HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Jul 18, 2012, 10:25 AM
Hawk Fanatic
SkylineFlyer's Avatar
United States, KY, Louisville
Joined Jul 2008
7,213 Posts
Very much so. Thanks Anlucas!
SkylineFlyer is online now Find More Posts by SkylineFlyer
Reply With Quote
Sign up now
to remove ads between posts
Old Jul 18, 2012, 04:57 PM
Registered User
4stripes's Avatar
Canada, ON, Burlington
Joined Jan 2009
2,930 Posts
Blew another fan up today with only 2600watts in my HTG Mig 15! Fan was balanced, and dynamically balanced running 7S with a XK4074-B-1400. Blades were crazy glued in.
I didn't expect this failure after only 4 flights as my FF F100 (with the same setup) has many more flights without incident.
Positive there was no FOD or any other prior damage to the fan. Two blades with their hub section were ejected from the hub during the failure and the rest of the hubs stayed put. The sad part is the motor shaft bent.

I can only deduce that there are some batches of blades that are weaker than others, perhaps caused by different plastic quality. 2600watts isn't too much to expect from a fan, or is it?

Back to the work bench to see if I can remove the bent shaft. If anyone has any pointers on removing an inrunner shaft please chime in!
Thanks Eric
4stripes is offline Find More Posts by 4stripes
RCG Plus Member
Latest blog entry: Some photos of the EDF fleet!
Reply With Quote
Old Jul 18, 2012, 05:53 PM
Registered User
Thomas Nelson's Avatar
Calgary, Alberta, Canada
Joined Sep 2002
2,900 Posts
Did the shroud fully contain the broken blades? I mean, did any blast their way through the airframe?

I hand-launch mine (2.1kw) throttling up simultaneous with the throw. Mine too is very well balanced. I'd like to think that in the worst case scenario the shrapnel will be contained by the rather robust CS shroud. Not my cranium.

Thoughts?

tn
Thomas Nelson is offline Find More Posts by Thomas Nelson
Reply With Quote
Old Jul 18, 2012, 05:59 PM
world's slowest builder
Air-Jon's Avatar
CA
Joined Oct 2006
740 Posts
Kevlar tape around the shroud (covering blade disk area). $14
http://www.amazon.com/Kevlar-Tape-in.../dp/B0035DBGPC
just like car/truck racers that cover the torque converter wit a kevlar blanket so when th TC lets go.....blankey saves your butt.
Air-Jon is offline Find More Posts by Air-Jon
Reply With Quote
Old Jul 18, 2012, 06:05 PM
Lee Liddle
Knife Liddle's Avatar
Carrollton, Tx
Joined Dec 2006
8,010 Posts
Quote:
Originally Posted by 4stripes View Post
Blew another fan up today with only 2600watts in my HTG Mig 15! Fan was balanced, and dynamically balanced running 7S with a XK4074-B-1400. Blades were crazy glued in.
I didn't expect this failure after only 4 flights as my FF F100 (with the same setup) has many more flights without incident.
Positive there was no FOD or any other prior damage to the fan. Two blades with their hub section were ejected from the hub during the failure and the rest of the hubs stayed put. The sad part is the motor shaft bent.

I can only deduce that there are some batches of blades that are weaker than others, perhaps caused by different plastic quality. 2600watts isn't too much to expect from a fan, or is it?

Back to the work bench to see if I can remove the bent shaft. If anyone has any pointers on removing an inrunner shaft please chime in!
Thanks Eric
You don't just replace the shaft on an inrunner, it's a shaft assembly which includes the magnets which are all bonded to the shaft. Just remove the front cap, some press in others are threaded and screw in. Then just grab the shaft with pliers and pull out the assy. You will have to buy a new assy or find one from a donor motor that just burned the windings.

