Several weeks ago I posted an e-mail
describing poor climb performance on
our 912S equipped mono-wheel XS.
I received a number of responses
indicating that our gross weight climb
of 800 fpm at 1000 feet is less than
others are getting. The CAFE report
on Kim Prout's plane, for example,
shows a gross weight climb of 1300
fpm at 1000 foot density altitude
(Kim's plane has a Whirlwind
constant speed prop, as ours does,
but a smaller engine).
Since our cruise speed of 139 knots
(at 75%) seems comparable to other
XS, mono-wheel, constant speed prop
planes, we suspect the airframe is good,
but the engine/prop might not be delivering
fully. Our prop is allowing the engine to
rev to 5750 rpm on take-off, so lack of rpm's
is not the problem.
Looking at what is different about our
engine installation, the only obvious
deviation from a 'standard' 912S installation
is our use of the Skydrive carb heaters
between the carbs and the intake manifolds.
We have ours circulating coolant all the
time, as we were told it would have no
effect on performance to leave the heat
on all the time.
Anyone else have experience with
this carb heater installation? Any
comments?
Can anyone suggest other areas to
scrutinize for our less than stellar
climb rate?
regards,
Terry Seaver
N135TD
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