I dunno, Ferg! I just WAG'd the temps at 16,000, assuming you'll be
below the max airbox temp of 160F at 100% power. For these purposes,
I understand we calculate from absolute zero, so the temp difference
between S/L and 16,000 is actually small (better winter performance is
aerodynamic effect also). But 16" to 34" boost boost raises temp a
lot.
NASA has a 914-powered, unmanned aerial vehicle project, with target
altitude of 90,000 feet. Still very cold, but at FL900, ambient
pressure is about .5" Hg. Raise that to 30 inches for 80% power (best
they say they can do), and it requires a 3-stage turbo with _big_
intercooler. Turbo outlet temps exceed 350F at full boost, net of
OAT. Vented fuel cavitates too up there, so natch she's injected.
Nice also an agency that thinks in $10's of millions, could find
nothing more practical than a Rotax (as does the Defense Dept. for the
Predator UAV in Afghanistan lookin' for UbL).
Regards,
Fred F.
Fergus Kyle wrote:
>
> Cheers:
> "Fred,
> Don't forget that at 16000 feet the OAT is maybe minus 30 degrees, so the
> inlet air is that temp, then raised by compression in the turbo, and cooled
> by the intercooler to about 30 degrees warmer than ambient, so it goes into
> the cylinder at around 0 degrees, not 110 degrees F. Maybe a bit more HP
> than you figured."
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