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KAWASAKI Issues - how much
power does the Kawasaki 440 have compared to the Rotax 447?
The Kawasaki 440A is a wonderfully smooth engine
that is quieter mechanically, lighter by 7 lbs. than the ROTAX 447 and
generally speaking less expensive than the ROTAX. As a benchmark, when it
was all set up ready to mount on the HoneyBee Gyro with carb, exhaust,
redrive, etc., it cost us $1750, not $495 as advertised by J'Bird. There
was a lot to complete the package.
The problem we ran into however was not whether it
produced a similar power package to the 447 but rather did it produce
enough thrust to fly an ultralight gyro. A gyro is the second most
inefficient aircraft in existence behind a helicopter. After much ground
testing it just would not fly the HoneyBee Gyro. This significant problem
caused us to set up a test to measure the straight line thrust test
against Dr. Taggart's Gyrobee using a 447. Here are the results:
1. In the first test, the Kawasaki produced 130#'s
of thrust. The best we ever did in subsequent testing produced only 190#'s
of thrust on a hard surface. Quite frankly, that is why we could just not
fly with the Kawasaki 440A. It might have been different with a 440B.
2. In the first test, Dr. Taggart's ROTAX 447,
with a 60" IVO Prop, produced 230 #'s of thrust. with an engine that
was approx. 8 - 9 years old. This test was performed in grass and would
have been around 250+#'s of thrust on a hard surface.
In a matter of about an hour we began to
understand why the Kawasaki could only get us into ground effect. This
test set the stage for the "minimum thrust requirements" within
Part 103.
We immediately contacted Stewart "Prop
God" Gort of POWERFIN. Based on his experience and recommendation, he
told that if we could engineer a structure that would accept a 66"
Two Blade prop the thrust problem would be taken care of. That is exactly
what we did. The rest is history. This one change makes the power package
produce 283#'s of thrust and make the HoneyBee Gyro fly like an angel.
I understand the attraction to the Kawasaki which
has a good reputation in the fixed wing side. Being your own R & D
department is expensive, frustrating and sometimes dangerous. As a
"friend in the business" I would not recommend pursuing this
direction. One missed or botched departure/approach/power fade/etc. will
cause significant damage to the craft you have worked so hard on and may
cost you your life. Honestly, from one test pilot to another, your life is
not worth risking for the few "real" benefits that a Kawasaki
440 provides.
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