The Saturn S-II

SATURN

NO RTH AMERICAN

A V I A T IO IO N , IN C .

S P A C E and I N F O R M A T I O N S Y S T E M S D I V I S I O N

S-ll

Th Saturn

is the second second stage stage of NAS A's A pol lo moon-landing rock et The The most pow erful hydr ogen -fuel ed booster under production,

destined for A po ll o manned manned lunar miss missio ions ns and moon.

The S - l l

the

l help power three three Americans Americans to the

bein g developed and manufactured

No rt h America n's Space and Infor mati on Sy

he giant

t Seal Seal Beac Beach, h, Calif.,

ms Divi sion , Downey, Downey, Cali f.,

by under

the technical dire cti on of NASA's NASA's Ma nh al l Spac Space e Fli ght Cente Center, r, Huntsville, Huntsville, Ala.

stands ds 81-1/2 fe et high, ha has s a 33-foo t diameter, and weighs 80, 80,000 000 S - l l stan

Th

pounds em empty pty and 1,025,00 1,025,000 0

pounds loa loaded ded

It s

d ~

f an aluminum

al lo y (2 (2014 014-T -T6 6 aluminu aluminum). m). Wit h its fi ve Rocket Rocketdyne dyne J- engines of 200,000 poun pounds ds thrust each, the S - l l dev develo elops ps a total thrust thrust of one one mi ll io n po poun unds ds.. Graphic ally, Polaris missile could spin lengthwise on a string inside the S - l l , would reach the S - I l l s chest. (Figure

and a Minuteman missile

LIQUID HYDROGEN FUEL

Th S - l l is powered by a combination of liquid hydrogen and liquid oxygen prothe lightest pellants, Liqu id hyd hydrog rogen en a col colorl orless ess,, tastele tasteless, ss, odorless gas. Its atom known .

When reduced to a temperature of 423 deg degrees rees belo w zero Fahrenheit,

a li qu id .

t be becom comes es

Beca Be caus use e li qu id hydrogen offer offers s a max maximu imum m amount of energy per per po poun und, d,

beco be come mes s possible possible to

t payloads payloads wh ic h wou ld require three or more st stag ages es using other other

In its li ui d sta state, te, hydroge hydrogen n for forms ms the newest of the nation's space fuels.

fuels,

S - l l ASSEMBLY

Startin g a t the the top is the the forward sk irt to wh ic h the upper upper S-I S-IVB VB (thi rd stage) stage) connects.

Below it, occupying more than half the total length of the stage,

288,750-gallon

(I qui d

li qu id hydroge hydrogen n tank.

hydrogen h ydrogen)) bulkhead. cylinders. Below this tank

e dom domed ed top of the tank

the

called the forward

e tank' tank's s cy li nd ri ca l sid sides es comprise the six l iq ui d hydrog hydrogen en the common or intermediate bulkhead that forms the bottom

of the li qu id hydrogen hydrogen tank and the top of the 93,75 93,750-gallo 0-gallon n li qu id oxygen tank. tank. Actually, Actua lly, i two bulkheads bulkheads i n one: one: the af t co comm mmon on bulkhe ad and the forward common common bulkhea d,

e bottom of the li qu id oxygen tank called the af (I qui d oxygen bolting ring attaches the liquid oxygen tank to the S - l l structure. Below

bulkhead. the af t bulkhea

the thrust struct ure and the

shield, and the interstage wh ic h

t sk ir t asse assembly. mbly.

Then Th en co come mes s the heat

attaches attach es to the bottom fir st stag stage e (S-IC) of the Saturn

(Figure 2)

NEW TECHNIQUES

e construction of a rocket o big, big, yet so so delica te, ca lle d for revol utionary to ol in g techniques.

w and preci se met metho hods ds had to be devised devised,, te teste sted, d, and retested.

SATURN S-II CUTAWAY mawing of the S-11. stage $haws interlor of iquid oxygen tank (above engines) zlnd th liquid hydrogen tank. The five J-2 engine$ develop of on million

~igam

ponnb.

