Silverado aerocap build thread

[cfg83]

Fubeca -

Ok, thanks. When I read your thread, I failed to understand that you had used plywood strips to support the curve. I was imagining plastic directly on the ribs and I couldn't understand why I didn't see the ribs through the plastic. This makes a lot more sense.

Have you considered making Viking ships, ?

CarloSW2

[mjboks]

Very impressive construction! You're giving me ideas for mine - when I finally build it. Have you given any thought to the third taillight? I'm not sure what the Wisconsin law is regarding a 3rd tail light?

[Fubeca]

I've thought about it. I think I will just run it as-is for now. Eventually I will add an inexpensive LED light surface mounted on the back top center. I will run the wires down inside the topper and out the crack between the tailgate and bed to the trailer light plug. I imagine WI requires it on a topper if the truck has it.

[Fubeca]

Originally Posted by ccrider

i wonder how much having sharp edged on the corners instead of rounded corners would hurt aerodynamics?

This is definitely something I would like to know also. It would be much easier to build without the curved "shoulders". I did it this way to test my building method ideas and to match the shape of the truck cab. I've seen several with fairly sharp "shoulders" - I certainly don't know how much of a difference it makes.

[ChazInMT]

Fubeca....thanks for the snaps of the interior, it really makes your construction technique quite clear. I posted yesterday here on your thread singing the praises of your work...then, I kept blabbing and someone rightfully moved my overblown post into it's own thread. So again Fubeca...Excellent Excellent work, your Aero Cap is far and away the best "Value" DIY cap on this planet right now.

I know I have not been at this aeromodding game long....(<24hrs) but I have spent some good energy thinking about this. I also have a keen intuition for what makes sense in the engineering world and at 47, have a good deal of life experience. It would seem that your rounded corners are better in the sense that flow tends to become separated at sharp corners. If a sharp corner is always parallel in the slip stream it won't matter much. But what are the odds we have guessed that right and have the corner right there?? And this would only be good for a calm wind day, any kind of cross wind will upset the balance, and turbulence will get created.

By having rounded corners, it delays the formation of this separation which causes turbulence and minimizes the separation if it does happen.

Fubeca, if I could make a suggestion on your design, as I see it, it would be to lower the trailing edge of your cap down so you don't have an additional 4 inches or so of vertical surface, You also could have included a 3 to 4 inch radius into this trailing edge instead of making it a sharp edge. I think a radius edge on the very back would help in reducing the size of the "Behind the Tailgate" vortex a bit more. Sorry to criticize, I just thought I'd put this out there for anyone else who may want to consider other ways of improving on the already amazing job you have done.

[Fubeca]

Thanks for comments.

I made the back about 6" above the tailgate to match the teardrop template. I may be able to go a little more aggressive and curve all the way down to the tailgate - but I wanted to err on the side of caution. I'd rather have a little extra drag than have detached flow at this point in time.



As far as curving the end, I don't know if that would help or not. I've read it can be good to have a clean separation point at the end - but I don't know for sure.

Good luck on your build!

[MetroMPG]

The sharp "chop" at the end of the vehicle is preferred to a radius, for clean separation as you mentioned.

See this current thread for more discussion on sharp trailing edges: http://ecomodder.com/forum/showthrea...all-11687.html

[CTarna]

Originally Posted by MetroMPG

The sharp "chop" at the end of the vehicle is preferred to a radius, for clean separation as you mentioned.

See this current thread for more discussion on sharp trailing edges: http://ecomodder.com/forum/showthrea...all-11687.html

I always heard a fish's tail was was most aerodynamic shape.

[Christ]

Originally Posted by CTarna

I always heard a fish's tail was was most aerodynamic shape.

google: Aerodynamics or Fluid Dynamics

You'll learn alot.

[aerohead]

Originally Posted by CTarna

I always heard a fish's tail was was most aerodynamic shape.

If you could do the complete fish body,well then you'd have your ideal drag minimum.
If you must compromise in length ( as the real world pretty much imposes ) then it has been found through research that slicing the tail off,as you would with a loaf of bread,has an advantage over cutting the tail and then rounding the edges.
Dr. Kamm premised his body of research around this very tenet and it has been verified over and over in succeeding decades ever since.