Quote:
Originally Posted by freebeard
My understanding is that The Template is a half body of revolution to insure that air doesn't want to move laterally because of pressure differentials between the top and sides, which leads to vortex generation.
If that's the case, wouldn't a half-square cross section serve as well, given equal cross-sectional area? If air is not wrapping across the edge, would no vortexes be created?
Here are three aeroforms, a cylinder, a superellipse and a square. Would their Cd be equivalent?
(These are not dimensionally highly accurate; I just eyeballed the proportions against The Template)
The next question: If the height/width proportion changes, what happens to the respective tapers? If the half revolution form is 7' wide, then it is 3 1/2' high. If the height is proportionally greater, does the side taper increase or relax?
TIA |
The streamline bodies of revolution are of the lowest drag 3-dimensional bodies known.
And their half-bodies lend themselves okay to a 2-door coupe or sedan and such.
Today's Bochum University', Cd 0.14 solar car would be a recent example.
There has been a tremendous interest in the 1948 NACA mathematical algorithm which became the 1976 Morelli shape as used by Aptera,although,with ground proximity and wheels,the Morelli form has failed to demonstrate lower drag than a half-body 'pumpkin seed.'
If you'll look at the full-boat-tail trailer thread there should be some pictorial drag tables which demonstrate the drag increase when side radii are lost on the streamline half-body.
An example would be the square fuselage of the 'Spirit of St.Louis' with Cd 0.247 and the 'round' fuselage of the Arado 'Smooth' of similar fineness ratio,at Cd 0.06.
You will never see a high performance,low drag fish,bird,airship,fuselage,submarine,torpedo,etc., with square edges.
There are a lot of graphical drag coefficient tables in the public domain from which to compare architectures.
I believe that if you will exhaust all avenues,you will come to the realization that you're not going to beat the 'Template.'I've been actively looking since 1973.