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Thread: Truss chormoly fuselage pusher

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    Registered User Jay Kempf's Avatar
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    Re: Truss chormoly fuselage pusher

    Your only real option is to buy say an unfinished Lancair kit and go much bigger on the engine and turbo and start doing any drag reduction you can do. You would have to completely evaluate the airframe to match VNE to your cruise goal plus a safety factor. If you got your hands on a kit that didn't have the wings closed you could do what was necessary to get it to be safe at the higher cruise speed. There are people modifying and racing these at Reno and getting the speeds you want so there are people to talk to to find out what, if any, mods were done to handle more power and more aero forces especially drag and increased low pressure zones on the wings. It would be a lot of math to do justifications but it can be done. I am not sure what airfoil the Lancair uses but reflex could reduce drag significantly at high speed cruise.

    Anyway just a thought. You don't have a lot of experimental options other than clean slate really. Clean slate would be A small low drag wing and a small sleek fuselage with a big turbo normalized engine and flower or some sort of advanced flap design like the Melmoth 2. Peter Garrison has done a lot of the homework for the design you are talking about but stopped short of your cruise goal.
    Jay K.

    VT USA

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    Re: Truss chormoly fuselage pusher

    Quote Originally Posted by Jay Kempf View Post
    Your only real option is to buy say an unfinished Lancair kit and go much bigger on the engine ...
    A Lancair IV (I presume this is what you mean) isn't going to operate out of a 1,200' runway either.

    The implications of the OP's requirement set are very clear: Big laminar-flow wing, with large flaps to slow the plane down for the extremely short runway. BIG engine to get the whole thing to climb out steeply, and up to the speed required. Fully-pressurized cockpit and probably a turbo-prop engine because of the altitudes needed for cruise.

    There's nothing I know of that currently meets all the requirements possibly excepting a Twin Otter, and certainly no homebuilts. There's none that ever did. There are/were several that came within spitting distance of the cruise requirement, but none of those would operate safely from a 1200' home-base strip.

    This is not a trivial design project. Can it be done? Sure. If you have the time, money, and skills necessary, or even more money to farm out the design process to someone competent at this level, and then the considerable sums necessary to build and power this sort of airplane. I'm all for pushing the envelope, but this seems to me to be a case of asking for too much. Cutting down the cruise requirement seems the wisest course. 240kts is asking a lot when you also want near-STOL capabilities.
    "If you have built castles in the air, your work need not be lost; that is where they should be. Now put the foundations under them." - Henry David Thoreau

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    Re: Truss chormoly fuselage pusher

    Maybe I need to convince my ranch neighbors to build a community strip! If I took the 240kt requirement off the table, and just said excess of 200knots, does that open up more possible options. The Glasairs maybe?

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    Re: Truss chormoly fuselage pusher

    Quote Originally Posted by Vector View Post
    Maybe I need to convince my ranch neighbors to build a community strip! If I took the 240kt requirement off the table, and just said excess of 200knots, does that open up more possible options. The Glasairs maybe?
    The Glasairs are no longer being produced, although there still are unfinished projects around.


    BJC

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    Registered User Jay Kempf's Avatar
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    Re: Truss chormoly fuselage pusher

    Quote Originally Posted by Topaz View Post
    A Lancair IV (I presume this is what you mean) isn't going to operate out of a 1,200' runway either.

    The implications of the OP's requirement set are very clear: Big laminar-flow wing, with large flaps to slow the plane down for the extremely short runway. BIG engine to get the whole thing to climb out steeply, and up to the speed required. Fully-pressurized cockpit and probably a turbo-prop engine because of the altitudes needed for cruise.

    There's nothing I know of that currently meets all the requirements possibly excepting a Twin Otter, and certainly no homebuilts. There's none that ever did. There are/were several that came within spitting distance of the cruise requirement, but none of those would operate safely from a 1200' home-base strip.

    This is not a trivial design project. Can it be done? Sure. If you have the time, money, and skills necessary, or even more money to farm out the design process to someone competent at this level, and then the considerable sums necessary to build and power this sort of airplane. I'm all for pushing the envelope, but this seems to me to be a case of asking for too much. Cutting down the cruise requirement seems the wisest course. 240kts is asking a lot when you also want near-STOL capabilities.
    Nope, regular old Lancair 320 from ages ago. Keep it light and small and put A LOT of HP on it turbo to keep all the HP you can at altitude. That is the only chance. Might have to slot the flaps but that is less of a chore than you would think. Like I said look to Melmoth 2 for guidance. Maybe the Lancair wing isn't adequate to the task but maybe it is. Probably a custom turboed version of an io-360. You would need quite a bit of HP to drive a prop with enough pitch but it could be done. 275mph isn't 450mph. It's possible. There are people racing these planes at Reno and they are getting 300mph sort of speeds out of them in relatively thick air. There is precedent.

