The Corporal Family of Rockets and Missiles

From “Getting ‘em Up There: An Historical Memoir of His Career in Missiles and Space Activities,” by Robert Bolles.
Edited for this website by Jenn Jett, Museum Specialist.

The Corporal story is a history about the beginnings of three separate but related activities:

1) the growth of the embryonic Jet Propulsion Laboratory (JPL) of the California Institute of Technology (CIT);
2) the education of old-line Army Arsenal personnel in the intricacies of guided missiles and the procurement of spare parts and;
3) the development of one of our first ballistic missiles to be deployed overseas.

The Corporal program was also the testing ground for organizational theories to determine the optimum relationship between a laboratory, its parent organization, and its chief funding agency, as well as perhaps even the role of science and technology in today’s society.

On the surface, the Corporal family was a collection of early American-developed ballistic missiles that initially weren’t very militarily significant. However, it was the vehicle on which various management and subcontracting philosophies could be tried and training of personnel from procurement through field operations could be conducted.

The Guggenheim Aeronautical Laboratory

The Jet Propulsion Laboratory began as the Guggenheim Aeronautical Laboratory, California Institute of Technology (GALCIT) in 1936. It was under the loose management of Dr. Theodore von Karman, an eminent Hungarian-born professor. It was reorganized, expanded and renamed the Jet Propulsion Laboratory in 1944 when it became a permanent installation operated by the California Institute of Technology for the Army Ordnance Corps. JPL is probably better known today for 1) its work for NASA on ten Mariner spacecraft sent to other planets of our solar system; 2) the Viking, which became the first spacecraft to soft land on Mars; and 3) the twin Voyagers to Jupiter, Saturn, and Uranus. But this story is about its early incarnation as a development laboratory with contracts from the Army to develop some of our early rocket systems.

Dr. Robert A. Millikan who headed the California Institute of Technology in the 1930s was interested in research on cosmic rays and thinking that rockets might be a useful technology, contacted Dr. Goddard, who replied in typically Goddard fashion, that his work was not yet ready for publication. Actually, Goddard preferred patents to publications for getting word out on his inventions, so he was of no help to Dr. Millikan.

Dr. von Karman, a brilliant aerodynamicist, as director of the Guggenheim Aeronautical Labs for the California Institute of Technology, agreed to let one of his graduate students start working on rockets provided that he demonstrate his ability to analyze the theoretical performance before any firing. So, with Dr. Millikan’s backing, Frank J. Malina, a graduate student from Texas A&M, who had been hired by the Guggenheim Aeronautical Labs to conduct experiments in their wind tunnel, and a couple of his friends, John W. Parsons and Ed Forman, started reviewing available literature and scrounging for funds.

Malina wanted to use rocket propulsion and flight characteristics of sounding rockets as the subjects for his doctoral dissertation. Neither Forman or Parsons had any college training, but they were logical team members since Forman was an excellent mechanic and Parsons had an almost encyclopedic knowledge of explosives and related chemicals from his work for various powder companies. In a similar manner, Dr. Goddard’s early assistants were not college educated, but they were excellent machinists and mechanics. Two of them later worked at White Sands Proving Ground, and one subsequently worked for Martin Marietta.

Frank Malina, just as Dr. Millikan had tried before him, started by contacting Dr. Goddard. He visited him at his test site near Roswell, New Mexico, but Dr. Goddard, perhaps feeling that the young graduate student was trying to benefit from his 20 years of experimentation just to write a thesis, remained secretive. Harry Guggenheim, who was funding both Dr. Goddard and GALCIT at that time, also tried to arrange a cooperative venture between the two but Goddard would offer only limited disclosure while von Karman insisted on full cooperation, so the joint venture never really got off the ground.

Malina had insisted that they develop an engine before trying to build a rocket, so he and his cohorts started looking for a location to conduct static firings, and they selected an uninhabited area in the Arroyo Seco near Pasadena, California. No GALCIT funds or facilities were available, so they pooled their sparse earnings to buy supplies and scoured Los Angeles for second hand equipment that wouldn’t cost too much. After working out the theoretical engine performance calculations in 1936, they built a test engine and conducted their first static firings from behind sandbags and in trenches in a manner similar to most early rocketeers. Also, in a manner characteristic of most early efforts, the first four static firing attempts were failures.

On November 28, however, the testing was more successful and the motor burned for about 15 seconds before anything went wrong. Von Karman was impressed, but insisted on a detailed analysis of the engine performance before any further testing. Based on their limited success, he did allow them 10 hours per week of additional student help for transporting, setting up, and disassembling the equipment at the Arroyo Seco test site.

