From: "Marko Bewersdorff" <marko@bewersdorff.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: RE: [FlyRotary] Re: New cooling Model example
Date: Wed, 22 Oct 2003 15:20:59 -0700
Message-ID: <HKEGKAHKFINFFEKPHLNAIECPEDAA.marko@bewersdorff.com>
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You can use this 1993 shareware version (dos) of prop optimizer to get a few
good starting points (even has a RV6 in it as a sample I think)

http://bewersdorff.com/wankel/propeller/propopt/
look for prop90.zip, I don;t know if prop20.zip is older or newer, havn't
gotten around to playing with it yet.

or another tool for windows in:
http://bewersdorff.com/wankel/propeller/propdesign/

Marko


> -----Original Message-----
> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On
> Behalf Of Ed Anderson
> Sent: Wednesday, October 22, 2003 2:15 PM
> To: Rotary motors in aircraft
> Subject: [FlyRotary] Re: New cooling Model example
>
>
> Hi Jim
>
> To answer your question, I have already done that.  You can now
> stick in any
> gear ratio you want.  However, the only thing that it really
> changes is the
> prop rpm.  In other words, this simple model does not yet have a "load
> factor".  I hope to be able to add that at some time in the
> future, but the
> problem from what little bit I know about propellers is that it would take
> some math model of prop loading on the engine, thrust and airframe drag
> factors. Then that would mean either everbody would have to know same for
> their airframe, or some sort of simplistic model would have to be used.
>
>  So while the model does permit your to put your gear ratio in.
> I'm afraid
> all it really does is calculate your prop speed for you.  Sorry
> 'bout that.
>
> However, the model will calculate the rest of the stuff IF you can achieve
> that rpm with your prop load (whatever that rpm may be).  You can also put
> in one or three rotors (or 4 or more if you want).  I feel 90-95%
> confident
> that the power and BTU calcuations are within 5% (perhaps less)
> of the real
> world based on data I have received.  That of course assumes you have a
> good induction and exhaust system.  If a bad one, then all bets are off.
>
> If you would like a copy of the spreadsheet as it now stands let me know.
>
> Ed Anderson
> RV-6A N494BW Rotary Powered
> Matthews, NC
> eanderson@carolina.rr.com