graeme, you've certainly done plenty of experimentation. Well done.
To change the shape of the tall screen should be easy. I've been trying, so far with limited success to make my own screen, and to bend it, I've used a normal heat gun. This works fine, but you must be patient, as too much heat will make the material craze.
What I've decided to do is to see if I can fabricate some small side pods to fit in the crease below the screen on either side, because this I think is creating the vortex that causes the buffeting and the additional noise.
I've tried simply lifting the MRA screen by 3/4 of an inch using aluminium spacers, and whilst the buffet is less, the wind noise is more. So more to be done there.
I'll get to it one day,
Mick
