>

     > IMHO a wood prop is not the way to go. The tensile strength
     > to density ratio is not as good as carbon fiber by a long
     > shot. That means the root shape must be made too thick
     > to accept the tensile loads. Also wood props are far
     > more flexible than carbon fiber and they tend to
     > twist more when loaded.
     >
     > Same goes for all the other stations. Thin is particularly
     > advantages near the tip as the prop tip operates in the transonic
     > range.
     >
     > IMHO a Paul Lipps or Perry Mick carbon fiber prop
     > would cool your pusher much better than a wood prop
     > due to a better angle of attack near the root and a thinner
     > profile with more cord and be more efficient in the bargain.
     >
     > Since your point groups did not have a point at the trailing
     > edge I had to make a best guess of where that might be.
     > Consequently Rhino lofting had a slight problem.
     > Never the less here are a few renderings of prop 2.
    Hi Paul;

    Valid points.
    His prop was wood core, carbon uni for tensile, mostly fibreglass and I
    believe carbon tips.
    A few layers of carbon instead of glass would be stiffer torsionally.
    All of his strength calcs ignored the wood contribution.
    His root was rather thicker than necessary and the airfoil was not a
    laminar foil either.
    I don't recall if the tip velocity was into the transonic drag rise
    region and might benefit from a thinner tip airfoil.
    He did have continuous twist from root to tip which did contribute to
    better measured cooling in flight -
    they postulated the prop eliminated reverse flow inboard near the hub.
    The general contruction method appears valid - although I would also
    make the changes above.

    I have seen Perry Mick's website. Has Perry or Paul Lipps published any
    detailed information on their
    design/construction methods?

    Thanks
    Cary

    I'll let them answer that if they want.

    Paul Lamar

I haven't published the details of my prop construction, the details are
of my own design and still proprietary for now. But here is my method in
general: The blades are all carbon fiber with internal carbon fiber
spars and are layed up in molds. The blades are done first and all
blades are built at the same time because they tie into each other in
the center, so a mold has to be built for each blade in the prop. The
last step is to build a laminated hardwood hub around the blades.

Perry

Thanks for the info Perry,
Can you say what the final prop weights were?
Cheers
Cary



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