LOU wrote on Oct 8^th, 2010 at 3:57pm:

The 707's had all kinds of engines. One of the early models was the 707-131. It was a "straight pipe" that had no fan. This was the early P&W turbojet, it also was water injected on takeoff. We nicked named it the "aqua-jet or water buffalo." Without the water this was a runway eater at high gross weight. You would line up for takeoff and start the thrust levers up slowly. I don't remember the EPR setting, but once at this setting and stabilized the F/O would turn on the water pumps. Then takeoff thrust was applied. This was supposed to increase the mass coming out the back of the engine. All I remember is it made more noise, and when viewed from the outside it looked like you were spraying for skeeters. Big mass of black smoke coming out the back and off you went down the runway like a herd of turtles. Also, some engineer at Boeing thought it would be cute to have two pumps in the water tank. One in the front of the tank and the other in the rear. Don't get ahead of me... The forward pump fed engines 1 & 2 and the rear pump fed engines 3 & 4. You guessed it - at 15 to 17 degrees nose up the forward pump ran out of water first and the left side would loose thrust and yaw left. Now that's design! You had to use ALL the water up since the 5,500 gallon tank was in the wheel well and any water left in the tank would freeze. Most pilots hated the water and would sometimes dump it during taxi. This -100 series Boeing was smaller than the -300 and we also had a -131B version which was the small plane with the high by-pass fans engines. All I can say is WOW could that thing could go.  8-) The -300 was the larger 707 with the straight pipe engines and it was a pig. All the other 707 were -300B's with various sub groups -300BA, -300BAH & -300C and these had fan engines. The different letters told you what kind of leading edge flaps the plane had as well as what strength landing gear the plane had. The CS707 is a high by-pass fan. You can tell by looking at the front of the engine and see the larger front cowl. A large part of the thrust came from the by-pass fan air. An aside - look at the cowl on the fan part and you will see a series of doors around the outside of the fan cowl. At high thrust settings, these doors were spring loaded, and would open to allow extra air to enter the engine. If you look out the cabin window as you apply takeoff thrust you will see the doors open as the engine reaches high power.

I assumed jet due to to the age and heavy smoke, I didnt know fan engines were available back then,  tks