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Thread: VW-powered, tandem-seat bush plane?

  1. #1
    Registered User cluttonfred's Avatar
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    VW-powered, tandem-seat bush plane?

    There are a number of side-by-side, high-wing taildraggers from kits and plans suitable for backcountry use that can be powered by a large VW like the 2100cc Aerovee, but not many with tandem seating. The Fisher Flying Products Horizon 1 and 2 come to mind, but they seem awfully light for rough use. Does anyone know of any other kits or plans that might be suitable? High-wing, taildragger, tandem seats, VW power, which imples light weight for decent performance.... Cheers, Matthew
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    Registered User billyvray's Avatar
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    Re: VW-powered, tandem-seat bush plane?

    I would argue that anything much heavier duty would not fly well with an Aerovee. But, some potential others might be:
    Preceptor Pup
    Just Aircraft
    both are steel tube frame instead of wood

    ~Bill

  3. #3
    Registered User cluttonfred's Avatar
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    Re: VW-powered, tandem-seat bush plane?

    As far as I know, the Preceptor Pup is not longer available and Just Aircraft doesn't make a tandem-seat model. Am I missing something?
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    Registered User PTAirco's Avatar
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    Re: VW-powered, tandem-seat bush plane?

    Bushplane implies rugged construction and STOL and that does require horsepower. I think its entirely feasible to make something like a lightweight Champ/Cub powered with a VW derivative, but you'll have to watch the weight very carefully and keep it very small. I doubt that it would end up robust enough or have a decent enough payload to be a practical bushplane though.

    Even the biggest VWs are marginal for two seat aircraft.
    "Aeronautical engineering is highly educated guessing, worked out to five decimal places. Fred Lindsley, Airspeed."

  5. #5
    Registered User billyvray's Avatar
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    Re: VW-powered, tandem-seat bush plane?

    You're right, I was wrong about Just Aircraft. Preceptor plans and projects are out there. There is a Yahoo Group that I'm pretty sure has plans posted there.


    ~Bill

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    Re: VW-powered, tandem-seat bush plane?

    A direct drive VW doesn't work as well with a bushplane. Swinging a large prop for better low speed thrust requires a redrive on a VW. Something to consider in your purchase.

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    Registered User Pops's Avatar
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    Re: VW-powered, tandem-seat bush plane?

    Very true. The aircraft that I fly is what you are thinking about. Single seat Cub, 450 lbs EW, powered by a 1835 cc, 60 HP VW, Culver 60"x26" prop. 120 sq' wing area, 141 lbs firewall forward weight, 1200+ ROC, 80 mph cruise at 2.9-3.0 gph. Take-off 200-250'. No electrics, hand prop only. I have done a lot of off field work with it. Space for me at 6'x225 lbs and camping supply's. Building a flywheel drive 80 hp VW engine for it that will weigh about 3 lbs more,( 82mm stoker crank).


    Quote Originally Posted by PTAirco View Post
    Bushplane implies rugged construction and STOL and that does require horsepower. I think its entirely feasible to make something like a lightweight Champ/Cub powered with a VW derivative, but you'll have to watch the weight very carefully and keep it very small. I doubt that it would end up robust enough or have a decent enough payload to be a practical bushplane though.

    Even the biggest VWs are marginal for two seat aircraft.
    Pops

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    Re: VW-powered, tandem-seat bush plane?

    Wouldn't a big wing (both in span and area) relieve most of the problems with a re-drived VW? STOL isn't as much about absolute (climb) speeds as it is about climb angles right?
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    Registered User Pops's Avatar
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    Re: VW-powered, tandem-seat bush plane?

    Correct, big wing and light weight. The re-drive is heavy and a starter is required plus all of the associated weight of an electrical system. It all adds up to a huge weight increase.

    Quote Originally Posted by autoreply View Post
    Wouldn't a big wing (both in span and area) relieve most of the problems with a re-drived VW? STOL isn't as much about absolute (climb) speeds as it is about climb angles right?
    Pops

  10. #10
    Registered User cluttonfred's Avatar
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    Re: VW-powered, tandem-seat bush plane?

    Hmmm, in that case maybe I should go REALLY old school and built a Pietenpol Air Camper as light as I can make it. With the biggest VW from Great Plains, perhaps a flywheel drive, it ought to be comparable to an A65-powered Piet' at the very least. Not fast, of course, but with some get up and go.

    Quote Originally Posted by Pops View Post
    Correct, big wing and light weight. The re-drive is heavy and a starter is required plus all of the associated weight of an electrical system. It all adds up to a huge weight increase.
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  11. #11
    Registered User Dan Thomas's Avatar
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    Re: VW-powered, tandem-seat bush plane?

    The weight of a PSRU usually justifies its contribution to performance. The VW spins a small propeller at high RPM, which tends to have a cost similar to the loss of L/D in a short-winged airplane like mine. Too much lift or thrust is lost to drag at high angles of attack (think tip vortices) and the high AoA is present at that propeller in takeoff and climb and on the wing in slow flight.

    Just watch a DD VW sometime on takeoff. Burns up a lot of runway. Very poor acceleration. My old A-65 generates its power at 2300 RPM, more than a thousand revs below a VW's, and the acceleration is pretty respectable. I used to have a 76" propeller on it, which gave even better performance, but I shortened it to 72" to get more RPM for better HP, and it ended up costing me both acceleration and cruise speed. Should have left it alone. A VW's prop is what? 50" or so?

    The Helio Courier, a famous STOL airplane, was a development begun using a Piper Vagabond with an A-65 engine, called the Helioplane. Besides mods to the flaps and wings and other stuff, they built a PSRU for the engine so they could swing a huge propeller. They might have gotten more than 65 HP out of it by doing this, but the spectacularly short takeoff roll was due largely to the great acceleration created by that big, slow-turning propeller.


    Dan

  12. #12
    Registered User Pops's Avatar
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    Re: VW-powered, tandem-seat bush plane?

    I use single port heads and 1 1/4" dia. intakes for low RPM torque. Lots of power at 2500- 3050 rpm with a 1835 cc VW and a 60" prop.
    And you ask, why doesn't AeroVee, GP's, etc use single port heads. They are in business to sell engines, and you can't buy new single port heads.
    IF you built a Piet as light a possible, without making it smaller, the drag would still be to high for adequate performance with a VW engine. Its a drag hog

    I have 2 neighbors that have A-65 powered Piets. Flying cross county in formation with them, I have to run at 2475 rpm to stay back with them and have about 3 times the ROC at WOT. I have more ROC at 2475 rpm than they do at WOT. I normally cruise at 2650 rpm at 80 mph and can climb at 650-700 fpm at that rpm.
    JBAZ likes this.
    Pops

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    Registered User BBerson's Avatar
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    Re: VW-powered, tandem-seat bush plane?

    Quote Originally Posted by Dan Thomas View Post
    The VW spins a small propeller at high RPM, which tends to have a cost similar to the loss of L/D in a short-winged airplane like mine. A VW's prop is what? 50" or so?

    Dan
    My prop is 64".
    Limbach L2000
    Hoffmann prop

  14. #14
    Registered User Joe Fisher's Avatar
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    Re: VW-powered, tandem-seat bush plane?

    I was helping a friend cover a Petenpol it looks to me like a flying lumber yard way to much wood. It could built a lot lighter and could use a lot better airfoil. To my eye it is not a bad aerodynamic airplane for what it is with the parasol wing it could be a good short field airplane.

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