beetle kammback

[skyking]

dp

[freebeard]

kafer65 -- Well it's complicated. Possibly the best example would be the Porshe Carrera GT


http://www.moibbk.com/gallery/model-684/porsche-carrera-gt-black-8.jpg.html

A straight line from the parking light on top of the front fender to the door handle passes through the hinge line. Only a shallow V-notch would be required.

[aerohead]

Originally Posted by freebeard

0.12<0.16<0.20. So you can get to 50% of the full boat tail effect without adding length?

I need a body kit for my Superbeetle that bulges out the door and rear quarter panels to full fender width. It would hide the external hinges and the drip rail down the front of the door. 0.40—>0.32?

Yes.
Kamm's lowest drag K-3,built on the Mercedes-Benz 170 chassis was rated at Cd 0.23.Twice the drag minimum.

You can see that the tufts are pretty clean until the rear radius,now 'fixed' with Fachsenfeld's 'tearing edges'.

He and Koenig-Fachsenfeld advocated building 'personnen kraft wagen ' (personal automobile) bodies which were chopped off where the wake equaled 50% of frontal area.It was just a matter of practicality with respect to parking garages,spaces,and urban traffic.
Koenig-Fachsenfeld made provision for lower drag for highway-only travel by incorporating an extensible tail.

The Beetle is considered a pseudostreamlined car.At Cd 0.495 it was quite good in a day when Cd 0.62 was not uncommon.
By 1975,the Beetle was down to Cd 0.44

Kit.I wish I'd bought a copy of Hot VW Magazine when I was at Edwards AFB.The Rabbit was coming out and the Beetle vanishing.A contributor to HVWM did a beautiful rendering of an aero tricked-out Bug,with all the mods you're talking about.It was ART!
Cd 0.32 would be reasonable considering the Airflow mule.

[skyking]

So, my beetle at .38 was quite an improvement. Funny to say that out loud
I have high hopes of dragging it ( pun intended ) down below the .3 mark with full skirts and a kamm.

[aerohead]

Originally Posted by skyking

So, my beetle at .38 was quite an improvement. Funny to say that out loud
I have high hopes of dragging it ( pun intended ) down below the .3 mark with full skirts and a kamm.

When Kamm et al. was messin' around with their models,they were considering aspect ratios of the aft-body of the car.
When the tail was 3.5X body height,they had Cd 0.21 with a simple wing shape.
When they cut the aspect ratio down to 1.6X it increased to Cd 0.33.
With your New Beetle,because of it's curved upper body,at any length you'd have an advantage.
Rounding off the body transversely like Jaray did, lowered drag from 0.21 to 0.13.
Sub-0.30 should be a cakewalk!
Here is a 1937-40 Adler 2.5-Liter sedan that they modified in full scale

With K-Tail

*The shortest body length went from Cd 0.33,to Cd 0.25

[freebeard]

I wish I'd bought a copy of Hot VW Magazine when I was at Edwards AFB.The Rabbit was coming out and the Beetle vanishing.A contributor to HVWM did a beautiful rendering of an aero tricked-out Bug,with all the mods you're talking about.It was ART!

What month and year? I might have it.

I think the New Beetle gets 0.44—>0.38 by having integrated bumpers and shallower fender bulges.

The Fachsenfeld 'tearing edges' should be applied to a clone of the Volkhart-Saggita to bring it "up to date".

[skyking]

I see those "tearing edges" as synonymous with the box cavity.

[freebeard]

Everything old is new again, eventually.

[aerohead]

Originally Posted by freebeard

What month and year? I might have it.

I think the New Beetle gets 0.44—>0.38 by having integrated bumpers and shallower fender bulges.

The Fachsenfeld 'tearing edges' should be applied to a clone of the Volkhart-Saggita to bring it "up to date".

I'd have to guess '74/'75 time period.
There were convoys of pre-release Rabbits traveling between Los Angeles and the Mojave Desert on HWY 395 outfitted with black boxes.
The Beetle was doomed in the USA.
I should have bought the issue.I was a Ghia guy,so I didn't have that much attachment to the Bugs.And wouldn't have thought at the time that we'd be interested in them 40-years later.

[aerohead]

Originally Posted by skyking

I see those "tearing edges" as synonymous with the box cavity.

Some of the current passenger cars use a form of it on their rear bumper fascias which were originally quite rounded.It's that 'burst' thing Chrysler folks have mentioned,and kill the bi-stable flow Hucho has warned us about when angles get near 30-degrees.