VEHICLEDESIGNATED

A NATIONAL

HISTORIC

MECHANICAL

ENGINEERING

LANDMARK

BY THE-

AMERICAN

SOCIETY OF

MECHANICAL

ENGINEERS

MARCH 1, 1985

“Atlas has very little to draw

on except engineering courage,”

So wrote Aviation Week in

1955. Since then, like a giant

stylus skywriting across the

heavens. Atlas has written

space history for almost three

decades. This is the story ofthe formative years.

Charlie Bossart: “Tremendous stridespushing the state of the art were required, often withno guiding precedent.”

In October 1945, Convair signed a contractwith the Air Force to come up with ideasfor missiles in four ranges, from 20 to5,000 miles. The assignment went to engi-neers at Convair’s Vultee Field Division,near Downey, California. They werealready working on a short-range, rocket-powered missile for the Navy. Charlie Bos-sart, chief of structures at Vultee, headedthe group. Bossart was born in Belgium,graduated from the University of Brussels in1925, then came to this country and at-tended MIT, where he studied aeronautics.

When Vultee closed, the engineersmoved to San Diego. Almost from the start,they decided to concentrate on the toughest,but potentially most powerful, of the fourmissiles the study contract specified: a5,000-mile ballistic missile.

Thus, an informal group of a few engi-neers set into motion what the Air Forcewas to call, “the greatest research and de-velopment undertaking in the history of theUnited States, exceeding in scope even theManhattan Project.”

Research rocketTheir initial assignment was to develop theAtlas forerunner called the MX-774 re-search rocket. The direct precedent was theGerman V-2 of the Second World War. V-2engineers, in turn, were much indebted toAmerican rocketeer Robert Goddard, whoseexperiments in the 1920s and 30s they hadcarefully studied. The V-2, like Goddard’srockets, was a one-stage, liquid-fueled af-fair, with vanes that moved in the exhaustas a crude steering device.

The German weapon had a range ofonly 200 miles, carried about a ton of ex-plosives, reached an altitude of 50 miles and

speeds of 3,500 mph. The word accuracybarely applied. In a 200-mile flight, the V-2would miss its target by 10 miles.

Bossart had to do much better than that.His first concern was weight. “You kidyourself right out of the picture if you don’tguess your weights correctly on a long-range missile,” Bossart pointed out. Hisengineers came up with several break-throughs that drastically reduced weight.Bossart reasoned that since only the war-head (the actual weapon) need return toearth, why not separate the rocket rightafter the engines shut down in space, abovethe earth’s atmosphere? Then, the muchlesser stress and heat of ascent would be allthe missile had to withstand. The separablenose cone of the Atlas was the result.

Robert Goddard, writing of world’sfirst successful flight of liquid-fueled rocket: ”It rose41 feet and went 184 feet, in 2.5 secs.”

The second major weight problem theytackled was the airframe. The V-2 was noprecedent here because its airframe wasbuilt like a kitchen stove: a heavy, double-walled structure braced inside with steel ribsand stringers. There was a reason. The V-2had to contend with the tremendous stressesof reentering the atmosphere, still attachedto its warhead.

A fellow engineer said of him: “JimCrooks has the biggest body and the biggest heart andthe biggest brain around here.”

The solution was to use a single,pressure-stabilized fuel tank that needed nointernal bracing. (The theory was not new,but Bossart, who arrived at the idea inde-pendently, was the first person to put it intopractice.)

The MX-774’s hull was thus both thebasic structure and the fuel tank. Internalpressure needed for the tank to keep itsshape was exerted both by the liquid propel-lants and by the gas used to force-feed thepropellants into the engines. When the rock-ets were stored or transported without fuel,the gas alone kept the tank stabilized. Theengineers now had an airframe-to-propellantratio three times better than that of the V-2.

Swiveling, or gimbaling, engines forflight control were another key innovation.The concept is as simple as turning a boat’soutboard motor to control direction. (TheConvair people didn’t know that V-2 engi-neers had rejected the idea as unworkable.)

