Wow, Mike I never knew... but then again we never talked 'tanks'... This is a stretch, but maybe you'd know: Was there a wind-speed/direction sensor mounted on the turret? My dad was a specialized engineer contracted to DARPA a number of years ago, I'm thinking late 80's. He was tasked with developing a highly reliable and shockresistant sensor system that could instantaneously measure windspeed/direction. He couldn't tell us more than that, but I caught snippets of the development and came to suspect it was for the Abrams' fire control system. A prototype I once saw at the workshop looked like a 3" cylinder that popped up some 12-18" out (of the turret?) for a second to take the measurement, before retracting and the gun would fire. Who knows - maybe it's declassified and he can tell me about it now.
Cheers,
- Art