EcoModder Forum whats the mathmatical forumula for ideal template curve?

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 08-12-2010, 06:19 PM #1 (permalink) EcoModding Apprentice   Join Date: Jun 2010 Location: CT usa Posts: 224 Thanks: 11 Thanked 7 Times in 6 Posts whats the mathmatical forumula for ideal template curve? Whats the mathematical formula for ideal template curve?
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 08-12-2010, 06:37 PM #2 (permalink) Master EcoModder     Join Date: Jan 2008 Location: Sanger,Texas,U.S.A. Posts: 14,174 Thanks: 22,030 Thanked 6,610 Times in 4,161 Posts equation for 2.5:1 teardrop My template is based on a Zeppelin airship,teardrop form,with a length to diameter ratio of 2.5:1. Teardrops as short as 2.1:1 have the same Cd,but if you use them for a template,out at 80% aft-body they violate Mair's maximum boat tail tangent angle of 22-degrees. The 2.5:1 'body-of-revolution was the 'shortest' teardrop I could come up with that maintained the 22-degree angle limit at 80% of potentially useful length.Teardrops with greater fineness ratios will begin to accrue additional drag due to increased skin-friction from the additional wetted area. Someone with a calculus background could probably help write the equation for the curvature. 'Apology for the rough graphic of the template.At larger scale,a french curve could be used for curve smoothing to take the 'bumps' out.
 08-12-2010, 09:08 PM #3 (permalink) EcoModding Apprentice   Join Date: Jun 2010 Location: CT usa Posts: 224 Thanks: 11 Thanked 7 Times in 6 Posts I wanted to know 1 curiosity 2 to get better resolution 3 If i build a boattail with 4 or curving 6 sides the edges im going to have to cut is going to be the template curve multiplied by the template curve.
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Quote:
 Originally Posted by aerohead .... Someone with a calculus background could probably help write the equation for the curvature. 'Apology for the rough graphic of the template.At larger scale,a french curve could be used for curve smoothing to take the 'bumps' out.....
I think that the curve could be curve could be duplicated by developing a polynomial curve fit.

It would take a little doing up-front to 'prepare' the data by developing a curve that has a gradually increasing radius, and build a data set for generating the polynomial coefficients.

Maybe someone with fresh calculus background can do it faster, but I'm reasonably sure it can be done by other means as well.

Jim.