    Did I miss the pressurized part? Cabin heat and oxygen would be sufficient below airliner main roads in the sky.
    Jay K.

    VT USA

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    Re: Truss chormoly fuselage pusher

    The problem with bringing Reno into the picture is they fly behind hand grenades for engines they only have to last a week. Sustainable 2000 hr engine they are not. They are lucky to get two years of racing out of them.

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    Re: Truss chormoly fuselage pusher

    Quote Originally Posted by Vector View Post
    Maybe I need to convince my ranch neighbors to build a community strip! If I took the 240kt requirement off the table, and just said excess of 200knots, does that open up more possible options. The Glasairs maybe?
    If you bring the speed down to 200+ KTAS, then a Rocket fills the bill right now, today.

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    Re: Truss chormoly fuselage pusher

    Quote Originally Posted by Toobuilder View Post
    If you bring the speed down to 200+ KTAS, then a Rocket fills the bill right now, today.
    ^ This. Plus there's build support on this design, and it's well-known and established. Hard to see how the OP could go wrong here, unless that 1200' runway has obstructions at either end.
    "If you have built castles in the air, your work need not be lost; that is where they should be. Now put the foundations under them." - Henry David Thoreau

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    Re: Truss chormoly fuselage pusher

    Quote Originally Posted by Toobuilder View Post
    If you bring the speed down to 200+ KTAS, then a Rocket fills the bill right now, today.
    How much endurance do you have on your Rocket. I suppose if endurance were an issue, I could put a tank in the back and plumb it to the exiting tank set up. Could also serve as a good location for my golf clubs!

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    Re: Truss chormoly fuselage pusher

    Many Rockets (including mine) have an extended bagage area which will physically swallow a set of clubs, but CG can be an issue. Also, many Rockets have a "big tank" option which brings the total capacity to 58 (from 42) gallons. This gives the airplane 1000 mile legs with reserves. An "average" Rocket should be able to do better than 200KTAS @11 GPH, and some will do better than 210 @10 up in the low teens. My airplane does not have the big tanks yet, but it is on my short list of future modifications.

    The above applies to the Harmon versions of the airplane. There is also the Team F-1 Rockets which are a slightly different animal. The F-1 sport wing features 52 gallon tanks out of the box and are otherwise a direct copy of the Harmon. The Evo, on the other hand features a longer span, tapered planform wing which was adapted from another aircraft. As its from another, heavier airplane, it is apparently about 50 pounds heavier than required, but is said to be indestructable. The planform is reportedly much better at altitude than the original Hershey bar wing. F-1 Evos are rare and expensive, however.
    Last edited by Toobuilder; February 18th, 2017 at 11:06 AM.

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    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

    What airplane did the F1 Evo wing come from?

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    Re: Truss chormoly fuselage pusher

    Anyone mention maybe a clipped wing racing saiplane? Or even a Blanik? Maybe one of those grounded L-13's, if it's possible to reinforce the stab and somehow stiffen it up to avoid flutter. Just the thing for a teensy jet engine or two. Or maybe put a regular sort of engine where the front seat is now? Ought to have considerably less drag than most powered aircraft.

    I don't know how feasible it is, though, to stiffen up the controls, control surfaces, etc. Nor whether clipping the wings is enough to deal with the structural issues that ground them.

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    Re: Truss chormoly fuselage pusher

    I am leery of an aircraft with acclaimed record that has been on the market for considerable amount of time. Granted the asking price maybe a little high, I have to wonder what else is wrong that I may not know.

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    Registered User Jay Kempf's Avatar
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    Re: Truss chormoly fuselage pusher

    Quote Originally Posted by TFF View Post
    The problem with bringing Reno into the picture is they fly behind hand grenades for engines they only have to last a week. Sustainable 2000 hr engine they are not. They are lucky to get two years of racing out of them.
    Bringing Reno in only provides a benchmark that that airframe can do the task. Yes you would have to find a non-racing engine solution. But hanging more HP can be done reliably.
    Jay K.

    VT USA

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