The Razorback construction thread

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by rtfm, Jul 11, 2008.

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  1. Oct 27, 2008 #41

    Dana

    Dana

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    Re CAD: Don't waste your time with AutoCAD; it's pretty much obsolete (and discontinued by AutoDesk). Also if possible, don't waste your time with any 2D program; working in 3D is actually easier and a must for the kind of shapes you need for aircraft design. The "move up to 3D" advertising hype a lot of programs are using sets my teeth on edge as good affordable 3D for PC has been available for over 20 years now.

    The parametric history based modelers (Pro/E, Solidworks, Inventor, etc.) can be very powerful but IMO aren't the best tool when you're doing preliminary design and making significant changes as you go along. If you have the basic shape down and if you model it correctly from the start, changes can be very easy to make. However, the possible changes are limited by how you created the model in the first place, and you're very limited in what you can do imported files. Pro/E is probably the most complex of the bunch to use... not for the amateur.

    It's been some years since I used Rhino; it's a good surface modeler, but the drafting tools were kinda weak... I don't know what it's like today.

    My personal preference is KeyCreator (formerly Cadkey). It's what they call a "pure geometry" modeler, no worrying about parameters or history... you can make large sweeping changes regardless of how you started, even if the original design came from another CAD program. It has the best surface modeler around in its price class; there isn't a shape it can't handle (which can't be said for most parametric modeler).

    All of the above programs are in the $3-4000 range, but all have substrantial student discounts if you're eligible.

    -Dana

    A seminar on Time Travel will be held two weeks ago.
     
  2. Oct 27, 2008 #42

    AVI

    AVI

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    Re: CAD

    Thanks, Mac790 and Dana
    I've got an old version of Rhino that's been sitting on the shelf for years. Maybe it's time to dust it off and start playing around with it, trepidation in facing a new learning curve or not.
    Thanks,
    Alex
     
  3. Oct 29, 2008 #43

    Mac790

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    Duncan
    Sorry for impatience but are you going to post some pictures in the near future? I'm f.. curious how it looks. I'm afraid that I(we) oversized your plane special after I compared it with my car. (attachment) So please don't test our patience and post something.

    Seb
     

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  4. Oct 29, 2008 #44

    Dana

    Dana

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    But anything looks big next to a Lotus Seven (isn't that what that is?)...

    -Dana

    Q. What's the difference between Mechanical and Civil Engineers?

    A. Mechanical Engineers build weapons; Civil Engineers build targets.
     
  5. Oct 29, 2008 #45

    Mac790

    Mac790

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    Yes you are right but I still worry about size (special if you check out Duncan's previous versions), it's some kind of obssesion, I even compared his plane with others small planes (attachment) like Sonex, Kr.

    I built that car some time ago, It's inspired by Lotus Seven but it isnt exact copy. You can see it in the first few seconds of this movie [video=youtube;-XCHwodME_8]http://www.youtube.com/watch?v=-XCHwodME_8[/video]

    Seb

    I love it, nice one.
     

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  6. Oct 29, 2008 #46

    rtfm

    rtfm

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    First, I share your curiosity, and am also aching to see what it looks like. Problem is, my workshop is too small to build it in. I tried, and had to abandon the attempt. The plane takes up nearly the entire width of the garage, leaving me no room to move.

    I am now waiting for my hangar to become vacant. I am told this will be in two weeks time. So the best I can do at the moment is to make sure I have the templates lined up accurately, numbered, and put aside waiting for the big move.

    As far as the size is concerned, I am not concerned. It is about 43in wide which is right on the money for a side by side, and it is 18.4ft from tip of spinner to tip of rudder. That's right on the money too, especially if you bearin mind that the spinner is just over 2ft!

    So we both have to be patient, Seb. I come home in the evenings, and my hands are just itching to do something. But it won't be long now.

    Regards,
    Duncan
     
  7. Oct 29, 2008 #47

    Mac790

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    Duncan
    Sorry for pushing you to hard. When you wrote "When I finish the template mounting (later today?) I'll take a photo, and post it here for your amusement" I thought that you are going to make some pic before moving to new hangar. But it seems that your garage is too small for it. Ok I'll wait another few weeks,

    Are you going to subtract 0,5inch(foam thickness) perside, otherwise width of your fuse rise to 44in.
    I believe in it.
    Ok so it mean that your garage is too small or your plane is too big, I'm hoping that the first sentence is correct:).

