Watched about 2 hours of "Bombing Hitler's Dams" on PBS: Nova this evening.
Recreation of sorts of the Barnes Wallis development of the "bouncing bomb" used for "dam busting".
Did not know of his history with the R100 airship and the Wellington bomber and his use of geodetic design. Also did not realize that though successful in execution, the effects were not all that long lasting with a lot of rebuilding of lost capacity done about 4 months later.
Machining content to build the scaled down versions of the cylindrical bombs and also including the different thickness of paint coats (two different colors, one on each half so as to help track the rate of spin) putting the whole thing out of balance...if I heard correctly, about 800lbs and they were trying to get balance within 20 grams (it could have been 200 grams).
It was a little disconcerting watching some of the early model spin tests as they used what looked to be 3/4" or 1" plywood to create a box and on those edges mounted the bearings carrying the shaft running through the "bomb" center (at this point the bombs were not up to even scale weight...it was more to see they could even get them spinning fast enough so as to spin long enough to be at the correct rpms when dropped so as to actually bounce/skip).
Tests done in northern BC and it actually worked pretty well on the first scale test...successful enough to test no further.