[SPAM] RE: Unusal Props

[Wayne Galligan]

MessageI admittedly am no rocket scientist but I think it has to do with the efficiency at the speeds the props spin.  Full scale props are most likely more efficient because they don't cavitate in their own wake as bad as a model prop does.   And model props develop mucho noise as the tips reach mach speed.  I think Bob P. has a prop speed chart on his website illustrating that.   Thus the shape of the tip and blade is important in our part of keeping them quite as well as creating efficient thrust.  There are people who can convey this idea better then I can but why does a larger model fly better then a smaller one even though it has a higher wing loading?  I think the relationship in prop sizes, full scale vs. model,  has a similar reference.
I am told so therefore I am I think.  hmmmmmm!

WG

  ----- Original Message ----- 
  From: Fletcher, Richard 
  To: 'discussion at nsrca.org' 
  Sent: Wednesday, November 17, 2004 1:04 PM
  Subject: RE: [SPAM] RE: Unusal Props


  Dean, 

      It is interesting that no other prop manufacturer has been nearly as successful at marketing this design as APC has. The have essentially dominated the glow engine prop market. In the giant scale market this blade style has not shown nearly as much efficiency. The Fuchs line is semi scimitar in shape and their props work well but other brands with more traditional designs work as well, or better. I once owned an APC 22X12 three piece prop and again it was really not much better then a traditional design wood prop. I wonder why these props work so well at the smaller sizes?



  Rich  
    -----Original Message-----
    From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On Behalf Of Dean Pappas
    Sent: Wednesday, November 17, 2004 1:56 PM
    To: discussion at nsrca.org
    Subject: RE: [SPAM] RE: Unusal Props


    That's right, and it was a closely held technology until only a few years before APCs became available.

    The benefits of the scimitar shape for delaying compressibility effects at high prop tip Mach numbers have been known since WW2. As it turns out, Von proved the value of knowing how to read!

    Dean Pappas 
    Sr. Design Engineer 
    Kodeos Communications 
    111 Corporate Blvd. 
    South Plainfield, N.J. 07080 
    (908) 222-7817 phone 
    (908) 222-2392 fax 
    d.pappas at kodeos.com 

      -----Original Message-----
      From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of DaveL322 at comcast.net
      Sent: Wednesday, November 17, 2004 1:44 PM
      To: discussion at nsrca.org
      Subject: [SPAM] RE: Unusal Props


      I believe the CAD/CAM, software, algorithms, etc used to develop the technology/process for the APC prop line came from "quiet" propellers on submarines.

      Regards,

      Dave Lockhart
      DaveL322 at comcast.net

        -------------- Original message -------------- 

        Dave Von Linsowe was experimenting with semi-scimitar shaped props at that time, I wonder if APC was influenced by his efforts.



        Rich


          -----Original Message-----
          From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On Behalf Of Rcmaster199 at aol.com
          Sent: Wednesday, November 17, 2004 1:32 PM
          To: discussion at nsrca.org
          Subject: Re: Unusal Props


          Yes we do. The semi-scimitar design was a huge departure from the "Normal". I heard from many "...what an ugly prop.....never will use.... blah, blah, blah...." among other things. But performance has silenced everyone.

          Matt


          In a message dated 11/17/2004 1:24:21 PM Eastern Standard Time, rcaerobob at cox.net writes:
            Mostly the Rev Ups were used because they made our motors SING!!!  I mean FAST...LOUD...but never went anywhere.
                We didn't know better.

            Then came MK and Asano....
            Then this maverick APC thing....Boys, we remember when THOSE first hit the pits, don't we??????????

            Bob Pastorello
            NSRCA 199  AMA 46373
            rcaerobob at cox.net
            www.rcaerobats.net


              ----- Original Message ----- 
              From: Eddie Batchelor 
              To: discussion at nsrca.org 
              Sent: Wednesday, November 17, 2004 12:18 PM
              Subject: RE: Unusal Props


              True  It might be that.
              I don't think I've ever seen a prop labeled as to how many blades.
              Interesting thought
              I like you're "tlarld"

              the prop markings are like this
                        2
                    12  O  5
                      REV-UP

              with the "O" being the hole in the middle.

              It's times like this I wish the "list" could handle pictures. <G>

              Eddie

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.f3a.us/pipermail/nsrca-discussion/attachments/20041117/34f6bf9b/attachment.html