SIX MILLION POUNDS OF MOON SHIP

Press, Volume CVI, Issue 31161, 10 September 1966, Page 13

SIX MILLION POUNDS OF MOON SHIP

(By

NEAL STANFORD

in the “Christian Science Monitor'’)

BpHE Apollo Saturn V vehicle, that will take men to the moon, is the most awesome, complex engineering and | construction job yet undertaken by man. The vehicle itself stands 364 feet high—nearly the equivalent of a ■O-storey building. It weighs some 3000 tons.

. Its Saturn rocket generates 8.700.000 pounds of thrust in its three stages. This is roughly equivalent to the horse-power of a line of 1966 automobiles stretching bumper to bumper from New York to Los Angeles. Saturn can put a pay-load of 45 tons on the moon’s surface. Its three stages carry 5.000.000 pounds of propellants. It burns this all up in less than 17 minutes—about 95 per cent of it in the first 10 minutes, when the vehicle is overcoming the earth’s gravity for the 25.000 m.p.h. trip to the moon.

This moon mammoth has three main elements: (1) the three-stage Saturn launch rocket: (2) Saturn’s instrument unit, or IBM “brain”; (3) the three section Apollo spacecraft that Saturn blasts loose from earth’s gravity.

The Saturn 5 is the raost| jowerful rocket jet devised. Its three stages produce a total thrust of 8.7 million sounds. This compares with, ihe 530.000-pound thrust of the two-stage Titan rocket that puts Gemini spacecraft Into earth orbit and the 18.000-pound thrust of the Redstone booster used in the two suborbital Mercury shots. Saturn’s three stages are known as S-IC, S-2, and S-48. The first, the S-1C is by far the mightiest Its five F-l Rocketdyne engines each generate 1,500,000 pounds of thrust—or a total of 7,500,000 pounds. Their job, in the srst two and a half minutes, is to lift this 3000-ton vehicle 30 miles above the earth. This stage is built and assembled bj' Boeing at its Bichaud plant outside of New Orleans. At that point, its fuel and power exhausted, the S-1C stage is jettisoned and the second-stage S-2 takes over. Its five Rocketdyne J-2 engines, each generating 200.000 pounds of thrust, or a total of 1,000,000 pounds, in the next six and a half minutes propel the spacecraft up to 100 miles, which is close to orbital altitude, before dropping away. These

A re-start capability is built into this engine, for it must first place the Apollo in an “earth-parking” orbit, and then re-start to place it on its trajectory to the moon. The Douglas Aircraft Company is prime contractor for this third stage. Ori the pad the Apollo Saturn 5 weighs some 6.000.000 pounds. With the I combined 8.700.000 pounds thrust of its three stages it! puts about 240,000 pounds' into earth orbit Its last stage then sends the 90.000-pound spacecraft to the moon.

But Saturn 5 did not spring full-blown from the drafting boards down at the Marshall Space Flight Centre in Huntsville, Alabama. Saturn 5 is the third in the family of Saturn boosters. Such boosters became a necessity when the United States decided to put men on the moon by 1970. These Saturn boosters are known as the Saturn 1. the Saturn 18, and the Saturn 5. Three Stages The Saturn 1 and the' Saturn IB are two-stage vehicles. The Saturn 5 is al three-stage one. The Saturn I 1 produces (or produced, for

into earth orbit, or shoot a, 45-ton pay-load to the moon. | These three vehicles in the Saturn family can also be I compared by weight and size. I The Saturn 1 stands 190 feet high, or about the height of a 20-storey building. An S-1B stands 225 feet on its pad. or some 24 storeys high. The three-stage Saturn, however, rises 364 feet off the ground —or nearly the equivalent of a 40-storey structure. A weight comparison shows the S-1B weighing not much more than the S-l (1.300,000 pounds to 1,165.000 pounds) i due to some careful redesigning. But the S-5 weighs 6,000,000 pounds. I In brief descriptions of these three Saturns: gathered in a recent visit to their production sites are: Its S-l first stage is powered

by eight clustered H-l engines with a total of some 1,500,000 pounds of thrust. Its S-4 second stage is powered by six Pratt & Whitney RL-10A3| engines with a total of 90,000 j pounds of thrust. Chrysler.! was the builder of the first) stage, Douglas of the second., Saturn 18. Its S-1B first stage, built by j Chrysler is, like the S-l, powered by 8 H-l Rocketdyne! engines but uprated ones, so i [the total thrust is closer to] 1.600,000 pounds. Its S-4B second stage uses a single J-2 | Rocketdyne engine, with 200,000 pounds of thrust, instead of six RL-10A3 engines, which gave a total S-4 thrust of only 90,000 pounds. Saturn 5

The S-5 is far more powerful than its predecessors. The S-1C stage, built by Boeing, is powered by five F-l engines, each producing 1,500,000 pounds of thrust—for a total of 7,500,000. This is what it I takes to lift that 3000-ton monster off the ground. Its S-2 second stage clusters five J-2 engines for a total thrust of 1,000,000 pounds. North American manufactures and assembles the S-2 stage. The third —and top—stage of the Saturn 5 is the same S-4B unit used as a second stage on the Saturn 18. In Orbit I Its 200,000-pound-thrust engine will first insert the

Apollo spacecraft in a parking orbit and then, some hours later, fire again to launch the Apollo moonward. I While the various stages of these Saturn vehicles can be confusing, the two main things to remember are that: There are three models of the Saturn: the S-l, the S-18, and S-5. There are three basic engines in the Saturn IB and Saturn s—the F-l, in a cluster of five for the S-1C [ stage of Saturn 5: the H-l, in a cluster of eight for the S-1B stage of Saturn IB; and the J-2, used singly in the S-4B stage and in a cluster of five in the S-2 stage of Saturn 5.

