The Saturn V rocket cannot rest on its rocket nozzles. How could the points of contact where spacecraft bears down the megatons of its weight survive the weight? The answer is: Saturn V rocket was supported on four support posts that supported the weight of the Saturn V. Each column was topped by a “Hold-Down Arm.”
They were located 90 degrees apart around the vehicle base, and each arm had a preloaded force of 700,000 lbs. The hold-down arms then swing around in a backward arc once the Saturn F-1 engines had reached proper thrust levels.
Furthermore, in addition to the four “hold-down arms,” three tail service masts would also stand on each launcher’s base. These provided support for electrical cables, hydraulic lines, propellant loading lines, and pneumatic lines servicing the first (S-IC) stage of the Saturn V.
What Are Saturn V’s Three Stages?
The Saturn Five was split up into three stages; they referred to each stage by a technical name. The first stage was called the S-1C and was powered by five F1 rocket engines. The second stage was called the S2 and was powered by five slightly smaller J2 rocket engines.
The third stage was called the S-4B and was powered by only one J2 rocket engine. It takes about 12 seconds for the rocket to clear the tower completely. But how did the Saturn V rocket stay solid and glued to the ground before launch?
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Were the Saturn V rockets standing on the launch pad with all the weight going through the F1 engines, or was it held somehow?
The millions of pounds of weight were never sitting on the engines. The importance was held in place by fasteners to the launch structures by mechanical means. If they ever tried to set all the weight on the rocket motors, they would have been severely damaged by the weight or destroyed by the explosive forces of the ignition of the liquid hydrogen and oxygen.
The motors were suspended over a concrete diversion trench that allowed the engines to ignite and reach launch thrust while diverting the toxic exhaust and much of the sound waves and sending them in a more safe direction.
The F1 engines did not even touch the Mobile Launcher. They hung off the S-IC thrust structure and dangled into a square tube (called the F1 Engine Exhaust Chamber) that passed through the entire depth of the Mobile launcher and led to the Flame Trench in the center of the pad.
What Are The Hold-Down Clamps, Hold-Down Arms, or Launch-Clamps?
Sometimes called hold-down clamps or Hold-Down Arms, Launch-clamps are the devices that support and hold rockets on the launch bed. Launch clamps secure rockets in place before and up to the moment of liftoff. They bear the rocket’s weight on the pad and prevent the Saturn V rocket from swaying or tipping and protecting against strong winds.
They also hold the rocket down after the engines are ignited to give engines time to build up to full thrust. It allows the rocket’s computer systems to confirm all engines are running as intended. If the flight-computer detects any problems, the engines can be shut off, and the rocket will remain safely in place on the ground.
Saturn V’s “Hold-Down Arms”
They were massive structures that intruded into each side of the square engine chamber. These are the four support posts that supported the entire weight of the Saturn V.
Each post was topped by a ‘Hold-Down Arm.’ These hold-down arms spent months supporting the rocket’s total weight from the time the S-IC was first erected in the VAB, right through vehicle assembly, rollout, pad checkout, and fuelling.
A flange on the S-IC thrust structure was gripped between the support plate on the hold-down arm and the massive clamp. Those four clamps held the tail of the Saturn in a vicelike grip and were the only support the rocket got.
But shortly after ignition, they switched from being “hold-up arms” to being “hold-down arms.” Those same launch clamps had to restrain the Saturn and keep the five F1 engines’ tremendous power from lifting the rocket off the ground until the computers could verify that full thrust had been achieved.
And when the Saturn V checks were complete – the linkage in the hold-down arms was collapsed either by a high-pressure helium pneumatic primary mechanism or an explosive bolt back up. Then the clamp rotated back. The Saturn was then released for its journey to the Moon.
What is The Thrust Structure Of Saturn V?
At the base of the first stage of the Saturn V, a framework known as the “thrust structure” held the five engines and transferred the thrust to the rest of the rocket.
This was connected to the pad by four latching points, which had to hold the rocket up before launch, then hold the rocket down as the engines built thrust between ignition at T-8.9 seconds and the actual liftoff time T-0. This single structure formed forged aluminum and accounted for roughly 10% of the stage’s empty weight.
Saturn V’s Explosive Launch
The rocket was held down to the launch pad using exploding bolts. The engines pointed down into a concrete-lined pit full of water that absorbed the engines’ sound, which would otherwise have shaken the first stage apart.
When the Saturn V engines were ignited, the rocket was held down until all the engines were firing normally. When it all looked good, the explosive bolts were detonated, and the engines throttled up and lifted the rocket into the sky.
At this point, the engines were holding up the whole weight of the rocket, plus the added thrust that allowed it to gain the speed it needed to enter orbit.
But the beefy part of the engines – the part holding up the rocket – was the back of the engine’s combustion chamber, up inside the first stage and at the other end of the engine from the rocket nozzles. The nozzles were very delicate and couldn’t have held much weight if they were placed on the ground.
That’s it, and I hope you enjoyed this article. Please check out this exciting article that will reveal the Apollo Saturn V rocket’s inside and its significant components. See for yourself these fantastic drawings. You will be amazed.