That's why I've gone almost exclusively to outrunners. They can almost always be rebuilt with bearings, magnet wire and shaft material.
Knife Liddle is online now Find More Posts by Knife Liddle
RCG Plus Member
Old Jul 18, 2012, 06:09 PM
Registered User
4stripes's Avatar
Canada, ON, Burlington
Joined Jan 2009
2,930 Posts
The foam surrounding the shroud contains the shrapnel very well. Some bit embed into the foam and the rest go out the thrust tube. This time was the first that the motor broke out of the shroud mount, and also the first bent shaft.

Further evidence that all testing should be done with adequate safety gear as you never know when the fan may go on strike.
4stripes is offline Find More Posts by 4stripes
RCG Plus Member
Latest blog entry: Some photos of the EDF fleet!
Reply With Quote
Old Jul 18, 2012, 06:14 PM
Lee Liddle
Knife Liddle's Avatar
Carrollton, Tx
Joined Dec 2006
8,010 Posts
Oh, the shaft assy has to come from the same exact size and manufacturer, of course, but it doesn't have to be the same kv rating. The windings determine the kv not the magnet poles.
Knife Liddle is online now Find More Posts by Knife Liddle
RCG Plus Member
Old Jul 18, 2012, 06:28 PM
Registered User
United States, GA, Alpharetta
Joined Feb 2009
403 Posts
Quote:
Originally Posted by Knife Liddle View Post
You don't just replace the shaft on an inrunner, it's a shaft assembly which includes the magnets which are all bonded to the shaft. Just remove the front cap, some press in others are threaded and screw in. Then just grab the shaft with pliers and pull out the assy. You will have to buy a new assy or find one from a donor motor that just burned the windings.

That's why I've gone almost exclusively to outrunners. They can almost always be rebuilt with bearings, magnet wire and shaft material.
I have replaced two inrunner shafts using hardened steel precision 4mm shafts from McMaster & Carr. I heated the bent shaft with my 600 Watt soldering gun and tapped the bent shat out with a mallet not the bent end, the straight end. I put he new shaft in the magnet carrier and put some Hysol 9462 (thin) on the shaft and in the tunnel then gently tapped the new shaft in place. After 24 hours the hysol is fully set and both motors (one is a RC Lander 4000KV and the other is a Neu 1112/1Y, that is now a 4mm shaft), both are working just fine.

The shaft can be removed and changed, with care.

Oh, I would also suggest new bearings as the bent shaft probably did in the front bearing as was the case with the RC lLander motor..... the front bearing lasted for about 10 flights at 50,000 RPM.
rfodor is offline Find More Posts by rfodor
Last edited by rfodor; Jul 18, 2012 at 06:33 PM. Reason: Added Info
Reply With Quote
Old Jul 18, 2012, 08:20 PM
Registered User
4stripes's Avatar
Canada, ON, Burlington
Joined Jan 2009
2,930 Posts
Thanks for the input!
I was able to straighten the shaft within a hair of perfect. Didn't read the post from rfodor about the bearing in time... it's all back together with another fan I have glued previously with PU glue.
Will dynamic balance the set tomorrow. Should the front bearing make any trouble in the future, I do have a couple spares from another low time burnt XK motor with the same bearings.
Hope these blades are better this time.
Cheers Eric
4stripes is offline Find More Posts by 4stripes
RCG Plus Member
Latest blog entry: Some photos of the EDF fleet!
Reply With Quote
Old Jul 18, 2012, 08:32 PM
Hawk Fanatic
SkylineFlyer's Avatar
United States, KY, Louisville
Joined Jul 2008
7,213 Posts
Your going to attempt to use a shaft that bent? I understand that you straightened it back, but still, I'd think that the shaft is now slightly fatigued, no?
SkylineFlyer is online now Find More Posts by SkylineFlyer
Reply With Quote
Old Jul 18, 2012, 08:35 PM
Registered User
4stripes's Avatar
Canada, ON, Burlington
Joined Jan 2009
2,930 Posts
I'll let you know how it goes. It wasn't too badly bent.
Cheers
4stripes is offline Find More Posts by 4stripes
RCG Plus Member
Latest blog entry: Some photos of the EDF fleet!
Reply With Quote
Old Jul 18, 2012, 10:25 PM
Lee Liddle
Knife Liddle's Avatar
Carrollton, Tx
Joined Dec 2006
8,010 Posts
Quote:
Originally Posted by rfodor View Post
I have replaced two inrunner shafts using hardened steel precision 4mm shafts from McMaster & Carr. I heated the bent shaft with my 600 Watt soldering gun and tapped the bent shat out with a mallet not the bent end, the straight end. I put he new shaft in the magnet carrier and put some Hysol 9462 (thin) on the shaft and in the tunnel then gently tapped the new shaft in place. After 24 hours the hysol is fully set and both motors (one is a RC Lander 4000KV and the other is a Neu 1112/1Y, that is now a 4mm shaft), both are working just fine.

