Hello,
I was doing my first flights today. And guess what... I crashed !
The crash did happen because the quad flipped (fortunately I was landing and thus almost on the ground) at the same time that one propeller collet came loose off the motor's shaft.
I want to express here some real frustration toward 3DR because of a fault by design in their kit. I had indeed an issue with fixing tight this collet since the 3DR kit was delivered. Although 3DR reads and cannot ignore the massive amount of people loosing props with these stupid collet systems, I wonder why 3DR continues to deliver them. There exist much better propeller's mounts that can be screwed on the motor and that makes it impossible to loose it !
Since I already lost this collet off the motor's shaft during some previous bench testing, I paid extra attention and efforts to fixing it correctly before external flights: i used blue loctite, i made sure I screwed the collet tight enough, etc.
That this is really a mount's design issue : such a system cannot ensure with enough certainty, even if you fix it right, that you will not loose a collet.
Anyway, as a result I broke two propellers, I damaged the protective acrylic arch (glad I had it!) and the responsible collet is of course unusable. (I guess I can be happy it is not overall too much damage)
I would really like 3DR to take lessons of this and change their propeller's mounting systems in their future kits.
Do you imagine what would have happened if I had lost this collet higher in the air ? This is serious.
Hugues
Replies
Reason # 47 why collet prop adaptors suck.
Spend hours diagnosing why quad keeps flipping.
Discover one of the set screws holding the shaft into the endbell is loose. Just enough to stop the propeller from turning at full power. The shaft is spinning in the end-bell. Try to re-tighten said set screw. Discover it's soft, strip the socket. Destroy end bell trying to get it out for replacement.
Huges: I replaced the stock prop adapters that come with 3DR/RCtimer motors with these ones from HK -> http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=19586
Much better.
I find many parts of the 3DR kits quite well thought out and well documented, but overall I much prefer a platform like the Flamewheel for a lightweight quad and for an AP / Gimbal platform either Rusy's UAP1or2 frame or Quadframe's SIXCopter. The 19mm arms of the 3DR frames are just far too weak and not cost effective to keep replacing everytime you have a "hard landing" or just breath on it funny.
For a long, I'm using the 650 v4 engines XAircraft, recommend them because they are extremely reliable and excellent quality.
Xaircraft 2212 950kv motor weight: 57.4gthe only problem is the selection of propellers 10x4.5 I can only use plastic or carbon
dji are also those are very good.
actually I stay with this because my octoquad up to 2.5 kilograms
sufficient for canon camera and an excellent performance
http://www.foxtechfpv.com/
Ouch. Yesterday I was flying and a prop flew off. The quad tumbled into the ground for its second crash. I was aware of the prop issue and had those suckers on tight but had not checked them during the last few flights. Bummer. My message is only to confirm that this problem is indeed real. It appears that roughing up the motor shafts with sandpaper is in order.
Mike
Hi!
I use Hacker prop mounts, Graupner should also be good.
Does rc timer has the same mount system for the 3dr 880kv?
sorry about your accident, I recommend rc timer motors
http://www.rctimer.com/index.php?gOo=goods_details.dwt&goodsid=... =
3dr are the same I have eight and got some perfect for 2 years.
this place
http://www.rctimer.com/index.php?gOo=goods_details.dwt&goodsid=....
Bearing only recommend change for a better quality oil or grease with automotive grade 20 w50.
I've used the collets alot and even with a bad crash I never had problems. You have to make sure that the collet 'takes' when you tighten them. I always check with a magnifier to see that the collet is fully compressed around the engine shaft and I usually check tightness before flying. I've re-tightened mine several times and they haven't failed yet.
Shaft Length:
Yes, the shafts are much longer than they need to be. I cut mine down. I put the motor in a bag, and pushed just the shaft through. Then used a dremel wheel to cut the shaft. The bag serves an important role of keeping the filings out of the motor!
I don't think multicopters have "special needs". In a hover, they are making about the same thrust as they would on an airplane. I think the only difference, really, is that these collets were invented as the cheapest possible way to attach a propeller onto an RC Car electric motor from WAY back in the day when electric flight got started. And it's just stuck. It continues to be a really poor solution, but the airplane guys live with it because of "inertia". It works well enough, and "why fix what's not broken?" I mean, it IS broken, but for an airplane guy, the loss of a prop means they have a dead-stick landing, go find their prop, and laugh about it as they stick it back on and go for another flight.
The only thing special about a MR is that the prop loss means you crash.
And you don't have to buy new motors to use the screw on adaptors. I bought some Turnigy NTM adaptors to put on mine. They won't quite fit because the counter-bore is too small. I can fix that on my lathe, most can't, but I think with some shopping around we can find some adaptors that fit. They're only a couple of bucks.
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