Drag coefficient...?

[Andy_with_a_screwdriver]

Originally Posted by COLVERT

I can clearly remember in the traffic light grand prixs that I never had to go above 2,000 rpm in any gear to make the cars around me become small dots in the rear view mirror.


This low drag thing. Volvo estate cars started to compete in the saloon car racing but I think they were banned because they had a great advantage due to the much smaller drag co-efficient. It was because their rear end was flat.--

I can remember me Dad explaining that to me years ago.
He proudly told me his Type 2 VW (Transporter) had a better drag coefficient than the Type 1 (Beetle) due to it's straight edges and flat sides. I've just had a look on the Wikipedia https://en.wikipedia.org/wiki/Volkswagen_Type_2 and it seems he was right, the Germans were doing this in the 1940s and probably before that too.

Interseting read here: https://en.wikipedia.org/wiki/Automo...ag_coefficient

[T-Cut]

Originally Posted by grout20

I wonder if the change of styling for the facelift model made much difference?

I suppose there may be differences in the third decimal place, but for 'practical' purposes I reckon they'll be the same.


TC

[coab]

The MK2 R75 and ZTs would have a better drag co. Due to all the project drive things taken off it!

[Lord of Hog]

Originally Posted by mss

Not at all. Drag works against forward movement and has no impact on upward/downward forces acting on the object.

The Mercedes CLS is a case in point - a super heavy car, with a large downward force when moving, but with a drag coefficient of only 0.26.

Like the old Audi, which was hardly streamlined, the important bit isn't how the air hits the front of the car but how it leaves the rear of it. Steeply inclined rear screens and stubby boots encourage just enough turbulence to push down on the rear without interfering with the forward progress of the car. Hence spoilers on "performance" cars to break up the flow of air as it leaves the vehicle. Ed Straker's car from "UFO" must have been a pig to drive at speed.

[MSS]

Originally Posted by Lord of Hog

Like the old Audi, which was hardly streamlined, the important bit isn't how the air hits the front of the car but how it leaves the rear of it. Steeply inclined rear screens and stubby boots encourage just enough turbulence to push down on the rear without interfering with the forward progress of the car. Hence spoilers on "performance" cars to break up the flow of air as it leaves the vehicle. Ed Straker's car from "UFO" must have been a pig to drive at speed.

Again, not correct. It is the whole shape that determines the airflow and associated vortexes, not just the rear.

You really have to disassociate drag, which acts against forward movement, from devices used to provide downward force to make the car "stick to the road". Such devices will of course have their own impact on the drag and and this needs to be managed in the design.

[slovcan]

The teardrop is almost the perfect aerodynamic shape with the pointy part at the back. Look at all the university engineering project 500 mpg vehicles that get built in such a shape. Have a look at the top view of a Formula 1 car. Alos, have a look at the profile of an aircraft wing. It's a teardrop. Frontal area and shape play a big role in drag but the whole package is more important for aerodynamic efficiency.

[Discofan]

Meanwhile the Landrover Defender had a slightly less slippery 0.63

[SCP440]

I had a Calibra in the 90's, that had a very low drag coefficient. From memory I think it was 0.26, seemed impressed at the time but its one of those things that does not seem to be advertised anymore.

Maybe it has less effect on the overall economy than they thought it would.

I cant believe some of the boxes people drive around in today are very good but they still seem to return impressive mpg figures.

[MSS]

Originally Posted by SCP440

I had a Calibra in the 90's, that had a very low drag coefficient. From memory I think it was 0.26, seemed impressed at the time but its one of those things that does not seem to be advertised anymore.

Maybe it has less effect on the overall economy than they thought it would.

I cant believe some of the boxes people drive around in today are very good but they still seem to return impressive mpg figures.

Yes - I also had a Calibra. It was quite an impressive touring car and the drag coefficient was amazing for the day. https://the75andztclub.co.uk/forum/s...8&postcount=36


The aerodynamics only contribute about 65 TO 8% to the overall efficiency of a car. It was a bit of a marketing feature in the 1980's but these days engine and grearbox efficiencies are recognised as being far more impacting on the overall economy.

[Andy_with_a_screwdriver]

https://en.wikipedia.org/wiki/Automo...ag_coefficient

Scroll down about 2/3 to the section on Drag Area,
Opel Calibra is No.2 in production cars, according to Wikipedia.

Also some incredible looking designs in the concept section, especially VW XL1