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Posted on behalf of "Lance A. Neibauer" <lancen@lancair.com>:
Folks,
I recently read some comments on turbines that lacked some areas of
accuracy so here I go again. Other than always wanting more power, the
turbines possess worth in other areas as well. The Walter run-outs from
fields in outback Russia are indeed a bad idea, almost as bad as the
chopped off Avia props that usually go with them. Consequently, I went
straight to Walter and we've worked out a good program for factory rebuilt
601E's. 750 hp, .67 SFC's, with good ram recovery up to 400 hp at 25,000
ft., 2,000 TBO that is very realistic and 8 years (for seals etc.). Total
overhauls are about 40,000, maybe less. So, cutting to the chase at the
lower flight levels we typically run 265 hp with the Continental, burning
around 21 gph since the Cont. doesn't care for lean of peak operations in
the flight levels. That comes to about .46 sfc. The Walter will burn 26
at that power setting for a .67 sfc., 27% more fuel by gallons. If the jet
fuel cost were 27% less then fuel costs would be equal. (Actually one
would save considerable fuel dollars operating in Europe, Asia or South
America - virtually anywhere other than good old USofA.) But, while jet
fuel is generally less in the USA, it's not that much less so there is
added fuel cost here but it's really not too bad. The difference is that
there will be over 100 hp still available, it will run quieter and
smoother. And while I can't complain at all about reliability with the
Continental, there is little discussion as to the great reliability with a
good turbine. By the way, cooling drag drops from significant to nearly
non-existent and prop efficiency should go up. The Walters that we've
selected all come with Auto-start. Push the button and in 19 seconds, it's
either sitting there running and ready to go or it has shut itself down
automatically. There is also a very nice braking feature available with
the engine/prop. Hartzell is now building a custom prop that will be
similar to that which we ran on the Tigress.
Having looked seriously at all the possible turbines, this was the only
one that fit - generally from a cost viewpoint. While every maker offered
us a demo engine, literally all others were too expensive. The Garrett had
the best sfc's being a direct drive, it's exhaust straight out the back
would be a serious cabin heater, Allison was too low of hp and the new
Williams - too light if you can believe that! I'd need two of them up
front - hmmm?
Lance
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Please send your photos and drawings to marvkaye@olsusa.com.
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