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  1. #26
    Bob Pastorello's Avatar
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    RE: Pattern ship winglet.

    Me, sorry, too...I confused T with "winglet"....which I guess is technically a fin because of it's vertical aspect. I think on the Voodoo, and on Mark's Designs, the fins add to the "side lifting area" of the fuse for rolling maneuvers, which is probably a cat of a different breed, purpose-wise, from the "canalizer T".
    Great discussion - hope to learn more about these mysteries.
    "I learned long ago, never to wrestle with a pig. You get dirty, and besides, the pig likes it." - George Bernard Shaw

  2. #27

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    RE: Pattern ship winglet.

    The main effect from the fins, t-canns, etc is to straighten the spiral slipstream. It's hard to call their use a band-aid for a design problem, when there isn't any standard fuse design that can straighten spiraling airflow otherwise.
    Doug Cronkhite

  3. #28

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    RE: Pattern ship winglet.

    Doug,

    I agree. I installed the T-canns in 4 Abbras. The main effect that I noticed is a net reduction of k.E. mixes. Rudder became more effective so less rudder was need it. Of course they are connected. When people ask me what is that? I tell them that I am sponsored by Carnival Cruise. Here a picture.
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    Vicente \"Vince\" Bortone

  4. #29
    DaveL322's Avatar
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    RE: Pattern ship winglet.


    ORIGINAL: serious power

    Hi Dave,
    I don't doubt ,at all, what you say or have found.
    With that said I will add the following;
    It was CPLR that brought the the T Can,, to this party.
    He has removed the vertical component and now sits the 'winglet' directly on top of the fuz,, .
    I'm assuming he finds it as good or maybe even better.

    All I am saying is that there is ,so far anyway, no one size fits all solution but there are clearly benefits to these 'winglets'.

    Brian
    [/quote]

    Brian,

    We are in agreement that CPLR was the first to use a Tcan configuration, and I am not doubting the effectiveness on his planes. My point (perhaps lacking clarity) was more that simple strakes could provide similar effects as the TCan. And we are certainly in agreement that a given winglet, TCan, or strake should not (and from my experience does not) be expected to have the same result on every design.

    Nat Penton was the first I know of to use extensively use strakes - however - I think Nat was coming from different direction. Nat wasn't using small strakes to tweak the airflow around a "cool" looking fuse. Nat ditched the aesthetics and used a minimal fuse with gobs of airfoiled side area where it counts the most - at the CG.

    Regards,
    Regards,

    Dave Lockhart
    Team JR Americas, Thunder Power, Castle Creations, F3A Unlimited, NeuMotors, Team Contra, Central Hobbies, Tech Aero

  5. #30
    RC_Pattern_Flyer's Avatar
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    RE: Pattern ship winglet.

    Dave,

    AGREED, i understand the intent of the Pentathlon was to evolve Nats design to something a little more eye appealing to bridge the gap between the limits.

    Personally, I feel that the added side are on the CG allows the plane to carve through integrated rolling maneuvers much easier and also allowing any rolling element to require less rudder due to the increased area at the CG.

    It is interesting to feel the effects it has on crabbing in the wind and how it is affected by speed.

    Chuck Hochhalter
    Mark Hunt Designs

  6. #31

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    RE: Pattern ship winglet.

    Chuck can you describe the effects on your plane in crabbing and wind and speed ? I want to compare it to my Pentathlon.

    Thanks Kirk

  7. #32
    RC_Pattern_Flyer's Avatar
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    RE: Pattern ship winglet.

    If I am flying too slow....the plane will start to fly into the wind..so out requires opposite rudder.
    Also same for uplines in heavy crosswind.

    Chuck
    Mark Hunt Designs

  8. #33

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    RE: Pattern ship winglet.

    That is what mine does . Still learning to work with it .

    Thanks Kirk

  9. #34
    mithrandir's Avatar
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    I am gonna suggest the "T-can" is as it is to reduce the angular flow from the prop... and the reason it is a horizontal surface
    is so that the induced forces are in a roll direction that the wing can easily damp out... were the t-can vertical... it would still
    effectively straighten the flow... but the forces would act in a yaw direction that would be more damaging to flight path and
    more difficult to damp out....

    that would be my guess anyway...

    just curious... are any of the Contra folk noticing improvement with vs without the T-Can?
    Last edited by mithrandir; 10-30-2013 at 02:00 PM.
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  10. #35
    IMHO the T-canalizer is a hack fix, it's function eclipsed by the fine work of Alex Voicu.
    Airflow visualisation

    The T-can is now an EX-Fad.
    After 5PM slip brains through slot in door.

  11. #36
    Jetdesign's Avatar
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    Turbulators

    This is interesting to read.

    from Dick Shevell's AIAA paper Aerodynamic Bugs: Can CFD Spray Them Away:

    DC-10 wind tunnel tests showed a significant loss in maximum lift coefficient in the flap deflected configurations, with landing slat extension, compared to predictions. This resulted in a stall speed increase of about 5 knots in the approach configuration. The initial wing stall occured behind the nacelles and forward of the inboard ailerons. The problem was traced by flow visualization techniques to the effects of the nacelle wake at high angles of attack and the absence of the slat in the vicinity of the nacelle pylons. The solution was developed in the NASA Ames Research Center 12 ft. pressurized tunnel and turned out to be a pair of strakes mounted forward on each side of the nacelles in planes about 45 degrees above the horizontal. The final strake shape was optimized in flight tests. The strakes are simply large vortex generators. The vortices mix the nacelle boundary layer air with the free stream and reduce the momentum loss in the wake. The vortices then pass just over the upper surface of the wing, continuing this mixing process. The counterrotating vortices also create a downwash over the wing region unprotected by the slat, further reducing the premature stall. The effect of the strakes is to reduce the required takeoff and landing field lengths by about 6%, a very large effect.
    Joe Marri
    Enjoying all things aviation.

  12. #37
    mithrandir's Avatar
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    Quote Originally Posted by gaRCfield View Post
    This is interesting to read.

    Cool huh??

    and at high speed.. they align with the local flow...so no big drag penalty!

    Click image for larger version. 

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    http://yokotajoho.cocolog-nifty.com/...101004h868.jpg

    http://www.fas.org/man/dod-101/sys/ac/c-17.jpg
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  13. #38
    Jetdesign's Avatar
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    Yeah, very cool Every other day I kick myself for not taking that aero job. But if it's meant to be, it will happen.
    Joe Marri
    Enjoying all things aviation.


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