M. J. Powell wrote:
In message , W. D. Allen Sr.
writes
The British needed special design spinning finless 7000 lb bombs to break
through the Ruhr Dam during WW II. Half the bombers on the mission were
lost, most before they got to the dam.

The Ruhr Dam? Where this? And when was the raid.

http://en.wikipedia.org/wiki/Operation_Chastise

-HJC