Rutan Catbird

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Rik-, Sep 21, 2019.

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  1. Sep 22, 2019 #21

    Jay Kempf

    Jay Kempf

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    "130 nose,swivel,spar angle rule"

    Anyone have any information on this part of the Catbird specs?
     
  2. Sep 22, 2019 #22

    Hephaestus

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    In this era you'd be better to just redraw in CAD - it's overall a pretty simple shape and create a new mold (male or female) to work from.
     
  3. Sep 22, 2019 #23

    Rik-

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    If only we could get the plane and a 3D scanner together for a week.
     
  4. Sep 22, 2019 #24

    Hephaestus

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    Photogrammetry would get you ballpark off existing photos Airfoils are known roncz, fuselage shape is pretty simple, you could ballpark it pretty quick and easy.

    At that point it's working out the numbers to get incidents etc worked out
     
  5. Sep 22, 2019 #25

    Jay Kempf

    Jay Kempf

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    Does scaled still have the molds?
     
  6. Sep 22, 2019 #26

    wsimpso1

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    Doubtful. They built it over 30 years ago...
     
  7. Sep 22, 2019 #27

    henryk

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  8. Sep 22, 2019 #28

    bmcj

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    Plus, Scaled is now owned by a corporation in which a craft like the Catbird likely does not fit into their long range plans, so releasing them to someone else does nothing for their business model and would only open them up to potential liability.
     
    Last edited: Sep 22, 2019
    Topaz likes this.
  9. Sep 22, 2019 #29

    Topaz

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    ^ This. If someone wants a Catbird, you're looking at a from-scratch redesign. Talk to John Roncz and see if he owns the airfoil data, still has any of the aerodynamic/geometric data for the airplane, and if he's willing to part with it. Then it's "just" do the design work.
     
  10. Sep 22, 2019 #30

    plncraze

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    It might not be that difficult. Check the UIUC airfoil database to see if the foils are there and then see if Airfoil Tools has the specs. The wings are partially hot wired and Sport Aviation has some pictures and the design story. The plane was meant to be pressurized and Rutan put the aft bulkhead far back to make it small. Sport Aviation had pictures of it a few times. It was optimized for the CAFE race. Also check out the horizontal stab. It's swept forward to minimize drag.
     
  11. Sep 22, 2019 #31

    Hephaestus

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    Doesn't look like catbirds have ever been released. The incomplete guide to airfoil useage just says John roncz airfoil. Apparently similar to melmoth2's but those aren't exactly ones you'll find either.
     
  12. Sep 22, 2019 #32

    plncraze

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    Lednicer and Roncz did an SAE paper which I have lost, that talked about airfoil design for Melmoth2. It covered the how's and whys of their design. From memory; inboard airfoil is turbulent, middle is laminar and outer is positive pitching moment.
     
  13. Sep 23, 2019 #33

    Rik-

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    Does anyone think/believe that the canard on the catbird actually has a “significant” affect?

    I mean they look so tiny I’m kinda wondering how much they contribute to the planes handling and flying.
     
  14. Sep 23, 2019 #34

    TFF

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    The shape of the plane is the easy part, it is the inside that matters of the build. If you were given the molds, you still don’t know the internals. Lifting the shape from pictures will get pretty accurate.

    I did not see it this year when they had the Rutan gathering in the center. Is the forward wing trimable? Something like that probably broadens the loading range while keeping the CG range in reason. Probably more stable for IFR if it was too sporty without. Horizontal is pretty small looking. But you are also dealing with an experimenter who experiments; he learned something; that he would do it that way again would only be found out if he designed something like that again. He is the only one who knows if it helped or hurt the total design; even if it is successful to us.

    It would be nice to have a non kit home buildable fast glass plane that’s not a canard. Instructions and drawings for success. Building one, who knows, but it would sell a lot of plans.
     
  15. Sep 23, 2019 #35

    Hephaestus

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    The canard would carry a fair bit of the load. The forward swept wings (all 3), 5 seats... It pretty much needs to be that way to balance and for typical canard deep stall resistance.

    Curious how controls are worked... Hstab could be just trim? It's pretty small as mentioned...

    It would be a better homebuilt tweaked for more normal use - how many are actually going to pressurize? I wouldn't want to... I'll stick to 10-12k that's high enough for me.

    While it says io360 it also was written up as 210hp(?).

    I'm still hunting for a 200kt cruiser, this is up my alley ;)
     
  16. Sep 23, 2019 #36

    Rik-

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    I agree on the pressurization thoughts, however I see it is flown at 17,500’ on occasions so I guess if it’s there someone will take advantage of it.

    I’ve been searching for a 200 knot plane, this is one that doesn’t have to be at pressurized altitudes in order to achieve it. I was wondering what the benefits of the canard actually were as at some level it’s drag too.

    The cockpit might be configured for CG and bragging rights of 5 seats as I think if it could be a 4 seater it’s good enough. I believe the engine is a turbo charged one as the pressurization would reap the benefits handsomely.

    So how do we make a 200 knot plane with 200 hp?
     
  17. Sep 23, 2019 #37

    BJC

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    Turbocharge it, like the Catbird, and fly it at 17,500.


    BJC
     
  18. Sep 23, 2019 #38

    Kyle Boatright

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    I've been fascinated by the Catbird for years, but there is relatively little public information on it.

    I think a reworking of the Catbird concept might have been a better solution than the pusher canard layout of the Raptor.
     
    Last edited: Sep 23, 2019
  19. Sep 23, 2019 #39

    Hephaestus

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    EAB have enough issues with fuel systems... Unlike scaled we don't have beechcraft engineers to put a system together. To me pressuring is a non starter.

    As to how to do it... **** good question ;) generally 470/540 engines in a glassair or lancair seems the norm. But the fuel cost to feed those engines...
     
  20. Sep 23, 2019 #40

    Rik-

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    Yea but this thing will do it at 8500’
     

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