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.
-----
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