S-III
| Country of origin | USA |
|---|---|
| Used on |
Saturn C-2 (stage 2) Saturn C-3 (stage 3) |
| General characteristics | |
| Diameter | 27 ft (8 m) |
| Engine details | |
| Engines | 2 J-2 engine |
| Thrust | 400,000 pounds-force (1,800 kN) |
| Fuel | LOX/LH2 |
The S-III (pronounced "ess three") was a proposed third stage of the early Saturn C designs for a five-stage Saturn launch vehicle. The Saturn C configurations were based on a "building block" approach, in which the upper stages would be test-flown before the intermediate stages. The S-III was to have been a LOX-Hydrogen fueled stage powered by two J-2 engines. The original Saturn C-2 design would have been a three or four stage launch vehicle using the S-I plus S-III plus S-IV stages plus, for some missions, S-V.
So, the very first Saturn (SA-1) consisted of an S-I stage and dummy S-IV and S-V stages. Before a live S-IV was ever flown (as the second stage of SA-5, the first of the Block II series), the idea of an S-V stage was dropped.
The Saturn I series gave way to the Saturn IB. The first stage of this rocket was modified and renamed to the S-IB. The second stage of this rocket was an uprated version of the S-IV, the S-IVB; this stage was considered sufficiently similar to the S-IV stage that it was sole-sourced to Douglas without the usual bidding process.
Of course, the S-IVB would also be used as the third stage of the Saturn V. Its first stage was the S-IC. Since no stage initially designed to be a second stage had ever been manufactured (remember, the second stage of the Saturn IB was still an evolved version of the initially-envisioned fourth stage), it received the S-II designation.
With the Saturn S-IC, S-II, and S-IVB stages already in development, there was no need for another stage to be designed as a third stage, so the S-III stage was dropped.
A number of Saturn stage configurations (A, B, C) were considered between 1958 and 1960. One early version was the Saturn A-1, which had the familiar S-I stage plus a Titan I 1st stage as a 2nd stage and a Centaur as a 3rd stage. The Saturn A-2 was the same except that the 2nd stage consisted of a cluster of 4 Jupiters rather than a Titan 1st stage.
In the Saturn B-1, the 2nd stage was a custom-developed LOX/RP-1 stage powered by 4 H-1 engines. Again, the Centaur was to be the 3rd stage.
...
Wikipedia