Conical vs Ogive, or eliptical or von karman...

I guess I can see why conical is convex, but not why elliptical is concave? Seems that with an elliptical transition the angle at the join is 180 degrees?

That's fine, thanks for taking the time to answer.

Reply to
Darren J Longhorn
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Thank you. I will look up "wetted surface area".

Reply to
Darren J Longhorn

Thanks. I'm not actually trying to optimise a nose cone for a particular rocket and flight profile, just explain the difference in what I noticed in rocksim. I think I'm getting a feel for it now.

Reply to
Darren J Longhorn

A transition with a 180 degree angle is just a coupler. A transition goes from one size tube to another. The joint at the larger tube is convex; the joint at the smaller tube is concave (or else the transition itself has a concave angle somewhere in it). You can't have a transition without a concave angle or curve somewhere.

Reply to
David

I understand what you're saying now, I thought you were just referring to the angle where the transition joined the aft bodytube.

Reply to
Darren J Longhorn

Paint area...

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow

I've never heard the terms "concave" and "convex" used to refer to angles before. I've only heard them in terms of surfaces.

The terms I've heard for angles are:

Acute angle (less than 90 degrees) Right angle (exactly 90 degrees) Obtuse angle (greater than 90 and less than 180 degrees) Straight line (exactly 180 degrees) Reflex angle (greater than 180 degrees) Those Northumbrian bastards (usually spoken by Saxons)

The cross-section of every rocket transition I've ever seen has had a pair of reflex angles (going from the largest tube to the transition shroud), and a pair of obtuse angles (going from the transition shroud to the smaller tube:

______ \ \_______

_______ / ______/

The surface of the rocket in a small patch centered on a point on the vertex of the large-to-shroud angle is definitely convex, as you stated. However, the surface of the rocket in a small patch centered on a point on the vertex of the small-to-shroud angle is most definitely *not* concave. It is, rather, saddle-shaped, like a Pringle's potato crisp. It curves downward to the sides, and upward to the fore and aft.

- Rick "Amateur topologist" Dickinson

Reply to
Rick Dickinson

Some transitons can themselves be sections of ogive nose cones (ie Bumper V-2 w/Wac Corporal, or other shapes).

(going from the largest tube to the transition

Reply to
Jerry Irvine

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