View Single Post
Old 05-11-2020, 05:26 PM   #8 (permalink)
Master EcoModder
aerohead's Avatar
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 11,229
Thanks: 17,998
Thanked 5,976 Times in 3,633 Posts

Originally Posted by JulianEdgar View Post
Did you look at the video I did on the Porsche Cayenne, linked in the above post? They quote real data from a real car which supports what I said. (And of course, there are plenty of other examples of this on other cars.)

And streamline bodies cannot create lift? Unless you are using a unique definition of what streamlining comprises, streamline bodies can certainly create lift!
*The Cayenne's aft-body is mutilated,allowing a moment arm extending rearwards,beyond the greenhouse,of which the low pressure of the turbulence can act to produce lift.The Jaguar I-pace has the same flaw,as well as others.
*If the roof-line and greenhouse are extended,separation-free,along with the lower body,to the end of the vehicle,the entire wake is of uniform low pressure,and cannot act vertically to produce lift,as you've eliminated the moment arm.
*A streamline body,by definition,is separation free.As a drag-minimum body,they are in the 'bucket',as Abbott and Von Doenhoff would describe it,at an angle-of-attack which is incapable of generating lift.Yes,the growing longitudinal cross-section does produce accelerated flow and lower pressure as per the Bournoulli Theorem,however,any' lift' generated by the differential there is cancelled by the high pressure attacking the forebody,and pressure recovery over the tail.They are a zero-lift shape.
I know that you are prejudiced about data from non-moving floor wind tunnels,but I'll mention that Spirit of Ecomodder measured essentially zero lift at DARKO,at 135-miles per hour,Cd 0.218 as a BEV, 128-mph speed potential according to one of the racing teams at Bonneville,and with a nearly 50-50 weight distribution,was rock solid cruising at 108-mph on the interstate highway in Arizona,in a crosswind.Everything done to the truck was inspired by Jaray's research of 1922.
Photobucket album:
  Reply With Quote