One such new technique developed by North American specialists automatic skate welder

skate wel din g.

operate oper ated d b y an elect ric al weld pack package age that regulates regulates and

skat ates es over the part to be remembers every welding operation. This welder li te ra ll y sk welded on a track that hel d n positio n by vacuum-ope vacuum-operated rated suction cu cups ps.. An operator operator fo ll ow in g the automatic welder can adjust the the prog programe ramed d we ld procedure. procedure.

e track

sheet ets s to be welded and rem remain ains s fix ed throug throughout hout the tri trim, m, is pre cis ely positioned on the she weld, and subs subseque equent nt X-ray inspection. Ea Each ch of these these three procedur procedures es is accomplished mounting the respective head on the track. unique welding technique wa

introduced to prevent entrapped ga bubbles

the fabrication of the S - l l . requires trimming, polishing, deburring and vacuum cleaning. Operaton may no touch cleaned joint surface before welding, because fingers deposit undesirable chemical particles on the edges to be welded which eventually would dissolve the molten weld metal. These bubbles would solidify the weld metal, causing

defect

the weld bead.

Mo re than 2,5 2,500 00 fe et o f se ms on the S - l l must be welde welded. d.

o accom plish this,

revolutionary giant weld fixtures were designed to accommodate final assembly of the stag st age, e, bulk bulkhead heads, s, and cylin ders.

Fi ve bulkh ead fix ture s were required:

one fo r the

forward bulkhead, bulkhead, two for the forward common common bulkhead, one for bot h the

t commo commo

bulkhead and the af t bulkhead, bulkhead, and one for the assem assembl bled ed co comm mmon on bulkhead to the l iq ui hydrogen cy li nd er.

Bulkheads are made made up of gores. gores.

Twelve aluminum go gore res s compri comprise se one bulkhead.) welder

gore

shap sh aped ed lik e a slice of pie.

One weld fi xt ure

alled the "dollar"

used us ed to wel d three-foot diameter domed domed sect sections ions,, wh ic h resemble large

si lv er dollar dollars, s, t the apex of the bulkhead bulkheads. s. Another fix tur alled the thick-to-thin welder used us ed to we ld the two segme segment nts s o f the a t commo common n bulkhea d together, l of th thes ese e weldin g fixt fixture ures, s,

except the thick-to -thin section we weld lder ers, s, are located

in the the bulkhe bulkhead ad fabricat ion bui ldi ng t Sea Seall Bea Beach ch.. e thick-t o-thin we weld lder ers, s, whi ch are required for certa in tw o-piec e go gore res, s, were transferred transferred to No rth American's Slauso Slauso Angeles because because of space space lim itat ion s. So Some me of th these ese tools are show shown n i facility in Figure 3. Figure shows a welded aft common bulkhead on its welding fixture. Figure 5 sh ws the a t commo common n bulkhead and the forward co comm mmon on bulkhe ad weld ing fixture s inside the bulkhead bulkhead fabrication building

FACILITIES

Th

bulkhead fabrication building

154- by 300-

50-foot-high structured

steel frame building with 30-foot wide staging area, Inside are two cab-operated, interlocking bridge cranes; an electrically-powered gantry crane to position the bulkheads the autoclave; sliding walls and roofs; and other massive tooling. The autoclave is the largest pr pres essu sure re cooker in the the world. Actua lly, t is hemispherical, covered, pre pressu ssure re ve vess ssel el,, 38 fee t i n diame ter by 20 fee t h high, igh, use used d to bond and cure the core insulation between the aft common and forward common bulkheads.

S-I1

MAJOR

ASSEMBLIES FWD SKIRT

BULKHEAD

-FWD I

k

-

1

~

lIlmmm

mmmmm-BOLTING

~ YLINDER SUBASSY (6)

RING COMMON BULKHEAD BULKHEAD

-AFT

THRUST STRUCTURE AF SKIRT ASSY (5)

=ENGNES STATIC FIRING SKIRT (GSE)

HEAT SHIELD INTER-STAGE SUBASSY (8) Figure

2.

MAJOR MAJO R TOO LING CONCEPT HIGH ENERGY FORMING DIES

BOND JIG COMMON BLKHD

COMMON BULKHEAD

SEGMENT THICK

COMMON FT 1° BULKHEAD HYDROSTATIC TEST BULKHEADS

BULKHEAD WELD JIGS LH FW COMMON

*6:ffiyN

ONGITUDINAL WELD JIG

THICK TO THIN GORES LH2 CYLINDER

Figure

FINAL ASSEMBLY

Figure AF COMMON BULKHEAD first 6-11 bulkhead which shown on the welding fixture a t North North w i l l be used for sta tic tests is shown American's Seal Beach facility. Horizontal and vertical lines indicate the che mi ca l preparation used used to protect the weld areas. areas. Liness also indica te how the bulkh Line bulkhead ead was fabricated.

