Cheers Brian, I read somewhere when I did a forum search on this topic that fuel normally descends at 500ft/min so from your stuff I guess that it'll take a max time of 8 minutes to totally evaporate from your 2nd point that "fuel jettison above 4,000ft AGL ensures complete fuel evaporation". Just gives me an idea of where not to point a/c behind one thats unloading its tanks!
Is there any chance of following a/c igniting dumped fuel they fly through or is it a case that they'll just suffer an engine surge?