Marc Zeitlin
Exalted Grand Poobah
I appreciate the explanation of what TC'd aircraft do, but that doesn't explain how stock 100LL systems on E-AB aircraft, with no facility for dealing with vapor pressure issues, were able to work just fine up to 35K ft. (and even 47K ft., for BB) I'm missing some connection here...Certified airframe/engines deal with Avgas vapor pressure limitations by pressurizing the fuel tank... However the 'main' item that keeps them running (at least in IO or TSIO) is a vaned fuel pump designed to push bubbles out and back to the return tank...The point is simply that these problems are not trivial and simply making a claim that we are "going to 35K" without a lot of careful work is doomed simply to vapor lock and engine failure...
Maybe Ross's graph above explains it all - as long as it's cold, the VP is low enough that all the fancy crap on TC'd aircraft isn't necessary? And it's always cold up high?