Just to be complete.
Here's the link to the pilots manual I was using:
http://www.scribd.com/doc/42209938/F...ok-FOI-1944pdf
page 7 say the bit about F4U-1 being ~ 800 lbs heavier than the F4U-1C/1D under full fuel and ammo loadout with no external loading (i assume this means no droptank) also, you figure the pilot weighs ~ 200 lbs and that probably isn't included in the figures.
page 65- the takeoff chart under varying scenarios (hard surface, soft...etc.)
it looks like the information from different sources differs a bit. not sure what is considered "official" for the game.