Windshield on or off for aerodynamics?

[MetroMPG]

Originally Posted by oldtamiyaphile

Well, I have all I need to do it

It would be fun to see some numbers.

[cRiPpLe_rOoStEr]

Removing the windshield and the rear window doesn't sound like a good idea at all. Depending on the roof curvature at its end, air getting directed downward and trapped there might actually increase the drag in a way similar to the tailgate of a truck.

[aerohead]

Originally Posted by EcoCivic

I would not, but I heard that you can reduce frontal area and therefore your Cd by removing the windshield and back window so the air can easily flow through the car instead of getting shoved off to the side by the windshield. Does that make sense to you? It does not to me. Thanks

So far,no one has actually tested it and published the results.The closest thing would be a comparison of racing coupes,roadsters,and spyders.
*a sports car Coupe of Cd 0.50
*as a roadster might be Cd 0.75
*and as a spyder,Cd 0.42,with half bubble and head fairing
* and cleaned up with detail optimization,Cd 0.31,as I've seen at Darko.
I agree with CrippledRooster that the presence of a roof without glazings could be an aerodynamic torture chamber,because of pillars and roof camber and all the interference drag.

[freebeard]

The one place I can see an advantage is in off-road racing where you are traveling in a cloud of dust and rocks.

But it's a safety advantage, not aerodynamic.

[TheEnemy]

Originally Posted by MetroMPG

When I saw the thread title, I thought this was going to be about Jeeps with the fold-able windshields.

I wonder if anybody who owns one cares enough about MPG to have tested the difference.

Approximately 2 mpg...

As far as legality the driver is required to wear eye protection.

[cRiPpLe_rOoStEr]

Originally Posted by freebeard

The one place I can see an advantage is in off-road racing where you are traveling in a cloud of dust and rocks.

But it's a safety advantage, not aerodynamic.

IIRC some heavy off-roaders replace the windshield with a metal screen exactly in order to avoid not just the debris from the route, but also due to the shrapnels that one could release if broken.

[aerohead]

Originally Posted by JockoT

When you think about it, the aero screen and tonneau cover of the 20's and 30's was spot on. Here is a more recent rendition.

I think that it was CAR and DRIVER that did a road test of the Caterham 7,Lotus 7 homage car.With the roof on it was reported at Cd 0.62.They didn't give a number for the roof down.
Walter Korff reported Cd 0.75 for 1960s era sports roadsters.Ouch!
Small frontal area,light,and great power-to-weight ratio though.