What is the absolute max take-off rpm on a turbo 13b that you still consider
safe enough?
Considering a 1 to 2 minute take-off power.

Thanks, Mike Arndt

8500 RPM on an RX8 motor and 7500 RPM on all the rest.

The rotary  is not at all like a piston engine. There are no pistons
trying to jerk off the end of the connecting rod. Jerk happens
to be a technical term meaning the rate of change of acceleration.
In a piston engine when you are in the dyno room with it running full chat
you kind of have the feeling you are about to receive shrapnel
wounds at any second. The tendency is to flee.

You can stand along side a rotary under the same circumstance and
feel entirely comfortable. Kind of like a large electric motor.

However having said all that nobody to my knowledge has ever taken
off at over 7500 RPM. Well maybe Ken Welter with his 3:1 belt reduction
and nitrous oxide injection.

Paul Lamar ...No rotor no motor.

With the 3.17 to 1 gearbox I would run up to 7500 on takeoff with
nitrous and with the 2.95 to 1 that I am now running  I only twist it
to 7000 with nitrous.
Ken

Ken,

How is the Dodge gear set looking?  I recently made up a chart listing the
different gear set ratios.  With the 3.2:1 ratio at 6000 rpm, the prop is
swinging at 1875rpm. Compared to  2105 rpm for  2.85:1 gearbox.
Does that play havoc with your props pitch setting? In other words will they
still maintain their efficiency level at the lower rpms.

The other point I am wondering if most C/S props are designed to be halfway
efficient at lower speeds under 2000 rpms? Angle is coarse more lift. but
more drag??

Doug in Japan


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