Yes the idle might be a problem. Power Sport and others put butterflies close
to the rotor housing and claimed the idle was much better but I don't
have any numbers. On the other hand with a 2.85:1 PSRU the engine can idle
at 1750 RPM while the prop is turning only 600 RPM. About the same
as most direct drive AC engines can idle. I am almost certain a P-port with
the throttle close to the rotor housing will idle at 1700 RPM.
Here is a P-port slide throttle that is worth 10 or 15 HP over butterflies.
I am working on designing a sheet metal version that will be cheaper to
makes.
Paul Lamar
"Echo Lake Fishing Resort (Georges Boucher)" wrote:
Hi! Paul
Ivopro's site shows an electrical in flight adjustable prop & Warp drive doesn't show a controlable prop.
Did you have it mixed?
Thanks.
& Gail Boucher
2126 Creighton Valley Road
Lumby, British Columbia
Canada V0E 2G1
(250) 547-6434
www.echolakefishingresort.com
www.echolakefishingresort.ca
Yes that is correct. IVO is not really a variable pitch prop however. The blade
is twisted rather than pivots like a true adjustable pitch prop.
The Warp Drive is ground adjustable. Also as Ken mentioned you can add
more blades for more blade area. Ken has years and years experience
with rotary powered Coots. Here are a couple of pictures of Ken's Coot.
Apparently blade area pays off in high static thrust for getting you
up on the step and off the water. Sensenich makes air boat props with
lots of blade area. Here is a shot of a Sensenich air boat prop.
This one is also ground adjustable.
There are other ways to go. You could use a Mistral gear box that has provisions
for a hydraulic constant speed prop. Cost is around 7,000 as I recall and another
500 to 1,000 for a governor used or new. Then there is the prop it self at 2,500
to 6,500 used or new.
Another way is to use the Tracy Crook gear box and a German Hoffman or MT electric
prop. About 3,000 for the gear box and 10,000 for the prop all US dollars.
Frankly with a Christavia sea plane on floats take off and cruise speed are pretty
close together due to the high drag so a ground adjustable prop like the Warp Drive
or Sensenich is the low cost way to go. You will see little advantage with
a true adjustable pitch prop.
Paul Lamar
David Staten wrote:
What kind of plane is this, Paul?
Dave
It is a Coot amphibian.
BTW Ken, what is your new web site URL?
Paul Lamar
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