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Thread: OPERATION PHOENIX JR. Phase 1- Hirth motor identification

  1. #1

    OPERATION PHOENIX JR. Phase 1- Hirth motor identification

    Hello all! This is my first time posting so I will give a little introduction and background. My name is Ben and I am a professional pilot, paraglider, and A&P. But I only work on my own aircraft. Perpetual student and a sponge for knowledge. Certified MIG and TIG welder with a pretty extensive history in metal fabrication.

    By some strange coincidence I have acquired all of the makings of a (likely) very bad, but very fun idea. Through a series of horse trades I have acquired a Hirth 650cc engine and direct drive cast aluminium propellor. 1974 vintage from what I can tell. I was told by the previous owner that it came from the CAF museum in Heber Utah. After a bit of research I believe it was the very first of the ultralight engines that Hirth made. The numbers donít cross reference with the snowmobile world. And 1 plug per cylinder, and a direct drive prop make me believe it was an early model before they upped their game to become an ultralight and UAV supplier. A call to Their North American distributor informed me that they have no idea what engine I have.

    I also acquired a airworthy hang glider wing and a small 2 man flycraft raft. So after a few too many long nights looking around the hangar, I am pretty convinced I have everything I need to make ďOPERATION PHOENIXĒ a go.

    Since i I was a kid, the movie flight of the Phoenix intrigued and motivated me to become a pilot. I think it would be fun to use up all the spare parts I have combined with my skills to make a small flying craft. Iím not fanatical about only using what I have but as an homage to the movie I would like to keep it in the spirit of using up the things available as much as possible. But Iím lacking a good bit of knowledge in the aeronautical engineering department and will have to educate myself more on thrust lines for pusher props, weight shift flying, and wing loading among other things.

    Iím in no rush. And if this project is simply a hangar queen/conversation piece after its maiden voyage over water, then Iím ok with that. But I would love some insight from anyone with experience on the old Hirth motors and anyone with experience flying weight shift powered aircraft. I will need to fabricate a motor mount for the raft, along the entire assembly below the wing and set up motor controls.

    My shop is right next to a large shallow lake so I have easy access to test and tune.

    My question is this- who is the resident Hirth motor expert that may be able to educate me more on the engine as I begin the initial assessment?
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  2. #2

    Join Date
    Jan 2012
    I am not the resident Hirth Expert but may have something to contribute. I have worked with Recreational Power and Hirth Factory Reps and have an engine background.

    My big contribution would be in the overall design and operation of the aircraft. I am CFI WSC land and sea and have some experience with manufacturers.

    Call or text 425 495 7946 for info.

    More info needed on "small 2 man flycraft raft".

    Sound like a very iffy project. A true "PHOENIX OPERATION".
    Last edited by jedi; 03-19-2018 at 05:33 PM.

  3. #3

    Join Date
    Oct 2011
    Doesn't look like a pusher prop. Usually, a custom design needs a custom prop. Perhaps a bit larger diameter wood prop with glassed tips.

  4. #4

    Join Date
    Jul 2011
    Clarklake, MI
    If that is a cast prop, be sure to put a containment shroud around it.

  5. #5
    Dana's Avatar
    Join Date
    Jul 2011
    I don't think that engine was made for ultralight use, note the fins on the cylinder head... they go crosswise, not aligned with the airflow from the propeller. Though Rotax uses some crossflow heads, but with a fan. As for the prop, it looks too short for a plane, more likely it's a "test club" or a fan for a hovercraft or airboat. Are you sure it's a Hirth? It looks kind of Kawasaki, but those are mostly 440s.

    Some people have adapted hang gliders for powered flight, but they generally reinforce the keel tube. You also need to be sure it's of relatively recent vintage, some of the older designs were decidedly unsafe by modern standards.

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