Quote:
Originally Posted by freebeard
aerohead -- What benefit do you reckon from leaving the tail as-is and going to a Talbot-Lago/Volkhart-Saggitta style cowl and windshield area?
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From wind tunnel experiments,the big dogs say that there's nothing magic about the fore-body of a car as far as drag goes.
Once the leading edge radii are optimized and you've got attached flow,your essentially 'done.'
For further drag reduction you've got to extend the rear in a way which allows the flow to de-accelerate,lose it's velocity,and regain it's former static pressure (minus what is inevitably lost due to the turbulent boundary layer); reducing or eliminating the turbulent wake.
This is the entire premise of automotive streamlining.It's all about the back of the car.
Both the Lago and Sagitta suffer from attached longitudinal vortices and lager-than-necessary wakes because of their steep rooflines.Hucho calls them 'pseudo-fastbacks.'
In this photo series,the center image is a 'pseudo-fastback' with large flow separation over the roof and attending longitudinal vortices.
The bottom image is a proper fastback,with only TBL flow disturbance basically,and zero vorticity.
These cars are all pseudo-fastbacks
They all have short aspect ratio greenhouses.'Kamm' was obsessed with this body relationship which was referred to as something like Ver'u'ngenverhaltnis.
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These cars are proper fastbacks (truncated)
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