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Old May 29, 2011, 04:49 PM
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Strange failure - first auto


a few days ago, I was flying my HK450 Pro, doing a few loops and flips, when the motor started to scream. Thinking the pinion had slipped off the shaft, I managed to flip to throttle hold and auto down into long grass without any damage. It turns out the pinion hadn't slipped - the motor shaft had broken off, and the pinion was still there loose, on top of the motor, a Turnigy Typhoon 2218. It seems odd to me that the shaft should break like that.
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Old May 29, 2011, 05:11 PM
zen@lanset.com is offline
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2Doggs— motor shafts do break on several manufacturers' motors. I have had output shafts break on two Align 430L motors. Some people think that having the pinion too tightly pressed against the big drive gear contributes to these failures.
Old May 29, 2011, 08:53 PM
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ooooh yeah
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I doubt the pinion has anything to do with it, to get it tight enough to put enough sideways loading on the shaft to weaken/snap it would make for a horrible gear mesh and an amp hungry motor. Most likely it's crappy steal and not quite perfect machining, especially with the cheaper motors that causes the failures
Old May 29, 2011, 08:59 PM
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I lost a pinion gear on my copter but they sent me a new one with a screwdriver no problems since. Unfortunately plastic, but still very strong.
Old May 29, 2011, 09:14 PM
zen@lanset.com is offline
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It's hard to imagine a plastic pinion gear on anything larger than an indoor micro heli.

I got a little airtime at the Berkeley Marina this afternoon. First I flew my first test flights with an Easy Glider Pro powered sail plane. A few short hand launches, then turned on the power to get high enough to really crash it! There were so many kites in the area that I put it away and flew old reliable T-rex 450 SE #1. As always the kids came running so I landed it for a little show-and-tell and decided to call it a day.
Old May 29, 2011, 10:20 PM
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dont play with rc anymore
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Quote:
Originally Posted by arbilab View Post
Your plains winds should be a lot like ours, micro. (I was born there [stl] and live here.) Even CALM wind has gusts.
I guess I'm used to windy conditions...gusts up to 5mph or so over the "steady" wind speed are pretty normal around here, so that doesn't bother me at all. 10-20mph gusts are no fun, though.
Last edited by micronut; May 30, 2011 at 02:18 AM.
Old May 29, 2011, 11:03 PM
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The helicopters I have cant fly in any wind whatsoever, guess I have a lot to learn about remote control copters! lol
Old May 30, 2011, 03:11 AM
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Quote:
Originally Posted by zen@lanset.com View Post
2Doggs— motor shafts do break on several manufacturers' motors. I have had output shafts break on two Align 430L motors. Some people think that having the pinion too tightly pressed against the big drive gear contributes to these failures.
This was my first motor shaft failure, and quite a surprise. I'd never tried to do an auto on a 450 before. The shaft broke at the retaining clip groove, where there would be stress concentration. I wonder if it was fatigue failure. The pinion is obviously not perfectly balanced, since it uses a single steel grub screw. My maingear mesh was actually a bit on the loose side - I was intending to tighten it up. Previously, the same motor was suffering from the front bearing spinning in the housing, and after I sorted that out with some CA, there was evidence that the shaft was spinning in the inner race. Maybe that weakened it. All of the above are no doubt cheap motor issues, but at $12 a pop, they're almost disposable. Maybe I'll treat myself to a Scorpion one of these days!
Old May 30, 2011, 03:44 PM
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Flew a 4s for the first time on my 450. I will probably slowly shift to 4s, because it now has awesome POWER! Wow, the climbouts are like twice the speed compared to 3S. Well ok, maybe not but it is much faster. It also seems to drain the battery real quick though

Now I "only" need to finally get the tail to never let go, which it does sometimes. I also really need to know if my one-way bearing is up to the task, because something is slipping under load. I'm guessing the belt, but I'm still not sure.
Old May 30, 2011, 05:12 PM
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Originally Posted by sandos View Post
Flew a 4s for the first time on my 450. I will probably slowly shift to 4s, because it now has awesome POWER! Wow, the climbouts are like twice the speed compared to 3S. Well ok, maybe not but it is much faster. It also seems to drain the battery real quick though

Now I "only" need to finally get the tail to never let go, which it does sometimes. I also really need to know if my one-way bearing is up to the task, because something is slipping under load. I'm guessing the belt, but I'm still not sure.
you might check the one way - or at least the mainshaft cover. On my HK 450 Pro, the cover wears out quite quickly, though it normally first shows up as the OWB jamming. The clone metal is far too soft, though i've yet to try an align part on it.
Old May 30, 2011, 10:37 PM
Luvmyhelis is offline
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Professional heli wrecker
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Here are the remains of my last flight with my 6s modded heli. Found it though!
Old May 31, 2011, 12:15 AM
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What's Nitro?
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Ouch. I thought the "Fly Mentor" was supposed to prevent that kind of thing?

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Originally Posted by Luvmyhelis View Post
Here are the remains of my last flight with my 6s modded heli. Found it though!
Old May 31, 2011, 02:13 AM
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Originally Posted by RCnGuy View Post
Ouch. I thought the "Fly Mentor" was supposed to prevent that kind of thing?
I had it almost turned down to 0. I was hotdogging right after taking my afternoon bash of pain meds, and did one of the most stupid acts of my flying history and got it lost over the treeline. Our weather is on a historic cold streak in the northern U.S. and opportunities to fly have been rare. So when a break happened in the weather I took it. Bad move all the way around. Had the FM been turned up this honestly would have never happened. It is an amazing system. Now I am upping this to an fbl build with an SK-720.
Should be interesting.
Old May 31, 2011, 07:20 AM
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Quote:
Originally Posted by sandos View Post
Flew a 4s for the first time on my 450. I will probably slowly shift to 4s, because it now has awesome POWER! Wow, the climbouts are like twice the speed compared to 3S. Well ok, maybe not but it is much faster. It also seems to drain the battery real quick though

Now I "only" need to finally get the tail to never let go, which it does sometimes. I also really need to know if my one-way bearing is up to the task, because something is slipping under load. I'm guessing the belt, but I'm still not sure.
I'd look in to 6S before shifting to anything. Seems to be fairly common (long topic on helifreak about running 6S on 450 pro). Some dude even had 8s on his.
Old Jun 01, 2011, 12:49 AM
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hovered my scale project today. without scale body. just in the testing phases. so far 2 failures. my cascade type tail rotor failed on the bench due to an out of balance issue (need to make another shaft) and then during a hover the belt drive gear (plastic) melted during one of the hovers, luckily i was mere inches off teh ground. i found one that was aluminum and replaced the gears. its better but the belt got trashed in the failure so i need to replace the belt. sheesh what a pain. a 5 blade head sure sounds awesome at speed. after i make another shaft for the tail it should be better. it did not have enough authority on the tail.


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