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plasticuser · 01-19-2013, 08:14 PM

How I arrived at my curve:

I decided that many people have already done good research on the terminal angle for the aerolid - I think there's a consensus that the final angle in Bondo's design is perfect. However, I wanted to have a curve that happened a little later to maintain headroom inside the bed.

I took a 1x8 board, and angled the two ends so it would sit in position, with 2" of fixable surface at the front, and 1" of height at the back. There is over 4" of contact on the bottom edge.

From here, I drew a line at the terminal angle from the back, and a line level with the roof from the front. I then got a piece of PVC pipe and made it into the curve that naturally intersected the lines I'd drawn at both ends.

This gave me an even curve. I didn't want that, but wanted more of the curve biased towards the front of the lid, and the rearward portion to be a flatter curve.

I printed out a few side images of others' aerocaps, cut them out then stood back and compared them with my drawn curve. A couple of tweaks and I was happy with my curve, just by gut feel.

I rough cut it on a table saw, as straight lines within 1/4" of the intended curve. Then I created the curve on the table saw, which I find the most accurate way of making large diameter curves.

I used a belt sander and my eye to take out a couple of 1/16" variations, and ended up with a curve I am completely happy with.

Next, I'll duplicate the curve to three more pieces of 1x8. I'll make two pairs, then drill a hole for a nut/bolt/washers hinge about 3" from the front. My idea there is to let the hatch open and have an EPDM rubber strip sealed to both sides of the hinge outside so it is flexible, doesn't interfere, and is aerodynamic.

Also, I note there's a gap between the cab and the front of the cap. I intend to put a curved piece of wood in there to bring down the gap to 1/2", then fill and shape the section with foam to create a more smooth join.

01-19-2013, 08:14 PM	#2 (permalink)
plasticuser EcoModding Lurker Join Date: Jun 2011 Location: Austin, TX Posts: 74 Annette - '04 Ford F150 FX4 Penelope - '08 Mazda CX-7 Sport 90 day: 23.47 mpg (US) Thanks: 10 Thanked 27 Times in 15 Posts	How I arrived at my curve: I decided that many people have already done good research on the terminal angle for the aerolid - I think there's a consensus that the final angle in Bondo's design is perfect. However, I wanted to have a curve that happened a little later to maintain headroom inside the bed. I took a 1x8 board, and angled the two ends so it would sit in position, with 2" of fixable surface at the front, and 1" of height at the back. There is over 4" of contact on the bottom edge. From here, I drew a line at the terminal angle from the back, and a line level with the roof from the front. I then got a piece of PVC pipe and made it into the curve that naturally intersected the lines I'd drawn at both ends. This gave me an even curve. I didn't want that, but wanted more of the curve biased towards the front of the lid, and the rearward portion to be a flatter curve. I printed out a few side images of others' aerocaps, cut them out then stood back and compared them with my drawn curve. A couple of tweaks and I was happy with my curve, just by gut feel. I rough cut it on a table saw, as straight lines within 1/4" of the intended curve. Then I created the curve on the table saw, which I find the most accurate way of making large diameter curves. I used a belt sander and my eye to take out a couple of 1/16" variations, and ended up with a curve I am completely happy with. Next, I'll duplicate the curve to three more pieces of 1x8. I'll make two pairs, then drill a hole for a nut/bolt/washers hinge about 3" from the front. My idea there is to let the hatch open and have an EPDM rubber strip sealed to both sides of the hinge outside so it is flexible, doesn't interfere, and is aerodynamic. Also, I note there's a gap between the cab and the front of the cap. I intend to put a curved piece of wood in there to bring down the gap to 1/2", then fill and shape the section with foam to create a more smooth join.