Ken Welter wrote:

from ken welter
    just got a computer so i need catch you up to speed.
 I fly a rotary coot with 900 hr on
it. I also build the glass kit for the coot  and cog belt
reduction units for Mazda's .

 At a gross weight of 2800 lbs it is the heaviest flying
rotary bird know of.  The gear ratios I make are
2.25  2.8  2.95  and 3.11 to 1  I have run all of
the ratios and found the 2.95 and 3.11 to be the best the 2.8 was all
right but lost a lot of take off thrust and climb out performance
the 2.5 would not  work. No way
no how even with 125 hp nitrous jets I could not get two people
out of the water.

  The props I have used are 70 inch warp drive 4 - 5 and 6
blade the best being  4 on the 2.5  5 on the 2.8  and 6 on the
2.95 and 3.11 ratios.

 The first 500 hr on this coot
was with a Ross 3.17! That is right! 3.17 not 2.17 and a 6 blade
prop it worked fine but after I lost three engines in flight
the last one being at 6000 ft and a 500 ft ceiling. Thank god for my
garmin 195!  Shot an instrument approach in to the columbia river. 
Nice to have a boat under you.

I hit the  water all three times. At that point I
went to cog belts and after 400 hr  I have had no problems.  Cog
belts may not be for every one they raise the prop
seven to ten inches on the coot you can lower the engine and get a
lower CG I do not know how this offset would be on an
RV gear box may be better and if it works don't fix it.

 On to the engine. It is a 13 B with
a 52 weber with air ram and mixture  control and
nitrous oxide. With the nitrous I can pitch the prop for high alt
cruise still get heavy loads out of the water. I run 50 hp
Nos jets for sea level and 100 hp jets for high lakes and
I have run hundreds of lbs of nitrous through the engine
with no problems. 

As to
what RPM the mazda will take. My coot packs 100 gallons of gas and I
climb out at 6800 to 7000 rpm and cruise at 6500 rpm for up
to ten hr's at at a time.

For more information contact
me at rotary.coot@verizon.net                           or by phone
at 360-834-4089

Welcome aboard Ken. Yes I think I have seen your airplane at Arlington 
a couple of times. I also have some more pictures around somewhere. 
Ah yes here they are.

Well folks there you have it. We are not running the Mazda near fast nor 
hard enough. 900 hours and hundreds of lbs of nitrous oxide no less.

Paul Lamar
 
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