So the 3:1 redrive gives you more hp? Skip

Absolutely. It is like magic. :-)>

Props are limited in the RPM they will
run as the tips run into the high drag sound barrier. Most props have this
problem around 2700 RPM. If you multiply that by 2.17 you get 5859
engine RPM. So any geared aircraft engine with that ratio will run 
into a brick wall at around that RPM. 

A 3:1 gear box like Ken is using will give 8100 RPM at 2700 prop RPM. 
All other things like intake breathing (BMEP) being the same. Any  
free breathing engine will generate more HP at 8100 RPM than it will at
5859 RPM. That means Ken can use more blade area to get more thrust
at 2700 prop RPM. And in fact he does with a five blade Warp Drive
prop. 

Perry on the other hand uses no gear box but his prop diameter
is much much smaller so his blade tips do not run into the sound
barrier until his prop reaches about 5400 RPM.

The down side to such a prop is it is not as efficient so it will 
not generate as much thrust as a larger diameter prop absorbing the same
amount of HP. Perry's airplane has a max speed around 150 MPH while
Tracy's airplane goes 200 MPH with roughly the same rotary engine.

Ken on the other hand has a high drag amphibian so he only goes about
110 to 120 MPH despite having more HP than Tracy. Here is a picture of 
Ken's airplane. That is me getting ready to go for a ride with Ken. 
The cockpit is a bit tight for me.

Paul Lamar
 
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