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Thread: Best gyrocopter engine

  1. #1
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    Question Best gyrocopter engine

    Can somebody please tell me what the cheapest gyrocopter engine would be for an ultra light gyrocopter, and where to get it? I would like it for the top speed to be around 80 to 90 mph.

  2. #2
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    Re: Best gyrocopter engine

    Then don't call it an ultralight... unless of course you're not American. In any case, give us some more information: what gyro, weight, etc.

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    Re: Best gyrocopter engine

    I'm building a Benson KB-2. Everything is all set except for the engine. like which would be best, Rotax, Subaru, Volkswagen and keep it under 245.

  4. #4
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    Re: Best gyrocopter engine

    Subie will never keep it under the weight, unless I'm way out of whack. The VW won't if you're talking about the whole thing, the 1/2 VW won't have the power for you I'm sure (rotorcraft are not exactly the most efficient...). Rotax or one of Mr. Stull's suggestions in the other copy of this are your options. I think you'll have to keep it to 2-strokes to make the weight limit with that power, which of course still doesn't make you legal with that speed.

    The KB-2 needs, claimed, 90 hp to do 65-70 mph... you'll need more.

  5. #5
    Registered User wally's Avatar
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    Re: Best gyrocopter engine

    I am not familier with the KB-2. If it is a 2 place then you are going to need the 90 hp like Jmillar said.

    I helped a guy several years ago who was building a single place gyro. I made an adapter to install a warp drive prop (I think it was) to a subaru engine. It was direct drive. I don't remember which Subaru engine it was. It worked pretty good. The builder was Maxie Wildes - my neighbor years ago.

    I have also seen a VW engine pushing a single place gyro. I doubt it could push a 2 place tho.

    You can still find the McCullough target drone engines sometimes. Four cylnder two cycle. They come in 72hp or 90hp versions. Very light weight as well as very LOUD.

    Best wishes,
    Wally

  6. #6
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    Re: Best gyrocopter engine

    Rotax 2stroke [ size will depend on rotor loading] or, if money isnt a hinderance, a 912 4stroke.

  7. #7
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    Re: Best gyrocopter engine

    Could a DIRECT DRIVE single-rotor Mazda Rotary power a pusher(or tractor)gyro?

    Duncan Aviation(Comanche, Okla.) many years ago listed in their brochure a direct-drive single rotor Mazda RX-7 bridge-port aircraft engine. They machined the crank to accept a new main-bearing located on the front of the engine. The main-bearing was housed in an easily-machined circular housing. Propeller-boss was attached to the front of the re-machined crank.

    Engine was rev-limited to 60hp at 4000 rpm. Engine could be fitted with a fixed-pitch prop, or cockpit-controlled variable-pitch prop( Warpdriveprops makes a carbon-fibre one, and their website has a good tip-speed calculator). Duncan photo of this single-rotor engine shows it fitted with a 2-blade in-flight adjustable prop.

    WEIGHTS:

    Basic engine with oil-pump, fuel-pump, water-pump, Posa 32 mm Super-carby, ignition, engine mounts and prop-flange was 110 lbs.

    To this must be added: alternator (4lbs), starter(5.5lbs), 9" x 14"engine coolant radiator(5 lbs), and 7" x 8" oil cooler(1.8lbs)

    This gives a DRY INSTALLED WEIGHT of 126.3 lbs.

    Engine-coolant( 10.4 lbs) and oil (6lbs) must be added...which brings wet-weight up to about 143 lbs..... not bad for 60hp continuous with 3.5 gph fuel-burn(regular or unleaded) and a 3000 hr TBO.

    How much static-thrust could be obtained from such an engine reving at 4000rpm?

    A McCulloch 72 HP ( 68 actual) two-stroke in a gyrocopter swinging a 48" or 50" diameter prop delivers about 260 lbs of thrust at around 4000 rpm.

    Igor Bensen said that for "respectable performance" a gyro requires 1 lb of static-thrust for every 2 lbs of gross weight, so a 520 lb gross gyro looks feasible. A small 4-stroke chain-saw engine(with a hand-pull recoil-starter) could replace the heavy starter-motor, and could also pre-spin the rotors. A smaller and lighter battery and alternator could thus be used. Maybe EFI and a turbo would give more power (thrust), for little nett additional weight.

    Duncan were also offering an "Aerodyne Model 2.66 VATN turbo(Variable Area Turbine Nozzle)" , which weighed 15 lbs and which would increase power and quieten exhaust noise.

    Duncan also offered a single-rotor fited with a Uniroyal HTD cogbelt(belt rated at 300hp). Reduction ratio was 3:1 and output was 120hp at 9,000rpm for 5gph, and a DRY INSTALLED WEIGHT of 165 lbs. This power output agrees with the output of a Racing Beat single-rotor bridge-ported engine which NASA tested in 1982 which produced 128hp at 9000 rpm.

    Does anyone else think a single-rotor direct-drive looks attractive as a gyro-engine?

    Overall length of the Duncan engine was 1'9" (measured to the front-face of the crankshaft's propeller-flange)

  8. #8
    Registered User Tim Chick's Avatar
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    Re: Best gyrocopter engine

    A KB-2 frame was set up for a converted direct drive McCulloch drone engine. The maximum size prop for a KB-2 as built to specs is 52". If you use a Rotax you can use a 52" prop with 2:1 gears in the redrive. I had a Rotax DCDI 503 set up like this on my KB-2. With a short prop like that the 503 is the smallest engine I would recommend. With this setup 55 mph was a comfortable cruising speed. Here are a couple videos of me flying with the 503 on my KB-2.






  9. #9
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    Re: Best gyrocopter engine

    i have make a gyroplane with folex wagon motor please help me?
    you are have manual for make this device?

  10. #10
    Moderator Dana's Avatar
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    Re: Best gyrocopter engine

    Quote Originally Posted by saeed_myheart View Post
    i have make a gyroplane with folex wagon motor please help me?
    you are have manual for make this device?
    You've already asked this... perhaps if you explained what a "folex wagon motor" is you might get more help. Do you mean Volkswagen?

    -Dana

    I've noticed that the press tends to be quite accurate, except when they're writing on a subject I know something about.
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