Originally Posted by
1967brutus
It would... But I have no idea about its longevity or its linearity, Probably with a dry airflow service life is less than optimal (movement and no lubrication) but crankcase pressure always contains some oil mist. That should ensure proper sealing.
I could see that working, but probably you will need an additional sensor to control the actual sensor, because I think the RPM will have influence on the gasflow. Especially with 2-strokes, where the throttle affects crankcase peak pressure.
Concept
Using checked crankcase pressure with the solenoid tee'd into the line between the check valve and fuel tank. Crankcase oil would drain through both the check valve and the solenoid to provide lube. The solenoid would serve as an adjustable pressure relief valve. Our existing fuel channel curve would become a tank pressure curve, tied to throttle position.
I have no idea of validity of the idea but it seems like it would provide varying fuel pressure just as muffler pressure does. The final pressure curve would be tuned in flight, just as with our current configuration.
The headroom for additional fuel during unloading is an unknown to me. It seems there would be additional tank pressure/fuel pressure available as the prop unloads, above ground peak rpm, without further adjustment of the solenoid/relief valve but I'm not sure if it would be enough to meet fuel demands. It may require some compromises.
As usual, I've probably over simplified the whole thing and I really don't think the concept will control engine fueling with the granularity of the current setup. It may however work good enough, getting rid of the severly over rich midrange common to glow/gas conversions and get rid of that pesky crap trap.