On January 16, 1937, they had a more successful run of 44 seconds duration. This modest success attracted some support in the form of two other GALCIT graduate students—Apollo M.O. Smith, and Hsue-shen Tsien, a Chinese-born research engineer who was brilliant in applied mathematics. Another graduate student, Weld Arnold, who was studying meteorology, also expressed interest. He not only volunteered to obtain $1,000 for the project, but a few days later bicycled from Glendale to Caltech with the first installment—$100 in one and five dollar denominations wrapped in an old newspaper. He didn’t volunteer his source nor did the rocket enthusiasts persist in trying to pin down the names of their benefactors. Again, typical of the early rocketeers, much of the initial funding of small amounts of money came from the rocketeers themselves rather than hopelessly fighting the bureaucracy for funds or hardware through purchase requisitions or procurement authorizations.

Even Caltech provided only limited support to the fledgling effort. Their first direct financial support was to pay $200 for Malina to travel to New York City to present a paper that he and Smith had written on the theoretical performance of rockets as a way of achieving high altitudes. The paper was presented at a symposium of the Institute of Aeronautical Sciences (IAS) and subsequently published in their Journal. Malina and Smith had cautiously predicted heights of 1,000 miles could be achieved with rockets, which excited the press.

Time and the New York Herald-Tribune reported the speech, the Los Angeles Times lauded the rocket effort in an editorial, a Hollywood radio station wanted to broadcast the sound of a rocket motor firing and, by spring, a number of reporters had descended on the test stand at GALCIT. The AP had even distributed a long story on rockets nationally. All of this fuss gave Malina and von Karman a taste of the publicity that Goddard had been exposed to in the 1920s and, despite their attempts to down play their efforts, fantasy stories of moon voyages and passenger carrying rocket ships were portrayed taking off from the Los Angeles Civic Center.

America’s Rocket Program During World War II

Back in the real world, not the fantasy world of the press, events were about to catch up with the embryonic rocket engine development efforts at GALCIT. General “Hap” Arnold, commander of the Army Air Corps, was alert to any scientific developments that might help the Air Corps perform its mission and he paid a surprise visit to the GALCIT laboratories in the spring of 1938, and became fascinated with the potential of the rocket work. He asked the National Academy of Sciences (NAS) to start research on a number of projects including rocket-assisted takeoff for aircraft. Both Millikan and von Karman were members of the NAS committee so they could help shepherd a funding request through to support the early efforts at GALCIT.

Malina proposed investigating both liquid and solid propellant rockets, and in January of 1939, he received a $1,000 grant to prepare a proposal for rocket-assisted takeoff, which might have an immediate application for the Army Air Corps. By mid-year, the NAS committee granted GALCIT $10,000 for additional work, so the small rocket group that had scrounged for enough to buy second hand parts was suddenly inundated with funds. An aide to General Arnold, Major Benjamin Chidlaw, didn’t share the General’s enthusiasm for the new field of rocketry and asked von Karman if he really thought “the Air Corps should spend as much as $10,000 for such a thing as rockets?”

By fiscal year 1941, the Army Air Corps had taken control of the GALCIT grant and increased its funding to $22,000 and the rocket group at GALCIT eagerly left the Caltech campus, a move welcomed by Caltech as well, since one rocket static firing had filled the Guggenheim Laboratory with smoke and fumes and the noise from their static firings had been creating quite a disturbance. They negotiated with Pasadena for seven acres in the Arroyo Seco on the condition that the lease would be terminated at the end of the war. By Fiscal Year 1942, with America’s entry into the war, their funding by the Army Air Corps had increased to $125,000.

In August of 1941, their first solid propellant rockets were ready to be tested. They had 2 pounds of black powder pressed into a 10-inch-long cylinder about 1 and 3/4 inches in diameter, which generated 28 pounds of thrust. The first tests of jet-assisted takeoff (JATO) vehicles were conducted at March Field near Riverside using a small Ercoupe that weighed only 753 pounds. Three of the black powder cylinders were mounted under each wing. During the first tests with the plane anchored, one of the cylinders blew off its nozzle, tearing a small hole in the aft end of the fuselage.

