Here is a slight variation. The plenum and snorkel are fixed
     and the U tubes move in and out. A 3 inch movement of the U tubes
     is an over all change in length of six inches. About 15 or 16 inches to
     21 or 22 inches overall. A little more thought needs to be given
     on how the force is applied to the U tubes to prevent them from
     cocking in the bores.

     I think Bill Jepson came up with this idea a year or so ago (May 2003) but we never
     developed it to this stage. Bill called it the Trombone intake as I recall.
     Are you planing to build one Bill? Here is Bill's 3D as well.

     When we get further info on the RV10 I will do a layout for the three rotor
     p-port version. It is a bit much to ask to have six tubes slide in and out
     rather than only three.

     This could be applicable to a 3 rotor street car as it is almost impossible
     to do a dynamic chamber 3 rotor engine. I think that was a factor in the demise
     of the 3 rotor Cosmo affecting both low speed torque and BSFC.

     Paul Lamar

Paul, I have been considering PP on the 20B due to the much simpler
plumbing. I agree that the Trombone slide would be almost impossible on the
6 runner intake. 3 tubes would be much simpler. The interesting part for the 20B
was Francois comments on best BSFC. Injecting full charge unto the large side
port. The ports on the 20B are set up for this from the factory, I'm not sure
which set are the primary injectors. There is a set of the two per rotor shooting
directly into the larger ports. The 20B is a 6 port (like a 13B 4 port engine).
I plan a full engine check out, (disassembly) prior to running.
Bill Jepson

I realize I'm pointing out the obvious here but the trombone slide version lengthens the intake tube with half as much movement as the "moving the plenum" version because you get lengthening on both
ends of the tube. Should be easier to fit inside the cowling and to work up a mechanism. Also a mechanism that involves half the movement should be less prone to cocking in the tubes. Finally,
because the trombone slide part is not exposed to the wind, the mechanism won't have the lateral force on it and therefore is more likely to work.

My question is whether you'd have this slide mechanism on a manual control like mixture or cowl flaps (i.e., tweaked by the pilot, with perhaps three settings: climb, best power, best economy) or
whether you'd try to rig up something that automatically advances it connected to throttle position (or more challlenging, rpm).

Barry Gardner
Wheaton, IL

Good points there Barry. I would start out with manual. I get bored on long 
cross countries and I need something to do. I can fiddle with this and watch
the fuel burn.

Paul Lamar
 
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