Hey, chopperfan:
Looks like I got your attention with the S-3 comment :-)
I think that would be a great lease on life for the Viking after its military days are done with.
I can't visualize a 747 doing water drops. I would think the turbulence at such low levels and the pressure of keeping it low enough to be practical at firekilling against the updraft from the fire would mike for a very short lifespan on such a big airframe.
I'd like to get my hands on one of the TOKO 1/72 Antonov 72 "Coaler" kits and see if I can get enough information on the fire killer variant of it to do a correct conversion on it.
If I'd been thinking of fire bombers when I saw Revell Germany's reissue of Frog's 1/72 Avro Shackleton MR.3 a few years back, I'd have scooped the kit up and tried to make a fire killer out of it. Was the Shack ever used for fire killing? If not, its unfortunate, it probably would have done the job well.
I'd like to see them rig up a C-2 Greyhound for fire bombing.
A BAe Jetstream would also be intresting to see in that role, I see them all the time with those bolt on luggage containers under them and think what a short hop it would be from that to a retardant tank.