View Single Post
Old 02-25-2012, 10:03 PM   #267 (permalink)
ERTW
EcoModding Apprentice
 
ERTW's Avatar
 
Join Date: Jan 2012
Location: Toronto
Posts: 120

Bu - '08 Chevrolet Malibu LS
90 day: 32.29 mpg (US)
Thanks: 51
Thanked 65 Times in 31 Posts
Phil, do you have a front view and a plan view of the template? I don't think I'm getting the shape right. I set ground clearance at 10% of the body thickness with sharp edges and the Cd is coming in at 0.275 :/ Do you have a solid model?

I've also taken a 4:1 rear body with a 1:1 front end (same length as a 2.5:1 ellipse) which comes out to Cd 0.247. Using a 6:1 rear body (used to model dolphins) only dropped it to 0.243. Both had a 10% fillet and 10% ground clearance. What do you think?

edit: I rounded the bottom edge (R5" or 10%)...Cd 0.191, CL ~ 0.055. Sharp leading edges are a no no! I want to protrude the nose a little into the wake, and sharpen up the trailing edge. I believe it "wants" a 20% radius on the leading edge, and ~12.5 max angle. I think 25% ground clearance is closer to your template (and helps get it above the earth's boundary layer). I'll report it asap.
Attached Thumbnails
Click image for larger version

Name:	trajectory.jpg
Views:	145
Size:	108.0 KB
ID:	10346   Click image for larger version

Name:	isolines.jpg
Views:	136
Size:	54.9 KB
ID:	10347  

Last edited by ERTW; 02-26-2012 at 12:48 AM..
  Reply With Quote