Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post

aerohead · 08-05-2010, 06:37 PM

The new Beetle has 33% aft-body based on the 'Template',here are some comparison Cd's based on the roof/body style for a car of 36% aft-body:
*New Beetle with separation at top of backlight,pseudo-Jaray style-Cd 0.39
*Jaray-Zeppelin/'Template' style ( no separation )--------------------------------- Cd 0.215
*Kamm model J-form pseudo-Jaray with separation @ 21% aft-body-Cd 0.33
*Kamm model K-form style ( no separation but steeper than template )--------------------------------------- Cd 0.25
* Walter Lay model 18-degree roof slope/12-degree plan-taper----- Cd 0.1975
As you can see,the Cd for a vehicle with an aft-body of this dimension is all over the map,and is a function of clean vs separated flow which has to do with tangent angles of curvature at any given point.
The Beetle,for it's aft-body length,could have Cd 0.215 by filling in the void below the 'template,' just like Carl Breer attempted with the 1934 Airflow,and AUDI does exactly with the deployed-spoiler on the TT.

08-05-2010, 06:37 PM	#21 (permalink)
aerohead Master EcoModder Join Date: Jan 2008 Location: Sanger,Texas,U.S.A. Posts: 15,908 Thanks: 23,993 Thanked 7,227 Times in 4,654 Posts	Cd comparo for New Beetle The new Beetle has 33% aft-body based on the 'Template',here are some comparison Cd's based on the roof/body style for a car of 36% aft-body: New Beetle with separation at top of backlight,pseudo-Jaray style-Cd 0.39 Jaray-Zeppelin/'Template' style ( no separation )--------------------------------- Cd 0.215 Kamm model J-form pseudo-Jaray with separation @ 21% aft-body-Cd 0.33 Kamm model K-form style ( no separation but steeper than template )--------------------------------------- Cd 0.25 * Walter Lay model 18-degree roof slope/12-degree plan-taper----- Cd 0.1975 As you can see,the Cd for a vehicle with an aft-body of this dimension is all over the map,and is a function of clean vs separated flow which has to do with tangent angles of curvature at any given point. The Beetle,for it's aft-body length,could have Cd 0.215 by filling in the void below the 'template,' just like Carl Breer attempted with the 1934 Airflow,and AUDI does exactly with the deployed-spoiler on the TT.