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Thread: MY FIRST DESIGN AT A HOMEBUILT

  1. #1
    Registered User Harley's Avatar
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    Talking MY FIRST DESIGN AT A HOMEBUILT

    Hey Guys,

    First off don't laugh I didn't spend alot of time drawing these up, there more for getting an idea on a page.

    The 3 images are different ideas of the same project, and I am looking for your corrective criticism for scale and size of different parts. Of course there are no weight or balance dimensions yet but they will be coming.

    I wasn't sure if I am going to be making it out of wood or metal. I am trying to keep weight and size down, I want this to be a small sleek little craft. No wasted space or length.

    The width of the aircraft should be no wider then shoulder width (tight fit!)

    What sort of engine do you think would be a good choice?

    Do you think its possible to make this an ultralight?

    Does this design resemble other ultralights or homebuilts or light sport planes?

    If you have a similar design please show me!

    I think of this as a micro version of a P-40. to give you a visual.

    Thanks guys!
    MY FIRST DESIGN AT A HOMEBUILT-plane1-001.jpgMY FIRST DESIGN AT A HOMEBUILT-plane2-001.jpgMY FIRST DESIGN AT A HOMEBUILT-plane3-001.jpg

  2. #2
    Registered User rtfm's Avatar
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    Re: MY FIRST DESIGN AT A HOMEBUILT

    Hi,
    I like the design, even though it is still in the rough and early stage. I'd drop the last design concept, however. You don't want the fuse bottom to step up at the wing trailing edge. Air from the wing is going down, and you'll be forcing air under the fuse at that point to go up. Not good. Separation of air streams will cause significant drag.

    Your middle sketches (especially the top one, looks good.

    Question: why do you want to sweep the wings forward? Aesthetics? And don't go for the low aspect ratio version. I'd definitely look at increasing the AR for better Lift/Drag ratio, better climb.

    Nice work. Keep the sketches coming.

    Others may differ in their opinions, of course.

    Duncan
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    Brisbane, Australia
    Builder's Blog:
    http://rtfmaero.wordpress.com/

  3. #3
    Moderator Dana's Avatar
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    Re: MY FIRST DESIGN AT A HOMEBUILT

    Looks more or less OK. Sort of like a Volksplane with tapered wings. Tail might need to be increased. Making an ultralight not easy but not impossible... take a look at the Hummel Ultracruiser and the MiniMax.

    -Dana

    "The world that we have made as a result of the level of thinking we have done this far creates problems we cannot solve at the same level of thinking at which we created them." -- Albert Einstein

  4. #4
    Registered User WonderousMountain's Avatar
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    Re: MY FIRST DESIGN AT A HOMEBUILT

    Making an ultralight is not particularly hard. Making an ultralight that doesn't sacrifice a lot to be an ultralight is. This has been covered succinctly and at length here in the past. I second Dana's tail suggestion. Very few pilots complain their tail is too big. More importantly tail arm is helpful in dynamic stability.

    Personally, I disagree with the comment about forward sweep-but it's highly construction dependent. Wing divergence can occure with sweep, but more likely to cause problems in a sailplane which can bend quite visably at their tips.

    However, I fully agree with the aspect ratio notion. Everything below 6 looks stubby to me, and the numbers back me up.
    If you want an ultralight, you'll have to have a minimum of 100ft^2 ~ 9M^2 and there's some regulation to meet. Most ultralights are high wings, but can anyone really say why?

    Start looking for a lightweight reliable engine. It's easier to design knowing exactly what's going under the hood.

    And so it begines!

    Wonderous Mountain

  5. #5
    LongEazyMan
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    Re: MY FIRST DESIGN AT A HOMEBUILT

    I like it, it looks like a VP-1 with a VW engine. I do agree with everyone else and what there saying, but cool.