Sandwiched between 'the third stage of Saturn 5 and the Apollo spacecraft is a three-foot-high cylindrical “wafer,” nearly 22 feet in diameter.

Mechanical Brain I Saturn engineers call it an I instrument unit, or “1.U.” I This is the “brain” or “nerve centre” of the Saturn [vehicle. It is this three-foot ! “wafer” that takes over at the | moment of lift-off and does all [the guidance, calculation, and .correction for the crucial first [lO minutes. Then the pilots take over, as the I.U. drops away with Saturn’s third stage S-48. It would be impossible for the crew to do what the I.U. does in those first 10 minutes. The human mind doesn’t work as fast as that. In those 10 minutes the I.U. makes 7,000,000 calculations, checking the rocket’s flight with the vehicle’s digital computer. It samples acceleration 100 times a minute telemetering 3000 numbers back to earth. In that 10 minutes it issues 45,000 steering signals to the vehicle to keep it on the right course and trajectory. The interior of the cylindrical I.U. is filled with 67 different units and miles of wiring. These units issue navigation commands during the crucial 10 minutes changing the speed and altitude of the vehicle as it senses the need to keep it on the right path. They control the thrust of the gimballed rocket engines so the huge

I launch vehicle stays on the, j most efficient course to reach I [ earth orbit. I Even if one of the : Saturn's engines fails, the ' computer in the I.U. would , issue signals that would j cause the other engines to change directon to compenj sate for this loss of power.

The I.U. also controls booster separations, shuts down the engines, communicates the vehicle’s position.' and keeps up a running flow of data to the ground. This extraordinarily com-, plicated bit of engineering is the responsibility of International Business Machines

Corporation, prime contractor for the I.U. These I.U.’s are assembled at 1.8.M.’s Federal Systems Division at Huntsville, Alabama, site of the Marshall Space Flight Centre. 1.8. M. has a contract for 27 of these units —12 for ; the Saturn IB programme and 15 for the Saturn 5. Each costs about £2.5 million. Check System I There are some unique features in the I.U. aimed ! at assuring utmost reliability. I One is a duplex memory

[ system. Two separate memory' systems operate , simultaneously during the [ crucial lift-off. Each memory 1 system has stored in it . 920.000 data bits. If there ,is a transient error in one [memory system, the other .corrects it. and vice versa. , According to 1.8. M. officials the mathematical probability, that both memories would I fail at the same memory word 1 address at the same time is , infinitesimal. This makes the [ system as nearly selfcorrecting as possible. ' Then there is the triple modular redundancy feature with a unique “voting" procedure. When a problem is presented to one module, it is presented simultaneously to its triplets, and all three act on the problem together. But results are reached independently and then fed into a majority rule “voter" circuit. Any dissenting "vote" is discarded as an error. Onlj’ identical signals put out by at least two of the three modules are passed along by the voter circuit. This voting procedure doesn’t appreciably slow down the computer. The worst delay, say 1.8. M. officials modestly, is only 100 nanoseconds—loo billionths of' a second. Essential To Men The I.U. is only a threefoot "wafer” squeezed between the Apollo spacecraft and the Saturn rockets. But these three feet are crucial. The astronauts know they cannot do without them.

Perched atop all this power and complexity, is the payload: the three-man Apollo spacecraft that will flj’ to the moon and back.

While the spacecraft proper consists of three sections, a fourth unit is tacked on to to top. This 33-foot section, looking like a miniature Eiffel Tower, is the escape system—E.S.

In case of failure of the booster before or during launch, the E.S.’s motors can lift the command module (with the three astronauts inside) away from the Saturn 5 booster and, using three parachutes, bring it to a safe landing. If there is no trouble at launch the E.S. is jettisoned right after the second booster stage ignites. Below the escape system is the command module, the cone-shaped, 12ft-high living quarters for the threeman crew. It is built like a vacuum bottle, with an inner crew compartment and an outer heat shield to protect the astronauts from the 5000-degrees F heat generated during re-entry to the earth’s atmosphere.

Service Module

Below the command module is the service module, a 13ft - long, cylinder - shaped structure which houses the main propulsion engine for

the return trip from the moon, fuel cells for electrical systems, fuel tanks, and other equipment.

Corrections

The 21.900 - pound - thrust engine can make raid-course corrections both on the way to the moon (after Saturn s's third booster stage is discarded) and provides propulsion for attaining lunar orbit and for the return flight. It can operate for up to 12| minutes with as many as 50 separate short burns, jettisoned just before the command module starts reentry into the earth’s atmosphere.

Moon Vehicle

Below the command and service module is the lunar excursion module (L.E.M.), the part of the Apollo spacecraft which will land on the moon with two astronauts.

The L.E.M. is housed in a 28ft-long tapered adapter housing during launch and parking orbit flight. After Apollo is set on its course for the moon, the adapter will drop off with the S-4B stage, leaving the L.E.M. free for the complicated manoeuvre by which the L.E.M. is swung to the hatch of the command capsule and docked.

Back To Ship

| The L.E.M. itself has two .engines. One is a 10.500- ! pound-thrust descent engine to control the L.E.M.’s critical descent to the moon's surface. The other is a 3500-pound-thrust engine to lift the cabin of the L.E.M. ■off its excursion section and carry it back to the Apollo mother ship that has been I orbiting the moon.