Quote:
Originally Posted by mwilliamshs
The picture aerohead posted, is that just my wake as-is, or is that the shape a tail should have, etc? I'm interested in a kamback and have started designing it but don't know the correct angles. Any help would be appreciated!
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It's approximately the shape a kammback for your vehicle should take. You'd want it to taper in from the sides, too.
In the Aerodynamics section of the forum there's this:
http://ecomodder.com/forum/showthrea...ower-6341.html
That will allow you to paste a translucent image of the idealized aerodynamic profile over a photo of your vehicle. Match the overlay's highest point to the rearmost high point of your vehicle, and you can see how a kammback should extend behind your vehicle to fill in its pressure wake.
For the side taper, you would use mirrored versions of the profile overlaid on a top-down photo of your vehicle. That can be a little tricky.
I don't remember where the cutoffs are and I'm a little pressed for time right now to look them up, but there's a point where extending the tail further doesn't contribute meaningfully to further improvement in the vehicle's aerodynamic performance. It will improve, but those improvements are small enough to be lost in the noise of tire alignment, carb jetting, etc. The good news there is that it means you can make a big improvement without having a ten-foot-long tail sticking out. A much shorter tail might be sufficient.
It's worth checking out TrailerTails:
TrailerTail | ATDynamics – Fuel Efficiency Aerodynamics Technology for Tractor Trailers saving over 10% with TrailerTail and Side Skirts They're getting useful improvements with not subtle sculpting of the tail's contours. It helps to be an aerodynamicist and make things really perfect, but it isn't crucial. And like I said about tail length, TrailerTails are available as short as 36" - long enough to make a useful difference.