Next question: What about guidance,the electronics system that would tell theengines how to steer the rocket? Enter JimCrooks, in 1946. Fresh out of Kansas Statewith a degree in electrical engineering, Jimjumped right into the technical nightmare ofguidance. He and the engineers workingwith him soon decided that the answer wasa combination of ground stations and on-board avionics. They set to work designinga complete ground tracking station, alongwith developing ultrasensitive autopilots,transponders, and other electronics packagesthat comprised the missile’s on-board guid-ance system.

Using discarded parts, running crudetests with a hand-drawn cart playing missile,and finally conducting a few tests with air-craft, Crooks soon devised what was namedthe Azusa tracking system for ballistic mis-siles. The Azusa Mark II system became thepermanent tracking system for all ballisticmissiles launched at Cape Canaveral.

Lean daysThe ideas kept flowing, but not the money.In July 1947, the MX-774 contract wasabruptly cancelled in an Air Force economymove. At best, the engineers had been shorton funds, but they had ordered three testmissiles built and got hold of an old oil der-rick as something they could use as a teststand for captive firings. The contract mayhave been cancelled, but they were makingtoo much progress to stop now. Theyagreed to carry on as best they could.Crooks recalled, “Charlie Bossart was thespark. He kept us all going.”

They set up a test site on Point Loma inSan Diego and hunkered down to carry onwith what MX-774 funds remained, plussome money from Convair.

Following test firings in San Diego, thethree MX-774s were launched in 1948, atWhite Sands in New Mexico. Prematureengine burnout marred all three tests, butnot before they had verified the three con-cepts that became basic to Atlas success:separable nose cone, gimbaling engines, andpressurized tank. Also encouraging was thefact that in reaching supersonic speeds, themissiles had successfully passed through themost critical vibration, control, pressure,and aerodynamic stages.

With the outbreak of the Korean war inearly 1951, defense appropriations in-creased. Things loosened up and Convairgot an Air Force contract to study the re-spective merits of ballistic and glide rockets.Having maintained momentum on their own,the MX-774 group was ready.

General Schriever: “Our prestige asworld leaders might well dictate that we undertakelunar expeditions and even interplanetary flight.”

As in the earlier study, Bossart’s teamchose the ballistic concept. The Air Forceagreed and Convair began studies and com-ponent development for an ICBM based onthe proven features of the MX-774. Theyhad their work cut out for them. The AirForce now requested a rocket capable ofdelivering a 3,500-pound warhead 6,325statute miles (5,500 nautical miles) thatwould land with an accuracy of two to threemiles from its target.

The engineers had done their work wellin developing the MX-774 as a springboard.But now, like athletes in the Olympics, theywere challenged to go faster, higher, andfarther. That’s the only way their rocketwould meet the requirements.

New answers neededThe question of holding down weight whilegreatly increasing size needed new answers.They had used aluminum for the MX-774tank, but that would have to be riveted andthey rejected that material. The answer wasa special cold-rolled stainless steel thatcould be welded. Convair engineers devel-oped a new welding technique specificallyfor the Atlas. It was one of many contribu-tions to manufacturing technology the Atlasprogram was to make.

Tank weight with stainless steel wouldbe acceptable, because every one of thesections was thinner than a dime. The tankthey developed for Atlas (and still the basictank today) was pared down to a diameterof 10 feet and a length of 75 feet (dependingon the nose cone).

The question of fuel led engineers toconsider everything from alcohol throughexotic concoctions until they settled on acombination of a kerosene derivative calledRP-1 and liquid oxygen.

For propulsion, the engineers developeda unique one-and-one-half-stage system theyhad first advocated in 1949. Here’s how itworks. The Atlas has a total of five engines.At launch, all five are ignited, combiningtheir power for maximum thrust at liftoff.

