Wrathall Mark wrote:

Is the butterfly valve in the Peripheral port really nessesary in an
aircraft engine? If you run a ross 2.17 redrive, everyone is reporting that
you need to idle above 1500 rpm due to resonance avoidance. If you do need
need valve in the port can you use it to replace the throttle butterfly?

Yes they replace the throttle body. This low speed resonance problem is a function
of the vibration isolators used. So far nobody has tried a p-port with the
Ross to my knowledge. Everett used a PSRU of his own design which incorporated 
and internal gear reduction with no vibration isolator and he felt the butterfly 
valve in the peripheral port was really necessary.

Paul Lamar
 
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