[NSRCA-discussion] Hacker Comp overheating

[Earl Haury]

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: 
    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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