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Old Nov 16, 2009, 07:20 PM
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Old Nov 16, 2009, 07:29 PM
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That's what is so brilliant about this thread, swapping techniques. Everyone moves on faster..
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Old Nov 16, 2009, 08:34 PM
It actually Flies!
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Salmon Arm, British Columbia, Canada
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Originally Posted by Harpye View Post
... you could trim the mid part and move both halves from each other ( afterwards close the gap by a surf or an extrusion...) or secondly ... what is the more difficult way ... move the groups of control points fromeach other ....
DUH!! Why did I not think of that easy fix!! I will split the surfaces between the tubes and then do a surf inbetween!! Such an easy fix. I always like to think of more complex ways of doing simple things!! Thanks very much for that. Exactly what I needed!!

Cheers!

FF

PS. I will have two shots of Scotch tonight in Harpye's honour!!!

I also just noted that I am only 26,934 posts behind vintage!!
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Old Nov 17, 2009, 12:14 AM
Build it again, Sam!
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Funny ... Arbo ... I did the same http://www.rcgroups.com/forums/showa...5&d=1253809724
http://www.rcgroups.com/forums/showa...4&d=1253287733

http://www.rcgroups.com/forums/showa...5&d=1253266877

http://www.rcgroups.com/forums/showa...9&d=1253134487

Float flyer.... safe a glass for me ...
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Old Nov 19, 2009, 01:43 PM
Build it again, Sam!
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Tried to sort out my pics and found some renderings I did .. just to show...
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Old Nov 19, 2009, 03:23 PM
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Originally Posted by mcg View Post
tsplines can do many other things, but this procedure for using 3 views to sculpt a box into a fuselage or hull or whatever particularly interested me. The finished shape can be converted back into NURBS (that is, into a Rhino object) at one click.
Just stumbled onto this Rhino thread. Yaay! (Im a v4 user).

Im particulalrly interested in the mention of Tspline plugin. Has anyone done much aircraft related TS/Rhino work they can share? (or maybe under a different thread if more appropriate). Im trying to understand the general workflow concept, is it best to 'start out' with TS to get nice smooth nurbs surfaces, then 'proceed' to rhino for other details, slicing for structural components etc? Any good related TS tutorial material links?

Re rhino, one thing I still struggle with is making nice fillets on the wing/fuse intersections. Especially 'top wing' models where the wing is only slightly submerged into the fuse profile. If you have techniques or samples Id like to see them.
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Old Nov 19, 2009, 04:49 PM
Build it again, Sam!
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Easy or scale ????? An easy way is to create the seams using panellines from procections or similar and intersecting those with wing an d fuse... afterwards to create single fillets as splines and mesh the whole thing.....
as most fillets are not 90 of an arc they are fre form surfaces ...
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Old Nov 19, 2009, 06:03 PM
Sink stinks
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United States, GA, Atlanta
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So, TurboCAD has this functionality when drawing or adjusting called SEKEs, Single Equivalent Keyboard Entries, which are essentially hotkeys for snaps. So as I'm drawing a line, if I want to use a snap like vertex snap when it's not enabled, I can just put the cursor over another line and press 'v' and it will automatically snap to the vertex. So instead of constantly enabling and disabling different snaps, I can just use the SEKEs whenever I want. It saves a whole lot of time. Does Rhino have anything like that?

Also, with TurboCAD I can select an object and move it very easily by entering values into boxes at the bottom for delta x, y, and z, or I can easily enter in a rotation around x, y, or z. Can you do that in Rhino?

I've been playing with the trial and I really like all the 3D modeling functionality but it seems to lack some of these basic features that make life easy.
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Old Nov 19, 2009, 08:18 PM
KE your cub.
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in the gutter, again....
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In rhino I use the Osnap menu. It's generally at the bottom
you tick boxes of whatever you want to snap to and it uses the smart cursor method where you can scan over an object or curve and it will tell you what it can snap to.

