It happened again - prop failure #2...

[KB_Colorado]

I experienced the exact same failure as you, one blade broke off and the drone took a dive. I was showing someone the speed mode, flying about 30’ high, and I could see the single blade fly off the copter. Luckily I had DJI Replacement coverage at the time.

 

[Loz]

Reading with great interest from afar, wondering if carbon fibre props (are they available for P4?) are worth considering too? Just thinking aloud here

 

[Harleydude]

I experienced the exact same failure as you, one blade broke off and the drone took a dive. I was showing someone the speed mode, flying about 30’ high, and I could see the single blade fly off the copter. Luckily I had DJI Replacement coverage at the time.

This is VERY good to know. Glad I'm not alone! I HATE it when I'm the only guy on the planet seeing multiple failures.

I was discussing this with my business partner yesterday. I don't know if you're aware, but the Obsidian propellers have a tighter fit than the standard P4P props. So I'm pretty much dumping the P4P props into the "b-bag" and will be experimenting with using Obsidian props. Once I've tested the Obsidian props (say 10 flight hours without incident), I will probably make a video.

Have you tried Obsidian props? If not, you should. They fit tighter, which tells me there's more to them than a simple color difference.

D

 

[RedDog7]

Gee, Non DJI props fail (rarely) and they're immediate "Crap" DJI props fail and everyone goes scurrying for the excuses. I'm not being sarcastic, those using the less expensive props were roasted only last week for daring to use them and comments poured in about how DJI props are so much better than the rest. Doesn't this sort of negate those comments? Brand new DJI props failing, who'da thunked it? I'll let my wallet decide which ones to use.

Many moons ago when I began flying quadcopters I used to purchase 3 sets of props as spares. I now have 3 shoes boxes full of spare props and the only props I've damaged were my own fault, usually from tip overs and no more than 6 due to silly crashes, again my fault. But no matter what the brand I doubt any would have fared any different. Not one of them were DJI and not one of them failed for no reason. In fact in a total of 62 years of flying planes I've never had a prop failure in those either. Gee I must be the luckiest flyer around, I may buy a Lottery ticket

 

[snownut]

harleydude, you mentioned mapping at 25mph, that seems rather fast. I assume your doing waypoint mapping with timed photo taking. What are the parameters your using? Elev, photo timing, % of overlap?

 

[RedDog7]

Reading with great interest from afar, wondering if carbon fibre props (are they available for P4?) are worth considering too? Just thinking aloud here

Hi Loz Carbon Fiber props are Great, especially if your current props are too soft. I've seen a few quads being released with props you could easily bend at 90 degrees. They were quickly swapped for CF types and the difference was easy to spot. Much faster top speeds and take offs (if that sort of flying interests you). However they can tend to shatter when meeting an immovable object and sometimes movable ones as well. Try not to be too close when it happens,because pieces tend to fly everywhere and they can be very sharp. The prop itself and in one piece can have a sharp edge, much sharper than plastic props I've found. All the better for slicing the air, but never ever get you fingers in the way, it'll be goodbye fingers for sure.

I haven't as yet heard of any blades parting company from their hubs, but I guess nothing's impossible. I intend trying a set on my P2, just to see how they fare, but I wouldn't expect much advantage because today's props tend not to be that flimsy or soft. But if you're interested, give them a try, I would however steer clear of the cheap variety. I've seen far too many supposedly Carbon Fiber tubing from China fail miserably as wing spars in large RC planes. HobbyKing sold miles of the stuff, overcooked noodles would have done a better job

 

[Harleydude]

harleydude, you mentioned mapping at 25mph, that seems rather fast. I assume your doing waypoint mapping with timed photo taking. What are the parameters your using? Elev, photo timing, % of overlap?

1"/pixel resolution, which puts us @ roughly 300' AGL. I used photo distance (not timing), 75/75 overlap. That said....

My typical shutter speed of 1/1600 pushes motion blur to roughly .2 or .3", which is very crisp. We try to keep motion blur < .6" at all costs.

Ironically, if I use default "Auto" camera settings, typically, software will close the aperture to f/5.6 (if memory serves), and sets ISO to 200(or 400?), and then sets shutter for (what I assume) to be an E.V. of 0. I can only assume this is to avoid lens and/or color aberrations (which isn't really an issue with the P4P camera for mapping photos), and set ISO to native. Ironically, this almost always drives motion blur into .7", which is unacceptable. Therefore, I never, ever, ever use auto settings. If it gets dark enough (due to clouds) that I have to slow shutter speed to 1/800, I'll raise the ISO to 200 so I can speed up the shutter. But that rarely happens. And FWIW, I always manually set color temperature, too, for GS Pro (because auto settings change WB all over the friggin' map). I do the same for Map Pilot, but unfortunately it usurps my manual WB setting, and only offers "sunny, cloudy or auto." So naturally I choose "sunny" or "cloudy." I never choose auto. Not only do these settings produce consistent results, but the photos are always crisp. My business partner (who does all the Pix4D stuff) REALLY appreciates the quality of the photos I provide.

D

 

[offroadpyro]

I have props that have a little wiggle also and have used them yet.Now I won't so thank youGod.I have p4 and p4 obsidian,you are correct the obsidian ones fit nice and snug.