    *It's not how you fly the plane, it's how you fly the plane in that situation*

    "Leroy" CFI

  6. #6
    Registered User flying2bill's Avatar
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    Re: MY FIRST DESIGN AT A HOMEBUILT

    it's a good start but to go further some things need to be decided, ultralight, experimental, experimental (light sport eligable). A short tail moment makes for twitchy flying, taper wings require more building (more different ribs). Have you tried drawing in cad. You can download a demo version of Deltacad for free, easy to use (speciallee for us non collegiants, seat of the pants injunears). This is what I have been playing around with, mixed elements of 3 different planes
    MY FIRST DESIGN AT A HOMEBUILT-2seat.jpg
    Altitude is like my paycheck, I seem to run out of both before I am done enjoying them

  7. #7
    Registered User Harley's Avatar
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    Re: MY FIRST DESIGN AT A HOMEBUILT

    Quote Originally Posted by flying2bill View Post
    it's a good start but to go further some things need to be decided, ultralight, experimental, experimental (light sport eligable). A short tail moment makes for twitchy flying, taper wings require more building (more different ribs). Have you tried drawing in cad. You can download a demo version of Deltacad for free, easy to use (speciallee for us non collegiants, seat of the pants injunears). This is what I have been playing around with, mixed elements of 3 different planes
    Attachment 12883
    Awesome thank you for the updates and tips ! these are the things I am talking about when I need advice. I was hoping to make it an ultralight, but it might be to hard with the weight limit so prob experimental. I will download that demo tonight, also is the CAD program "Rhino" a good software?

    Please keep the updates and tips coming and your plane looks great keep the creative juices flowin!

  8. #8
    Moderator Topaz's Avatar
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    Re: MY FIRST DESIGN AT A HOMEBUILT

    Quote Originally Posted by Harley View Post
    ...also is the CAD program "Rhino" a good software?...
    Been discussed several times here on the boards, including its strengths and weaknesses. A search on "Rhino" should turn up those threads.
    "If you have built castles in the air, your work need not be lost; that is where they should be. Now put the foundations under them." - Henry James Thoreau
    Member of the Lake Elsinore Soaring Club.

  9. #9
    Registered User D Hillberg's Avatar
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    Re: MY FIRST DESIGN AT A HOMEBUILT

    Never,Never,Never design a cockpit for a "tight fit" 1. in a crash the cockpit may deform and screw you up & 2. The most improtant, Make future plans to get FATTER and
    Balder with age.

  10. #10
    Registered User rtfm's Avatar
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    Re: MY FIRST DESIGN AT A HOMEBUILT

    Hi,
    For a single seater, go for 24 or possibly 26 inches of shoulder width. A two-seater, 42 inches, or even 44, or 46. The truth is, you will be completely unable to notice the difference of a couple of inches width difference. So go with the more portly. You soon will be...

    Duncan
    ====================
    Brisbane, Australia
    Builder's Blog:
    http://rtfmaero.wordpress.com/

  11. #11
    Registered User Harley's Avatar
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    Re: MY FIRST DESIGN AT A HOMEBUILT

    Hey Guys,

    I really don't get the reasons of keeping a cockpit larger due to getting "Fatter" I think thats a really poor reason. The reason due to crashing is a much better arguement in my opinion. Thanks for the all the info guys!

  12. #12
    Moderator Topaz's Avatar
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    Re: MY FIRST DESIGN AT A HOMEBUILT

    Quote Originally Posted by Harley View Post
    Hey Guys,

    I really don't get the reasons of keeping a cockpit larger due to getting "Fatter" I think thats a really poor reason. ...
    Ah, you're safely under 35, aren't you?
    "If you have built castles in the air, your work need not be lost; that is where they should be. Now put the foundations under them." - Henry James Thoreau
    Member of the Lake Elsinore Soaring Club.

  13. #13
    Registered User D Hillberg's Avatar
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    Re: MY FIRST DESIGN AT A HOMEBUILT

    Ever see an older fellow cry after spending years to build his dream and not being able to fit in it? pretty sad. . . . .

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