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There has been a lot of buzz about the IV-PJ and the Walter 601 mounted up
front. I was curious whether or not the IV-PJ could travel a reasonable
distance and still have any Jet-A left in the tanks when it arrived at its
destination.
I contacted the factory and inquired about what numbers they used for flight
planning in the IV-PJ. I wanted hard numbers from the factory rather than
the piecemeal snippets I had gathered from several magazine reviews. Lancair
provided me with the following spreadsheets developed by Lance himself early
in the test program of the PropJet. For the last few weeks I have been
working to clean up a few of the formulas in the factory supplied
spreadsheets in cooperation with Lancair's Chief Pilot, Pete Stiles.
The factory has given me their blessing to post these spreadsheets on the
list, provided that most of the cells are protected from modification.
I have no way of verifying the Specific Fuel Consumption (except for the max
power figure posted on Walter's website), Horsepower, or True Air Speed
values in the spreadsheets, however, they do appear reasonable and in line
with other figures I have seen reported by the press and in the CAFE report
of an L-IV with a Lycoming TIO540. In general, the changes I made before
posting these spreadsheets to the list were to remove a few simplifying
assumptions in the original formulas. The impact was pretty minor except in
the calculations for distance traveled during climb or descent. If you find
any errors in the formulas, please let me know off-list and I will make the
corrections and repost them to the list.
For those of you still on the fence about which engine to put on the front
of your Lancair IV, I hope these spreadsheets help you make your decision. I
know they helped me decide.
Have fun with the numbers!
Best Regards,
Mike Hutchins
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