    Seb
     
  8. Nov 15, 2008 #48

    Mac790

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    Duncan
    I was thinking about your "male mold" construction, and I think it will be easier to work with two separate halves. I know you probably worry about difficulties in matching them but I think that I have a very simple solution for it.
    Check attachments:
    -first build one halve completely beam, templates, wooden strips (pic1)
    -second turn it 180 deg and add beam (another perpendicular beam is a good idea) for another halve (pic2)
    - add templates to the second halve, match them corectly with another halve and screw both halves together (pic3)
    - add about 10 or layers of wooden strips to both sides (pic4)
    - unscrew it and add rest of wooden strips "planks"

    Please note it's only conception and of course you need to add more "wood" to make it stronger and stiffer.

    Seb
     

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  9. Dec 5, 2008 #49

    Mac790

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    Duncan

    Have you seen "Poliwagen" (composite two seater) plans/manuals, if not try Poliwagen page download documentation from 1984, 1981 is a little bit less useful. You will find many useful (in my opinion) information and layup schedules for almost entire plane, like for example, how to mount wings into fuselage pic1, seat belt fittings, seat construction pic 2, h-stab construction (it's all moving surface T-type pic3, we were discussing this option). Poliwagen has a very simple method of the fuse construction pic 5 but its a little bit square shaped in comparison to yours.

    I think it's a great reference source, of course some solutions in these plans are better some worse, for example seat construction a really dont want to have that pipe in my backbone in case of accident, no way.
    The side view is similar to yours pic 4

    Seb

    Page link, try plans section Polliwagen Archive
     

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  10. Dec 5, 2008 #50

    rtfm

    rtfm

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    Seb,
    You are an amazing fellow. The Polliwagon site is a mine of information. The plans are exactly the sort of thing I was wishing I had. And now I do. The Polliwagon is very similar to the Razorback, and I think I will be able to use the drawings, plans, tip and techniques contained the the Polli plans to extremely good advantage.

    I feel very much more confident that I will actually be able to build this aircraft now.

    Thank you again for your help.

    Regards,
    Duncan
     
  11. Dec 5, 2008 #51

    Midniteoyl

    Midniteoyl

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    Awsome find, Seb. I love adding to my collection :)
     
  12. Dec 6, 2008 #52

    Mac790

    Mac790

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    Unfortunately building your own plane even from kit is in my fu.. country almost impossible (people have to register their planes in other countries, unless they buy Cessna), I have to wait till I finish school next I'm out, till that everything what I can do is to help others, so I'm trying, I believe that your and others experience will help me in the future.
    btw check it out just in case http://www.homebuiltairplanes.com/forums/beginner-questions-answers/4214-personal-design-25.html#post35364
    Jim you welcome, I'm glad you like it.

    Seb
     
    Last edited: Dec 6, 2008
  13. Dec 19, 2008 #53

    rtfm

    rtfm

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    Building the shell

    Hi,
    Well, building has finally started. I'm in hangar F2, I've got tons of space in which to work, and my son is giving me a hand with the building. Things are happening. Here are the first of many photos which will document the build process.

    Photo 1:
    My little hangar, and my even smaller car.

    Photo 2:
    Inside the hangar. This is not a place for storing aircraft (the doors are too narrow, anyway) but a place to build them. Before me, a guy built an RV-4. After me, there will be others...

    Photo 3:
    Believe it or not, these four thin slivers of foam carefully wrapped in protective cardboard cost me almost $800 That is right - $200 per sheet. Thank goodness I only need four of them... It is Airex structural foam (80kg/m^3). Cut into strips, these will form the "planks" with which I am going to cover the templates.

    Photo 4:
    On my hands and knees, measuring a piece of foam. Easy to cut with a Stanley knife. Each plank is fitted next to its neighbor and attached to the supporting templates.

    Photo 5:
    Son Daniel being forced to work by a gleeful dad wielding a deadly hot-way glue gun. The foam planks are tied to the templates with light string to keep them in place. Then they will be bonded together with two-pot foam and shaped. This photo was taken before lunch. By the time we'd packed up for the day, over half the plane was covered. The foam planks form beautiful curves over Seb's templates. And having the entire thing on a rotisserie (made from an engine stand) makes it easy to work.