The autoclave's bonding temperature is 340 degrees Fahrenheit and its pressure pounds pounds per square square inch , augme nted

10-pound-per-square-inch vacuum pulled

y

between the two bulkheads. Nea r the the bulkhead bulkhead fabrication build ing In this this fa cil it y,

building.

the 120-foot-high ve rti ca l asse assembl mbl

the major compo compone nent nts s of the S - I l are welded together and its

flight systems are installed. four ver ti ca l assem assembl bly y stat station ions, s, (each about 110 110 feet h igh T h i s bu ild ing includes four an

35 feet i n diameter) opening n floors for welding,

and combined syst system ems s checkout.

insulation, sy tem tem installat ion,

t also includes two hydrost atic test stations for l iq id

oxygen tank tank and l iq ui d hydrog hydrogen en ttank ank h idr ost ati c (wate (waterr-pre pressu ssure) re) testing. Another Seal Beach facility is the water condition ing plant which contains contains tan tanks ks and equipment equipment to furnish furnish demine ralized water, water, heat detergent solution and trichlor oeth ylene for the hydrostatic testing and clean ing operation.

t includes water pump pumps s and a storage storage

tank f or f ir e fight ing , and com compr pres esso sors rs and equipment to furnish

r

t 100 pou pounds nds of

pressure pressure per square square inc h. The structural static test facility includes a test tower with hydraulic struts for structural testing on an initial test stage.

The The tower, tower,

138 138 fee t high, high,

l be enclosed on

three sides. Ot her f ac il it ie s inclu de the service service building, which house houses s supportin supporting g person personnel nel and andther andther bu ild in g for the pneumatic pneumatic te t, paint, and packaging operation. of these facilities contain revolutionary tooling to accommodate the various components of the

I.

These components are described below.

THRUST STRUCTURE

The five

engine eng ines s are in stall ed on the thrust thrust structur structure, e, a riveted , skin-stringer

and inte rnal frame frame construction wh ich rese resemb mble les s a mi niatu re amphitheat amphitheater. er. fabri cate d

n four four panels and h s a machined cy lin dr ic al ski rt.

T h i s part is

heat shield atop the

thrust structure prot ects the bas base e area of the. the.st stage age against re ci rc ul at io n of h ot engine exhaus t ga es and heat from the exhaust.

The The heat sh ie ld

protected by low-dens low-density ity abla tive material. inte rsta ge

of lightweight construction

This This structur structure e fits pa rt ia lly into the af

assembly assembly and around combust ion chamber of the engines; engines; the assembly assembly

shown shown i n Figures

and 7.

INTERSTAGE

e interstage, interstage, fabri cate d at N or th American's Tu sa plant, monocoque, monocoque, skin-s tring er c ons truc tion .

of riveted, semi-

(Semimonocoque (Semimonocoque me mean ans s tha t the S-11's skin

primarily without an internal framework). he interstage is inches long with 396inch diameter and ha 3030-inch access door. master mating gauge used to d r i l l the b o l t pattern so that the interstage fits to the S-IC stage below. thrust structure delivered to Seal Beach fo

An

skirt and

us on the static test stage w i l l be used

engineering development laboratory personnel fo stress-load testing.

FORWARD FORW ARD A

The forward skirt also

D AF AFT T SK SKIR IRTS TS

a riveted, se semi mimon monoc ocoqu oque, e, skin- stri nger structure.

137 inches lon g and h s a 30- y 30- inch acces access s door. it h extern al longerons and su suba bass ssem embl bled ed inte rna l fra frame mes. s. construction, is 88 inches long. A master mating gauge ed to d precisely to the upper and lower stages.

is

fabricated in four panels he t skirt, simil ar

ll the bo lt pattern to ensur ensure e that the skirts skirts mate

BOLTING RING

e bo ltin g ring supp suppor orts ts the liq ui d oxygen oxygen tank by attaching

t to the

structure wi th 600 bolts,

A top flange of the ring conne connects cts to the first li qu id hydr hydroge oge J" section of th tank tan k cy lin der and a bottom bottom flange connects connects to the t skirt. common bulkhead is welded to the first cylinder.

CYLINDERS

Each of the six liquid hydrogen cylinders comprises four panels welded together. Five of the cylin der pan panels els are 8.3 fee t high and and 27 feet lon long, g, the other panel inches inc hes high.

