Quote:
Originally Posted by aerohead
If you've ever seen a soft tonneau cover on a pickup going down the highway,you may have seen how the back is 'bird-bathed' with a distinct depression,and the front is bulging upwards as if Yoda was under there trying to get out.
The depression is created by air slamming straight down on the fabric ( this is what air-cooled VWs and Porsches use for induction and cooling.
The bulge is created by the partial vacuum of the locked-vortex directly behind the cab,literally attempting to suck the fabric into it....
Also,adding a short distance of roof extension will help direct the momentum of the air towards the trailing edge of the wing and not down into it.This worked very well on the CRX.
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Aha. Thanks, aerohead.
That pretty much explains the center panel flexing. If I perceived it correctly (via rear view mirror only of course), mine was "bowing down in the mid section and up at the rear", which was before adding the stiffeners. The forward edge was laying on the glass (not taped down at that point) so couldn't go down. If it had gone up I would have seen that, with the edge not lining up on the defroster wires as it was cut to fit there.
So it seems the air is slamming down around the mid point of the panel. And possibly there's a suction pulling up on it at the rear.
Roof extension should be helpful if/when I can make one. I'm sure it will be one of those conical section things, a lot like a front windshield. Patience is needed to make one of those panels. I can do it but it's not something to attempt to do quickly between other responsibilities.
Anyway, it's back to the drawing board, one way or another, next time I get to work on it.