In a message dated 99-08-19, you write:
<< I think that the fuel consumption increases with height because the Bing
carbs
are not fully height compensating.
>>
Has anyone tried leaning the Rotax' mixture at altitude by introducing a
controlable air leak (via a needle valve) through the fitting provided for
connection of a manifold pressure gauge? Manifold air leaks generally cause
undesirable leaning -- this would be an attempt to use a controlled manifold
air leak to achieve desired leaning.
Unfortunately, this crude approach would be sensitive to power setting:
reducing power with the leak open would (I think) cause the mixture to go
leaner. The pilot should close the valve before changing power to avoid
over-leaning. But it might, in careful concert with EGT readings, allow
better efficiency during stable cruise at altitude. With the danger, of
course, of the engine quitting or being damaged if the pilot changes power
setting without closing the leak. As with early turbochargers, the pilot
could damage the engine through unconsidered use...
John A044 Newtown, CT
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