The three main engines consist of twoboosters and a sustainer in between. Afterabout two minutes of flight, the boosterengines stop firing and drop away. The sus-tainer engine continues to burn until therocket reaches top speed. Then, its job fin-ished, that engine shuts down. Two smallvernier, or trim, rockets are mounted exter-nally on the tank base. They are directed byon-board guidance to fire, if necessary, tomake final, precise course adjustments forthe nose cone before it streaks ahead on itsown, after separating from the main body.

This staging system also licked the big-gest propulsion problem of the early 1950s:ignition reliability, which was then less than50 percent. With Atlas, all engines wereseen to ignite properly before liftoff, andmission success did not also require second-stage engine firing in space.

Guidance for the earlier Atlases wasradio-inertial, making use of Jim Crooks’Azusa ground tracking system in tandemwith on-board (or inertial) avionics. Guid-ance later became all inertial.

Top priorityIn early 1954, when it looked like a prettysure thing to the Air Force that nuclear war-heads could be made small and light enoughto ride atop an intercontinental missile, theAtlas program was given top national prior-ity. All hands now began a crash effort tobuild both the missile and a network of 11Strategic Air Command ICBM Atlas basesfrom Maine to California.

General Bernard Schriever was madeoverall director as commander of the AirForce Ballistic Missile Division. Born inGermany, Schriever came to this country at

Jim Dempsey: “In many areas, it isnot technology that is holding us back; it is our abilityto manage the task.”

the age of seven. He received an engineer-ing degree from Texas A&M and a master’sin aeronautical engineering from Stanford.He joined the Air Corps in 1933. Assignedto the Pentagon after WWII, he soon beganto attract attention for his persuasive interestin the potential of missiles as weapons inthe Air Force arsenal.

General Schriever summed up the Atlaseffort: “The ballistic missile requires for itsown operational capability its own vast sup-port structure — launching pads, gantrycranes, blockhouses, tracking equipment,testing, maintenance, and supply facilities,along with its own production base, theindustrial plants of America.”

Many major concerns were now in-volved besides Convair, among them theRocketdyne Division of Rockwell Interna-tional, General Electric, Burroughs, andAerospace Corp. The Ramo-WooldridgeCompany reported to Schriever as technicaldirector and systems manager.

Schriever and his staff of Air Forcepersonnel were responsible for productionof both missiles and warheads and for build-ing the Strategic Air Command bases.

“The Air Force put an umbrella overus,” a Convair executive recalled. “We hadplenty of dog fights underneath the um-brella, but without the Air Force, wewouldn’t have gone anyplace. Those guyswere thrust into managing as complex aprogram as ever existed. That meant heartattacks and ulcers and divorces. They hadthem all.”

Nor were the Convair people immunewhile playing a major role in the huge jobof activating Atlas bases. They planned baselayouts, supervised construction, developedcountdown procedures, and trained fledglingAir Force missilemen, while continuingwork on the missile itself.

Enter new leadershipThe vastly enlarged Atlas effort at Convairneeded a new manager. The company’schoice was Jim Dempsey, a West Pointgraduate with a master’s in aeronauticalengineering. He was only 33 when he cameto Convair, in 1953. Dempsey was a goodchoice. He could handle both administrativeand technical problems.

Shortly thereafter, a man of boundlessimagination joined the Atlas team: V-2alumnus Krafft Ehricke. From the first, hebegan to generate ideas for using Atlas as aspace vehicle. (Later, Ehricke was to play akey role in developing Convair’s Centaurupper stage, the first space vehicle success-fully fueled by liquid hydrogen.)

As the basic Atlas design task began towind down and production planning in-creased, Mort Rosenbaum took over aschief engineer. He had joined Convair in1936, after graduating from MIT.

By the end of December 1954, Convairhad redesigned Atlas to its present basicconfiguration. In January 1955, productionbegan. In less than five years from thatdate, Atlas became operational as an ICBM,in September 1959, at Vandenberg AirForce Base in California.

Krafft Ehricke: “The Atlas is like abig truck. You can use it to carry men, equipment, mostanything you want, into space.”

