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Thread: Articles

  1. #1
    Super Moderator orion's Avatar
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    Articles

    The recent rebuild of our company's web site has eliminated the "Documents" page - I found it interesting that in the two days it's been down, I've gotten several inquiries as to where the articles and reports have gone. I hope to eventually incorporate them into an HBA library but for now I'll post them here.

    Please keep in mind that these are for general reference. Some of them may be relatively dated and some of the information may not be as applicable as when the article was written. But I did review them and for the most part, the information will most likely still be useful for those seeking a bit more information about the represented subjects. Hope you find them useful.

    I just added the paper on hull design - there will be one more (WIG overview) however it still has a formatting error that the PDF creator does not like so I'll have to go through it and do a bit of editing.
    Attached Files Attached Files
    Last edited by orion; August 7th, 2011 at 11:20 PM.
    "To live is to learn; to learn is to live" (author unknown)

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    Registered User Hot Wings's Avatar
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    Re: Articles

    Thanks!

    I stumbled across your airfoil article many years ago and consider it one of my standard reference articles. Anytime someone asks me a question about airfoil selection I point out your paper as a good common sense approach to the subject. It saves a lot of 'spainin
    Conventional wisdom and practices yield conventional results. If that is good enough for you:
    Problem solved.

    "--and pompous fools drive me up the wall. Ordinary fools are all right; you can talk to them, and try to help them out."
    Richard P. Feynman

    “Without deviation from the norm, progress is not possible.”
    Frank Zappa

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    Registered User 4trade's Avatar
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    Re: Articles

    I appreciate that you shear these fine articles here, thanks!

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    Registered User BenoitLescot's Avatar
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    Re: Articles

    I also remember a very fine article about flying-boat hull parameters selection

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    Super Moderator orion's Avatar
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    Re: Articles

    I will try to get those back up but I haven't had a chance to do that yet. I need to convert them to PDF (they are written in Adobe PageMaker) but there seems to be something in the files right now that is crashing the Distiller.
    "To live is to learn; to learn is to live" (author unknown)

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    Registered User BenoitLescot's Avatar
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    Re: Articles

    thanks orion, no worries I printed my copies

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    Registered User clanon's Avatar
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    Re: Articles

    Regarding the airfoil selection pdfs:

    Why the LS(1)-0413 airfoil and the GAW2 airfoil are tested as a different airfoils ...aren't the same?
    "Do what you can, with what you have, where you are"

    (Theodore Roosevelt)

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    Super Moderator orion's Avatar
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    Re: Articles

    My data indicates that they are two separate families with relatively distinct properties. I have the original NASA reports for both - each identifies the sections as unique.
    "To live is to learn; to learn is to live" (author unknown)

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    Registered User clanon's Avatar
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    Re: Articles

    Good to know!
    Thankz
    "Do what you can, with what you have, where you are"

    (Theodore Roosevelt)

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    Re: Articles

    Orion,
    I appreciate the work you have done on airfoil selection but what if I am selecting a foil for the 1,500,000 to 3,000,000 RE# range?
    Is there anything that makes the selection more focused on that group of foils?
    What would a "high performance" foil be when the speeds are below 65 mph? (high performance meaning high lift, minimal pitching moment, High L/D when never exceeding 65mph with a "draggy" ultralight? Consider a cantelever designed, top wing, of 30 foot span, and an aspect ratio suited to the ultralight - say 5 - 6.

    Paul

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    Registered User clanon's Avatar
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    Re: Articles

    That would be the airfoils on the best known ultralight out there :
    Kolb ; Hawk ; Challenger ; Chinook and Beaver ;etc .
    All TLAR airfoils arround Clark y ; USA35B and the UI1720 on the CGS Hawk (all modified though)
    PS: Sorry to jump-in.
    "Do what you can, with what you have, where you are"

    (Theodore Roosevelt)

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    Re: Articles

    all modified..... There is the rub.
    under-cambered wings make a lot of lift but at the expense of pitching moment, the original Clark Y foil was designed for faster aircraft and would need much more camber and a flat bottom to be good at ultralight speeds. with 150 - 180 square feet of wing and a MTOW of 585 pounds you are looking at wing loads of 3.25 to 3.9 pounds per square foot. The Clark Y was designed for much higher loads. There must be a better foil for ultralights.

    Paul

  13. #13
    Registered User clanon's Avatar
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    Re: Articles

    Well , yes .The UI1720 was modified on that way for the Hawk ; the challenger is as TLAR as it gets but there was some discussion about using some of the TSAGIs (P2 y or P3) and or the Wortmann FX 63 series...:
    Maybe you should start a topic...

    airfoil : Airfoils R Us

    PS: After years of xfoil and eppler and everything else out there...i ended up with something very close to the kolbs airfoil (lots of L/D ; some Drag and some Cm)
    "Do what you can, with what you have, where you are"

    (Theodore Roosevelt)

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    Re: Articles

    I really don't want to join a Yahoo group just to look at the files. I don't (haven't in about 10 years) build models anymore - though I will build a large scale model of my UL design as part of the testing. Do model aircraft operate in the RE 1.5meg to 3 meg range?

    Clanon, I got the dat files that you sent but I need a spreadsheet that will plot them - do you have anything like that? Or know where I can get one or an open source software that will do the same?

    Paul

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    Re: Articles

    Hello,

    I am new here...I found this place looking for info on CG. Orion's posts sold me immediately! Great work buddy!

    Uh...I have a few questions and some info....

    First of all, you may know these links but they are interesting for airfoils:

    Airfoil Investigation Database - Welcome
    that one has some good info...and coordinate data

    UIUC Applied Aerodynamics Group
    that one has a TON of low reynolds number stuff..probably good for windmills, sailplanes and RC

    anyway...a question.

    I am trying to design a cargo plane...like 12,500 gross. I don't know what will come of this, but it's just
    one of those things I want to do, to sort of kick my chops in the ass. This is just a hobby thing, but I have
    been designing machines most of my life and I have been doing CAD for 20 years. I have always liked planes
    and thumbnailed a few over the years, but never did one in CAD...so..I am now.
    Anyway, I kind of have a concept, and have a rough layout, but I am having the damnedest time finding out
    component weights. The worst being engine and prop combinations WITH the CG location of the assembly.
    I am designing around a PT6, because it seems like the correct fit for this kind of plane and they are in LARGE power
    ranges. The problem is, I can't find any data on CG and mounting points.

    I wrote Pratt and Whitney[ the PT6 site ] and they basically blew me off...below is the email from me and them...
    I wrote:
    Hello,

    I am working on an aircraft design and I am planning on using a PT6 in the
    design.

    My problem is, I can't find any information on Center of Gravity location,
    with and without propeller and mounting points, and such details.

    Some type of CAD drawing would be nice too.

    Can you direct me to a source of this information?

    Thanks much!

    Their answer:

    Dear Jim,

    We checked with the technical team to provide you the details of engine and drawings however they confirmed that the information is restricted and confidential therefore any details about engines or drawings will not be provided. You can contact any authorized service centres or aircraft manufacturer to check for the details.

    We are sorry for the inconvenience.
    --------------
    Are you KIDDING?

    I just wanted CG and mounting points...not CAD drawings of fuel controls and turbine with with the metallurgy..

    So...where do I ask about this...? PT6..? with prop?...
    yes, I know there are many PT6 and prop combinations, but just ONE to start with would be nice.

    They are all pretty much the same size, and weight...and at this early stage, I would like to plug one into
    the design and see about preliminary CG locations for the whole aircraft...

    Any ideas guys?

    Thanks

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