Dave,
I remember looking at this when you posted about it previously. Not sure a race is quite what I had in mind, but better than nothing. I think documented performance numbers at typical cruise configurations would be more useful. Cant argue with your bang for the buck numbers - one of the primary reasons I went rotary as well. I still dont think it's fair to claim an economy victory based on the price/use of Mogas because you CHOOSE to burn it and your Lyc powered RV buddies CHOOSE not to.
I dont know about you guys but the typical questions/comments are:
1) It will weigh more than a Lyc powered RV (in my case true).
2) It will be slower and climb slower than a Lyc powered RV (the jury is out in my case).
3) Those rotaries burn more gas than an aircraft engine.
4) You're crazy to fly behind a car engine.
My responses to 1 and 2 are maybe, to 3 is it varies depending on how its operated. My response to 4 depends on my mood and how the comment is made.
Anyway, it would sure be nice if a number of guys flying did as good a job of documenting and advertising their performance as they do documenting their build process. There are enough flying now to have some statistical relevance. I'd like to be able to point to a website when someone quizzes me on performance.
Mike

    ----- Original Message -----
    *From:* David Leonard <mailto:wdleonard@gmail.com>
    *To:* Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
    *Sent:* Tuesday, March 03, 2009 9:12 PM
    *Subject:* [FlyRotary] Re: Questions on buying a rotary plane

    Hey Mike,

    I have done such a real world direct comparison.

    We did a race where where were filled tanks before and after to
    compare fuel burn as well as speed. Scroll down here to see the
    results:
    http://www.rvproject.com/race.html

    Bear in mind:
    1) the fastest 2 planes were tandem, and had an advantage.
    2) the slowest 2 planes were trying to win the efficiency contest
    rather than the speed contest.

    Of the 5 remaining planes, mine was right in the middle in terms
    of speed and fuel burn. All other planes were 180 or 200 hp lycs
    with c/s props. I had the only f.p. prop and my installation cost
    at least $15k less than any of the others. Because I was the only
    one able to use MOGAS, my fuel cost were the cheapest (of the
    non-economy flight profile group).

    Bottom line: the rotary proved to be very comparable in terms of
    power and fuel burn. (as others have noted).
    ---------
    I now have 370 hours and almost never remove the cowl anymore. I
    fly it hard and put it away wet. I have not had an engine or
    engine systems issue in nearly 200 hrs.

    Compare that the the first 100 hrs where I was putting in almost
    10 hrs of maintenance for each our of flying and she has really
    come a long way.

    Way worth it!

    --     David Leonard

    Turbo Rotary RV-6 N4VY
    http://N4VY.RotaryRoster.net
    http://RotaryRoster.net


    On Tue, Mar 3, 2009 at 7:55 PM, Mike Wills <rv-4mike@cox.net
    <mailto:rv-4mike@cox.net>> wrote:

        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 -----
            *From:* Al Gietzen <mailto:ALVentures@cox.net>
            *To:* Rotary motors in aircraft
            <mailto:flyrotary@lancaironline.net>
            *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