First flightsAs the missiles began coming off the assem-bly line at Convair’s new Kearny Mesaplant in San Diego, built specifically for theAtlas program, engineers continued to playa vital role in test and development. Theirflight test plan for the complicated missilewas to move from the simple to the com-plex, building up to a complete missile thatcould carry out the full ICBM mission. Inthis way, missile components and systemscould be progressively tested, with short-comings more easily identified and correctedas testing proceeded.

Thus, the A series was the simplestpossible missile that could leave the ground.This missile did not have the sustainer en-gine and only rudimentary guidance. It wasintended for a flight of only 600 miles.

Mort Rosenbaum: “If you don’t per-form, you better get out of the business.”

Flight testing, at Cape Canaveral, beganin June 1957. That very first flight had tobe terminated after 51 seconds, but that wastime enough to collect valuable data and toprove the basic principles of Atlas. Thepublic got a different story. Sample head-lines from the day after: “Mile-High BlastEnds First Big Test of AF Weapon.”“Rocket, Believed an Atlas, Explodes.”

Yet, several years later, in a period of lessthan nine months, Atlas made 21 successfulflights in a row.

The first successful flight of an A series— and therefore of any Atlas — was in De-cember 1957, from Cape Canaveral. Theflight was a shot in the arm for America’ssagging confidence in the nation’s spaceprogram. Just a few weeks before, the Sovi-ets had launched Sputnik I. That had beenfollowed in the U.S. by the spectacular fail-ure of a Vanguard rocket. Coincidentally,that first Atlas flight was made on the 54thanniversary of the Wright Brothers’ firstsuccessful flight.

A real brotherhoodThe tempo of the flight-test program in-creased and so did the stresses on everyoneinvolved. Looking back several years later,an Atlas engineer commented, “We wereinventing ways to test things that had neverbeen built before. Then, sooner or later, wehad to fire a rocket with the whole worldwatching. But let me tell you, we were allfused in a real brotherhood. Something hap-pens when men are scared together.”

As a weapon, Atlas had become thenation’s strategic Sunday punch with per-formance beyond expectations, includingflights of more than 9,000 miles and placingthe missile’s nose cone within 800 yards ofits target.

As a space booster, Atlas was rapidlyachieving prominence. That role was dem-onstrated worldwide in December 1958,when an entire Atlas was sent into orbit andbeamed back to earth a recorded Christmasmessage from President Eisenhower. A fewyears earlier, Ehricke had mentioned to JimDempsey that an Atlas could easily be putinto orbit and when Washington asked what

Convair could do quickly to bolster nationalprestige with a space spectacular, Dempseyremembered and suggested putting that four-ton object into orbit.

On-board avionics also received andrelayed messages from ground stations inthis country. Atlas thus became the nation’sfirst booster for communications satellites.Even bigger headlines about Atlas in itsspace role were to come in February 1962,when the vehicle boosted Mercury astronautJohn Glenn into orbit.

Atlas contributions continueNational defense considerations led to thedevelopment of Atlas. Yet it was part of aweapon system for only six years, from1959 to 1965, when the rocket was phasedout as an ICBM. Its role in space is now inits third decade. In early years, Atlaslaunched the first interplanetary flyby, thefirst lunar impact by an American space-craft, the first televised pictures of themoon, and the first closeup pictures ofMars. Its many other contributions to spaceexploration can only be touched upon here.Alone, or in combination with Centaur andother upper stages, Atlas has launched com-munications satellites that provide world-wide television, telephone, and radio serv-ice, weather satellites, planetary missions,scientific space probes that have been usefulin many areas, navigation satellites — allthese and more. Atlas is an example of thehighest achievements in aerospace engineer-ing. As an ASME National Landmark, itcommemorates the efforts of the engineersand craftsmen who made it a reality.

For more information about this and other programssponsored by the ASME National History and HeritageCommittee, please contact:

ASME Public Information Department345 East 47th Street

N e w Y o r k , 1 0 0 1 7(212) 705-7740