> Festive greetings to all,
> In the noble quest, there has been much debate and recommendation.
> Has anybody considered using ram air to feed the carb plenum on a
> normally aspirated engine? Would it offer a significant performance
> increase?
> Peter Kember had designed a chin mounted ram inlet, principally for
> cooling, but I believe it could also supply induction air if required.
> Just wondering...........
>
> Rog Sheridan (still building!)
Ditto on the festive greetings, but doubtful on the "boost," I think.
120 kts produces only .33 PSI of "ram", or about .6" more manifold
pressure into a closed container. But it's not closed, as the engine
is sucking on the other end, so the boost is some fraction of .6" MP.
A scoop feeding a semi-closed system adds drag, and there's a square
root in the formula to compute the effect of the drag, but a cube root
to predict increased velocity from that small boost in power. Could
all net out, depending upon size/design of the scoop and duct. Some
benefit from the cooler induction air, but could aggravate carb ice
potential.
Few production planes use the concept; Grumman did on the Traveler,
but abandoned in favor of a more streamlined cowling on Cheetah/Tiger,
for a few more MPH net. It's all in the drag, not the HP.
Regards,
Fred F.
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