Takes a little getting used to but once you're rolling, it's easy.

Heres some of my work.
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Old Nov 19, 2009, 08:57 PM
Stranger in a land
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Hawaii
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Quote:
Re rhino, one thing I still struggle with is making nice fillets on the wing/fuse intersections. Especially 'top wing' models where the wing is only slightly submerged into the fuse profile. If you have techniques or samples Id like to see them.
On a high-wing model, it's easiest to use a variable fillet between two surfaces; those being a fuselage side and the lower wing skin. Rhino doesn't like to create projected fillets such that you'd want to see off of the trailing edge in some cases, so the workaround there is to take a root airfoil section, project it to the side of your fuselage a little enlarged, then draw the leading and trailing edges so that you can sweep2 or split it into upper and lower curves and use curve network.

As always, use the preview button to fiddle with your handles until the surface is pretty and fair. Takes some mucking around.

I'd love to comment on your T-spline question as it seems to me a very natural workflow for when you want to create some from a visual concept and not loft an existing 3-view drawing. Being able to so finely manipulate the surfaces with so few handles looks exactly like I would prefer to work, then convert to NURBS and do the slicing and dicing.

Nice renders you guys, what is your rendering engine of choice for the above samples?

Here's some fillets...

Carl
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Old Nov 19, 2009, 10:39 PM
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Originally Posted by Montag DP View Post
Also, with TurboCAD I can select an object and move it very easily by entering values into boxes at the bottom for delta x, y, and z, or I can easily enter in a rotation around x, y, or z. Can you do that in Rhino?
Rhino uses inputs similar to autocad. When moving an object, you can type in the world or relative coordinates to move the object to.

For example, if you select an object, start move, and type in 2,2,2 , the object will move to 2,2,2 in world coordinates. If you want to move the object 2 units up and 4 units in the z direction, you would type @2,0,4 . The @ is for relative coordinates. You can also use R , but @ is an autocad thing and what I'm used to.You can also tell it to move a certain distance at an angle, such as @4<45 or just type <45 and it will constrain your movement along a 45 degree line.

For a 2d rotation, you start rotate, pick the central axis, the start point can be arbitrary and then just type in the angle you want to rotate. 3d rotation is a bit different.

I would recommend going over the level 1 book that comes with the manual. It goes through the basic commands and shortcuts.
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Old Nov 19, 2009, 11:13 PM
Sink stinks
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United States, GA, Atlanta
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Originally Posted by nristow View Post
Rhino uses inputs similar to autocad. When moving an object, you can type in the world or relative coordinates to move the object to.

For example, if you select an object, start move, and type in 2,2,2 , the object will move to 2,2,2 in world coordinates. If you want to move the object 2 units up and 4 units in the z direction, you would type @2,0,4 . The @ is for relative coordinates. You can also use R , but @ is an autocad thing and what I'm used to.You can also tell it to move a certain distance at an angle, such as @4<45 or just type <45 and it will constrain your movement along a 45 degree line.

For a 2d rotation, you start rotate, pick the central axis, the start point can be arbitrary and then just type in the angle you want to rotate. 3d rotation is a bit different.

I would recommend going over the level 1 book that comes with the manual. It goes through the basic commands and shortcuts.
Hey, thanks for the tips. I only evaluation copy demo from the website, so I don't have any manual.
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Old Nov 20, 2009, 10:38 AM
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Originally Posted by Haole View Post
..so the workaround there is to take a root airfoil section, project it to the side of your fuselage a little enlarged, then draw the leading and trailing edges so that you can sweep2 or split it into upper and lower curves and use curve network.. Here's some fillets...
Carl
Thanks Carl. Those are nice.

