> >
> > You might ask Perry Mick if he will make a prop for you.
> > His props, like Paul Lipp's props, have the required twist near
> > the hub that is necessary to suck air out of the cowl.
> > That could improve your oil cooling and get you
> > the right pitch in the bargain.
> >
> >
> > Paul Lamar ...No rotor no motor.
> >
>
> Thanx Paul!
> I'm going to re-do the oil cooler plenum anyway. The one in the
> picture is
> the old one before I increased the size of the armpit-scoop. After I
> increased the size I did a cut-and-patch job to get a plenum of sorts
> attached to the new scoop and the oil cooler. It is really ugly -
> both in
> looks and functionality. But for the time being it appears to be
> adequate.I'll remake it in the fall - or when I'm making more
> power and have to
> improve the oil cooling - which ever comes first.
>
> I bought a prop design program/spreadsheet with the intent of
building
> another prop - but I don't have the CAD software to generate the
> cross-section templates. The program/spreadsheet outputs the x-yu-yl
> coordinates for import into Rhino or SolidWorks - but I don't have
> either(and probably wouldn't know how to use if I did). Attached
> are import files
> for the 2 props I'm looking at building - each file, 1 to 7, is
> station 15%,
> 30%, 45%,
> 60%, 75%, 90%, and 100% of length (66" for 2 blade and 64" for 3
> blade).
> Thanx,
> Joe Hull
> Cozy Mk-IV #991 (In Phase1 Flight Test - 40.2 hrs flown)
> Redmond (Seattle), Washington
>
> I'll work on it tonight Joe. Don't have my Rhino computer here.
> --
> Paul Lamar ...No rotor no motor.
Joe, I'm curious as to what program that is.
Attached is a PDF showing the various stations at 1:1 scale. I only did
the first prop..
if this is what your looking for I can do the second one also. You'll
need a tabloid size
printer [ "B" format] or print it in two pc's on 8.5 x 11.
Jarrett Johnson
Good work Jarrett. Do you need me to do something else Joe.
--
Paul Lamar ...No rotor no motor.
Wow! That's great Jarrett. I think Paul is off the hook :)
Jarrett - Could you put a vertical and horizontal center line down
them as a
reference?
The "program" I'm using is "JC Propeller Design" by Jan Carlsson. It is
really just a very sophisticated Excel spreadsheet. It even graphs the
cross-section profile - but not to scale.
Attached is a picture that contains 3 images - the top one is the
graph he
creates in the Excel spreadsheet and the bottom 2 show the kind of
template
that needs to be made from the cross-section drawings.
Thanx,
Joe Hull
Cozy Mk-IV #991 (In Phase1 Flight Test - 40.2 hrs flown)
Redmond (Seattle), Washington
Hi Joe;
I'm not sure if you have seen this page -
Phil's prop was loaned and flown on another cozy4 with very good results.
Also made a really good snow blower :) - don't think the plane will make
Osh this year, maybe next...
Take a look at:
http://www.canardzone.com/members/PhillipJohnson/Propeller/propeller.htm
http://eaa245.dhs.org/Presentations/CozyProp/index.html
Cheers
Cary
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
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.