Cd and blunt front ends

[gone-ot]

...also see SAE paper #700036: "The Aerodynamic Development of the Chager Daytona for Stock Car Competition," by R. P. Marcell and G. F. Romberg, both of Chrysler Corp.

...lots of good info about front and rear spoilers, as well as backlight angles.

[aerohead]

Originally Posted by Old Tele man

...also see SAE paper #700036: "The Aerodynamic Development of the Chager Daytona for Stock Car Competition," by R. P. Marcell and G. F. Romberg, both of Chrysler Corp.

...lots of good info about front and rear spoilers, as well as backlight angles.

Yes,Romberg was one of the rocket scientists named in the MOPAR article,who was at the proving grounds.They had fixed the sunken backlight and bucket nose for the Charger 500 but it still wasn't winning and perhaps it was Marcell who penned the nose and wing on the napkin to show Chrysler big whigs who were looking to win races.
Looks like the cardboard and duct tape got turned into fiberglass for the wind tunnel refinement.
I'll try and get to the SAE article.I'd like to know about the fender-top vents,brake cooling duct inlet location,A-pillar smoothing,etc. that are pictured in the article,but no details provided.
Thanks mucho for the source!

[aerohead]

I had an article from some Mopar magazine about Bobby Issacs #17 Dodge Challenger which had won NASCAR doing laps just over 200-mph.
That car was taken to Bonneville,and with the 426-Hemi,did the flying-mile at 217 mph for a world record.
I recently ran across an article in HOT ROD Magazine where a NASCAR Winston Cup Dodge,also #17 was taken to Bonneville where it set a new LSR,at 244 mph.The car was claimed to have a "NASCAR-Spec" engine.There is no information about whether the restrictor-plate was installed.(They didn't exist in 1968).
HOT ROD also did an article about the "blunt-nosed" Camaro which ran around 268-mph.From the photographs you can see that the nose is completely sealed.All it's features are either painted on or are decals.That car developed 1,200 Bhp,the blower absorbed 250 Bhp,and they calculated that the aerodynamic drag imposed by the bug-catcher/blower housing/drive pulley,etc.exposed to the airstream required 150 Bhp to push through the air at their speed.
Their next attempt will be with the Pro-Comp scoop which has remarkably less drag.
" Speed costs money!" E.C.Burnett

[aerohead]

I spent some time digging through HOT ROD Mag..
In the Feb. 2008 issue they did a piece on their Camaro.Here are some interesting tidbits:
* full depth front airdam
* the car is lowered
* nose is completely sealed
* mirror delete
* wiper delete
* full aluminum bellypan
* extended rear spoiler

With the supercharged engine and 1,178 Bhp the car's top speed is 249.832 mph.

With a single 4-bbl Holley Dominator,normally-aspirated,and 175hp shot of NOS,developing only 925-950 Bhp,but with a Pro Stock hoodscoop,top speed is 261.602 mph.
A close inspection of the supercharger suggests that airflow would separate at : * driven pulley
*idler pulley
*blower front plate
*throttle shaft/accelerator-pump pivot plates
*carb body
*float bowls
*air cleaner body
*"accordian" filter element
*blower explosion-proofing buttresses

Also,it looks like maybe,the rear wheel inner wells have been removed.

All these would conspire to aggravate flow,especially the blower.

I'm including a photo of the HR Camaro and also a shot of Gary Spencer's # 630 Camaro,which sports the Pro Stock scoop.
I've also got a shot of the underside of a 1944 North American P-51D.I think you'll see a resemblance to the HARWOOD scoop.
These would be considered a modified Bauman snorkel,with reflexed,double-radius inlet,to defeat both vena-contrata inlet losses,as well as prevent separation on the outside of the scoop,with minimum frontal area added.Inside,these scoops provide for a 7-degree divergence for static-pressure regain and air gap to allow proper carburetor metering.
The "raised" inlet addresses boundary layer issues.
Walter Korff chose these same scoops for the 409 mph Summers Bros. Goldenrod.
When Al gets free I'll post the pics.