That sounds like the general methodology I eventually started to figure out. I vaguely recall not being able to do it entirely with rails & messed around with curve network. Hopefully these pics will illustrate the wing/fuse relationship I was trying to model. What makes it kind of complicated (to me) is I can't project the entire root profile onto the fuse because the wing is only partially submerged into the top of the fuse (vs something like a mid-winger where the root would project entirely). So in my case, the fillet kind of wraps around the LE portion on the upper surface + entirely on the lower (saddle)surface + then then kind of a dart shape extending off the TE into the fuse. I guess you would have the same issue upside-down on a low-winger & Ive seen some nice examples of that.

I thought I had a solution by making both the fuse & wing panel 'solids' & using solid filleting. But that starts to fail pretty quick, presumably with non-uniform shapes, Im not entirely sure why.

What seems so easy with a rounded popsicle stick & putty filler is a bit more complicated in the 3d cad world.
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Old Nov 20, 2009, 10:49 AM
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Here are some of my rhino relics of an electric model (round cells... what are those ). Anyway, I was using rhino's 'analyse' tools to locate centroids of the bits & pieces, then with a simple spreadsheet & known weights, figuring out c/g & then altering component layout accordingly. Never built the model, but did come to appreciate the power of 3d cad, especially on these space cramped models. - Peter
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Old Nov 20, 2009, 12:12 PM
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East Anglia, UK
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Originally Posted by ptxman View Post
Thanks Carl. Those are nice.

That sounds like the general methodology I eventually started to figure out. I vaguely recall not being able to do it entirely with rails & messed around with curve network. Hopefully these pics will illustrate the wing/fuse relationship I was trying to model. What makes it kind of complicated (to me) is I can't project the entire root profile onto the fuse because the wing is only partially submerged into the top of the fuse (vs something like a mid-winger where the root would project entirely). So in my case, the fillet kind of wraps around the LE portion on the upper surface + entirely on the lower (saddle)surface + then then kind of a dart shape extending off the TE into the fuse. I guess you would have the same issue upside-down on a low-winger & Ive seen some nice examples of that.

I thought I had a solution by making both the fuse & wing panel 'solids' & using solid filleting. But that starts to fail pretty quick, presumably with non-uniform shapes, Im not entirely sure why.

What seems so easy with a rounded popsicle stick & putty filler is a bit more complicated in the 3d cad world.

Indeed. I've played with solid filleting a LOT and it works as long a there are no discontinuities in the edges to be filleted. If there is the slightes high value rate of change in the edge whatever algorithm they use blows up, and things shoot wildly off in all directions.

Its necessary at every stage with Rhino to keep curves smooth, by fairing, and to use loose lofting with low point counts, if you want to use blending fillets.
.

Sometimes you can use the fillet command to create a surface that works but doesn't attach: Then its possible to use it to generate a swept surface that you can turn into a slid, and boolean union that with the main parts.

Building complex surfaces is the hardest challenge really. I managed to do a canopy yesterday using curve networks..something I hadn't tried before, and that worked very well, but only after the curves had been manually edited and adjusted.

To me, getting the surface of the aircraft right, with proper manifold surfaces, is the biggest challenge, after that forming structure out of intersecting trimmed solids is mechanical grunt work, and the demeshing of those to flat cuttable sheet parts, is again, not hard. Just tedious

Another tip I found the hard way, is not to develop detailed surfaces into solids. Make them solids when simple, and then carve out bits later. I.e. lofting sweeping to generate surfaces works best on simple shapes, and surface offsetting works best on simple surfaces to develop sheets of 'thickness'

Likewise when making solids try and always use a much more easily manipulable curve to sweep what you want, rather than apply post solid shaping..an example is a round ended rod. Its FAR easier to rotate its cross section, than try and smooth the end off a cylinder.

IN short you have to learn what works well in a given instance: There is no one technique that always works.

Faced with really screwed up surfaces, I have even been known to take cross sections, repair and FAIR the curves and re-loft. Arguably if this thread had been going earlier, I wouldn't have gotten into that mess..but its always there as a last resort.
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