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Thread: canard CG


  1. #1

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    canard CG

    I'm wanting to design/build a canard fun fly plane. Does anyone know of a good web site or have info on how to balance a canard aircraft? All of the canard planes I have seen are like the EZ plane.

    Any help would be appreciated.

    Thanks
    Jack

  2. #2

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    canard CG

    here to do cg.
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    TEAM\"Jan & Adrian Strydom\" Israel

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    canards

    Adrian,
    That graphic method works well for conventional airplanes but doesnt take into account the physics of a canard. If it is used to calculate the CG for a canard odds are the airplane will be tail heavy.

    Jack & Adrain,
    If you like you can send me a PM and I can e-mail a mag article to you that covers basic canards pretty well. Warning - Some algebra
    may be involved for the calculations.
    Just a note; I have faith in the info because I built a small glider to test the math

    Cheers.
    James
    Revver Bro #202

  4. #4
    FLYBOY's Avatar
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    canard CG

    I used a program out of a magazine one time that showed cg and size of canard required. We used it to design a glider but I have no clue as to where the program went. It was in basic and was a lot of code to type. I had it working well, but that was long ago. I think we got it out of RCM a in the mid 80s. Might be the one James is talking about.
    Fly it till the wings come off.

  5. #5

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    canard CG

    There is some discussion going on over in the Aerodynamics forum about canard CG calculation. I posted a link to Ron Van Putte's formulas in a M.A. article that worked for me in a canard design I did some time ago. Read this thread: http://www.rcuniverse.com/showthread...369&forumid=19

    HTH )
    \"He who dies with the most good Cox engines wins!\"

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    canard CG

    Thanks HTH.
    Thats the one. I have a copy of that file on my other puter at home. Couldnt remember the author.

    Didnt use the calcs for the fin area cause I was going off a scale subject. So no comment on those numbers.

    Cheers.
    Revver Bro #202

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    canard CG

    Originally posted by mdlav8r
    Thanks HTH.
    Oops, I finally remembered to use some of that cool new-age internet abbreviation stuff (HTH = Hope This Helps) and now I got me a brand-new name.

    Regards,
    Milton Dickey
    \"He who dies with the most good Cox engines wins!\"

  8. #8
    wvarn1957's Avatar
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    Canard CG

    If anyone is interested I got a copy of an Excell spreadsheet a couple of years ago which will calculate the CG of canards, bi-planes, monoplanes, swept and tapered wings. It will also do the design calculations. you just plug in the span, chord etc. If anyone would like to have a copy let me know.

    Will Varnado
    W W Varnado

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    oops :p

    Milton (HTH) Dickey

    Prime example of what happens when your brain misfires while in a hurry.

    Cheers.
    James
    Revver Bro #202

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    wvarn1957, I would love a copy of that program

    Hey there WVARN,

    I would love a copy of that Excell spreadsheet. I have gotten hooked on building scratch built foamies in electric and small sail planes. That would help a lot on future projets.

    I'll be adding my new v-tail sail plane to the gallery as soon as I am done with it. (very soon!) Wing design had too much drag but is at 13OZ! Flies, but will be better after a different wing is on it. Looks like it will stay up forever untill forward speed drops off due to drag and then down it comes with a fast sink rate like there are spoiler up.

    Back to the drawing board.

    mshjhg@attbi.com

    **************************
    Epoxy is a beginners best freind!
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  11. #11
    wvarn1957's Avatar
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    canard CG

    Scott

    I tried to send you the spreadsheet using the address in your post, but it came back. E-mail me with your correct address and I'll try again

    Will
    W W Varnado

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    canard CG

    Hi WVARN - I would like a copy of that speadsheet too. A friend called me last evening to say that he is building a canard and asked if I know how to calculate the CG. His version will have swept wings and tip fins!
    Regards to all
    Gordon
    from way down here in Wellington, NZ

  13. #13

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    canard CG

    Well it would probably be easier if I included my yahoo email flywellnz@yahoo.co.nz
    Cheers

  14. #14

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    canard CG

    The link to download the excel sheet is available on this thread i think..

    http://www.rcuniverse.com/showthread...474&forumid=19]
    I live on Airtime

  15. #15
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    Canard CG

    Hi everybody,

    I have some recent experience with a large canard airplane, and found that, regardless of the formula you use, the fact is that it really depends on the lifting potential of the canard.

    In the case of the plane I worked on, I found that what "should have" worked didn't... By increasing the span of the canard, switching airfoils, (to an Eppler 197) and increasng the proportion of elevator to canard. (elevator was about 30% of the canard chord) everything worked great. (Andy Lennon's book, "The Basics of RC Model Aircraft Design", available through Model Airplane News, helps a lot.) I found that if the canard chord drops below about 5 inches, you may as well use sheet balsa, as opposed to an airfoil. (Reynolds effect, especially at lower airspeed)

    One bit of good news...
    Since canard aircraft generally have a wider safe CG range than conventional aircraft, you might find that simply moving the CG a bit aft will help a lot.

    When they're right, they're fun!
    Happy flying!
    Mike James
    RC Design and Building - www.nextcraft.com
    New CD\'s shipping now.

  16. #16

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    canard CG

    Here is the article by Ron Van Putte, June1980, Model Aviation on canard CG and vertical fin sizing

    http://www.angelfire.com/scifi2/wiza...es/Canards.zip

    It covers the major equations that were used in my spread sheet referenced in the thread above.

    Alan

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    canard CG

    Hi Guys,

    I currently have a Ducted Fan Canard jet in the early-to-mid design phase. I have a spreadsheet that I put together for calculating static stability. It's in pretty rough shape right now, but I could polish it up and make it available on my website.

    Just let me know who's interested.

    Ken - www.litkoaero.com
    R/C Laser Cutting and Design
    Ken - http://www.litkoaero.com/
    R/C Aircraft Laser Cutting and Design

  18. #18

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    canard CG

    CG calculations :

    The most efficient way is to build a reduced version of your canard as a glider and hand launch it from a litlle hill, facing the wind.
    Is is relevant to check the grass is high enough underneath, otherwise, finding the right Cg may be a very lengthy process...
    ProBro #2077
    http://image2-0.rcuniverse.com/e1/forum/upfiles/57402/Nl29490.jpg


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