View Single Post
Old 07-14-2024, 11:28 PM   #59 (permalink)
JohnForde
EcoModding Lurker
 
Join Date: Nov 2023
Location: MN
Posts: 93
Thanks: 35
Thanked 99 Times in 63 Posts
Quote:
Originally Posted by JSH View Post
A constant 19 degree angle is unlikely to keep the flow attached. GM did not design that rear trim for optimal aerodynamics.

You won't know until you test but if you are using straight panels I would shoot for 15 degrees. I would do some research on Class 8 trailer tails and see what angles they are using. No reason to reinvent the wheel.

As Aerohead said - it is a trade-off between build complexity, practically, and aerodynamic performance.
I actually think GM designed the cuff primarily for aerodynamics. But I am wondering if it is designed to allow flow separation but have some other benefit.

3" of rise over a 10" run is about 17 degrees.

Weather should be good here starting Tuesday so I may have a working, adjustable prototype late in the week and do some testing: both tuft and efficiency.
Attached Thumbnails
Click image for larger version

Name:	IMG_20240710_094612074_HDR.jpg
Views:	14
Size:	61.0 KB
ID:	34889   Click image for larger version

Name:	IMG_20240630_182132471.jpg
Views:	13
Size:	38.9 KB
ID:	34890  
  Reply With Quote
The Following User Says Thank You to JohnForde For This Useful Post:
aerohead (07-15-2024)