CdA list

[teoman]

Being longer is usually better for the Cd.

[Joggernot]

2015 Hyundai Genesis Sedan
Height 58.3"
Width 74.4"
Ground Clearance 5.1 - 5.3
Tire Size P245/45 R18
Cd .26

Not sure about years. Suspect 2011-2015 to be the same.

[aerohead]

Originally Posted by tasdrouille

One thing I noted though. In every single case where the frontal area was stated, the 0.81 correction factor on h * w you used gived an overly optimistic figure.

I recall reading a post by phil, must have been of of his aero seminars I'll have to search a bit, where he said to use 0.87 or 0.85, can't remember exactly.

Edit: it was from Aerodynamics Seminar # 6 - by Phil Knox

CAR and DRIVER used to be the 'source' for both Cd, and Af. Ever since Csaba Csere retired as technical editor there's existed a black hole for this information. It's almost a miracle nowadays to see aerodynamic specifics mentioned at all in reporting.
When Don Sherman returned to CAR and DRIVER, and did the 'Drag Queens' article from the A2 Wind tunnel, they used telecamera files and a SIEMENS software package to count pixels, and come up with frontal areas, the first time in decades to report frontal areas.
As cars have given up some ground clearance and grown obese in tire widths, the net fraction of frontal area has grown from around 0.81 of Hucho's mid-1980s, to around 85.5% of gross area for contemporary automobiles, as in the case of the Tesla Model S.
It's an estimation only, and as mentioned by members, 'way out ahead of nothing.'

[hat_man]

From a Triumph website

https://www.triumphexp.com/forum/tri...ients.1116208/

'82 TR-7
Cd 0.360
Area m² 1.765
Area ft² 19.00
Cd x m² 0.64
Cd x ft² 6.84

Not sure about the math. Just a cut/copy/paste

Height 49"
Width 66"
Length 160"
Wh. Base 85"

[hat_man]

From this article it's hard to imagine the TR7 having the same Cd as a 2018 Dodge Ram 1500.

https://www.inverse.com/article/6135...an%20object%20

[aerohead]

Originally Posted by hat_man

From this article it's hard to imagine the TR7 having the same Cd as a 2018 Dodge Ram 1500.

https://www.inverse.com/article/6135...an%20object%20

Between Pininfarina in 1976, and Hucho et al., around 1978, Triumph would have had access to all the recently published aerodynamic 'detail optimization' research. Without altering the 'look' of the TR-7, it might have been straight forward, chiseling the drag down to Cd 0.36.
R.G.S.White, at MIRA, had published a 'recipe' for a Cd 0.245 automobile in 1969. Spirit of EcoModder-I is based on White's recipe, coming in at Cd 0.244 without mirrors.

[freebeard]

Pix or it didn't happen.

Originally Posted by DDG

delta-Cd/ delta MPG rules of thumb - Fuel Economy ...
https://ecomodder.com/forum/showthre...umb-38370.html
That said,at the time of publication, R.G.S. White had already delivered a Cd 0.245 'recipe' car in 1969. Dr. Alberto Morelli and Pininfarina had given us a 'production-ready' Cd 0.204 production car by 1978. The same year, Mercedes-Benz demonstrated the C-111 III, with a Cd ranging from 0.237,to Cd 0.178, depending upon the degree of boat-tailing.

Aerodynamic improvements to the body and cooling system of ...
https://www.sciencedirect.com/scienc...67610581900787
Journal of Wind Engineering and Industrial Aerodynamics, 9 (1981) 63--75 63 Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands AERODYNAMIC IMPROVEMENTS TO THE BODY AND COOLING SYSTEM OF A TYPICAL SMALL SALOON CAR* W.R. STAPLEFORD Motor Industry Research Association, Nuneaton CVIO OTU (Gt. Britain) Summary As part of a broader project to reduce the fuel consumption ...

I found a unicorn! A thread where aerohead and Julian Edgar were getting along. Or at least trying to. It didn't go anywhere.

The paper sounds interesting, but I can't say if it's related, it's being paywalled.

[aerohead]

Originally Posted by freebeard

Pix or it didn't happen.

I found a unicorn! A thread where aerohead and Julian Edgar were getting along. Or at least trying to. It didn't go anywhere.

The paper sounds interesting, but I can't say if it's related, it's being paywalled.

My late-1970s copy of the CRC Press, HANDBOOK of CHEMISTRY and PHYSICS contained White's recipe, derived from a SAE Paper on 'Estimation of Automobile Drag Coefficients', published in 1969.
Hucho covers this work, and lists the source in his reference section.
White breaks a cars architecture down, numerically, into around 13-categories, showing the worst-to-best forms for each category.
A formula is presented, using a summation of the total, added from the 13-categories. If the 'best' of each category is used to create the composite vehicle, you arrive at Cd 0.245.
Hucho will argue the point, but it turns out that many contemporary, low-drag cars embody all the low-drag features of the thirteen categories of the 'recipe.' And one will recognize White's work when you follow Hucho et als' 'drag optimization' techniques of 1976. It's very intuitive.

[freebeard]

I think I remember it, but I haven't squirreled away a copy, apparently.

Black-and-white line art in a grid, all facing left?

[aerohead]

Originally Posted by freebeard

I think I remember it, but I haven't squirreled away a copy, apparently.

Black-and-white line art in a grid, all facing left?

Yeah, they're schematic renderings, and with the exception of front views, all face left.
Cooling systems, mirrors, wheelcovers, skirts, and diffusers are not addressed.
Carr was doing underbody and diffuser research at MIRA at the time White published.