"IMM" wrote in message
...

"John Aston" wrote in message
.. .

Aidan wrote in message
om...

snip

Thanks, Aidan. For the benefit of The Wall, I've posted a revised
drawing
at
http://tinyurl.com/5lx84 (although it has one DCV too many).

I can't see much which has been revised. Still lots to do to get it
right.

This revised drawing reflected Aidan's comments. Whether my design is
feasible is still open to discussion.