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Thread: Truss chormoly fuselage pusher

  1. #106
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    Re: Truss chormoly fuselage pusher

    Quote Originally Posted by Rick Frost View Post
    As I understand it: 1) The construction of the surfaces would be more exacting, hence the molded composite construction.
    And stiff. Oilcanning as you'll see on any metal plane will likely obliviate any extended laminar flow.
    2. Getting a prop far aft might require either a long shaft with its potential for TV problems or perhaps an electric motor with hybrid propulsion.
    Or a boomed tail. Given the problems with TV and the huge market problems (you're locked in to one engine/drive-shaft/prop combination), a boomed tail is probably a better choice, unless one goes to an electric motor. Both the tail below the prop (Carmichael, J5/J6, Strojnik) or two tail booms (like the C337) works great.
    3. Providing for reasonable ingress/egress while preserving laminar flow on the front part of the fuselage could be tough.
    Could. Sailplanes solve this by having the front edge of the canopy very far forward (good pressure gradient) and keeping a negative pressure in the cockpit. Flow over the canopy will stay laminar. Flow on the sides will form turbulent wedges, which is why the edges of the canopies on the sides are flat.
    The Cobalt Co50 solves it another way... heavy and complex.
    Forward sliding shell is more practical, but still messy.

    I solved it sailplane-style. Not perfect, but a good balance of practical and laminar.
    What else about the design do you see as a 'lot more involved'?
    Every single decision. Or most of them.

    Your traditional tractor plane is mostly linear. Increase engine weight and you move the wing FWD a bit. Or you extend the tail a bit.

    On my design (boomed pusher), increasing engine weight means changing the entire fuselage shape and wing position. Basically a new design.

    CG considerations. Tractor front seats are roughly in the CG. Pusher front seats are highly disturbing the CG. Try a 4-seater for fun ;-)

    And there is simply way less good prior art with pushers. Especially conceptual, systems and layout design is really an order of magnitude harder than in a tractor.
    Kennis vermenigvuldig je door het te delen.
    (You multiply knowledge by dividing it)

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  3. #107
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    Re: Truss chormoly fuselage pusher

    Relative to Commutercraft:

    Quote Originally Posted by TFF View Post
    The company was hashed out on this forum. No flying aircraft yet.
    Not correct. The aircraft flew in late 2015 or 2016. The initial flights were from my home airport.

    As to whether it meets the needs of the OP or will ever be released commercially, who knows.
    Last edited by Kyle Boatright; February 22nd, 2017 at 05:10 PM.

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    Re: Truss chormoly fuselage pusher

    Have they got it out of phase tests?

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    Re: Truss chormoly fuselage pusher

    Quote Originally Posted by TFF View Post
    Have they got it out of phase tests?
    Dunno, but if I was a betting man, I'd bet on "Yes".

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    Re: Truss chormoly fuselage pusher

    The AJ-2 was a 250+ mph cruise. If you have 5000 hrs to build it.
    http://cessnateur.blogspot.com/2011/...aj-2-n9aj.html

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    Re: Truss chormoly fuselage pusher

    Quote Originally Posted by BBerson View Post
    The AJ-2 was a 250+ mph cruise. If you have 5000 hrs to build it.
    http://cessnateur.blogspot.com/2011/...aj-2-n9aj.html
    I like that. I intend on sending a mail to registered owner. I hope something comes of it. I will report back to the group.

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    Re: Truss chormoly fuselage pusher

    Someone mentioned that Reno air racers' engines were flying bombs. However, those airplanes, or at least some, go a lot faster than 240 knots. I imagine backing off on the throttle would result in reasonably durable engines. Or smaller, conventional engines could be used. It's probably much too expensive, but isn't the Nemisis NXT supposed to cruise at 280 knots? That's probably at 50 percent power, because it's supposed to be capable of 350 knots. You could use a much smaller engine and cruise at 240.
    --------
    It sounds kind of crazy, but I wonder if some flutter problems could be addressed by fly-by-wire using hydraulic actuators or something to make everything really stiff?
    ----------
    I also wonder what kind of performance could be extracted from a carefully detailed, stretched Cassut with laminar wings?
    ---------
    autoreply:
    There was a series of high performance homebuilt sailplane designs which I think were supposed to preserve laminar flow on metal skinned wings. As I recall, the skins were bonded to many foam ribs close together. Called HP or HB or something. But you probably know about them, I suppose.

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    Re: Truss chormoly fuselage pusher

    A pusher would probably be the ideal test case for an "electric redrive", with battery capacity where it is at the moment.
    Basically a motor-generator pair, with possibly battery-assist for takeoff.
    It would be a fair bit heavier than a pure mechanical system, but gives a lot of packaging options. You also have less issues with TV.

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  12. #114
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    Re: Truss chormoly fuselage pusher

    Quote Originally Posted by lr27 View Post
    There was a series of high performance homebuilt sailplane designs which I think were supposed to preserve laminar flow on metal skinned wings. As I recall, the skins were bonded to many foam ribs close together. Called HP or HB or something. But you probably know about them, I suppose.
    That would be Dick Schreder's HP- series. Some info here http://www.soaridaho.com/Schreder/

    BoKu right here at HBA knows them well.


    BJC

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    Re: Truss chormoly fuselage pusher

    Quote Originally Posted by BJC View Post

    BoKu right here at HBA knows them well.
    "Can I Build an HP-Series Glider From Scratch?
    Bob Kuykendall, 16 August, 1999"


    ... been at it a long time too!
    Quote Originally Posted by BoKu View Post
    The vast majority of engineering failures are the results of failure of imagination rather than failure of calculation.

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    Re: Truss chormoly fuselage pusher

    Quote Originally Posted by BBerson View Post
    The AJ-2 was a 250+ mph cruise. If you have 5000 hrs to build it.
    http://cessnateur.blogspot.com/2011/...aj-2-n9aj.html
    Thank you, BB, I've been looking about info on AJ-2 for a long time...

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    Re: Truss chormoly fuselage pusher

    The AJ-2 was made for racing. Going fast is expensive, and very risky.
    Traveling is different from racing. I think I would rather fly in a safe comfortable cabin for 6 hours rather than be cramped in a noisy racer for 4 hours.
    If the cabin was comfortable, it would be almost like sitting at home. The brain really can't detect speed without some input from looking out the window or staring at a GPS. So set the autopilot and stay distracted and dont look at the airspeed (if that's possible)
    It took 24 hours for my trip by airliner to Oshkosh with all the connections and layover. Average of 87 mph.
    So 150mph would be a huge improvement.

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