    Regards,
    Duncan
     

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  14. Dec 19, 2008 #54

    Mac790

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    Re: Building the shell

    Duncan

    It seems that Santa Claus came this year a little bit faster:gig: Big thanks for these pictures.:ban:
    800$ just for four sheets? Shipping was so expensive? I have to check out that price. I'm hopping that quality of Airex is equal to it price. I'm also surprise that these planks fit so perfectly, over these templates, I thought Airex is stiffer, but I've never worked with it so I wasn't sure about it.
    And the small :)plane. I was worring,I thought it's to big but it seems just fine. Is it top side?
    He doesn't look unhappy about it.:)

    What type of glue are you using to "connect" these planks each other. I see that you use hot-way glue gun to "connect" them to templates.
    Are you going to use similar to Poliwagen method of construction, are you going to use hot wire method, or maybe just sand it to shape over templates (top and bottom).

    Seb

    Btw pic4 nice shoes did you made these holes by yourself or did you buy them like that, it's a great idea for a sunny day.
     
    Last edited: Dec 19, 2008
  15. Dec 19, 2008 #55

    Gray Out

    Gray Out

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    Hello to all,

    Very very nice. I will be following it closely.:)
    Good job and best wishes and luck.

    I can't wait until I'm at that point!

    Thanks
     
  16. Dec 19, 2008 #56

    rtfm

    rtfm

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    Re: Building the shell

    Hi Seb,
    Transport from the store to the hangar was $6 only. This stuff is ridiculously expensive. I will take some more close-up photos, but the reason the foam fits so well is that I am cutting them into 50mm strips, and laying them side by side over the templates. The strips overlap at the ends (ie front and back) so I cut these to size. The result is a really well-fitting series of 50mm strips. Getting them to stick to the templates is a much bigger problem. Photos will show exactly how we are doing this, but it is basically by "stitching" the strips onto the templates with string. The hot glu gun just happened to be nearby and was used as a prop for the photo only.

    I'll sand the foam to shape using the end templates, I think. I would prefer to hot-wire it, but I don't have a hot-wire setup. Sanding should work just fine...

    I bought the shoes like this - they are Crocks. Really nice.

    Duncan
     
  17. Dec 20, 2008 #57

    rtfm

    rtfm

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    More pictures of fuselage being built

    Hi,
    Here are a few more pictures of the fuselage, and some details of how the foam is being laid over the templates.

    Duncan

    Photo 1:
    From the side. At this point, the fuse is about half covered (LHS). The tail has not been added yet. But notice the beautiful lines formed by the foam. This is going to be a very clean machine.

    Photo 2 & 3:
    Different views

    Photo 4, 5 & 6:
    Shot of the nose. Followed by close-ups of the foam detail.

    More to follow as the build progresses.

    Duncan
     

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  18. Dec 20, 2008 #58

    Mac790

    Mac790

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    Duncan

    Hmm I've never liked this method very much, I believe only in plugs, moulds etc. But you chose that method It's fine your choice but, why don't you stick/glue these planks each other at that stage, are you going to make it later? I'm not experienced in this method but I think it's easier to stick/glue these planks now than later. I would rather use pins/nails at 45-60 deg than these strings/twines. I would also cover templates edges with a Scotch tape, so epoxy won't stick to the templates.

    Seb

    Btw I used Rom pic I'm hoping he doesn't mind.
     

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    Last edited: Dec 20, 2008
  19. Dec 20, 2008 #59

    AVI

    AVI

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    Mac790 - what site did those pictures come from?
    Do you have more info on the female mold shown in the last picture?
     
  20. Dec 20, 2008 #60

    Mac790

    Mac790

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    Iceman

    picture 2,3,4 I took from Canardaviation it's about designing a new Cozy IV fuselage
    Canard Aviation Forum - View Single Post - Designing a new Cozy fuselage

    picture 1 I took from russian site (unfortunately in cyrylica, I dont understand it either) It's a Berkut fuselage.
    Àññîöèàöèÿ Ýêñïåðèìåíòàëüíîé Àâèàöèè - Intruder

    Pic 5 I took from Rom thread
    http://www.homebuiltairplanes.com/forums/composites/4128-strip-method-other.html

    I don't have more info about the female mold method, like I said I don't like these methods, I prefer "old school" method, plugs, molds, etc

    Seb
     

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