[NSRCA-discussion] Cooling outrunners

[Rex LESHER]

I actually looked at doing that...  After I put the small spinner on, I decided it was butt ugly and wasn't about to be caught in public with it
like that....  LOL   
I have a ramp built into the chin cowl that diverts the air up to right behind the motor, then flows through the battery tray.  After carving the 
spinner and backplate, the motor temps went down.  In the hot weather, say around 100F+, I noticed sometimes that I was beginning to have a 
few power problems.  I also noticed that these power problems were coming in outside, push manuevers...  I figured it might have something more to do with airflow through the fuselage, so I increased the air outlet in the bottom of the fuselage(doubled the size).  All of the cooling problems 
went away, and I noticed that the overall temps went down considerably.   I probably made 20-30 flights after that in the heat and had no temp 
problems.  Since then, I have installed the curved "tounge"  like Chad uses, to divert air directly onto the motor can.  I'm guessing I'll have no temperature problems at all now, but I'll have to wait till June to find out.
Flying electrics is like wine, they get better with time!!!!

Rex
  ----- Original Message ----- 
  From: Chad Northeast<mailto:chad at f3acanada.org> 
  To: NSRCA Mailing List<mailto:nsrca-discussion at lists.nsrca.org> 
  Sent: Tuesday, December 19, 2006 9:29 PM
  Subject: Re: [NSRCA-discussion] Cooling outrunners


  We actually asked ZN about producing an add-on piece to do just that on 
  the Twister while at the Worlds in France.  They were concerned about 
  making a composite piece that small strong enough so it never really 
  went past discussion.

  Dez however, did run a smaller spinner on his motor for a while.  IIRC 
  it made a small difference to the temperature but not enough to overcome 
  the  decreased aesthetics :)

  The motors are around 2.25" OD, spinners up around 3.25"+, so even 
  dropping down to a 2.75" spinner still provides a lot of blockage to the 
  motor can.

  Chad

  Rcmaster199 at aol.com<mailto:Rcmaster199 at aol.com> wrote:
  > One way this could be done is to allow enough annular room around the 
  > spinner, completely bypassing the cheeks and chin. You only need about 
  > 1/8" annular opening. Just use a smaller spinner than needed and 
  > fashion the model nose to recess the spinner slightly into the annulus.
  >  
  > I have done that on Temptress (engine powered) with good results.
  >  
  > Use the cheeks and chin to route air to the bats.
  >  
  > MattK
  >  
  > In a message dated 12/19/2006 9:28:10 AM Eastern Standard Time, 
  > bob at toprudder.com<mailto:bob at toprudder.com> writes:
  >
  >     */Chad Northeast <chad at f3acanada.org>/<mailto:chad at f3acanada.org%3E/>* wrote:
  >
  >         The problem with a lot of composite fuse models (Twister
  >         included) is
  >         that the inlets in the chin and cheeks are often right at the
  >         rear or
  >         even behind an outrunner.....so ducting toward them is very
  >         difficult.
  >         I have to agree that a proper ducting system is crucial for
  >         cooling. I
  >         use a very simple short radius 90 bend in a peice of depron
  >         that pulls
  >         air in from the chin, I see about a 20C rise in temp without
  >         it, other
  >         than that I dont really do anything special. The motor will
  >         operate at
  >         up to 170F without complaining so as long as its 20-30F below
  >         that all
  >         is good :)
  >
  >         Chad
  >
  > ------------------------------------------------------------------------
  >
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