Napkin sketches

Discussion in 'Hangar Flying' started by Autodidact, Mar 28, 2017.

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  1. Nov 17, 2017 #221

    mcrae0104

    mcrae0104

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    Nice work, AutoD.

    No plugins required. SketchUp can do quite a bit if you don't require the mathematical sort of precision of Solidworks or Catina.
     
  2. Nov 17, 2017 #222

    Autodidact

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    That's normally how I think, too. But I was impressed by a very credible sounding statement in another thread not long ago about the durability of airdrome aircraft and how the structure stayed nice and tight despite a lot of use and even some abuse by mother nature.

    I think this type of spar would probably only make sense in a fabric covered wing.
     
  3. Nov 17, 2017 #223

    Autodidact

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    Thank you guys for the compliments, it's very gratifying.

    I have to say that I first spent about a month (at least) reading Sketchup for Dummies 2014. That was very helpful. My problem with DesignCad 3D Max is that the tutorials are pretty sparse in comparison.

    Sketchup has a minimum number of basic commands, but it is pretty "smart" in that it allows you to snap to many different points in many ways without explicitly typing in an instruction. Most commands can be modified by pressing the control or some other key to make it a copy command also (move, rotate) or some other additional function. To make a squashed tube end, for example, I do a little arithmetic to find how long the "straights" would be with a small radius at the ends, then select the end of the tube with a window and scale it down. Then, since the circles (and everything else) in Sketchup are really a few straight lines (you can adjust the number) I pick half the tube end (need to draw two lines across the end to break the circle in half leaving a straight to stretch when the half circle is moved) and then move it the right distance and then do the same to the other half. You can be pretty precise with this program, but it lends itself to fudging really well and so I have come to a compromise - if it is as accurate as a real part would be, then I'm good with it. I am careful to make sure everything is a solid (group or component) so I can list that part's internal volume. It has its limits, but I think it can be accurate enough to actually design an aircraft from, although I don't think General Dynamics is going to be using it. I draw triangular planes a lot to help me find points because a line piercing a face highlights as an intersection that can be snapped to, and the rotate icon also likes to snap to any handy face and that helps to rotate in odd directions. So far I have used no plugins, but I'll delve into that pretty soon. Here's a squashed tube end as I'm currently doing them:

    Strutends.jpg

    PS, here's the use of a plane to find a clearance distance:

    elevatorPTclearance.jpg
     
    Last edited: Nov 17, 2017
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  4. Nov 17, 2017 #224

    Jay Kempf

    Jay Kempf

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    Kewl!

    I actually liked DesignCAD a lot before I got into the higher priced stuff. Couldn't make Sketchup do much I wanted it to do. But I'm a modeler snob at this point with a 3DConnexion problem and vintage trackball jones plus all the horsepower to do analysis and rendering without waiting much. What I see people doing with Sketchup is pretty amazing including CNC stuff. Sometimes I think a simple freeware setup would be a dream.
     
  5. Nov 18, 2017 #225

    Topaz

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    The tools out there are pretty amazing now. Did you know Onshape now does sheet metal? Including creating a flat pattern from your 3D part design, including bend allowances, etc. The kicker is that OnShape has a full-featured free version.

    Here's a third-party video showing some of that function. The official video is 40 minutes long, but typing "OnShape Sheet Metal Essentials" into YouTube search will pull it up.

    [video=youtube_share;LQP6uMLOEnI]https://youtu.be/LQP6uMLOEnI[/video]
     
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  6. Nov 18, 2017 #226

    rotax618

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    A dream of mine. 9E464696-58B8-417A-AEA4-98F561B866D9.jpg 86E00256-3CC5-4D17-B697-DC381405B1E2.jpg
     
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  7. Nov 18, 2017 #227

    Autodidact

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    That looks great, is it a single place?
     
  8. Nov 18, 2017 #228

    Autodidact

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    I've been making a mistake in calling the pop-riveted tube and gusset planes Airdrome-Baslee style; Robert Baslee is Airdrome Aircraft - Graham Lee is the Lee I was thinking of and not the same company but very similar structure... So, Airdrome-Lee type, I guess?
     
  9. Nov 18, 2017 #229

    Autodidact

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    I am developing a desire for a more sophisticated 3D capability. Maybe by getting used to 3D modeling with Sketchup, I will be less intimidated by DesignCAD, which I own and is really all I can afford.
     
