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Ed,
I remember reading that the 80% duty cycle rule (of
thumb)was originally developed for the racing industry.
Given that probably 100% will never be reached in
the day to day vehicle use - the 80 % duty cycle most probably doesn't
apply for sizing. However bigger injectors are standard in vehicles where the
RPM limit is much higher than what we may experience in our Aviation
application, even if for only short periods of time.
Given that our RPM is on the high end for climb and
take-off, but not as high as it could be (not max RPM), and cruise is for the
most part only 6,000 rpm, do we really have to held to the 80% DC rule, where
perhaps 90% DC (for short periods of time) may well give sufficient safety
margin to maintain longevity of the injectors.
Not that there is a major benefit in having
borderline injector duty cycle, as you so rightly pointed out - it's just
that it would be interesting to
know!
George (down under)
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