View Single Post
Old 12-02-2013, 05:03 PM   #50 (permalink)
Master EcoModder
aerohead's Avatar
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 15,274
Thanks: 23,399
Thanked 6,907 Times in 4,407 Posts

Originally Posted by Otto View Post
Granted, the airflow may stay attached on the upslope even if the entry shape is not so smooth, but per Hucho's page 158 graphics, the "optimum" nose looks a lot like that of the early Porsches, i.e., smooth, well radiused curve, with stagnation point set at ~20% of vehicle height.

I doubt we get much attachment with cars, especially after the airflow turns the front corners. A sailpane, otoh, can stay attached all the way to and sometimes beyond the thickest point of the fuselage, assuming excellent contour and surface quality. Not gonna happen with road vehicles.

I'm also curious about optimum shape of the nose as seen in planform, i.e., from above. Seems to me the lateral airflow would be best with an elliptical planform, smooth surfaces, no irregularities, as with Porsche 718.

Google Image Result for
In Hucho's 2nd-edition,p.61 "On the drag problem of a body,it might be mentioned finally that the shape of a body in front of the largest cross-section has only minor influence on the total drag.The main contributions to the drag force originate from the rear part of the body.It is not important to find a proper shape to divide the oncoming flow but it is very important to design a rear body surface which brings the divided streamlines smooth;y together.Optimum shapes are 'streamlined' bodies having a very slender rear part."
Bear in ind that the 2013 C-MAX/Focus already has a nose which is far superior to anything manufactured when Hucho penned these words.
Photobucket album:
  Reply With Quote