Porsche 911 Ducktail - Study/Alternate

[aerohead]

The December, 2022 MOTORTREND, page 65, contains a vignette on the 1972 911 Carrera RS 2.7, by Aaron Gold.
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Aerodynamicist Hermann Burst was charged with addressing the rear lift/high-speed instability of the 911, associated with the drawbacks of the sloping rear.
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Burst was a graduate of the FKFS at the University of Stuttgart, where the 'Kamm-back' was developed from Fachsenfeld's patents, with Dr. Wunibald Kamm riding shotgun on the research.
And Burst already had success in Porsche's Le Mans-winning long-tail kammtail racing cars. The 1968 907 long-tail was Cd 0.27. The 1969 908 long tail was below the 907's.
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Burst's 'solution' for the 911 was an airdam, along with a kammtail roof.
Porsche management was okay with the front, but shot down the K-form roofline. The silhouette of the 911 was not negotiable.
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Over three days, three rear spoiler designs were hashed out. The 'ducktail' is the one-out-of-three designs approved for homologation and production.
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The spoiler was incrementally increased in height until lift and drag reached a 'reversal point,' after which performance degraded again. ( Sweet-spot ).
Drag dropped from Cd 0.4239, to Cd 0.40.
Top speed improved from 149.2-mph, to 152-mph.
Separation-induced lift was killed off.
Engine cooling was improved.
Taillight back-soiling was mitigated.
As Wolf H. Hucho had commented in 1986, the spoiler performed almost as well as simply lofting the roofline up to where the 'tearing edge' of the ducktail ended.
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In 1973, the kammtailed ROVOMOBIL debuted, with Cd 0.23.
Presently, Porsche is using the 1930s K-form roofline. The lower performance variant of the Taycan is Cd 0.22, close to ROVOMOBIL.

[freebeard]

jalopnik.com/: Meet The East German Beetle-Based Supercar With Better Aero Than Tesla -- By Jason Torchinsky

I suspect that in 1974 the commies ripped off Luigi Colani's 1960 Colani GT

At the same time, Luigi Colani advanced his plastic designs and this culminated in the years 1960 with his compact sports car Colani GT, which was available as a DIY kit on a VW platform and quickly became an icon of life in the years 1960.

https://www.carstyling.ru/en/car/1965_colani_rs/

[aerohead]

Curiosity led me to print off the blueprint for the 911 Carrera 2.7.
I scaled it to my stack of 'rooflines' and took a look on the X-ray reader.
The engine air inlet below the backlight is slanted on a 23.5-degree angle.
The 'ducktail' tearing edge lofts the 'body' at that location up to a 17-degree slope.
Extrapolating the contour happens to generate a perfect match the 2013 AST.
Aerodynamicist Hermann Burst's original 'solution' for instability was to add a kammtail roofline, intersecting the 17-degree tearing edge position.
Had this been done, the lift issue would be gone, the car would have lower drag, engine cooling would have been improved, and the higher base pressure mitigate the taillight lense back-soiling issue.
The car would no longer 'look' like a 911, so it was shot down by the Paris Dressmakers.
Fortunately, in the intervening years since 1972, Porsche has incrementally 'raised' the back of the 911 in each new iteration.
Today, Porsche finally has the contour Tony Lapine co-designed with Larry Shinoda, for the Chevrolet Corvair Monza GT of 1962.
GM's head of design,'Wild Bill' Mitchell hated the kammback too!

[freebeard]

VW also relented on the New Beetle. The new New Beetle had a roofline relaxed from the original archetype


cartype.com/pics/1594/full/wv_beetle_2012_plug.jpg

[kach22i]

In Czech but fascinating pictures.

https://siol.net/avtomoto/zgodbe/kul...jo-foto-580614

[kach22i]

Originally Posted by aerohead

.............
Fortunately, in the intervening years since 1972, Porsche has incrementally 'raised' the back of the 911 in each new iteration........

Hermann Burst in 1992 raised the rear of his hail damaged 911 similar to what would follow decades later, and the front looks like 2011 911 in many ways.


https://www.paledog.de/Automobile/19..._rear.jpg.html

Caption

This car is a one-off based on a 911 Carrera 4 (Type 964). After a hailstorm the orginial body was destroyed. Hermann Burst decided to create a new roadster body as a reminiscence to the 1960s on the original chassis. 'R64' stands for Retro 64 and was built by Burst together with Jaroslav Fuska and Josef Iker.

http://www.speedhunters.com/2013/09/...rs-911-design/


https://www.paledog.de/Automobile/1990s/