False windshield for boxy car?

[brucepick]

I came up with another pipedream project.
This is another one that I doubt I'll have the courage to do but I want to ask what you think. Inspired by the fact that my car has a fairly steep windshield. Current Japanese high-FE products have a nearly continuous straight line from front of hood to top of windshield, except for a sort of cowling in front of the wiper blades.

(This is not my car, but the front body lines are the same. Mine = wagon)

I'd build it out of Lexan or whatever is the clearest, most scratch resistant plastic I can work with. This first version would need some clever hinging for when you want to check the oil. Which is why I thought of the second version...

[IMG][/IMG]
This is a more moderate version.

Trebuchet03 and basjoos and others, what do you think about the aero value of these?

I think the second version would still need to be clear, but it can be attached solidly to the hood so the hood will still open. Hood is spring loaded but I could add a prop rod if needed for the weight of the mod.

[GenKreton]

If you are thinking of the first design, why not extend it down further, past the grill? You could make the front a sharp edge. I'm not sure how to hold it on, but then you would definitely need a fairly easy way to remove it.

[brucepick]

My avatar shows what I've done for the nose area.

Motor vehicles here in CT won't let me add anything in front of front bumper or behind rear bumper (though I plan to look into that some more when I get a chance).

Back to the topic please - how much improvement do you aero guys think one would get from a false windshield, as in the two photos?

[brucepick]

This two piece version might let you open the hood without hassles. Might need to find exactly the right place to make the cut. Or maybe there would be no such place that would let you lift the hood completely.

[MetroMPG]

I assume you're asking for the wagon, and just using the sedan as a sketch pad. Because on the sedan, you'd get better gains putting that shape on the back than on the front (as long as there's attached airflow at the end of the roof, which I think is likely).

[Chris D.]

Originally Posted by Frank Lee

1. Rain
2. Fog

X2,
rain-x can only do so much..
glare can also be a MF as well as road debris ruining it fast not to mention the suns effect..

I'd just do a cowl to sheild the wipers..
Those Volvo's are built like bricks.. Once had a Turbo Brick myself..

[brucepick]

Windshield leaks. A cover over it would keep some water out.

It's easy to say "boattail" until you figure out it would have to be about 4-5 feet long and would probably not be road-legal here in CT. Plus would be a bear to build if you want to open the tailgate.

[boxchain]

I would think that a wiper cover would be the easiest-best way to proceed. Those angular transitions are going to play with your forward visibility. The moderate version look like they'll cause a detachment wake zone in front of the windshield.

The first one could fit if you just switched hinges so it tilts fwd

[trebuchet03]

IIRC Basjoos played around with a second windshield.... You may want to get him to put some thoughts in

[basjoos]

I have a false windshield for my car, but it is currently not mounted on it. I plan to remount it once I replace the clear vinyl with Lexan and make a few other changes to it. The clear vinyl had less than optimal visibility when viewed through at an angle, which the Lexan does not at the angles I will be using. The false windshield caused a noticable reduction in drag and eliminated the A-pillar vortexes visible on the side glass when driving through rain. I had Rain Magic (a Rain-X type product compatible with plastic glazings used by motorcylists) on the false windshield and as long as I was moving at least 35mph, very little of the rain impacted on the windshield and what was already on it got blown off. The main problems I had was with it fogging up on the inside when driving through heavy rain in cold temps as water that got past the front seal evaporated off the warm hood and condensed on the inside of the false windshield. Mine is hinged at the front, held down by 3 screws on the roof over the windshield and by 2 small locator pegs fitting in holes in the hood near the base of the windshield. When I needed to pop the hood, I just removed the 3 screws on the roof and the whole false windshield slid up over the roof as I raised the hood. Another effect of having the false windshield mounted is that I lost all ram air pressure to the air vents, so I had to run the vent fan whenever I wanted any intake air.

In its new incarnation, the false windhield will be Lexan, have better front and side seals to keep rainwater from getting under the windshield. Also a windshield wiper parked in a vertical fairing for minimum drag (to satisfy any legal requirements for wipers). Also am considering mounting some type of small blower/heater to clear any inside fogging.