View Single Post
Old 07-22-2018, 12:52 AM   #8 (permalink)
freebeard
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 12,284
Thanks: 2,929
Thanked 3,988 Times in 3,163 Posts
Air brakes are perpendicular [in use]. The perforations increase turbulence over a solid plate, thus increasing drag.

For the parallel case, I saw a PDF (that DDG can't find today) on using round holes on the front of the sides of cattle trucks, over horizontal rectangular slot the length of the sides (as is the fashion) to prevent animals suffocating. So location and shape/size matter.
__________________
.
Milton Waddams: Excuse me, I believe you have my stapler...
_________________
  Reply With Quote
The Following User Says Thank You to freebeard For This Useful Post:
aerohead (07-25-2018)