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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