Tuesday, January 8, 2013

S-1D First Stage

One of the most promising developments of the Saturn V was the S-1D 1st stage.

Take the S-IC Saturn V first stage and modify the thrust structure, to turn it into a F-1 powered Super Atlas. The rocket would lift off under the power of all five F-1 engines and fly normally until 70% of the propellants were gone. Then the outer 4 engines would shut down and the engines, thrust structure, the outer skirt, fins and fairings would be jettisoned.  The center engine would continue thrusting and propel the entire S-ID stage with it's payload into orbit. The payload capacity would have been 50,000 lb.s (22,600 kg) with a 33 foot (10m) diameter payload envelope built in.  Just by itself, the S-ID could nearly match the shuttles payload at a lower cost.

For $150 million(1968) and 3 years of development, the payload capability of the entire Saturn family could have been enhanced by almost a third.  Boeing engineers had to change the thrust structure by mounting the center engine on a cylinder, attached to a new conical thrust structure on the back of the stage, to transfer the thrust to the stages skin.  The center engine would need to be able to gimbal to control the vehicle.  The outboard engine thrust structure would have been cross beams with a hollow cylinder in the center large enough to clear the center engine, by removing the cruciform where the center engine was originally mounted.  The outboard structure would made to separate from the new center structure.  The propellant lines would have needed shutdown and separation joints on the outer engines.  The IU (instrument unit) ring normally carried atop the third stage S-IVB would be reworked and mounted atop the S-ID.

The outer ring of booster engines could have been made recoverable. The payload would have been even greater had the stage's fuel tanks been enlarged as proposed for various Saturn V upgrades.  The F-1A engine with its higher thrust and efficiency would have also boosted the payload numbers.

Studies were done with various upper stages, showing about 30% improvement.  For example,the Int-20 Saturn, put a SIVB (third stage for the Saturn V) on top of the S-ID first stage. This could launch 180,000 lb (81,600 kg)  into orbit, an increase of 48,000 lb (21,800 kg) over the standard S-1C stage version.  The first version of the SLS is supposed to put 70 tons in orbit, this version of the Int-20 beats that.

The S-ID would have been operational in 1972, probably would have been used in the third order of Saturn Vs.  But in 1968, budgets were already being cut.  The second run of Saturn Vs was canceled before Apollo 11 landed on the moon.  Plans for enhanced Saturn Vs, space stations, and moonbases were not to be.  The saturn rockets were scrapped in favor of the space shuttle which promised cheaper flights and reuse.

The S-1D would have weighed 5,099,000 lb (2,300,000 kg) at takeoff.


  1. Godsdamn. This really paints the shuttle as a tragic diversion from the path of progress.

    I loved the shuttle - it's definitely the most beautiful thing Humans have ever put in space - the most incredibly capable, too... but this thing... wow.

    If I were Jeff Bezos, with my predilection for Apollo artefacts and my ground-breaking rocket company, this is the concept I'd be looking at... though I may balk at the "recoverable" engine ring - sounds like an expensive sea landing to me.

    1. The space shuttle was the biggest space boondoggle mankind ever built,the facts and 14 dead astronauts speak for themselves, no pun about the astronauts speaking,sorry.Saturn 5 was the antithesis of the space shuttle, the greatest space achievement of all of mankind,more self speaking facts.I'm afraid that was also for the rest of mankind's future with Space X being a temporary hick-up in our history as there's not much time left for us as the human race.Was fun while it lasted until Apollo 17 and Sly Lab missions were successfully concluded.

  2. We are Anonymous, We must find a way to pay NASA all the moneys and get them back to space

  3. Hi, great article, I know it has been a while but do you have any readings about this project of rocket.

  4. Why astronauts when return from Moon they were so silent?. Forbidden to say: On Moon there are Extraterrestrials, of course forbidden by the religious, because "God" only "is" on Earth. For that reason recent declarations of an astronaut: "We do not can return to Moon".