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Alan Bransom  
#1 Posted : Tuesday, January 21, 2014 11:18:31 PM(UTC)
Alan Bransom

Rank: Junior Member

Joined: 4/14/2007(UTC)
Posts: 17

Hi Guys,
Quite sometime ago it was mooted that 3D compound curves: aircraft wingtips and the like, coupled with airfoil sections, was in the process of development. Diagrams of tool icons were shown at the time with a request for submissions as to what these tool should be named. I am currently running 2D3D v8 and have just looked at the tool palette for v9 and the (beta) Pro v9 and don't see anything like these functions. Has the idea of including these functions been dropped or can they be achieved using existing functions? I have done many wing tips in the past but have never managed to successfully close off the leading and trailing edge compound curve.
Regards,
Alan.
blowlamp  
#2 Posted : Wednesday, January 22, 2014 5:14:42 AM(UTC)
blowlamp

Rank: Senior Member

Joined: 6/28/2008(UTC)
Posts: 648

Can you post a picture of the shapes you need to make?


Martin.
Alan Bransom  
#3 Posted : Thursday, January 23, 2014 7:50:04 AM(UTC)
Alan Bransom

Rank: Junior Member

Joined: 4/14/2007(UTC)
Posts: 17

Hi Martin,

It's been a while since I added an attachment, so here goes. The ViaCAD skin shows the areas that are difficult to complete and always leaves an open end.
The shot of the model tip shows how it should be. Even the ViaCAD model isn't really usable as it shows an error message when the drawing is reopened, 'inconsistent edges'. I've shown the tip transparent so that you can see the structure.

Thanks for the quick response.

Regards, Alan.
Alan Bransom attached the following image(s):
ViaCAD Skin.jpg (65kb) downloaded 1 time(s).
Model wing tip.jpg (32kb) downloaded 0 time(s).

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ZeroLengthCurve  
#4 Posted : Thursday, January 23, 2014 5:08:29 PM(UTC)
ZeroLengthCurve

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In you attachment VIACAD Skin.jpg, I think I see the "open" wing tips you need to close.

Have you tried with the gripper to see if you can "rotate" sweep a surface from one section 90 deg or along an arc to the next position?

If the Gripper cannot help, try using one of the sweep tools. I'd probably start by creating a surface at one of the sections and sweep along the arc to the next, or some variation of that.

Also, try the Guide Skin Surface tool. You might have to duplicate one of the curves and then scale it, or maybe two of them, so that VCP/Shark can have enough curves to form a surface correctly. Try differnt orders in your selection of "Select curves for skin surface" and "Select guide curves".

Thanks, tho, for posting your question, as it reminds me I must reexamine my own model (5-bladed, skewed, raked, CP) propeller.
Alan Bransom  
#5 Posted : Friday, January 24, 2014 6:08:26 AM(UTC)
Alan Bransom

Rank: Junior Member

Joined: 4/14/2007(UTC)
Posts: 17

Thanks for the rapid response. Unfortunately only having ViaCad 2D3D my palette of tools are a little limited. I have tried several surfacing techniques within the confines of that limited palette, all of them unsuccessful. The major problem is that the curve shape of the leading edge is significantly different to the curve profile that extends around the wing tip. The trailing edge is not too different but it still will not close completely. I think I may have to resort to making it in solids, seeing that a sphere can be stretched and manipulated, then I'll split and shell it.
Thanks for the help guys. You could probably do a prop this way too, now that there is a twist function in the solids palette.

