Re: Optimum Prop Diameter

From: Bill Gowen <b.gowen_at_earthlink.net>
Date: Wed, 5 Sep 2007 14:51:50 -0400

For my purposes my props are usually as big as I can make them and still make the minimum weight for the class in question. Limited Pennyplane props have a 12" maximum diameter which is probably smaller than the ideal for that class. Some people flying extremely light EZB's are using pretty small props so maybe they can address that application.


  ----- Original Message -----
  From: calgoddard
  To: Indoor_Construction_at_yahoogroups.com
  Sent: Wednesday, September 05, 2007 2:40 PM
  Subject: [Indoor_Construction] Optimum Prop Diameter


  Assume that the rules for a particular class or contest specify a
  maximum prop diameter. In general, is it preferable to use the
  maximum prop diameter allowable, assuming the plane is still built to
  the minimum weight allowed under the rules? Clearly you still have to
  find the best prop/rubber width combination for a given prop and
  airplane after the pitch has been optimized. Obviously there are other
  factors to consider such as the airfoil of the prop blades, the total
  area of the prop blades, the coutour of the blades, etc.

  I have noticed that F1D, EZB, penny planes and so forth seem to have
  very large prop diameters relative to their wing span. There is
  clearly a conscious choice not to use a smaller prop diameter prop
  with less width on the rubber that would allow for packing in more
  turns, which, of course, is offset by the faster RPM.

  So my question is, in general, is the longest duration likely to be
  acheived by optimizing pitch/rubber etc. using the maximum prop
  diameter allowed under the rules?



   

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Received on Wed Sep 05 2007 - 11:52:21 CEST