Paul,
Another one of our SeaWind builders is considering a rotary now. I am
trying to come out with a way to describe and compare the potential Hp. of
the engines we are familiar with. Here is goes.
The Lyc. I0-540 is rated at 300hp. Perhaps with a turbo that will go up to
350Hp. Anything beyond that is pretty much for racing and/or a very limited
life. We could say the usable potential for the engine needing to reach a
TBO of 2000 hours is 300Hp.
Weight wise the three rotor all aluminum (except the intermediate housing)
P-port rotary engine would exceed those larger horsepower figures without
the turbo and weigh in lighter and should have a longer TBO because it is
being used way below its potential.
However I am concerned about the manner we are required to distribute that
420 lbs+ weight in the SeaWind. If we want to take advantage of mounting
two heat exchangers within that long cantilevered truss engine mount, then
we definitely need a lighter engine with the engine's CG moved farther
forward or more counter weights in the front. Any counter weights other
than the battery and hydraulic motor there now goes ....errr...counter to
ideal aircraft design practices:)
So ...I am suggesting an all aluminum P ported turbo 13B with Iannetti seals
and an aircraft grade TE-04 turbine with a large compressor. If he runs his
plane on auto gas he will have to limit the sealevel boost but can still
turbo-normalize it at altitude. I'll recommend Mistral's PSRU, and the Aero
Composite hydraulic constant pitch three blade unit. T.O. rpms can be 2750
on the 72" props and with the Mistral 2.82 :1 ?? ratio PSRU, it should
allow him an engine rpm of over 7700. Not as high as I would like but more
than enough to get him over the 300hp hump with less than 5 psi boost. The
weight savings on the engine configuration can extend his range or increase
his load and result in a better balance aircraft. The turboed 13B engine
life is the big unknown as there are no long lived turbo rotaries flying.
Good seals will no doubt help.
Your thoughts?
Regards
Doug Fir
It is true seals could be a problem at that power level.
I would go the three rotor p-port route for a Seawind.
an easy 375 HP. Bare engine weight without alloy housings
is 260 pounds.
Paul Lamar ...No rotor no motor.
Paul,
Are you saying Iannetti ceramic seals will have a problem at 6,000 rpm
cruise levels? Take offs with my present configuration would probably be at
8200rpm and then lowered to 7500rpm for a cruise climb. 500 rpm over what
would happen with Mistral's PSRU with an identical C/S prop. Maybe I
missed something over the years. Most guys are cruising at 5500 to 6000rpm.
right?
My friend wants to go with the 20B though he will want a turbo.
Doug Fir
It is a matter of surviving detonation not RPM.
The jury is still out IMHO on all that. Able Ibbarra uses
Iannetti ceramic apex seals on his 900 HP two rotor and 1400
HP three rotor. They are so brittle one can
snap them between ones fingers. I am a bit skeptical
about how they would hold up under detonation. I talked
to Jim Mederer about it and he said "don't let it detonate".
My inclination would be to go with 3 mm metal apex seals instead
of 2 mm apex seals. Be careful when buying after market 3 mm seals.
They must have a crown and they must be super smooth
and have a mirror like finish. If not send them back and demand
your money back as they will tear up your rotor housings
and leak.
Paul Lamar
Paul,
Ok understood. No detonation events. With ethanol fuel and basically low
boost I shouldn't have any but like you reminded me once a fuel pump acting
up, or an uncovered intake port may cause the engine to go suddenly very
lean.
Thanks
Doug
Yes Exactly.
Paul Lamar ...No rotor no motor.
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