Best regards, Alan.
zumer  
#6 Posted : Monday, January 27, 2014 7:52:01 PM(UTC)
zumer

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Joined: 11/4/2007(UTC)
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Your problem is degeneration in the corners where the tip ribs are orthogonal to the wing ribs. You can overcome this by not having the profiles intersect at that corner, although they can come very close to it. If necessary, a minute cover surface is possible to fill the hole, as I've done here, but it's only really essential if you want to build a manifold solid.
File Attachment(s):
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Alan Bransom  
#7 Posted : Tuesday, January 28, 2014 1:02:02 AM(UTC)
Alan Bransom

Rank: Junior Member

Joined: 4/14/2007(UTC)
Posts: 17

Thanks for the file, it looks pretty slick until you come to thicken it to skin thickness. Then you get an ACIS Error. (No loop through new edges and vertices_ Thick Solid 1423) what that means I have no idea. I will give it a try in my VC 2D3D v8 I noticed yours was Shark, if it was Pro it might be just a little more able than mine. The whole idea is to be able to 3D model the aircraft in its complete airframe so that skinning the wing creates all the rib profiles, the same goes for the fuselage formers. Many years ago, back in the days when TurboCAD was born out of Concepts there was a program that slotted into Concepts, that did these things. For reasons I forget, it dropped out of sight. After what I had readmentioned in my first post, I thought it was returning.

Thanks again,

Regards Alan.
Tim Olson  
#8 Posted : Tuesday, January 28, 2014 1:22:13 AM(UTC)
Tim Olson

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Hi Alan

if you can post a file with your upper/lower wing surface plus profile of tip, I'll give it a go. I've done wing tips before and they are not trival. Darcorp did a live demo at OshKosh airshow a few years back using aeropack and polyconic surfaces which takes several hours. I'm game for giving it a go with tangent cover with guide surfaces in shark.

TIm
Tim Olson
IMSI Design/Encore
Alan Bransom  
#9 Posted : Tuesday, January 28, 2014 1:45:09 AM(UTC)
Alan Bransom

Rank: Junior Member

Joined: 4/14/2007(UTC)
Posts: 17

Hi Tim,

Quite like old times. I'll post the same file I posted earlier, though this has the skin thickened. As you will find the abutting skin edges are anything but congruent even though they were generated from the same profiles. I realise my profiles are a little wider than I would usually use but this was just for an example.

Thank you for coming to my aid again. You might also like to look at my latest posting regarding a 'glitch' in Workplanes that I have never experienced in earlier versions.

Regards and thanks again,

Alan.
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Wing Trial.vc3 (251kb) downloaded 1 time(s).

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ALBANO  
#10 Posted : Tuesday, January 28, 2014 3:54:25 AM(UTC)
ALBANO

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Hi Alan,
I had quite good results in using tangent cover.
Build your wing profile with upper and lower surface. cut away enough of the leading edge radius so the tangent cover command resembles the profile.
cou can cut the upper and lower win panels with a curve bending towards the trailing edge. You end up with one edge on the upper and lower panel resembling the leading edge and extending into the wingtip root. Now you cover the gap and you end up with a smooth transition between leading edge and tangent continuous wingtip.
Only Problem is: making a solid of it and doeing subsequent operations can deteriorate the quality of the surface....always check!
I have brought that up a time ago. Tim, is there a solution to this?
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Alan Bransom  
#11 Posted : Tuesday, January 28, 2014 7:47:50 AM(UTC)
Alan Bransom

Rank: Junior Member

Joined: 4/14/2007(UTC)
Posts: 17

Sweet looking wing, has me positively drooling. The term 'Tangent Cover' doesn't show up on my ViaCAD 2D3D v8 tools menu so am I to assume this is Pro and maybe v9. If so it looks like I'm about to spend some money.

I really do appreciate all the work you guys have been doing it won't go to waste. Thanks muchly.

Regards,

Alan.
Alan Bransom  
#12 Posted : Wednesday, February 5, 2014 7:36:53 PM(UTC)
Alan Bransom

Rank: Junior Member

Joined: 4/14/2007(UTC)
Posts: 17

Hi Guys,

The problem is resolved, it was there all the time. I was unaware that Points could be used multiple times in lieu of a Curve, thus allowing a fan of arcs to produce a curved shell. This is what I produced at my first attempt, the nose shell is replicated in a much smaller size at the rear of the form. It may not be a wing tip but it is part of a good looking wheel spat. The construction is Net Surface.

Thanks again,

Regards,

Alan.
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