Rank: Senior Member
Joined: 6/28/2008(UTC) Posts: 648
Is it possible for any of the Conic functions in ViaCAD to do a tangent at their start and end points like Moi does in this link
http://moi3d.com/forum/messages.php?webtag=MOI&msg=2746.1 as shown in reply 12? The 'larger elliipse segment' added to Conic in Moi looks useful as well :).
Martin.
Rank: Senior Member
Joined: 2/2/2007(UTC)
Posts: 5,447
Was thanked: 502 time(s) in 353 post(s)
Originally Posted by: blowlamp Is it possible for any of the Conic functions in ViaCAD to do a tangent at their start and end points like Moi does in this link
http://moi3d.com/forum/messages.php?webtag=MOI&msg=2746.1 as shown in reply 12? The 'larger elliipse segment' added to Conic in Moi looks useful as well :).
Martin.
I like that, grabbing the conic tangents from the referenced curves! Regarding segment, we're stuck to using the quarter segment of the slice through the cone.
One thread mentioned conics were used to define airfoil shapes in the early days of aerospace. I have not heard of that before. Our airfoil creator in AeroPack needs spines to match the empirical data typically associated with how airfoils are designed.
At Lockheed we used conics extensively to define fuselage cross sections. Conics are great because they are smooth (no inflections) and you can easily increase or decrease the shape via the rho value while maintaining the end tangents. We used this feature to rapidly optimize shapes for aerodynamics where changes in cross sectional area impacted drag.
The polyconic surface is the 3D extension of the 2D conic section to surface modeling. The polyconic surface was by far the most frequently used surface in the construction of the F-16, F-22, and other military aircraft projects at Lockheed.
Tim
Tim Olson IMSI Design/Encore
Rank: Senior Member
Joined: 2/20/2007(UTC)
Posts: 302
Thanks: 6 times Was thanked: 28 time(s) in 15 post(s)
so when we build a net surface with conics it is a polyconic surface? ALBAN
Rank: Senior Member
Joined: 2/2/2007(UTC)
Posts: 5,447
Was thanked: 502 time(s) in 353 post(s)
Originally Posted by: ALBANO so when we build a net surface with conics it is a polyconic surface? ALBAN
Not exactly, but it should produce the desired results.
A polyconic surface is a procedural surface defined by a collection of law curves. The law curves define the 2D conic sections along with a spine. Types of law curves include rho, shoulder, slope control, edges, and surface edges.
The AeroPack manual describes them pretty well in Chapter 3 below.
http://www.darcorp.com/docman_uploads/AeroPack_Manual.pdf Lockheed was not the first to use polyconics. First reference I can find was the P-51. A great reference on conics, polyconics, and aircraft design is Mathematics for Computer Graphics by Roy Liming.
Tim
Tim Olson IMSI Design/Encore
Forum Jump
Punch! CAD
ViaCAD & Shark
- News and Announcements
- General
- 2D Drafting
- Surface Modeling
- Solid Modeling
- Subdivision Modeling
- Rendering & Display
- Import/Export
- Tips and Tutorials
- Suggestions
- Gallery
- PowerPack
- Punch Lounge
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.