Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Advice on aero-cap shape

hat_man · 06-23-2013, 06:50 PM

Well I guess it's time to bring back this old thread.

I finally got a chance to get started on my aerocap. Here are some pictures. The truck sits a bit higher in the back (about 3° or so) so I don't know if the template will overlay correctly. If anyone can compensate for this then I can get a better idea if I even came close or not.

It is still in the construction stage and can be changed. That's why I am asking for everyones opinion. I know the front edge of the cap is slightly higher than the cab of the truck. The 3rd brake light is a bit of an obstruction I still have to deal with. It will match the cab height when all is said and done. I know the picture quality isn't the best. I was in a hurry to get some pictures up and it was looking like rain. Don't look at the "lines" of the garage door to try and figure out "level". The door is in bad shape as is the whole garage.

ChazInMT sent me an overlay with my truck and AST II. It looks more aggressive then AST I. I was aiming for something closer to AST II. The angles between the ribs are roughly 3.5°/7°/10.5°/14° from left to right. Level with the cab height would be 0°. My last rib (closest to the tailgate) might have to be lowered a bit. The clouds were moving in and i didn't take my time with it.

The other question I have is this. Looking at the cap from the rear you can see I used a different radius at the top edge moving from front to back. The pictures from earlier in this thread (red/blue ones) look like the top edge is rather sharp making the sides stand taller. I guess I was thinking a "softer" edge would let the air flow across the topper better. I made the radii smaller near the cab (3/4" EMT bender) to try and match the cab corners and bit larger on ribs 2 and 3 (1" EMT bender) and even larger on ribs 4 and 5 (1-1/4" EMT bender). Rib 3 is where my question is. If the "softer" radii are better closer to the rear then should I use them on rib 3 beings it is still near the middle? I already bent 2 pieces just in case as I have to return the bender tomorrow morning. Any advice on this would also be appreciated.

I haven't decided exactly how to skin it yet. I have some ideas but I'll have to experiment with them first and see if it is worth going "all in" yet.

I'll be sure to keep up this thread now that I have finally gotten a start.

Thanks for all the advice from so long ago and for any that has yet to come.

06-23-2013, 06:50 PM	#42 (permalink)
hat_man Master EcoModder Join Date: May 2010 Location: Illinois Posts: 475 Oh Deer - '03 Ford Ranger XL 90 day: 33.97 mpg (US) Thanks: 55 Thanked 91 Times in 72 Posts	Finally got started! What do you think? Well I guess it's time to bring back this old thread. I finally got a chance to get started on my aerocap. Here are some pictures. The truck sits a bit higher in the back (about 3° or so) so I don't know if the template will overlay correctly. If anyone can compensate for this then I can get a better idea if I even came close or not. It is still in the construction stage and can be changed. That's why I am asking for everyones opinion. I know the front edge of the cap is slightly higher than the cab of the truck. The 3rd brake light is a bit of an obstruction I still have to deal with. It will match the cab height when all is said and done. I know the picture quality isn't the best. I was in a hurry to get some pictures up and it was looking like rain. Don't look at the "lines" of the garage door to try and figure out "level". The door is in bad shape as is the whole garage. ChazInMT sent me an overlay with my truck and AST II. It looks more aggressive then AST I. I was aiming for something closer to AST II. The angles between the ribs are roughly 3.5°/7°/10.5°/14° from left to right. Level with the cab height would be 0°. My last rib (closest to the tailgate) might have to be lowered a bit. The clouds were moving in and i didn't take my time with it. The other question I have is this. Looking at the cap from the rear you can see I used a different radius at the top edge moving from front to back. The pictures from earlier in this thread (red/blue ones) look like the top edge is rather sharp making the sides stand taller. I guess I was thinking a "softer" edge would let the air flow across the topper better. I made the radii smaller near the cab (3/4" EMT bender) to try and match the cab corners and bit larger on ribs 2 and 3 (1" EMT bender) and even larger on ribs 4 and 5 (1-1/4" EMT bender). Rib 3 is where my question is. If the "softer" radii are better closer to the rear then should I use them on rib 3 beings it is still near the middle? I already bent 2 pieces just in case as I have to return the bender tomorrow morning. Any advice on this would also be appreciated. I haven't decided exactly how to skin it yet. I have some ideas but I'll have to experiment with them first and see if it is worth going "all in" yet. I'll be sure to keep up this thread now that I have finally gotten a start. Thanks for all the advice from so long ago and for any that has yet to come.