Reversed Tear Drop

https://www.thetruthaboutcars.com/2010/02/an-illustrated-history-of-automotive-aerodynamics-in-three-parts/

https://en.wikipedia.org/wiki/Automobile_drag_coefficient

1947 gas powered reverse teardrop tether car.

Dang... not uploading image..

A little assistance?

Thanks!

Looking around a car park, I wonder at the drag coefficients of modern vehicles compared to those of the 1950's, where streamlined shapes were commonplace.

A partial list...

Drag area of production cars

https://en.wikipedia.org/wiki/Automotive_aerodynamics

A comparison is impossible until some 1950s cars are included in the list.

I think the insufficient amount of usable interior space versus the overall dimensions in a hyper streamlined vehicle was an unexpected drawback. Thus a two seater sports car (Porsche, Ferrari, Corvette, GT-R, etc.) will have a lower drag coefficient than many of those 50's era cars. Also most of the cars from that old era just looked sleek but they really didn't slip through the air as well as you might think. The smaller flat windshield did mean the driver looked through thinner glass that plowed through the air.

That is the part of my question that remains unanswered.

You obviously think a flat windscreen in the front is drag inducing but it is the rear end of a shape which dominates its drag coefficient.

I would like to see a common hatchback such as a Toyota Corolla measured both forwards and reversed, to see the cd and which is highest. I would not be surprised if the forwards one was highest.

There are so many things that affect aerodynamic drag. I do expect a flat windshield will produce more drag than a sloped and curved one. I expect many nuances in airflow through the engine compartment are overlooked by a novice like me. To my surprise the sleek, tiny, under powered Subaru XT has the same drag coefficient as my Altima sedan.

The Audi saloon was promoted on its Cd being 0.29 in the 1980s, which figure was among the lowest in road motor vehicles at that time.

I recall reading in the motoring press several decades back about the Porsche 928 having a better Cd in the reverse direction than the forward direction but I was unable to mine any data out of the Internet to actually support that claim.

I did see something about Myth Busters doing an episode but it would have been much easier (and more accurate) to perform instrumented wind tunnel testing with the car oriented in both directions. But not nearly as interesting to watch. That's been one of my gripes with M.B. is that sometimes (always?) the science played second fiddle to the entertainment value. But I get it, ratings makes the money.

Otherwise it would be on NOVA or some other PBS show.

There's a lot more to aerodynamic design than just trying to minimize drag.

For example, in the Army I was a flight engineer on CH-47 A Model Chinooks, eventually logging over 2000 hours. The A Models had a habit of wallowing through the air by swinging back and forth around the yaw axis (left/right), most pronounced at the rear of the helicopter. They were also difficult for pilots to fly straight, usually yawing some degree to the left or right depending on the pilot's touch on the controls. Even the built in SAS (stability augmentation system) couldn't correct the problem.

it was found that a major cause of this instability was that the aft pylon came to a sharp edge at the rear. Designing in a 6" or so flat area at the rear of the aft pylon (and adding airflow directional strakes under the rear ramp) added enough turbulence behind the pylon to significantly aid the yaw stability of the helicopter.

I later crewed a CH-47B at NASA with these seemingly minor changes and the performance and ride quality was significantly improved. All subsequent models of the Chinook have kept these changes.

Yes, that's apparent on cars too. I once owned a 1975 Datsun 280Z. It tended to get squirrely at high speeds, especially when there were winds. It felt like the air was getting under the car's relatively smoothly rounded under-nose, and "lifting" the car, thus reducing traction. I did some mods that included a front air dam (but no spoiler on the rear, like so many added on other cars), and the difference was remarkable! There was still a significant gap between the bottom of the air dam and the ground, but the shape difference from the smooth, rounded shell of the original nose made a big change.

I notice in recent times that automotive front styles are more like an air dam, so that airflow is around the sides rather than under the car.

Thats the thing aerodynamics, they can be almost counter intuitive.

Look at the Kamback design and its effects.

1925 Rolls Royce Phantom

��.. the little green car.. I would love to see it pulling a matching trailer with a couple passengers.

1983 Ford Thunderbird had a drag coefficient of 0.35 and was very successful in Nascar.

Mythbusters episode 154 - reverse-engineering

Tested. Busted. Looked like fun.