REFLECTOR: Fw: Mag cooling

[Douglas Holub]

I didn't realize that magnetos needed to be cooled. A timely post since I'm replacing one of my Plasma IIIs with a magneto this week. The last FAQ on Kelly Aerospace's magneto page says that the ambient temperature around the magneto should be kept below 160 F. 

http://www.kellyaerospace.com/magneto_FAQ.html

Doug Holub
Standard FG w/ electric nose lift

Speaking of electric nose lifts, I was at Brett Ferrell's website this week and learned that the first Velocity prototype was also a fixed gear with a retractable nose gear. Who knew?
  ----- Original Message ----- 
  From: Jim Agnew 
  To: Velocity Reflector 
  Sent: Wednesday, August 10, 2011 2:38 PM
  Subject: REFLECTOR: Fw: Mag cooling


  Click on the following URL to get PIX

  https://www.dropbox.com/gallery/7279544/1/2%20Mag%20cooling%20Pix?h=1e980f

  James F. Agnew
  Jim_Agnew_2 at Yahoo.Com
  Tampa, FL
  Velocity 173 Elite Aircraft Completed & Flying




    Hi Dave,

    Sam Dasilva & I both have the system that is shown in the attached picture.  The 3" 12V fan you can clearly see in the picture.  The fan hole allows air to come up behind the baffle and is sucked out by the prop vacuum so you do get some mag cooling.  What you don't see is a small solid state thermostat mounted on the back side of the baffle that turns the fan on when the temp exceeds a certain temp (that I don't remember so I will check). The fan is permanently supplied with power and neither of us have ever had the fan start in flight.  When you shut down after a minute or two the fan turns on and helps to cool down the engine since the  upper Cowl tends to trap hot air and natural convection is inhibited.  The fan gives a boost to starting the convection and normally only runs for a couple of minutes.  Blast tubes will help with mag cooling, however you still need an upper baffle air exit.  I have also attached a pix of the baffle back side that shows the fan & thermostat.
     Jim

    James F. Agnew
    Jim_Agnew_2 at Yahoo.Com
    Tampa, FL
    Velocity 173 Elite Aircraft Completed & Flying


      From: David Ullman <ullman at robustdecisions.com>
      To: reflector at tvbf.org
      Sent: Wednesday, August 10, 2011 12:00 AM
      Subject: Re: REFLECTOR: Mag cooling

      My Tech Advisor asked me to ask if anyone directs cooling air on to the
      magnetos?  I have two of them on the back of my IO-360-C1C and they
      currently get no air circulating over them at all.  Seems easy enough to
      bleed some off the ducts bringing air into the plenum. Is magneto heating a
      problem for anyone?

      David G. Ullman PhD ME
      Robust Decisions
      ullman at robustdecisions.com
      541-754-3609

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