  10. Nov 18, 2017 #230

    cluttonfred

    cluttonfred

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  11. Nov 18, 2017 #231

    rotax618

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    No need for napkins there are 2 free Autodesk 3D drawing programs, 123D is no longer supported but us available for download in both X86 and 64bit versions for windows I find it easier to use than Sketchup. The other program is Fusion 360 which is free for students and hobbyists, it is a full parametric 3D package. There are plenty of tutorials on Youtube, the best tutorial is “Learning Fusion 360 or die trying”.
    Freecad is another free 3D Cad, it is extremely powerful if you become familiar with all of the workbenches.
     
  12. Nov 20, 2017 #232

    Autodidact

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    To me it seems like the most powerful aspect of 3D CAD is to verify that the parts of a complex machine will work together correctly. Even if I never generated a template or tool path 3D would still be extremely helpful as a design tool. On the wing for the Gere Sport I had to use packing blocks under the aileron bell-crank bracket to tilt it a few degrees so as to clear the drag wires with the push/pull tube while keeping the bolts as close to the neutral axis of the spar as possible. The fuselage end of the push/pull tube moves up and down as well as back and forth and so I had to raise the wing root ends of the drag wires to clear the tube at full control throw (the spars are stabilized here by the compression rib and the fuselage fittings). The wires also had to miss each other and the rib bracing as well. PS, I know that a lot of details like rod ends and maybe cotter pins and such aren't really good practice, but I'm trying to add as little to the drawings I've found as possible:

    bellcranktilt.jpg dragwireposition.jpg torquetubecontrol.jpg
     
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  13. Nov 20, 2017 #233

    rotax618

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    Great work, I haven’t mastered any 3D system to provide that detail, my use is basically to sculpt shapes and recover sections for 2D drawings.
     
  14. Nov 20, 2017 #234

    ScaleBirdsScott

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    It will be a long time before CAD is so fluid and fast that doing concept sketches in 2D is not useful.

    3D work imo is almost by definition a level or two past the napkin sketch.

    When I think sketch I would want to see a thread full of:

    bb327099-7c35-4fa1-9a8b-d2b43c1ca6fe.jpg
    20ba3277-cb98-466f-8378-591cbf346d1f.jpg

    These types of sketches. Let the ideas flow.
     
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  15. Nov 20, 2017 #235

    Autodidact

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    I truly love these kind of drawings, but I am not as talented as you are so I can only live vicariously through what you and people that can, sketch up. And I agree, let the ideas flow any and all.
     
  16. Nov 20, 2017 #236

    Autodidact

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    On the subject of doers vs dreamers, there are hardly any more git-r-done focused people than hot rodders, and they seem to be very much into the concept sketch/rendering like those below (a little OT but meant to illustrate a point). I think it would be cool to see a page in Kitplanes devoted to this type of concept rendering; you know, new and different ways to do the same old thing or even something completely new. Often someone will see one of these artist's paintings and decide to build the thing in reality. I don't say that dreaming is better than doing; but doing happens slowly and needs to be supplemented by something that keeps the interest energized, and that is what Kitplanes, Sport Aviation, etc do, but it can always be improved and in fact the circulation depends on it - the older magazines used to do this but the art work was sometimes not so good and these days I think it could be of very high quality, like some of the things ScalbirdsScott and a few others have posted. Don't get me wrong though, I like the 3D stuff too, but I like seeing it all - from basic to refined.

    CampesiCorvair.jpg Sportstruck.jpg Charger.jpg
     
  17. Nov 21, 2017 #237

    rotax618

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    I always start with a pencil, then draw an elevation to scale in 2D CAD to get the proportions right. If it looks OK I draw a sketch in 3D.
     
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  18. Nov 21, 2017 #238

    Tiger Tim

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    A tip for the sketch artists: use it or lose it. I used to be really good at drawing what I saw with my mind's eye (from decades of being bored in class) until I got busy with more important things in life and didn't really pick up a pencil for six or seven years. Now I can't sketch to save my life. I know it can come back with practice, I just wish it had never left.
     
  19. Nov 21, 2017 #239

    Autodidact

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    I just can't do free hand sketches. I've done some pencil sketches that look OK, but that was work with straight edges and an eraser shield, not really a sketch and not terribly good art either. But I can do an elevation or 3 view in 2d CAD pretty quickly, as if I were sketching, so everything starts as 2D pretty much like all of you seem to be saying. If I could pencil sketch well, I would do it, because it has that craftsmanship thing that's always nice to look at.
     
  20. Nov 21, 2017 #240

    Hot Wings

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    Have you tried Iso paper? It can help with '3D' drawing.
     

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