cutting a solid cylinder with the "cut section" tool yields the vast majority of the time an ellipse, or probably more correctly a perimeter that looks like an ellipse. how do I establish a line tangent to a resulting perimeter that looks like an ellipse and a co-planer circle ??

if there's not currently a way to do it directly, is there a way to extract the major and minor axis from a resulting perimeter that looks like an ellipse??

Art
[email protected]

Murray-

thanks, very clever!! hadn't thought of a bounding box approach. "of course" it took a few more steps because the ellipse isn't aligned with the current work plane.... fortunately verify also provides max & min principle axis so a box can be constructed to enable replacing the perimeter that looks like an ellipse with a real ellipse. convoluted, but it gets there.....

Art
[email protected]

JL-

yes, but it's plenty good enough for estimating "clearance" center lines routing tubes.... it was a CAD mechanization question, not geometry.

Art
[email protected]

JL-

thanks! the postulated structural tubes had a huge impact on the degree of difficulty and the quality of the eventual solution. the triangular tubes pushed the exhaust aft AND pushed the point of maximum frontal area aft. without the structure "in the way", normally tube #3 defines maximum width. frontal area and taper ratio are really BIG deals in everything that influences aero drag......

Art
[email protected]