[NSRCA-discussion] Hacker Comp overheating

Tue Sep 1 10:06:07 AKDT 2009

Wait a minute. I thought electric power sytems were "plug & play" and nearly "maintenance free". You mean they're NOT???  LOL

John Pavlick

--- On Tue, 9/1/09, Richard Strickland <pamrich47 at hotmail.com> wrote:

From: Richard Strickland <pamrich47 at hotmail.com>
Subject: Re: [NSRCA-discussion] Hacker Comp overheating
To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
Date: Tuesday, September 1, 2009, 12:54 PM

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I have two Comps that I bought used--sent them off to Hacker to be checked as one had a gear problem and the other ran 'hot'.  Got them back and one still ran hot.  I disassembled and the interior lining had a small wrinkle in it that impeded air flow--I sanded and re-sealed it--and need to test it.  Hacker suggested it had gotten very hot along the way to cause the wrinkle and probably lost some magnetism.  Even after three or four flights in relatively close succession, the other motor only got into the high 120s--this one got to almost 160.  I'll try it, but I think a new rotor is in it's future..,.BTW, they say if it got high enough to de-mag, then the bearings ought to be replaced also...

Now for the cause of over-heating:  The configuration of these motors is a little weird--you would think they would do a front to back air flow as you would normally have positive pressure toward the front of the motor--but the fan integrated into the gearbox pulls air through the motor from the back where you would hope there would be negative pressure.  So it would probably help to duct air to the rear.  But it doesn't seem to matter if the motor is OK as it stays reasonably cool with fairly 'normal' ducting.  So I suppose flying with weaker batteries, lots of partial throttle under load, immediate successive flights, too much prop, wide open all the time, etc. could contribute to longevity/heating/ demagging issues.  I didn't used to pay that much attention to motor temps as my original C50XL14s seemed to run fairly cool--but then I went out for some quick flights for practice--hot, humid and flights in close succession and killed 'em both
 within a week--I was out of business....
RS

Date: Tue, 1 Sep 2009 12:01:39 -0400
From: schale at optonline.net
To: nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] Hacker Comp overheating

I called Hacker first person thought it was the phenolic disk from the fan being missing.  Next guy who was to take the order was less enthusiastic.  He thought it could have been a de magnetized issue.  Oh well off to Hacker it goes :)
I haven't flown the Pinnacle in over a year, guess it is time to get re-aquainted.
Thanks for the help.
Stuart

Richard Strickland wrote: 

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There's a pretty good chance the rotor has de-magnetized, draws more amps to compensate and heats it up.  Rotor is about $180.00.  Make sure the interior paper isn't rubbing the rotor and there is some clearance--as there ain't much to start with...
RS

Date: Mon, 31 Aug 2009 22:51:15 -0400
From: schale at optonline.net
To: nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] Hacker Comp overheating

The pencil line is straight, and it is a kevlar wound magnet.  I will call Hacker tomorrow and I am sure they will say send it in.  The input wire could be an issue.  I always noticed that if the wires were bent wrong it would cause friction to keep the motor from easily spinning.
I guess I will just have to fly the Pinnacle for a while, or switch that motor to my Beryll.  Does the reg Hacker swap for the comp model or are spacings different?

Earl Haury wrote: 

Stuart

As this is a change from the norm, it's apparent that something has changed with the motor. Higher temp is usually associated with higher load (more watts) which doesn't appear to be the case. A clue might be in the missing fan disc, I doubt that the change in fan efficiency is at fault due to the rapid temp rise. But, you might check the windings for damage from debris, as clearances are close between the rotor and the windings. You mention that the rotor doesn't have separated magnets. I assume that this rotor has the Kevlar thread outer winding. There's usually a pencil line drawn on the covering for the length of the rotor - ensure that the line is straight. If some magnet discs "slip" they may not develop a gap, but the pencil line will be discontinuous. (Although usually slipped disc symptoms are higher amps as well as temp.)

Another possibility is a partially broken motor input wire, the high resistance in one "phase" will imbalance the load on the windings and quickly generate more heat. (I've found it worthwhile to tie the motor wires together to minimize flexing.)

Good luck

Ear

----- Original Message ----- 
From: Stuart Chale 
To: General pattern discussion 
Sent: Monday, August 31, 2009 8:41 PM
Subject: Re: [NSRCA-discussion] Hacker Comp overheating

It has been in the same plane for 2 years.  Never noticed it getting this hot before.  I know the last time I checked (in hotter weather) it was not this hot.
Stuart

Vicente "Vince" Bortone wrote: 

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Stuart,

How long you have been running the motor?  Did you measure the temperature?  It will be good idea to duct air to the back of the motor.  If you don't have any ducting I suggest that you install some.  Air from the duct should blow as close as possible to the motor.  Probably you already did all this but I am not sure.  Also need to make sure that has enough exhaust opening to allow the hot air to exhaust the fuselage.  I am sure that you will get more suggestions.

Good luck,

Vicente "Vince" Bortone

----- Original Message -----
From: "Stuart Chale" <schale at optonline.net>
To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
Sent: Monday, August 31, 2009 7:13:08 PM GMT -06:00 US/Canada Central
Subject: [NSRCA-discussion] Hacker Comp overheating

I have a hacker 14XL Comp model that started overheating this weekend. 
I was hoping it just needed some grease.  Pulled it apart tonight and 
grease was still present (black as usual.  Regreasing time was near.)  
Cleaned it up and pulled the front housing off.  First thing I noticed 
was that the bottom portion of the fan (the phenolic disk) was missing.  
Some dust in the motor so I think it just got chewed up spit out or part 
of it ground to dust.  Pulled the rotor and the magnet looks fine.  I 
had a standard model where the magnet split part way down and was 
pulling higher amps.  Bearings fit the shaft freely, no play but slid on 
easily and seemed smooth.  Put it back together regreased.  Ran it up 
with a 21 x 13W APC pulled 67 amps 2300 watts at WOT but after a minute 
or so of 3 15 to 20 second full throttle bursts the motor was hot 
again.  Too hot to hold your hand around it.

Any ideas?
Thanks,
Stuart

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