The shaft can be removed and changed, with care.

Oh, I would also suggest new bearings as the bent shaft probably did in the front bearing as was the case with the RC lLander motor..... the front bearing lasted
for about 10 flights at 50,000 RPM.
That's good info! I stand corrected.
Knife Liddle is online now Find More Posts by Knife Liddle
RCG Plus Member
Old Jul 19, 2012, 12:03 AM
world's slowest builder
Air-Jon's Avatar
CA
Joined Oct 2006
740 Posts
Besides the material issue that is said to be causing blade failure...i thinl they tried to cram in too many blades. 10 blades would have allowed thicker blade hub dovetails and base features. Anyway i think in am going to just Hysol the entire assembly together..blades...shaft adapter...front and back hub lock rings...everything
Air-Jon is offline Find More Posts by Air-Jon
Reply With Quote
Old Jul 19, 2012, 04:44 AM
The wheels touch down FIRST??
BJ64's Avatar
Australia, VIC, Melbourne
Joined Jun 2009
24,650 Posts
Quote:
Originally Posted by 4stripes View Post
I'll let you know how it goes. It wasn't too badly bent.
Cheers
Erm...

Still fairly a novice here, but I'd be a bit careful running a previously bent shaft - you've already had a fan fail.

Unless you can dial-guage that shaft to be within a thou or two, you might just eventually bugger up your motor and/or have another fan fail.

I'd suspect that bent shafts, big fan blades and high RPM don't go all that well on motor bearings and fan balance - it really doesn't have to be out by all that much to exaggerate an imbalance at the revs you'll be pulling.

Take care...

BJ
BJ64 is online now Find More Posts by BJ64
Reply With Quote
Old Jul 19, 2012, 06:11 AM
Registered User
4stripes's Avatar
Canada, ON, Burlington
Joined Jan 2009
2,930 Posts
Quote:
Originally Posted by Air-Jon View Post
Besides the material issue that is said to be causing blade failure...i thinl they tried to cram in too many blades. 10 blades would have allowed thicker blade hub dovetails and base features. Anyway i think in am going to just Hysol the entire assembly together..blades...shaft adapter...front and back hub lock rings...everything
If you glue the hub to the adapter you won't be able to dynamically balance it. It is OK to glue the rest but keep the adapter free to turn.
Cheers
4stripes is offline Find More Posts by 4stripes
RCG Plus Member
Latest blog entry: Some photos of the EDF fleet!
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Sold Zurich sun blocking sun-glasses $40 shipped mjbennett9 Aircraft - General - Miscellaneous (FS/W) 7 Oct 06, 2011 10:47 PM
Sold Zurich sun blocking sun-glasses $50 shipped mjbennett9 Aircraft - General - Miscellaneous (FS/W) 0 Oct 05, 2011 09:14 PM
Sold Change Sun electric retracts Flip Flop Aircraft - Electric - Jets (FS/W) 3 May 23, 2011 06:20 AM
Sold Change Sun Electronic retracts w/Lander struts hole digger Aircraft - Electric - Jets (FS/W) 2 May 06, 2011 01:27 PM
Video 6 and 12 blade 90mm fan sound test tom bacsanyi Electric Plane Talk 3 Dec 10, 2009 07:01 PM