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Glad I woke you guys up! :-)
While it may appear from my post that I was trying
to discourage this guy and am not happy with my rotary powered airplane that is
not the case. I'm very happy with it. Will be even happier once I get all of the
little glitches fixed so I can just fly it.
I simply wanted to make sure William
understands what he's getting into. What appears to be a fairly straight forward
mod is a lot more complicated than it appears and there are potential pitfalls
that are not necessarily obvious.
My bad on the misread regarding fuel
efficiency - he was talking about homebuilt aircraft versus factory
built planes, not rotaries versus certified engines. I think he's still way
off base here which was why I replied to his post.
Al, I dont know anyone who actually
KNOWS what BSFC they acheive with their Lyc/Cont. I know that low .40s is a
published number that is stuck in my head. I know what kind of fuel
consumption I got with my Lyc powered RV-6A at cruise and I know there are
certainly enough flying Lyc powered RVs to pretty firmly establish a cruise
performance baseline. Since there are more flying rotary powered RVs than other
types, seems like we should be able to get at least an idea of how they
compare. Lets challenge the rotary RV fliers here to post real cruise
performance (altitude, TAS, fuel consumption) and answer the question. Or give
me a year and 100 hours and I'll let you know how my RV-4 stacks up against the
-6A for a data point.
As for your performance against conventional
powered Velocities, thats great news. I think thats one of the significant short
comings of our little group here. Common perception is that rotaries are gas
hogs and we dont do anything to accurately document and advertise our
performance.
Mark, I agree that burning Mogas definitely
makes a big difference economy-wise. But that's a red herring. You could legally
burn Mogas in a Lyc/Cont also - just that most guys who are too conservative to
choose an auto conversion are also too conservative to burn Mogas. Burning Mogas
isnt the exclusive territory of the rotary. I personally know a guy with a
200HP Lyc in an RV-8 who has burned Mogas exclusively for years. Really what it
comes down to is convenience and comfort. Lets be fair, compare apples
to apples, and while we're at it throw in the additional cost and hassle of
having to pour in 2 stroke oil for your rotary (assuming you do that as most
seem to do).
I do totally agree with you on the price of
parts. And that was one of my huge motivations for going this route. But really
the biggest motivation was to do something a little different. When my RV-4
finally makes it's appearance at a fly-in (hopefully this year) it's not going
to be lost in the sea of belly button RVs that show up.
Mike Wills
RV-4 N144MW
----- Original Message -----
Sent: Monday, March 02, 2009 9:51
PM
Subject: [FlyRotary] Re: Questions on
buying a rotary plane
I dont know where you got
the idea that rotaries are more fuel efficient. Lycosaurs/Continentals
typically have BSFCs in the low .40s. The commonly accepted number for a
rotary is about .50. Some here seem to do better, others worse.
Mike;
I’m not
disagreeing with the points in your message; but I am wondering if you know
anybody actually flying a Lyc/Cont and achieving BSFC in the low 40’s.
I see numbers like .43 or .45 bandied about, but I guess no one leans enough
when flying to get that for fear of burning out a valve – or worse.
I’ve yet to hear from anyone flying a Velocity like mine with a
Lyc who can surpass the speed/fuel burn that I get with the 20B. I don’t
know why – it surprised me; but there it is.
I think in the
real world operation the BSFCs are comparable. I may have a bit lower
drag because of smaller cowl; or other factors.
Al
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