Hi PatG
Very excellent work on the trains I must say.
for what its worth from
http://members.tripod.com/~nigelef/fireplan.htm
"Smoke screens, using base ejection (BE) smoke, were used in fire plans, they could be predicted, although a `tester' to confirm the local wind was often used. Screens could be multi or single battery and positioned about 250 yards from the enemy to be blinded. Gun aim-points were placed in a line, with the distance between them depending on the wind direction. If the wind was along the line of the required screen then points were 300 yards apart, if across the line they were 75 yards apart. Whenever smoke was used there were alternative HE targets in case the screen was ineffective. One technique was to create a lane for advancing armour a few hundred yards wide between two screens, these blinded defiladed anti-tank guns, if the wind was favourable these screens could be rolling. Smoke screens could be sustained for long periods, on at least one occasion all day. "
Best Regards Chuck.