Aerocap version 3

[NeilBlanchard]

It might be more accurate to move the template closer to the front; because the air flows off of the windshield and (may?) form a shallow pocket of air, and so the "virtual" high point of the pickup roof would be *about* at the front edge of the passenger side window?

The template would need to be scaled larger a little bit, as well as moved forward; resulting in slightly less "height" at the tailgate.

I could be wrong, and only trying it and tuft testing would tell for sure.

[t vago]

I was under the understanding that the template's 0 degree point was supposed to align with the highest point on the roof, and that the template itself was supposed to be scaled such that it was the same height as the vehicle in question. Any part of the vehicle was supposed to be "chopped off," as it were, because frontal shape is not quite as important as rear shape.

Was I mistaken?

[aerohead]

Originally Posted by t vago

I was under the understanding that the template's 0 degree point was supposed to align with the highest point on the roof, and that the template itself was supposed to be scaled such that it was the same height as the vehicle in question. Any part of the vehicle was supposed to be "chopped off," as it were, because frontal shape is not quite as important as rear shape.

Was I mistaken?

I don't think you're mistaken.Hucho infers that any front end as good as the 1st-gen Rabbit will be good enough to support aft-body mods.
You can see it in the smoke flow images from VW's wind tunnel.

[NeilBlanchard]

Okay, my theory fizzled...

[t vago]

Ah, don't worry about it, Neil. After all, this thread concerns correcting a pretty huge mistake in my first two aerocaps.

[t vago]

Here's the refined version that will probably be used for the actual fabrication.







Rear-facing area is approximately 3.1 square feet, which is more than the 2.1 square feet of version 2. I estimate the maximum streamline angle to be about 15 degrees, with an average streamline angle of 9 degrees. The center of the cap follows the aerodynamic template.

I'll (probably soon) do the streamline calculations for version 2, and post the results here, too. I suspect they'll confirm the observed streamlines that formed due to driving through the rain.

[skyking]

very cool. are you planning a tail section to sit on the open tailgate, or something similar for max performance cruises?

[t vago]

I was thinking of doing that, though my ideas are probably more complicated than they need to be.

Basically, I had two ideas: The first idea was of a detachable section on the cap itself, that would interlock with another section that would attach to my hitch receiver, somewhat similar to what bondo has for his aerocap.

Another idea would look similar to what a few trucking companies have already done for decreasing drag on their trailers. mcrews took some pictures in his Aero Semi-truck butt...... thread. I saw another one of these on the way to a beekeeping supply store this past Saturday.

[aerohead]

Originally Posted by NeilBlanchard

Okay, my theory fizzled...

Neil,hang on until I can get the railroad components graphic up at the trailer thread.
There is a self-propelled passenger railcar with integrated cow-catcher of Cd 0.08.It pretty intrigueing(sp?).
You'll be reminded of splitters of todays NASCAR.

[sgtlethargic]

Will you make your Excel file(s) available? Where did you learn to use Excel like that?