BrianG asked: It would seem that the 707-131 was not a big money maker for airlines being it held less passengers that the 300 series.Was the 707-131 used on shorter routes ? It seems in general the key to making a 707 profitable would be to keep it in the air on longer flights being it used so much fuel getting to cruising altitude. But with fuel at 15 cents/gallon back then maybe that really wasn't a consideration?
And what did water injection on the engines accomplish? Was that for addition power on take off? I just remember water injected engines created much dark smoke on take off.

The 707-100 series was a bit smaller, but the seating config was even more important to the passenger numbers. We had some 707-300's that were all first class and some that were all coach and the latter was not a nice product, but was necessary to be able to make money with charter fares. Either version was able to go coast-to-coast, but only the -300's went over the pond.

The 707-131 "water wagon" was a filthy plane on takeoff. It would carry 5,500 gallons of special water that was injected into the aft section of the engine. What it was intended to do was increase thrust by adding to the mass of the exhaust. It did do that somewhat, but what it did mostly was soot up the sky with copious black smoke and make a hell of a lot of noise. You had to use all the water since any left over would freeze in the tank and cause problems. Most pilots hated to use the water and some dumped it on the taxiway before take off.  :o

I remember taking off out of Shannon on a charter at max gross with a 707-331 and using every foot of the runway.  :-X This was an underpowered plane if there ever was one. The 707-131B on the other hand was a hoot to fly - Hang On here we goooooooo...  :D

Lou