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Piwoslaw · 03-26-2010, 10:19 AM

OK, I looked for the chart and found it. I was a little off, I got angles right, but mixed up lift (Cz) and drag (Cx). At my age, it's good I remember anything

Here are two charts, they are from Piechna's book. The data is compiled by the author from a few sources.

The first chart shows how drag first decreases, then increases, and finally airflow detaches, with the rear angle getting steeper.

The second chart is lift. When the roofline of the vehicle is flat lift is actually negative (=downforce). It grows linearly as the rear angle steepens, zeroing around 6°-7°, then abruptly falls to almost zero after 30°.

03-26-2010, 10:19 AM	#10 (permalink)
Piwoslaw aero guerrilla Join Date: Oct 2008 Location: Warsaw, Poland Posts: 3,760 Svietlana II - '13 Peugeot 308SW e-HDI 6sp 90 day: 58.1 mpg (US) Thanks: 1,356 Thanked 758 Times in 480 Posts	OK, I looked for the chart and found it. I was a little off, I got angles right, but mixed up lift (Cz) and drag (Cx). At my age, it's good I remember anything Here are two charts, they are from Piechna's book. The data is compiled by the author from a few sources. The first chart shows how drag first decreases, then increases, and finally airflow detaches, with the rear angle getting steeper. The second chart is lift. When the roofline of the vehicle is flat lift is actually negative (=downforce). It grows linearly as the rear angle steepens, zeroing around 6°-7°, then abruptly falls to almost zero after 30°. Attached Thumbnails __________________ e·co·mod·ding: the art of turning vehicles into what they should be What matters is where you're going, not how fast. "... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell [Old] Piwoslaw's Peugeot 307sw modding thread Last edited by Piwoslaw; 03-26-2010 at 11:34 AM..