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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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