trade-offs in choosing a material by the manufacturer. I would bet though that the stress cracks are created in manufacturer either from the mold process or during assembly (less likely) and it takes time for the owners to have the cracks expand to the point where they are visible.
When passenger jet airframes are checked for stress fatigue the inspectors are looking for microscopic symptoms of fatigue with highly specialized equipment. You can be sure that nothing similar is being done by DJI for its consumer level Phantom drones.
Stress cracks and frame failure is not at all uncommon with pickup trucks built prior to 2010 when fully boxes frames were introduced. Especially prevalent with many 4WD vehicles that for the most part were not really designed for off-road use.
When passenger jet airframes are checked for stress fatigue the inspectors are looking for microscopic symptoms of fatigue with highly specialized equipment. You can be sure that nothing similar is being done by DJI for its consumer level Phantom drones.
Stress cracks and frame failure is not at all uncommon with pickup trucks built prior to 2010 when fully boxes frames were introduced. Especially prevalent with many 4WD vehicles that for the most part were not really designed for off-road use.
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Does anyone know what type of plastic the shells are made from?
Maybe a switch to a polycarbonate like football helmets, etc are made from. Would be nearly indestructable.
Maybe a switch to a polycarbonate like football helmets, etc are made from. Would be nearly indestructable.
serious quality control issues here, until people stand together and demand they recall and fix this isue of crap plastic, they will keep getting away with this.
I agree. The big joke is that I am supposed to be giving a demo to a group of farmers on Tuesday that are potential customers. What should I tell them. I can't demo as my drone has cracked again. Lol
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It's really strange how some crack, and some don't. DJI should definitely start looking into "Why?". Is it "feature-based"? Is it "flight-profile-based"? There's got to be a reason why one drone comes off the production line and cracks ... and the next one doesn't. That said, in the meantime, they should just use better materials and fix this. I haven't experienced it on my P4P+ but I inspect heavily and am definitely nervous about it.
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Agreed, there are many sources for the stress, including turbulence. But repetitive stress has a way of cracking aluminum as well as plastic. So something is creating this stress, most likely flight stress and motor torque, from sudden changes.
Carbon fiber might be better, but much more expensive. My Vendetta 2 is carbon fiber and not cheap, main frame is $100, plus the 2 arms.
Still, it is a mystery why one cracks and another doesn't. Could be manufacture, could be individual flight stress, who knows?
PhantomWetSuits
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This can sometime happen when you forget which way to put the props on and you hold the leg or the jutt while pressing down and turning the wrong way. Some people place the props on when its still in the box with no support. This same thing happens to the legs , its just to much pressure placed on direct parts of the drone.
This is one of the reason why we leave the props on to avoid that type of stress repeatedly.
We have also had over a hundred hand catches and no stress cracks thus far.
We have also tested the hard breaking on the Phantom Wet Suits to see if in fact that we be a problem.
After months of hard breaking we saw no stress cracks and we were under the microscope at that time.
We did not see any wear and tear on the drone when we tore it apart either.
I would say that poor handling and placing of the props are a big part of both the legs and the juts cracking.
We also noticed that some people packed there Gray Phantom Cases and would add that little extra push to get them into the box.
We also have a buddy here in Ohio that runs a plastic mold company and he says it very rare that a plastic would just all of a sudden
just crack unless frozen and than heated quickly causing expansion to take place.
So as far as we can tell from are testing , hand catching is good, hard breaking is good, placing props on can be risky business.
You should always no which way to turn the props so you get right the very first time.
Here is a just 1 test of a 100 we did with a wet drone in heavy winds using the new firmware you can watch it.
We have been watching for these stress cracks very closely and nothing so far.
Coal
Phantomrain.org
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This is one of the reason why we leave the props on to avoid that type of stress repeatedly.
We have also had over a hundred hand catches and no stress cracks thus far.
We have also tested the hard breaking on the Phantom Wet Suits to see if in fact that we be a problem.
After months of hard breaking we saw no stress cracks and we were under the microscope at that time.
We did not see any wear and tear on the drone when we tore it apart either.
I would say that poor handling and placing of the props are a big part of both the legs and the juts cracking.
We also noticed that some people packed there Gray Phantom Cases and would add that little extra push to get them into the box.
We also have a buddy here in Ohio that runs a plastic mold company and he says it very rare that a plastic would just all of a sudden
just crack unless frozen and than heated quickly causing expansion to take place.
So as far as we can tell from are testing , hand catching is good, hard breaking is good, placing props on can be risky business.
You should always no which way to turn the props so you get right the very first time.
Here is a just 1 test of a 100 we did with a wet drone in heavy winds using the new firmware you can watch it.
We have been watching for these stress cracks very closely and nothing so far.
Coal
Phantomrain.org
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Fortunately I have not seen any stress cracks yet. I was wondering if anyone has tried plastaid? I have used it for numerous repairs from hot tubs to toys. It bonds molecularly to the plastic. Here is a link for it on Amazon https://www.amazon.com/gp/aw/d/B004...=Plast-aid&dpPl=1&dpID=41Lb1YBgOSL&ref=plSrch
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