Many thanks for those images!

Pretty sure the movie called "The Dam Busters" was about this. As I
recall, there were two spotlights under the wings, one on each, and far
apart; they were aimed so that their beams converged at what would be the
proper height above the water. When the spots merged, that was the
correct altitude (which was only some (tens of?) yards, iirc.

AS probably some/many of you know, the bomb[s] skipped, bouncing on the
surface of the water, to slow down their forward speed; when they stopped
skipping, they submerged, just on the upstream side of the dam.
Detonation must have been triggered by water pressure as the bomb sank.

hth, a bit. Apologies if almost everybody knows about these items.

--
Nicabod =+= Waltham, Mass.