More drag reduction studies

[California98Civic]

Originally Posted by PaleMelanesian

Outstanding! Too bad I can only give you one Thanks for that post.

What he said.

[aerohead]

Originally Posted by Sven7

I've been thinking about this some more. Do you think a sedan owner could create a plexiglass baseplate sticking up vertically from the trunk edge, essentially creating a phantom Kammback? This would be less intrusive than making the trunk unusable but would it give meaningful drag reduction?

Could you do a 'back of the napkin' sketch,I'm having difficulty visualizing this.Sorry!

[California98Civic]

I honestly don't think so:



Though perhaps a little depends on how high your vertical plexiglass plate rises from the trailing edge of the trunk lid?

james

[aerohead]

Originally Posted by California98Civic

I honestly don't think so:



Though perhaps a little depends on how high your vertical plexiglass plate rises from the trailing edge of the trunk lid?

james

I don't know the source of the pictorial drag table and associated Cds,but the numbers aren't in agreement with anything I've ever seen.

[California98Civic]

Originally Posted by aerohead

I don't know the source of the pictorial drag table and associated Cds,but the numbers aren't in agreement with anything I've ever seen.

Oh, darn. Nevermind. That's what I get for avoiding looking things up and just trying to get relevant info quickly. Sorry. But it is true that a vertical plate will have high drag, no?

[aerohead]

Originally Posted by California98Civic

Oh, darn. Nevermind. That's what I get for avoiding looking things up and just trying to get relevant info quickly. Sorry. But it is true that a vertical plate will have high drag, no?

Yes,next to a parachute they have about the highest drag.
Hoerner,Fachsenfeld,and Hucho(who uses Hoerner) show around Cd 1.11 for a flat plate.
'Conventional' parachutes are Cd 1.35
A 1906 Buick Model C Touring Car was measured at Cd 1.03 according to Tremulis.The highest drag ever measured for an automobile.
CAR and DRIVER's Don Sherman who did the Crisis Fighter Pinto and Z-Car found that when rear spoilers went above a 30-degree angle(from the horizon)that drag began to grow higher.
The Guerney Flap is vertical,but does not project vertically very far.Maybe an inch for the Ford Torino Talledega of 1969.

[riddleyo]

Originally Posted by Sven7

I've been thinking about this some more. Do you think a sedan owner could create a plexiglass baseplate sticking up vertically from the trunk edge, essentially creating a phantom Kammback? This would be less intrusive than making the trunk unusable but would it give meaningful drag reduction?

Originally Posted by aerohead

Could you do a 'back of the napkin' sketch,I'm having difficulty visualizing this.Sorry!

I think he is talking about these. I've seen them used in autocross to impart downforce on the rear tires, but if they are properly sized, it may create the "Phantom Kammback" effect we are seeking.

[aerohead]

Originally Posted by riddleyo

I think he is talking about these. I've seen them used in autocross to impart downforce on the rear tires, but if they are properly sized, it may create the "Phantom Kammback" effect we are seeking.

Thanks for the images.
Since the context of the photos is 'auto-crossing',then I'm presuming that the racers are trading speed for downforce (since highest attained speed in autocross is relatively low in comparison to other track racing).
Every example shown would incur a MPG penalty.Careful 'tuning' of size and angle could achieve a drag minimum at zero-yaw,but in a crosswind the benefits would be dubious.
For $2,000/hour,at Lockheed-Marietta you could find out.Eventually.

[Vekke]

I got a tip of this saab study today:
http://publications.lib.chalmers.se/...ext/143210.pdf

[paconassa]

Originally Posted by euromodder

You'll find them here, amongst other stuff:

dropbox com/sh/52o49bkrua0tb5m/0qtRLnijtK/ecomodder_studies

Could you share this again?

Does someone have this files?
Thanks!