I did look briefly on the internet but did not find clarity. Perhaps
I should look harder....anyway, here is the problem: Some of the LSA
engine prop combinations use quite short props, much shorter than I
am used to. Could some one tell me the tip speed of a sixty inch
diameter prop turning 3400 rpm.
Jerry-------- Forever humiliated to be so weak mathematically.
That is because of VW and the Jabiru, a close relative of the VW,
are rated at 3300 RPM. You are building an STOL. You need the
largest diameter prop you can get on there.
--
BTW Harley rear pulleys are under $100 new. They are up to 1.5" wide
and up to 72 teeth and you can stack two or more side by side and
use multiple $169
belts. There is a bunch on e-bay.
http://www.tejasthumpcycles.com/Parts/primaryclutch/
harley_belt_drives.htm
Download this catalog. http://www.sudco.com/
Paul Lamar ...No rotor no motor.
Jerry, just to give you an idea of the what you may have to look for.
I have on my Heavy Hauler AVID a 75" three blade Powerfin, driven
by a SOOB
100hp through a 1 : 2.62 Rotax C-box. I am happy with performance
in every
respect. Even with that slow running prop. I can still cruise at
100mph with
the engine running in the upper 4k. It is not noisy too.
This experience is the reason why I am using the 3.3 : 1 ratio on
the single
rotor.
When I built the AVID and settled on the SOOB with the C-box, the
only prop
I found over 72" dia was Powerfin. Idealy it should have been 76", but
Powerfin could not do it, so I settled on 75". My estimates gave me
a pitch
angle of 13deg at the tip, and that is what I am still flying.
Dont forget, "slow airplane = slow and large prop" means good prop
efficiency.
I hope this helps.
Richard Sohn
N2071U
Thanks Richard, I always value your comments. 3.3:1 is good. Are
you going to build the drive? The main thing I want with my 701 is
to leap into the air. I will be flying out of my back pasture, 800
ft between the trees at either end. Jerry
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.