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Art Smith  
#1 Posted : Friday, January 16, 2015 1:21:30 PM(UTC)
Art Smith

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Joined: 1/16/2015(UTC)
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just upgraded to FX v9 and would now like to tackle a classic "lofting" problem, ie: one with
known bulkheads at known locations. think of it as a balsa wood bulkheads for a fuselage or hull
problem; the entire range of projects is governed by the same incompressible flow equations.......
while not new to the game, I'm very new to the digital surface modeling game and would appreciate
any thoughts on how to proceed or references to "how to" examples.

Art
Tim Olson  
#2 Posted : Friday, January 16, 2015 2:15:24 PM(UTC)
Tim Olson

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Joined: 2/2/2007(UTC)
Posts: 5,447
United States

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Hi Art

Awesome! The first CAD system I did was for Lockheed's Advanced Design group (advanced F-16, F-22, F-35, NASP, etc).

For fuselage design, we would typically start by laying out three control splines.
--upper profile
--lower profile
--half breadth

We would then add in cross sections at key fuselage stations. To do this we would first add a plane at each station and intersect the plane with the three curves. These three points would then be used to create a conic for the upper fuselage and one for the lower fuselage. Once we had in our key sections, we would create a PolyConic surface. A PolyConic surfaces use the three control splines plus the conic sections to create a fuselage. If you're familiar with how the P-51 was designed, Lockheed used this approach for pretty much all their fuselage designs.


Since there is not a PolyConic surface in ViaCAD or Shark, so you might need to substitute a Skin surface.

I still support AeroPack which is a collection of add ons for aircraft design. Rutan still uses it for most of designs.

Darcorp has some videos at their site for fuselage design that might help even without AeroPack.


Tim

Edited by user Friday, January 16, 2015 2:30:18 PM(UTC)  | Reason: Not specified

Tim Olson
IMSI Design/Encore
Art Smith  
#3 Posted : Friday, January 16, 2015 3:09:53 PM(UTC)
Art Smith

Rank: Senior Member

Joined: 1/16/2015(UTC)
Posts: 351

Thanks: 49 times
Was thanked: 43 time(s) in 30 post(s)
Tim-

outstanding, thanks!! prior to retiring, I worked in another one of their business units in Sunnyvale where it was someone else's job to deal with the aerodynamics of "launch"............

Art
m.marino  
#4 Posted : Friday, January 16, 2015 4:11:17 PM(UTC)
m.marino

Rank: Senior Member

Joined: 8/1/2011(UTC)
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Very interesting as I am working on a hull at the moment.

Schooner based of the SV Tree of Life; which is a Ted Brewer design. This being a hull design I started with knowns (LOA, Beam, Draft, known freeboard) from that I set up stations based on a structural known for the material I plan on working in which gave me a station point every 21". from there used arcs and splines to rough in the frame and skins to give it shape. The more reference lines the smoother for complicated curves but otherwise it did a wonderful job of setting up an excellent skin to work from and start setting up internal tanks and bulkheads. I am using ViaCAD Pro V9 x64 beta on this to try and break the Beta (current build). Side note to Tim, haven't broke it yet but still trying.

Have fun and enjoy as this is all so the software I do work for clients with (though not the Beta, even though it is temping). Between ViaCAD and Aspire there is not much I can't get done quickly and effectively for a client.

Michael
SharkCAD Pro v10 w/ PowerPack Pro
Lenovo D20 2x E5620 w/ 64GB RAM, Nvidia 1060
OS: Windows 10 Pro x64
MM0MSU



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