Advice on aero-cap shape

[t vago]

No problem. Let us know if you decide to build something like this for your truck.

[hat_man]

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.

[hat_man]

It's not letting me upload my pictures. Something about a security token missing? I'm not a computer guy so I don't even know what that means. The pics are ones I took with my digital camera then moved to a folder on my desktop. Any ideas?

[hat_man]

I'll try again. I think the pics were too big.

[Xist]

Originally Posted by hat_man

I'll try again. I think the pics were too big.

Sometimes, instead of scaling my images, I post them privately (nobody can see them but me) on Facebook, and then link them, but many members use sites like Photobucket.

[JRMichler]

I like it. Could you add a closeup picture showing how you fastened the pieces of EMT to each other?

[hat_man]

Here you go JR.

I took steel 1/2" steel EMT couplings and drilled out the little nub on the inside that keeps the coupling from sliding all the way down the pipe. The two screws on the coupling are between the "jaws" of the workbench I used. Then filed off the crud so the coupling would slide down the pipe. This made assembly much easier. Then I had a friend tack weld the couplings together to make the T shaped pieces on the bottom and the stacked pieces on the top of the picture. The stacked pieces are for the "sliding" idea I have to have access to the bed. or at least as much of it as I need. That's the next step after I get the shape right. It works in my mind but we'll see how it works in reality. Cross your fingers.

After that it was a lot of trial and error to get the pieces bent and fitted. I leveled out the old wrecked bed on the garage floor to give me a good starting point and checked it between building each rib to keep everything as level as possible. The pictures of the frame on the bed don't look very square but as I said the rain was coming. I used an angle finder to check the slope angles and a tubing cutter to give me nice square cuts on the EMT.

[hat_man]

Here's some more. The top view gives you an idea of the taper from front to back. The cab is wider than the end of the bed. The frame isn't sitting square on the test bed but you get the idea. it also shows the 3rd rib that I am still questioning. Any thoughts on changing it to the larger radius?

No comments on my pristine organized workshop either. I get enough of them from my wife.

[Xist]

[ChazInMT]

Yer a Mad Hatter Man I'd Say!!!! Awesome work man!! I think this shape you have is close to perfect, and the bigger radiuses going front to back is the ticket! It'll ensure any swirlings that may want to start are nil by keeping drastic pressure changes far from each other.

As for image hosting, make your pics like 600 wide or so at most by using any photo type software to resize the picture. Then upload it to Tinypic which is free to sign up (I just noticed that you can upload your huge raw image files from your computer to tinypic and select the "Resize -> Message Board 640 x 480" option when uploading and it'll just automatically resize it for you), once there, it gives you exactly what you need to "Cut & Paste" in the form of the [IMG\] code thing. Just click it, copy it, then paste it to your post. The image then appears here.

Like this.





If you have a big pic you want to share, what I do is grab the URL address that appears in the navigation space there in the top left when I look at a big (1200-1600 pixel wide) image that I upload to Tinypic, when in Tiny pic I click the image itself, (It says "Click for larger view" when you hover over your pic, then when a larger view appears, at the bottom left, it says "View Raw Image" when you click that, it put up your image on its own web page. The URL address you see there is what you need to Copy, then come back to you post and Highlight the AWESOME TEXT you want as a link by holding left click and dragging over your chosen text, here I highlighted Awesome text above, then while that's highlighted click the Globe Chain Icon you see above, a box appears, right click in the box, hit paste. Now AWESOME TEXT is a link to your huge detailed photo. It sounds more complicated than it is, if I didn't explain it right on accounta I'm sometimes a little bit This, let me know and I'll try to explain or illustrate it better.

I love the ecomodder site, obviously, but I find the images needing help, and big photo's just bomb the page when you paste them, that's why it's best to just host the pics off site, then link to them.