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Old 12-16-2020, 02:22 PM   #11 (permalink)
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let me put

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Originally Posted by JulianEdgar View Post
You didn't actually address any of the points I made. Maybe read them again? (I've numbered them so you can address each in turn, if you wish):


1. You said: Kamm's lowest drag car didn't survive the war.Let me put that a different way: The car that did in fact survive the war proved to have a very much higher drag coefficient than the pre-war tests showed. To assume, therefore, that the other pre-war data is correct is a bit simplistic.

2. I am not sure why you pursue this fable that all significant car aero happened in the 1920s and 1930s.

3. I can draw similar parallels with car suspension eg the work of Messrs Lanchester, Olley and Milliken. They are incredibly significant people, and what they discovered we use every day - but they don't dictate the suspension rates I chose on my Insight. They certainly help inform those decisions, though. And it's exactly the same with car aero. Great to know about what the heroes of the 1920s and 1930s discovered, but only within the context of today's knowledge.
1) shame Hucho didn't include that data point in his handling of the Langenburg Castle car. It would also have been of benefit had you mentioned it.
2) Cd 0.09 for a body was recorded in 1922. The same Cd 0.09 Hucho talked about in 1987, as a future target. That's pretty significant.
3) Buchheim's VW-Flow Body ( long-tail ) recorded Cd 0.14, not far from Jaray's Cd 0.13 for a similar form.
4) Buchheim's Flow Body sans wheels measured Cd 0.0913.
5) Jaray's 1922 half-body sans wheels measured Cd 0.90.
4) Buchheim et al, in 1981, measured an identical Cd 0.16 for Wolfgang Klemperer's 'minivan' basic body of 1922.
5) Hucho reproduced the Cd 0.16 for the 'Lange' car, as was measured in 1938 at the AVA.
6) Hucho measured Cd 0.15 in model, to the AVA's Cd 0.158 for the 1:1-scale Schl'o'rwagen of 1938.

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Old 12-16-2020, 02:27 PM   #12 (permalink)
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Quote:
Originally Posted by aerohead View Post
1) shame Hucho didn't include that data point in his handling of the Langenburg Castle car. It would also have been of benefit had you mentioned it.
2) Cd 0.09 for a body was recorded in 1922. The same Cd 0.09 Hucho talked about in 1987, as a future target. That's pretty significant.
3) Buchheim's VW-Flow Body ( long-tail ) recorded Cd 0.14, not far from Jaray's Cd 0.13 for a similar form.
4) Buchheim's Flow Body sans wheels measured Cd 0.0913.
5) Jaray's 1922 half-body sans wheels measured Cd 0.90.
4) Buchheim et al, in 1981, measured an identical Cd 0.16 for Wolfgang Klemperer's 'minivan' basic body of 1922.
5) Hucho reproduced the Cd 0.16 for the 'Lange' car, as was measured in 1938 at the AVA.
6) Hucho measured Cd 0.15 in model, to the AVA's Cd 0.158 for the 1:1-scale Schl'o'rwagen of 1938.
[groan]

You segue between drag coefficients of shapes, models and full size cars as if their figures are all interchangeable in validity. That's massive confusion right there.

And you still didn't address my numbered points...
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Old 12-16-2020, 02:50 PM   #13 (permalink)
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Quote:
You segue between drag coefficients of shapes, models and full size cars...
It's like a stone skipping across the water. I'm left wondering which one is the Langenburg Castle car....
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Old 12-16-2020, 03:06 PM   #14 (permalink)
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Quote:
Originally Posted by aerohead View Post
1) shame Hucho didn't include that data point in his handling of the Langenburg Castle car. It would also have been of benefit had you mentioned it.
He does include this data point:

Quote:
The K3 is now on display at Langenburg Castle (Germany). Measurements on this car, made in the large wind tunnel of Volkswagen AG, resulted in cD = 0.37. Not too bad a figure, but much worse than the one Kamm published: from coast-down tests he concluded cD = 0.24.
And the reference, again:

Hucho, W.H. "Introduction to Automobile Aerodynamics." In Aerodynamics of Road Vehicles, 4th edition, W.H. Hucho, ed. [Warrendale: SAE, 1998], 30.

This answers freebeard's question too: the Langenburg car is Kamm's third car of 1938-39.
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Old 12-16-2020, 04:10 PM   #15 (permalink)
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confusion

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Originally Posted by JulianEdgar View Post
[groan]

You segue between drag coefficients of shapes, models and full size cars as if their figures are all interchangeable in validity. That's massive confusion right there.

And you still didn't address my numbered points...
Counterfactual information addressed specifically to comments you've shared.
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Old 12-16-2020, 04:14 PM   #16 (permalink)
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coast-down

Quote:
Originally Posted by Vman455 View Post
He does include this data point:


And the reference, again:

Hucho, W.H. "Introduction to Automobile Aerodynamics." In Aerodynamics of Road Vehicles, 4th edition, W.H. Hucho, ed. [Warrendale: SAE, 1998], 30.

This answers freebeard's question too: the Langenburg car is Kamm's third car of 1938-39.
Kamm had three wind tunnels at the FKFS, including a rolling-road wind tunnel. What are the three Cds from those tunnels?
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Old 12-16-2020, 05:07 PM   #17 (permalink)
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Quote:
Originally Posted by aerohead View Post
Kamm had three wind tunnels at the FKFS, including a rolling-road wind tunnel. What are the three Cds from those tunnels?
The first full-scale wind tunnel at FKFS opened in 1939--after the development of this car--which might explain why the drag coefficient of the real thing would have been calculated using coast down tests and why Kamm would have used that number in his published material.
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Old 12-16-2020, 05:25 PM   #18 (permalink)
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full-scale

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Originally Posted by Vman455 View Post
The first full-scale wind tunnel at FKFS opened in 1939--after the development of this car--which might explain why the drag coefficient of the real thing would have been calculated using coast down tests and why Kamm would have used that number in his published material.
Kamm's lowest drag car was built in the winter of 1941-42, after the 1:1-scale tunnel.
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Old 12-18-2020, 05:42 PM   #19 (permalink)
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Hucho-4th-Ed, & FKFS model question

In Hucho's 2nd-edition , he never got into the other research models at the FKFS.
As a follow-on to Walter Lay's 1933, 22- element, multi-configurational aerodynamic research model, Cd 0.33 to Cd 0.12, 'Kamm' did verification studies at FKFS, reproducing Lay's Cd 0.12.
I wondered if Hucho might have included these in his 4th-Edition.
Otherwise, Koenig-Fachsenfeld's book may remain the sole source of this information.
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Old 12-20-2020, 01:03 PM   #20 (permalink)
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