beetle kammback

[skyking]

I looked over the hatch. It is far from ideal in that it starts out narrow at the top and widens.
If I lift it up and fair that in, it will have some really *crisp* corners. Still, it will provide for an interesting A-B test. I have not found any evidence that others have tried it.

[freebeard]

http://ecomodder.com/forum/showthrea...tml#post384969

Did you look at this post? When he added a rooftop camper to his New Beetle, his mileage dropped from 48 to 38mpg; so he moved it to behind the backlight and the milege went up to 49.3mpg. And that was an unoptimized canvas bag of stuff.

I think it has to do with the top surface catching and reattaching the vortexes that like to form.

[skyking]

Yes I looked at that and posted. Very very nice. I have a run to make across the mountains and will A-B a lifted hatch for starters. It is a good 160 mile run. I have my scanguage in hand, but no chance to calibrate yet. I'll have to fill and run with hatch up and hatch down.

[freebeard]

What angle will you try? And how will you prop it open? You could seal the gap with that clear plastic they use to wrap pallets-loads for shipping. I think you could stretch it and layer it and make a custom U-shaped or O-shaped part. Then clip it to the inner lip of the opening. ..or maybe coroplast.

You could just run it open, like a wing over a pickup bed, even though it's sub-optimal; but the carbon monoxide and the base pressure pulling on everything in the interior are reasons not to.

[Xist]

Originally Posted by freebeard

What angle will you try? And how will you prop it open? You could seal the gap with that clear plastic they use to wrap pallets-loads for shipping. I think you could stretch it and layer it and make a custom U-shaped or O-shaped part. Then clip it to the inner lip of the opening. ..or maybe coroplast.

You could just run it open, like a wing over a pickup bed, even though it's sub-optimal; but the carbon monoxide and the base pressure pulling on everything in the interior are reasons not to.

I bought marine plastic off of e-bay for a reasonable price, they just require you to purchase at least 140 square feet.

[skyking]

I have some extra Coro to use. I'll pull it down against some plywood on the sides so it does not squeak or hurt the hatch, then seal it up with Coro and tape. I'll take a guesstimate at Template C.
One negative about the beetle is the roof rounds off too fast, even before the hatch. I will have a piece of Coro up there to blend the roof to the raised hatch.

[freebeard]

The gap at the top is never more than about 1", is it?

You could split the gap with a piece 16" or so front to back and run zip ties around the hinges; then wrap the ends over and screw them to the plywood wedges.

[skyking]

my weather window for that little test passed, and I am glad for it. The more I looked at it, the less sense it made to even try. I will build a proper kammback.
I went to Fiberglass Supply in Burlington to attend a free seminar. These are great folks and I got some materials and ideas for the kammback, rear wheel skirts and wheel covers.
I got a half sheet of 1/8" divinycell for the structure. They tossed in a nice sized scrap for testing out how it will bend with heat in complex curves.

[skyking]

This is the basic shape I came up with. I am trying out the look of several different trailing edges.
Call this one the normal rake

Shallow rake

sharky

[skyking]

I can't lift the template up or move the kammback forward without undergoing serious body rework.
The roof is immediately too steep. Not ideal. I get that and have figured a single piece design that will mount to the hatch and hit the roof a couple of inches aft of that antenna.

Looking at sharky, what I have in mind is a nice curve here to go with the rest of the body styling. I don't have the paint skills to draw it. Use your imagination and tell me what you think of that. I was thinking a nice curve from plan view as well, resembling a receding hairline of midlife crisis :P


Sawtooth or shuttlecock, if you prefer.