Aero Truck Cap Manufacturing

[MetroMPG]

I agree with the comments about the sharp transitions and the too "fast" looking slope.

For best marketing efforts (and for addressing the skeptics here and everywhere), you'll want to run a well-documented A-B-A test with the cap on & off at a range of speeds to demonstrate its effectiveness.

http://ecomodder.com/forum/showthrea...ery-11445.html

Where in Ontario are you?

I applaud your initiative!

[Big Dave]

Looks good. I like how it tapers in the plan view.

My old plywood and rubber apparition looked a lot the same. But you have a lid and that makes it much more practical.

I would offer an improvement. Don't carry your cab bulkhead section so far back. 6 inches max. then begin a smooth transition into your slope. Also you can more closely approximate the Hucho template. Also this approximation would leave the back of your slope about 8 inches above the top of the tailgate. While this results in a bigger wake area (bad) the flow stays attached to the slope resulting in less drag. Bondo made his beautiful fiberglass top that way and in the wind tunnel the smoke stuck to the lid all the way to the end. A higher rear lip allows the owner a wider array of freight - always important to pickup guys.

Get with Phil Knox (aka aerohead). He's forgotten more about pickup truck aerodynamics than most of us on this board will ever know. His crazy (but probably effective) ideas scream out for somebody with the manufacturing smarts your work evinces.

Depending on material costs, you design looks economical. Maybe you could even design it to be molded out of ABS. ABS commits you to high-volume tooling. The stuff is not easy to fabricate, but makes a good product. That's why it dominates in automotive accessory bodywork.

[ijames]

Originally Posted by Big Dave

Get with Phil Knox (aka aerohead). He's forgotten more about pickup truck aerodynamics than most of us on this board will ever know. His crazy (but probably effective) ideas scream out for somebody with the manufacturing smarts your work evinces.

Definitely talk with Phil, but not for a while - he's working night and day getting ready to take his truck to a wind tunnel in a couple of weeks .

[BMACM65]

The idea of the bulkhead section being a bit long is;
1. contractor-type hatches on the side for storage of tools.
2. that is where I'd change the size for different lengths of truck boxes, keeping the slope the same. Mine is a 76", there is a 67" and then the 96"
3. didn't want such a long lid due to the winter season, loading snow, getting too heavy.

I will be doing another when I get the cash and be selling this prototype.

I have a scangage but it isn't set up properly. It's reading too low. Tank to tank fillup was showing the 26 - 28mpIMPg. I gotta reset the gage but don't know how.
I was in Michigan when I bought the truck in March. I changed the oil to Amsoil. Then I moved to Canada. Now it has Mobil1 synthetic in it. Now the truck cap so I don't have a proper base mileage. I was originally going with the scangage numbers but that has proven wrong. I took a two day trip to Nova Scotia. That is when I did the tank to tank mpg check.

[MetroMPG]

Tank to tank testing isn't ideal.

If you want to be able to convince skeptics, read up on A-B-A testing (including coast-down tests). You need to remove as many variables as possible so you have high confidence the changes you see are just from the cap.

[COcyclist]

Originally Posted by BMACM65

I have a scangage but it isn't set up properly. It's reading too low. Tank to tank fillup was showing the 26 - 28mpIMPg. I gotta reset the gage but don't know how.

When you fill up select the menu by pressing the button outlined in red on the lower right, press "more", press "fillup", press the more or less arrows until it matches the amount of fuel you have used and press "done". It learns to more closely match real world mileage if you do this every fillup. Be patient, it may take a while. However, for A,B,A testing it may not have to be perfectly calibrated. We are more interested in a percent of change than mpg. For example, 3 mpg may not mean as much in my car as it would in a big work truck.