t_vago's compound curve foam board pickup aeroshell

[euromodder]

Originally Posted by NeilBlanchard

I think the profile is a fine 2D guide, but is 3D, the air can flow in from the sides so the taper can be steeper *if* the sides are also tapered?

It's been mentioned before that you can get away with a steeper angle if the sides also taper in smoothly.

The streamlining template used is only 2D - the ideal low speed aero shape is an ice-cream cone (with only one ball of ice-cream ) where there are no sides, only taper.

[BamZipPow]

Don't fergit the 3rd brake light...

[aerohead]

Originally Posted by NeilBlanchard

I had fun doing it -- and I now know how I'm going to build my CarBEN EV prototype shell. The 1/4" polystyrene is a revelation for doing compound curves.

The 12 degree slope in the thesis was for a straight surface, and the slope was only on the top. The 3D cap shows how a curved surface can work better -- and there have been a lot of discussions here on EM with 15d slope being ideal, and even 18d works on cars like the EV1 because of the air flows in from the sides, as well.

I'll look around for the "ideal profile" image and see how it lines up with this cap? And it is no "recurve" like the prototype, so the main descending surface is much longer than previously.

[Edit: Here's the "ideal profile compared to the SU cap model:



So, the cap may be a little steeper than ideal -- I'll try a less steep version.]

The comment about the side mirror sight lines not being blocked by the cap is something I had not thought about.

[Edit 2: On the other hand, here's the EV1 compared to the ideal profile:



As you can see, it deviates as much or more than the cap. And here's the Dolphin:



I think the profile is a fine 2D guide, but is 3D, the air can flow in from the sides so the taper can be steeper *if* the sides are also tapered?

What do you folks think?]

The sides have got to be tapered and well radiussed at the top to get the best benefit.Just like the back of an airship(Met Life,Goodyear,FUJI).
You can go as steep as 22-degrees but you've got to be more than a car height behind the point of max roof camber before you can get there.
I think I put Mair's boat tail graphic in the thread for the Aero.Stream.Template.Check that and see.It will give you the dimensions.The 'Template' gets to 22-degrees also.I set it as the limiting geometry because of Mair's work.
Many researchers used slab-sided models in wind tunnel experiments and never achieved the low drag of the Jaray/Klemperer 'zeppelinesque'forms.

[JasonG]

Instead of splitting the cap, hinge it on the passenger side.

Then you dont have to walk to the rear to grab something. Maybe hide the release in the fender well or use an old electric trunk release.

Looks good, cant wait to see it !

[bondo]

That is very cool Neil! Reminds me of the old Corvette Stingray styling and the way you integrated it onto the pickup truck works well. Again, very nice job.

I'd like to sculpt that one in clay!

And of course a great deal of credit to t vago for coming up with the great three dimensional shape this thread is following. Very excellent work as well!



Bondo

[alohaspirit]

Originally Posted by t vago

That looks similar to what I came up with for my truck.


Underlying frame


Side view, right-hand side

great work!

ill be following the progress on this one!




i second a side hinge on the passenger side

[t vago]

Nice work, Neil. You've given me a few ideas about what I can do with the finished product. I like that hinged version - it reminds me of a fighter jet canopy.

In the meantime, I have generated overlays of my own, of what I think the final shape will look like. Keep in mind that the sides will be filleted when this thing is actually made.


Version 2 aerocap update


Top view - Overlay onto Dodge Dakota Quad Cab


Side view - Overlay onto Dodge Dakota Quad Cab


Rear view - Overlay onto Dodge Dakota Quad Cab

[KamperBob]

Looking good, T.

I like the truck drawings. Where did you find them?

[t vago]

Originally Posted by KamperBob

Looking good, T.

I like the truck drawings. Where did you find them?

I acquired them from here. A little editing with Foxit, a little print-screen action, a little conversion with MS Paint, another little conversion with MS Office Picture Editor, and there ya go!

[KamperBob]

T, your V1 cap and V2 plans were inspirational. The 'vette back idea really grew on me. To slake the thirst I decided to model it. I'm positive this is not the most aerodynamic shape but I like it so much aesthetically that I may have to build it.