experiamental fighter jet style aircraft

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by T-51ls1, Dec 7, 2012.

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  1. Dec 30, 2012 #201

    topspeed100

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    You are quite right..only the middle one ( twin fan outboard engined ) has been developed further...and indeed there is a change made to lift the engines higher to cleaner air further from the vertical ( albeit not sure how far it ought to be from it ). My last design was a tractor model in classical style ( very conservative ).
    I am impressed by your expertize and keen observation...reading is always good thanks for the advice.

    14756d1322498701-my-130-pounder-twin-engine-aerobatic-speedster-aaa1_fnxiihigh_e35.jpg
     
    Last edited: Dec 30, 2012
  2. Dec 31, 2012 #202

    topspeed100

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  3. Jan 1, 2013 #203

    PaulS

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    Topspeed,
    Pulse jets are not capable of supersonic speeds.
    Their design limits their speed to 3-400 mph regardless of the amount of thrust developed.
     
  4. Jan 1, 2013 #204

    topspeed100

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    I see...I tought a ramjet is sorta like a pulse jet ?!

    How fast could two of the fastest ( most thrust ) model jet engine take you ?

    Jet Powered Bicycle - YouTube
     
    Last edited: Jan 1, 2013
  5. Jan 1, 2013 #205

    PaulS

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    I could insert any answer here but any answer I gave would only be correct in a very limited way.
    Your speed will depend on drag more than anything else but acceleration will depend on thrust.
    Ultimately drag, pounds of thrust, weight and velocity of exhaust will be the determining factors for speed.
     
  6. Jan 2, 2013 #206

    bmcj

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    No, a ramjet (like the turbojet) has a continuous combustion process.
     
  7. Jan 9, 2013 #207

    topspeed100

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    I think I got it now..here fitted with these might take you there ( 400 mph + ); PBS Velká Bíte

    First thought about the twin AMTs..but these have 450 lbs thrust now.
     

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  8. Jan 10, 2013 #208

    topspeed100

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    Slight fine tuning...still twin tail wheels..are they ok ?

    V-TRIKE-%u00252BAERO2_45.JPG

    Tail wheel dia is 120 mm.
     
  9. Jan 10, 2013 #209

    nerobro

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    120mm is very tiny. And probably only acceptable on perfectly manicured runways. A 120mm wheel might not clear a speedbump. While that design does address some of the tipover problems, you're still going to run into all sorts of other issues. Such as the torque that would come from a small crack in the road.

    This is very much one of your less crack-pipe inspired designs. I think that one might actually work.
     
  10. Jan 10, 2013 #210

    topspeed100

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    Thanks nerobro...I have to take this as a compliment. I also have a haunch it might work...as a canard it has just right geometry ( or the shape is following the guide lines of a good canard design literally )...I only wish Orion was still here to comment.

    I looked for luft46...and only Gotha and Messerschmitt seemed to have ever considered a canard...dr. Focke's friend mr. Wulf died in an canard accident. Then again Wright Bros flyer was a canard...and Stefanutti has made his SS2 already in 1937.
     
  11. Jan 14, 2013 #211

    nerobro

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    The wright planes were not very stable in pitch. They had most of their weight carried by the main wing, so the stabilizing forces were small. John Rocz says a "good" canard has roughly half the wing load on the canard, and that leads to a stable, un-stallable setup. It looks like you've got a design that's ment to carry a lot of the weight on the canard. That's good.

    Good luck. I still want to see you make something.
     
  12. Jan 14, 2013 #212

    Dana

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    The Wright planes weren't just "not very stable in pitch"; they were downright unstable, to the point of being dangerous. Then as now, though they didn't understand it back then, an aft C.G. is bad.

    I can't see needing to put half the load on the canard; then you're into tandem wing territory... which is fine if that's what you're after. For a "conventional" canard (is there such a thing?) what matters for pitch stability is that (like any aircraft) the dCm/dα for the whole aircraft is negative.

    -Dana

    The United States was formed to protect liberty. It now has a major party that is afraid that someone, somewhere, is doing something without permission.
     
  13. Jan 14, 2013 #213

    bmcj

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    This statement leaves itself open to interpretation...

    Does it mean:
    1) The canard carries 50% of the aircraft weight, OR
    2) The canard carries half the amount of weight that the wing carries, OR
    3) The canard is loaded at half the load per square foot compared to the wing?
     
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  14. Jan 14, 2013 #214

    nerobro

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    He says most successful canard designs carry half of the load on the canard. 50% of the aircraft's weight. The canard is intentionally heavily loaded, so it stalls long before the main wing.

    No kidding. It's also not just "aft CG", aft CG can be ok, ish.. if that's what you're aiming for. But they were also very close coupled adding to the problem.
     
  15. Jan 14, 2013 #215

    bmcj

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    I don't know if I subscribe to that theory. Borne weight affects the stall speed of a surface, but not the stall angle of attack. Canard design should be such that the incidence angles of the canard and wing be set relative to each other so that the canard reaches its stall AOA before the main wing. A heavier loaded canard will provide a smoother ride (less disturbance from gusts), but it will have no bearing on the canard stalling before the wing. It may, however, increase your minimum speed.
     
  16. Jan 14, 2013 #216

    nerobro

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    *shrugs* I'm a proponent of conventional designs versus canard. I also prefer stickshift, and motorcycles. John Rocz knows what he's doing. :)
     
  17. Jan 14, 2013 #217

    Apollo

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    The Long-EZ, Cozy and similar derivatives carry 21% to 24% of their gross weight on the canard. Their canards are approximately 15% of the main wing area, so the canards have a wing loading that is about 50% higher than the main wing. Depending on the CG location and relative sizes of the main wing and canard, many configurations are possible. As Dana said, if the canard is carrying 50% of the gross weight, you will be in tandem wing territory. The front wing (canard) of Quickie style aircraft carries slightly over 50% of the gross weight.
     
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  18. Jan 14, 2013 #218

    BBerson

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    Indeed.
    The Wrights early airplanes ( all canards) had the neutral point ahead of the C.G. Very bad indeed.
    The 1911 Wright Model B eliminated the forward surface and placed the tail in the back. This put the neutral point aft of the C.G. and all was well.
    This and more is explained in the book: The Wright Brothers as Engineers, An Appraisal by Quentin Wald.
     
  19. Jan 15, 2013 #219

    Starman

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    I think that when the canard carries half the weight that it's 'good' because you have less total wing area. It's also good because the CG shifting front to back is further from both wings and so therefore the plane has a greater CG range. If the CG is closer to the rear wing a small shift in CG puts a much greater change in the load on the canard.
     
  20. Jan 15, 2013 #220

    Dana

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    Only if the canard is large enough to carry that weight at or close to its max L/D in cruise. Otherwise you lose the theoretical advantage of canards, i.e. reduced trim drag.

    -Dana

    The first rule of intelligent tinkering is to save all the parts.
     

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