EcoModder Forum 1922 Rumpler "teardrop" limousine

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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%.
So, might a similarly shaped car with the drag due to the wheels minimized be about 0.14?

Last edited by sgtlethargic; 10-11-2020 at 11:42 PM..

 Today Popular topics Other popular topics in this forum...
 10-11-2020, 12:38 PM #2 (permalink) Tyrant-at-large     Join Date: Feb 2012 Location: Champaign, IL Posts: 1,700 Little Red - retired - '05 Honda Civic EX 90 day: 49.03 mpg (US) Pope Pious the Prius - '13 Toyota Prius Two Team ToyotaSUV 90 day: 59.04 mpg (US) Thanks: 178 Thanked 1,487 Times in 788 Posts Closer to cD = 0.19, I think. 0.28 = 1.50x x = (0.28) / (1.50) = 0.1866... = 0.19 __________________
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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
Oh, not halved. I overlooked that tricky percentage language.

 10-11-2020, 03:57 PM #4 (permalink) Master EcoModder   Join Date: Nov 2017 Location: Australia Posts: 991 Thanks: 62 Thanked 863 Times in 563 Posts The two that remain are just stunning in the flesh. __________________ Two of my books: Modifying the Aerodynamics of Your Road Car Car Aerodynamic Testing for Road and Track
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Quote:
 Originally Posted by JulianEdgar The two that remain are just stunning in the flesh.
That's cool. What about the aerodynamic strategy(ies) used?

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Quote:
 Originally Posted by sgtlethargic That's cool. What about the aerodynamic strategy(ies) used?
Well, fantastic for 100 years ago, but pretty pedestrian today.

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Quote:
 Originally Posted by JulianEdgar Well, fantastic for 100 years ago, but pretty pedestrian today.
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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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?
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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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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Quote:
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!