[aerohead]

here are some pics.
* Red Daytona,217 mph top speed with pointy nose
* Nextel Cup Dodge,244 mph top speed with blunt nose
* Spencer's red Camaro with Pro-Stock scoop
* P-51D belly scoop

[aspera]

Originally Posted by aerohead

Also,it looks like maybe,the rear wheel inner wells have been removed.

I just checked my Speedweek pics from a few years ago. The backseat area is solid. Metal is welded to block off every gap including the trunk. Besides the roll cage, there's little else back there except a few fire extinguisher bottles.

The things that I noticed about the Hot Rod Camaro was the *****in' aluminum race seat and the ugly light tan paint of the interior. (Tan does not look good on a white car on white salt.)

[aerohead]

Originally Posted by aspera

I just checked my Speedweek pics from a few years ago. The backseat area is solid. Metal is welded to block off every gap including the trunk. Besides the roll cage, there's little else back there except a few fire extinguisher bottles.

The things that I noticed about the Hot Rod Camaro was the *****in' aluminum race seat and the ugly light tan paint of the interior. (Tan does not look good on a white car on white salt.)

aspera,thanks for the heads up.I thought I was seeing some daylight through the back wheel.I'll get new glasses.
I didn't pay any attention to interior shots of the car.They may have ignored aesthetics altogether.
There may be a vision issue involved.I had to wear polarized sunglasses inside my helmet when I ran out there and the blue interior of the CRX made for good contrast between the white on white outside and shaded inside.
They don't run the single black line on the salt and between watching instruments and staying straight on course,it's kinda busy in there.
I can't even imagine 261 mph.I've only been to 145 and that must be like sitting in a rocking chair by comparison.
The tan interior may have been an oversight or may have been intentional for safety's sake.

[aspera]

I always like to poke my head inside the cars and check them out. The interior of the Hot Rod Camaro was "workman-like". The interior of Blowfish was spectacular. Blowfish had some new aero around the front wheel wells this year, too. Have you checked it out?

It IS possible that the Hot Rod guys cut up the rear wheel wells in the last year or so. The first thing that popped into my head was how the old stock cars used to cut holes in the wheel wells so that the driver could look towards the backseat area and see if the tires were flat...directly. They'd just cut a 3 inch hole so the driver could look right at the tire as he was driving. If they used a rear view mirror, they could look at the tires without even turning their heads.

I'm sure those little holes helped with airflow, too. That's seems to be a sort of "undiscovered country" of aerodynamics. (How can you improve downforce and reduce drag using holes between the outside and inside of the vehicle?)

[aerohead]

Originally Posted by aspera

I always like to poke my head inside the cars and check them out. The interior of the Hot Rod Camaro was "workman-like". The interior of Blowfish was spectacular. Blowfish had some new aero around the front wheel wells this year, too. Have you checked it out?

It IS possible that the Hot Rod guys cut up the rear wheel wells in the last year or so. The first thing that popped into my head was how the old stock cars used to cut holes in the wheel wells so that the driver could look towards the backseat area and see if the tires were flat...directly. They'd just cut a 3 inch hole so the driver could look right at the tire as he was driving. If they used a rear view mirror, they could look at the tires without even turning their heads.

I'm sure those little holes helped with airflow, too. That's seems to be a sort of "undiscovered country" of aerodynamics. (How can you improve downforce and reduce drag using holes between the outside and inside of the vehicle?)

I've got two HOT ROD articles on Blowfish,one,when it was under construction,and another from Dec. 2007 when she blew the four-banger to smitherines at 255.412 mph,on the way towards 300 like they hoped for.
They reported Cd 0.20 for the 'Cuda which seems very reasonable when you look at the car.
I agree that there are some un-turned rocks to look under for aero.Alex Tremulis was enchanted by a paper presented in the 1970s about using turbochargers to run pumps for boundary layer suction which would free up more horsepower through drag reduction than the turbo would add to the engine for a net gain in all around performance and economy.

[Cd]

I love the look of the 'Blowfish' 'Cuda.
I especially like how that they designed the front end to look just like the Superbird.
They chopped the roof some, and lowered the car as well. It is especially apparent in this video of the speed run.