This is the program I tried to send out zipped last week but it
was a little larger than the 300k limit. It was written by Ed Dokus
(and another guy - sorry I can't remember his name) and it states on
the Help page that it is in the public domain.
Anyone who would like a copy send me a email and I'll send it to
you. Maybe someone will put it on their website.
--------------
Original message --------------
From: "David Carter" <dcarter11@sbcglobal.net>
Bob, I think something along the
way stripped the .exe file from your e-mail - it substituted a short
"text" file that said the .exe file had been deleted - if the file is
needed, then have the sender send it as a .zip file.
I did a google search for this
program and found all the links "broken" except for one that has the
full set of DOS files in a zip file named PROP OPTIMIZER (tm) PROPELLER
DESIGN PROGRAM Copyright 1993 Donald R. Bates I unzipped just the
readme file and got the file name and Bates' Calif business info -
phone was disconnected.
For those of us who have
"graduated" to WinXP (which handles DOS programs in a "figure it out
yourself" mode - I run WordPerfect 6.0a for DOS in a "cmd" window with
some batch file that I accidentally cobbled together and works) I'm not
sure exactly how to run such a DOS program as this prop optimizer.
Have I found the program you are
talking about? If so, the link to download the zip file(s) is:
(I Googled prop90.zip and the 3rd
link was active)
Then I Googled prop20.zip and got
Version 2.0 (the other was V1), downloaded from
"PROP OPTIMIZER (tm) is NOT a
public domain program. It is copyrighted by
Donald R. Bates dba Bates Engineering/Software." (from VENDINFO.DIZ
changed to a .txt file so it could be read.)
David Carter
-----
Original Message -----
Sent:
Tuesday, December 27, 2005 4:24 PM
Subject:
[FlyRotary] Re: Props
Attached is
a Prop Design program, which I found some time ago, that has the
following explanation on its help page. You can play with the numbers
to match your prop and see what speed you will get or you can plug in
the variables and see what size prop you should have. I hope you can
receive the attached file.
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Thursday,
December 22, 2005 7:46 AM
To: Rotary motors
in aircraft
Subject:
[FlyRotary] Re: Props
I really do not know,
George. I have known folks with aircraft speeds somewhat faster than
the "screw" calculations would have predicted - perhaps this "lift"
factor played a role. Most figures I have seen puts efficient of prop
around 80-85% mostly around 80.
----- Original Message
-----
Sent: Thursday, December 22,
2005 4:45 AM
Subject: [FlyRotary] Re: Props
I like to reduce things
down to the simplest formula, provided one doesn't lose track of what's
relevant.
So I guess I should look
at this as 100 % theoretically efficient - whereas we may be looking at
only 80 % efficiency ( in real terms), Do you agree with 80%?
However your saying that
the lift may give more speed ( MPH, in real terms) - So are you
suggesting that these two (variables) may balance out?
Or should we use a fudge
factor, and that could be what?
I'm not looking for a
finite answer, just close enough to be able to access the experts
opinion, and we all know what an expert is - " A drip under pressure".
Yes, George. If we
assumed no slip in the prop then theoretically the formula will give
you the pitch of the prop you would need to screw through the air and
achieve your MPH at your RPM input. This is based simply on the screw
principal. I am certainly not a prop expert, but I also believe that
since the prop is a spinning wing (airfoil), that there is a lift
component in the direction of flight which may result in more speed
than the formula could account for.
Your second equation can
be reduced further from (Inches/Minute)/(RPM) =
(Inches/Minute)/(Revs/Minute) = inches/Rev
--
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