10-11-2020, 01:11 PM
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#1 (permalink)
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1922 Rumpler "teardrop" limousine
(Starting at page 17, "Aerodynamics of Road Vehicles, Fourth Edition"):
Quote:
CD = 0.28; A = 2.57 m^2
The value of this cD is particularly noteworthy because the wheels of Rumpler's vehicles are totally uncovered. _____ ... this must have increased drag by 50%.
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So, might a similarly shaped car with the drag due to the wheels minimized be about 0.14?
Last edited by sgtlethargic; 10-12-2020 at 12:42 AM..
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10-11-2020, 01:38 PM
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#2 (permalink)
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Closer to cD = 0.19, I think.
0.28 = 1.50x
x = (0.28) / (1.50) = 0.1866... = 0.19
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10-11-2020, 04:44 PM
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#3 (permalink)
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Quote:
Originally Posted by Vman455
Closer to cD = 0.19, I think.
0.28 = 1.50x
x = (0.28) / (1.50) = 0.1866... = 0.19
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Oh, not halved. I overlooked that tricky percentage language. |
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10-11-2020, 04:57 PM
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#4 (permalink)
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10-11-2020, 05:45 PM
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#5 (permalink)
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Quote:
Originally Posted by JulianEdgar
The two that remain are just stunning in the flesh.
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That's cool. What about the aerodynamic strategy(ies) used? |
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10-11-2020, 06:07 PM
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#6 (permalink)
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Quote:
Originally Posted by sgtlethargic
That's cool. What about the aerodynamic strategy(ies) used?
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Well, fantastic for 100 years ago, but pretty pedestrian today. |
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10-11-2020, 09:23 PM
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#7 (permalink)
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Quote:
Originally Posted by JulianEdgar
Well, fantastic for 100 years ago, but pretty pedestrian today.
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Are there any modern cars of that relative size (looks like it might seat 7-10 people) that has a (theoretical for the Rumpler) 0.19 cD? |
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10-11-2020, 11:03 PM
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#8 (permalink)
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Quote:
Originally Posted by sgtlethargic
Are there any modern cars of that relative size (looks like it might seat 7-10 people) that has a (theoretical for the Rumpler) 0.19 cD?
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In a modern wind tunnel it had a measured Cd of 0.28 and a frontal area of 2.57m^2.
As far as I know, they were five-seaters.
0.19 Cd and 7-10 people is how misinformation spreads! |
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10-11-2020, 11:11 PM
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#9 (permalink)
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Quote:
Originally Posted by JulianEdgar
In a modern wind tunnel it had a measured Cd of 0.28 and a frontal area of 2.57m^2.
As far as I know, they were five-seaters.
0.19 Cd and 7-10 people is how misinformation spreads!
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You've misread the thread! |
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10-11-2020, 11:16 PM
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#10 (permalink)
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Quote:
Originally Posted by sgtlethargic
You've misread the thread!
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I don't think so.
There's no justification for the 0.19 Cd figure - it's not the result of any measurement and is just a guess. As far as I know, the 7-10 people figure is wrong.
As I say, this is how misinformation starts and then spreads!
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