... they were sent to me back in 2001 by a friend with the exact same question. He got them from his father, a P-47 crewman in Europe. I redid the page in 2002 and a couple of the images seem to have gone missing- I need to fix that.
http://109lair.hobbyvista.com/articl...in/t_drain.htm
I certainly don't mind them being spread around, but proper credit would be nice...
Now, as to what it is, someone has suggested it is a smoke layer... all well and good, but that's an awfully large amount of kit for such a procedure. I had also heard it might've been involved in high-altitude deicing trials, but it would have to carry a LOT of water to dispense as ice crystals... so ultimately, who knows!
Lynn