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-   -   1922 Rumpler "teardrop" limousine (https://ecomodder.com/forum/showthread.php/1922-rumpler-teardrop-limousine-38670.html)

sgtlethargic 10-11-2020 12:11 PM
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?

Vman455 10-11-2020 12:38 PM
Closer to cD = 0.19, I think.

0.28 = 1.50x

x = (0.28) / (1.50) = 0.1866... = 0.19

sgtlethargic 10-11-2020 03:44 PM
Quote:
Originally Posted by Vman455 (Post 633425)
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.

JulianEdgar 10-11-2020 03:57 PM
The two that remain are just stunning in the flesh.

https://i.postimg.cc/kGty9D7L/IMG-2726.jpg

https://i.postimg.cc/xdThQGh7/IMG-2751.jpg

https://i.postimg.cc/xd4xSwKJ/IMG-3260.jpg

sgtlethargic 10-11-2020 04:45 PM
Quote:
Originally Posted by JulianEdgar (Post 633453)
The two that remain are just stunning in the flesh.
That's cool. What about the aerodynamic strategy(ies) used?

JulianEdgar 10-11-2020 05:07 PM
Quote:
Originally Posted by sgtlethargic (Post 633468)
That's cool. What about the aerodynamic strategy(ies) used?
Well, fantastic for 100 years ago, but pretty pedestrian today.

sgtlethargic 10-11-2020 08:23 PM
Quote:
Originally Posted by JulianEdgar (Post 633471)
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?

JulianEdgar 10-11-2020 10:03 PM
Quote:
Originally Posted by sgtlethargic (Post 633480)
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!

sgtlethargic 10-11-2020 10:11 PM
Quote:
Originally Posted by JulianEdgar (Post 633483)
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!
You've misread the thread!

JulianEdgar 10-11-2020 10:16 PM
Quote:
Originally Posted by sgtlethargic (Post 633485)
You've misread the thread!
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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