The freight train

What about the astronauts up top? Riding a Saturn V was never a relaxing experience for the crews, but a few usually those taking their second flight exhibited much lower heart rates than their rookie colleagues. Bill Anders, who flew to space only once, was part of the first crew’ to experience the rocket on Apollo 8. "The thing that impressed me about the early stages of lift-off w’as the very positive control during the gimballing of the S-IC engines. It was very positive."

In the initial moments of its flight, most of the w’eight of a Saturn V was at the bottom, particularly in the huge kerosene tank just above the engines of the first stage. The upper stages, although large, were taken up with huge tanks of relatively light hydrogen and, consequently, the centre of mass of the stack w’as quite low’, somewhere in the first stage. Anders therefore found himself on the end of a very long lever and w’as being jolted from side to side by the steering motions of the four outer engines of the first stage although they operated nearly 100 metres below him.

Steering of the first stage w’as achieved in all three axes by swivelling the four outer F-l engines in response to commands from the instrument unit’s computer. Roll manoeuvres w’ere made by moving opposite engines in opposite directions to give a slight screw effect to the vehicle. Moving them in the same direction at once allowed control for pitch and yaw manoeuvres, causing the vehicle to rotate about its centre of mass. Because the crew’ sat far aw’ay, on the opposite side of this point, they felt the vehicle’s rotation doubly as it shook them from side to side. Anders had expected this from rides the crew had taken in a simulator, one that was capable of moving and shaking them w’hile they practised their procedures but. as he noted, the simulation failed to live up to the real thing. “In fact, it felt to me on the first stage ride like an old freight train going down a bad track."

Later in the same mission, the commander, Frank Borman, gave his impressions of the very high noise levels at lift-off to a voice tape, the contents of which were later replayed to Earth on a separate channel. "The launch was nominal in almost every respect. There w’as no difficulty determining lift-off. Vibrations w’ere noticed before the thrust came up to commit to launch, and then when the hold-dowm arms released, the vibration went away." Anders by then had firmed up his impressions of the launch. “The thing w’as still rattling like a freight train as it became clear of the tow’er."

Ed Mitchell on Apollo 14 concurred with Anders’s observation. “Just can’t beat it, huh?" he told his crewmates. "Just like a railroad coach in this couch.” he added. In his post-mission debrief, Eugene Ccrnan on Apollo 17 even took the railway analogy right back to the start of the flight, “Yon could feel the ignition. You could feel the engines come up to speed. Ignition was like a big old freight train sort of starting to rumble and shake and rattle as she lifted off.”

The crew of Apollo 16 had similar recollections at their debrief as John Young brought up the next subject on the agenda: “S-1C ignition?”

“Wow!” was Charlie Duke’s instant reaction.

“Wow is right.” Young agreed. “There goes a train that is leaving. Lift-off – you can tell lift-off because everything is moving.” Duke elaborated further: “It is like an elevator slowly lilting off. It just kept shaking at the same frequency throughout the whole S-IC burn. You felt yourself going faster and faster and faster. I had the feeling it was a runaway freight train on a crooked track, swaying from side to side. That was all the way through the first stage.”