Aerodynamics Research on Vehicle Modifications
 

I did some research for college credit and tested various vehicle modifications to figure out Cd changes.
I ended up testing wheel well covers, vortex generators, and belly pans on all of the vehicles. I also tested tonneau covers, camper shells, and angled bed covers on the two pickups.
The results I got were fairly consistent with what I've been seeing on the website here, but there were a few results that were kind of surprising.
I'll get my results posted here and if you have any questions, just ask me!

(the vehicles I used are also listed on ebay if you would like to try to prove or disprove my results)

Results
 

Took me a few minutes to be able to figure out how to get these posted, and I hope they work!

If I interpreted your results properly, wheel well covers lowered your Cd, but vortex generators raised the Cd (didn't see any tests on belly pans in your spreadsheet). This is to be expected since the covers would smooth out the airflow along the side of the car. Vortex generators are usually used as bandaids to try to fix or reduce an aerodynamic flaw in a car's design and, depending on their positioning, can either raise or lower a car's Cd. Since their positioning is very critical and takes a lot of research or trial and error testing to find, for most people they will end up raising the Cd.

I see you made some dramatic improvements in the F350. The belly pan was worth 12%, the bedcover 17-20%, and the VGs 2%. That adds up to a 34% reductiion in drag, to Cd=0.32, which is very impressive if I interpreted that correctly.

What are 1.ozs and 2.ozs? How did you arrive at the figures in the "All Modifications" box? If this project also generates a report, I'd like to read it.

I'd be interested in the report as well. Thanks for posting.

Very interesting stuff Stephan. Thanks for sharing. Any pictures of the modifications or description of the methods?

Very interesting. I'm looking forward to some elaboration on your testing methods and some more interperetation of the results.

I don't know why all of the results aren't showing up, unless it had something to do with converting the Office 2007 file to the standard .xls?

I hope my results paper actually shows up correctly here. If you have any other questions or comments after reading my paper, just let me know. I'm no aerodynamics major, so please let me know if I made any mistakes.

As far as pictures, I do have some pictures and videos of some of the tests, and I'll try to get at least some of the pics up here soon.

Here are pictures of the F-350, I can't find any of the others at the moment. I'll get them up as I can find them.

The first time I read this, I thought it was hilarious. Yeah, I might spend $30k on a Ford F350 on Ebay to test some aeromods on it...

But if we're dealing with models, that changes things. First, if you test a scale model in a small wind tunnel, you need to scale the viscosity of the fluid, too. That's why some scaled-down tests are done in heated water.

Second, how accurately does the scale model represent the full-sized car? These models seem pretty good, but certainly not perfect.

Professors like it when you acknowledge and understand the limitations of your work.

Btw, I couldn't read your .docx. My copy of Word 2000, with the .docx compatibility filters, says it's not a valid file.