[NSRCA-discussion] Electric TT Spinner

[Keith Black]

My question is, other than looks, what is the purpose of a spinner an electric pattern plane?

- Reducing drag isn't a concern as recent designs are being built to be more draggy.
- Starters aren't used with electrics so having a nose cone isn't necessary for starting.

The only thing I can think of is to clean the air flow and reduce turbulence from the blunt nose so air going around the fuse and over the wings is smoother, however, with the prop chewing the air so close to the nose of the plane I'm not sure this is significant.

Opinions?

Keith Black
  ----- Original Message ----- 
  From: Terry Terrenoire 
  To: nsrca-discussion at lists.nsrca.org 
  Sent: Sunday, February 19, 2006 7:22 PM
  Subject: Re: [NSRCA-discussion] Electric TT Spinner


  I am adapting a 30 year old design to a pattern electric. This plane was designed around the Veco .19. I think I am going to use the E-Flite 450. Total weight looks to be in the 32 oz range. I just started drawing the motor cowl. What I am going to try to do is use a very small spinner, possibly 1 1/4, but make the ring behind the spinner backplate 2" to 2 1/2" diameter. That will allow air to enter the motor compartment from around the spinner. Another option I have been considering is 2 cheek scoops!

  Terry T.


  On Sun, 19 Feb 2006 19:48:52 EST Rcmaster199 at aol.com writes:
    It's no big deal to make cutouts in the spinner cone. Just requires more cereful balance. I've attempted it before on smaller spinners but wasn't happy with the results (on wet set-ups, and both cooling air flow wise and strength wise)

    Theory sounds good but in practice, don't expect much air flow to penetrate into the spinner when the motor is running at higher power output. The ribs that would be needed to still make the spinner functional, would likely block off air flow. Turbulence that could result, would likely rob power.

    BUT, one way it could work fairly well would be to actually refashion or bend the ribs in such a shape that air is literaly drawn in and forced through the spinner. Like a set of impeller vanes. The pitch of the vanes wouldn't need to be very high. It would rob some power from the motor though, so the practicality could be questionable. 

    On the other hand, an optimal pitch angle probably exists and could be found, that robs the minimum power and provides the maximum cooling air flow through the spinner. 

    Matt

    In a message dated 2/19/2006 7:28:01 PM Eastern Standard Time, jshulman at cfl.rr.com writes:
      I didn't know they were doing that. Thought they just cut out for the props
      and have the lightened back plate.

      Regards,
      Jason
      www.jasonshulman.com
      www.shulmanaviation.com
      www.composite-arf.com

      -----Original Message-----
      From: nsrca-discussion-bounces at lists.nsrca.org
      [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Pat Hewitt
      Sent: Sunday, February 19, 2006 7:18 PM
      To: patternrules at earthlink.net; NSRCA Mailing List; NSRCA Mailing List
      Subject: Re: [NSRCA-discussion] Electric TT Spinner


      Please advise,

      What are some of your thoughts on the cut outs of a True Turn Spinner for
      cooling on an Electric Pattern Plane not the back plate but the cone itself.

      Pat h.





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