 

[Harleydude]

I have props that have a little wiggle also and have used them yet.Now I won't so thank youGod.I have p4 and p4 obsidian,you are correct the obsidian ones fit nice and snug.

You would be smart to ditch the props with "wiggle." I'm essentially going to toss $50 worth in the garbage.

 

[Smokeywolf]

There could be many reasons that you could have prop failure.
Storage could be one.
The way the prop is held when fitted.
The torque they are being tightened too.
Temperature changes hot to cold.
Vibration
Not sitting flat on the motor.
I could go on.

 

[Harleydude]

There could be many reasons that you could have prop failure.
Storage could be one.
The way the prop is held when fitted.
The torque they are being tightened too.
Temperature changes hot to cold.
Vibration
Not sitting flat on the motor.
I could go on.

So your assertion is that propellers must be:

1) Held correctly
2) Torqued correctly
3) Operated within a tight, unspecified temperature specification
4) Not vibrated
5) and not sitting flat on the motor

on drones sold to the general public at Best Buy.

Yeah...no sale on that one, amigo. I'll give you a C for creativity, though.

D

 

[Safety71]

Can I replace the Phantom 4 props with the Obsideian props with lesser movement?

 

[WWI Flying Ace]

I would get a can of dye and spray for finding cracks in things, then check my blades routinely. I haven't seen this type of failure, nor have I seen it shown online before, seems rather odd.

I have been professionally performing dye inspections for 30 years and have been certified Level III in dye penetrant inspection. I have a hunch it would be difficult to detect cracking on these rotor hubs before failure due to the small size of the areas under stress and the dynamics of the large stresses they are under during flight. The crack inception-to-failure interval might be very short. But, if anyone has rotors they do not fly due to suspicion of possible cracking, especially the other 3 rotors Mr. Harleydude has from the set that failed, I could do some investigation into the development of an inspection procedure if that might be of help. An inspection before first flight, looking for suspected manufacturing QC/QA problems, could be indicated when subjecting rotors to flight demands such as Mr. 'dude encounters.

 

[Harleydude]

Can I replace the Phantom 4 props with the Obsideian props with lesser movement?

Yes.

 

[Harleydude]

I have been professionally performing dye inspections for 30 years and have been certified Level III in dye penetrant inspection. I have a hunch it would be difficult to detect cracking on these rotor hubs before failure due to the small size of the areas under stress and the dynamics of the large stresses they are under during flight. The crack inception-to-failure interval might be very short. But, if anyone has rotors they do not fly due to suspicion of possible cracking, especially the other 3 rotors Mr. Harleydude has from the set that failed, I could do some investigation into the development of an inspection procedure if that might be of help. An inspection before first flight, looking for suspected manufacturing QC/QA problems, could be indicated when subjecting rotors to flight demands such as Mr. 'dude encounters.

Once I get my bird replaced, I'll be happy to send you one of those rotors. I like the idea of a plastics/dye expert looking at these things. Part of me wondered if this was a dye issue.

 

[Timinator]

I;m curious to know why there is no play in the Obsidian props compared to the white ones. Is the mount different?

 

[2marley]

Hey doods;

So it seems it happened again...same problem, same conditions...

Deja vu for me....on a mapping mission this afternoon, I had a prop break mid flight. However, this time I have the prop. It seems this time, instead of the prop hub breaking, only one of the two rotors broke off the hub. So technically, I didn't lose a propeller. I only lost HALF a propeller.

Other than using my Phantom 4 an order of magnitude more than most guys, I'm doing nothing wrong.

So, once again I'm going to ask if any of you guys have seen prop failure. That's really the only information I can use at this point. Or if there are any plastics experts out there, perhaps they can look at the photos of the broken prop and share your thoughts.

Worth noting; the remaining 3 props remained essentially intact. One prop ejected upon impact. I know this to be true because the prop was a mere 8 feet from the drone (as opposed to 200' away had it ejected @ 300').

I've submitting an RMA to DJI. I purchased the Care Refresh for the replacement drone, which lasts a year from the purchase date mere weeks ago. The *warranty* ends May 10th. HA! So one way or the other, this will be replaced. Hopefully, sooner than later.

View attachment 98402 View attachment 98403

It's hard to believe this hasn't happened a second time...especially after DJI assured me it wouldn't.

Another thing worth noting, is that I notice the P4P props have the slightest amount of wiggle room on the hub. I can kind of rotate the prop 1° on the hub. They do the same on the Obsidian hub.

The Obsidian props, however, have zero tolerance. They are very tight on the hub. I think I'm going to purchase Obsidian props from now on.

D

 

[2marley]

Looks like a classic stress fracture...high speed turn over stressed the prop blade...I've seen it before, broke where prop blade extends, not between prop blades....slow down before turning....

 

[ussvertigo]

I was wondering about heat from motors since you fly so much at a time, but hearing another case and myself going 2 years on my P4 with no similar problems, and motors get warm but not hot, suspect maybe that rare(hope it’s rare)bad mold job, plastic not injected at optimum temp, press.? Don’t know a thing about it but a guess, and yes that’s a QC issue, dye won’t do any good if defect is below surface.

 

[lolo780]

I just checked my obsidian props and they have some play on the P4P mounts.