Longitud inal and and circumfer ential stiffene stiffeners rs are machine -milled on the the

inside surfac surface e to a rectang ular gri d pattern. inches. inche s.

I

28

e or igi na l thickness thickness of the panel

tw

mi ll ed to approximate ly a quarter -inch thic thickness kness between the stiffeners. stiffeners.

In order to preven t bo il -o ff of the -423 degree Fahrenheit li qu id hydro hydrogen, gen, insulation is bonded to the external surface of each cylinder. T h i s insulation made of phenolic honeyco honeycomb mb ll d wi th isocyanate isocyanate foa foam. m. Tw Two o laminate nylon external sealing skins are bonded to the honeycomb insulation. These cylinders are welded together during final assembly of the S - l l in the vertical assembl ass embly y bu il di ng . Figur Figures es and show these cylinders.

BULKHEADS

l o f the bulkheads bulkheads (Figur (Figure e 10 10)) are the common bulkhead

sli gh tly larger since i t m

me size wi th one exception. t

t over over the

e forward

ft com commo mon n bulkhead.

12 gor gores es th at comprise each each bul khead are appro ximate ly 20 fee t lon g and

3 inches wid e.

They Th ey vary in thi thickne ckness ss along the we ld land (l ongitu dinal ar area ea where where the gore gores s are welded together) from one-h alf inch to one-eighth inch.

They Th ey are welded together on an

el ect ric al ly control ed, hydraulic bulkhead bulkhead weld fixture. The Th e comm common on bul khe ad may be li ke ne d to two gia nt d me , one pla ced i nside the other, open end dow down, n, between them (Figures the bottom dome dome the

it h a layer of in sula tion (of var yin g thickness) thickness) sandwiched and 12).

The Th e top dome

t com commo mon n bulkhead.

the forw ard co comm mmon on bulkhead and

e af t com commo mon n bulkhead gore gore

from the other bulkhead gores in that each of its gores (resembl (re sembling ing a wa ffl e) a t the wid e end and a t hin section. section.

different

composed of a thick section e are welde d together on

the thick-to-th in weldin g fixture, The forward common bulkhead (sometimes called the lower LH bulkhead, Figure 13) cons 13) consis ists ts of a thin do dome me wi th a J-se ctio n on its periphery that allows for expa expansi nsion on of the bulkhead when i t is is fi ll

d wit h li qu id hydrogen. hydrogen.

e section res resem embl bles es a "J

an

the lower l p is is welded to the li qu id hydro hydrogen gen cylinder. In order to bond the phenolic honeycomb insulation to the aft common and forward common commo n bulkheads, several o perations are performed. fir st on the bonding fixture, honeycomb cor e insula tion,

e a t commo common n bulkh ead

a dome dome-s -shap haped ed to ol resembli resembling ng the bulkhead, n nume numerou rous s section sections, s,

fit ted to the bulkhea bulkhead. d.

placed

Then the The sections

are then tapered tapered to exa ct thickness thickness specifications b y machin machining, ing, the thickest par t being

4.75 inches.

They Th ey are then bonded and cured n the autoc lave.

e cured insulatio

removed and stored o the bulkhe ad can be l if te d by the huge 50-ton gantry cr crane ane inverte d, and transferred transferred to to the processing roo room. m.

e bul khe ad

inverted invert ed b y a

mecha nical and pneumatic turn-over turn-over sling. In the processing ro room om,, wh ich resembles resembles a huge sunken bath, the bul khe ad li fte d onto onto a circ ular wa ll and receives receives a spra spray y bath bath with a solution of 24 percent sulfuri c acid, detergent detergent,, and water. holds the hone honeycomb ycomb.. placed over

Aft er the adhesive

The entire assembly

cures cure s the adhesives. adhesives.

This pr prepa epares res t for rec eivi ng the adhesive adhesive which

put on the bulkhead, bulkhead, ins ula tion cores cores are

li ft ed onto the autoclave w hich pre pressu ssuri rizes zes and

Fu ll press pressure ure and heat

applied by the autoclave for an hour only,

although several hours are required before and after full pressure and heat to prevent too rap id a temperatur temperature e change change,, whi ch c oul d cau cause se bu ck lin g of the bulkhead. When the aft common bulkhead removed from the autoclave and placed on the bonding fix tur e again, again, the forward comm common on bulkh ead mated to it . o ensure ensure a pe rfe ct fi t, several impression checks are taken.

Then Th en the forwa rd com commo mon n bul khe ad receives