The second series of tests involved igniting the JATOs with the plane in level flight and five of the six cylinders fired satisfactorily. That was followed by having the plane taxing down the runway when the JATOs were fired and everything worked successfully, cutting the takeoff distance and time by almost half. To put that in perspective, the takeoff distance was reduced to 300 feet from about 600, and the takeoff time was 7.5 seconds, reduced from about 15 seconds. However, the group soon discovered that if the propellant were stored for more than a few days, it would blow up instead of burning, so that meant the JATOs were not useful for combat.

Shortly after the United States was plunged into the war on December 7, 1941, the Navy became intrigued with the possibility of using JATOs on aircraft carriers and they offered the GALCIT group a contract to develop rockets of 200 pounds of thrust and 8 seconds of burn time. This made finding a solution to the problem of exploding with ageing even more critical. Parsons came up with the use of asphalt instead of charcoal in the fuel since it was less brittle, and he selected potassium perchlorate as the oxidizer instead of saltpeter. These asphalt-based propellants were more rubbery and not as susceptible to handling problems, plus they could be stored indefinitely under a wide range of temperatures, as well as being easier to produce using more common ingredients, so the Navy used them extensively in the last two years of the war.

During 1940-1941 the GALCIT rocket office established a liquid propellant section headed by Martin Summerfield. Some top chemical engineers advised that there was a fundamental limitation that would prevent them from ever reaching 1,000lbs of thrust. One combustion expert said it would require a furnace the size of a house, which would probably weigh more than 1,000lbs, so the effort was pointless. But Summerfield kept searching and found a reference in the Caltech library from an old English chemistry test that claimed that a hydrocarbon fuel could be made to burn completely in a thousandth of a second when confined to a small volume.

His search for the right combination of propellants was limited by military requirements. Where Goddard and the Germans had used liquid oxygen with gasoline or kerosene, the military objected to liquid oxygen for practical field handling considerations. Once again Parsons came up with another inspiration—using red fuming nitric acid (RFNA). RFNA became the oxidizer of choice for several programs during the next few years. However, combustion instability continued to cause problems due to the delay between ignition and combustion with gasoline or kerosene.

Malina was visiting with Navy Lt. Robert Truax at Annapolis in 1942 and discussed the instability problem with him. Truax’s chemical engineer, Ray Stiff, had found in scientific literature that aniline would ignite spontaneously with nitric acid and suggested adding aniline to the gasoline. The next day Malina telegraphed Pasadena saying to try replacing the gasoline with aniline completely. They did and that eliminated the instability problem.

It is impossible to know whether decisions on both the solid and liquid propellant systems in those early days resulted from inspired intuition, educated guesses, or learned expertise, but for the next several years, acid/aniline became the liquid propellant combination of choice. In March of 1942, several members of the GALCIT rocket team formed their own company called Aerojet. In what may have been one of the earliest examples of what would now be called a conflict of interest in the rocket industry, von Karman and Malina, who had both put money in Aerojet, served as consultants to Aerojet and to the military while being paid by GALCIT. Summerfield, Parsons, and Forman left GALCIT to join Aerojet, and many of the Aerojet products were tested at the GALCIT test facility. But rocket expertise was in short supply during the war and the demand by the military was high, so no one bothered to look very closely at proper charging or conflicts of interest as long as results were satisfactory.

Firsts of the Corporal Family: The Private A/F

One of the first rockets in the Corporal family to be developed to the point that it deserved a name of its own was the Private. Private A was designed to be as simple as possible and deliver a payload to a range of 10 miles. It was a solid propellant weighing 530lbs, used the asphalt-based propellant and provided 1,000lbs of thrust for 34 seconds. The missile was 8ft long and was set between four guide rails of a 36ft long tower. It was boosted out of the tower by four solid rocket motors that produced a total of 21,700lbs of thrust for less than a second, giving it sufficient velocity that the control system could function. It had four 12-inch tail fins to provide aerodynamic stability in flight. Twenty-four Private A rounds were fired at Camp Irwin in the Mojave Desert and they recorded an average range of 10.3 miles.

The success of Private A and the urgency as a result of the war led the Army to press for an improvement in performance. Malina and Tsien suggested that the range could be extended by 50% with the addition of wings, but at the cost of a reduction in payload capability. In a quick and dirty solution to increased pressure from the military, two of the three aft fins on the Private A were extended from 12 inches to five feet, and two stubby wings added to the forward end of the missile like canards. The missiles were called Private F and transported to the Hueco Firing range at Ft. Bliss, where all 17 rounds were launched. However, all 17 also etched a corkscrew trail of white smoke against the sky as they each in turn went into a tailspin. Malina declared that the “F” in “Private F” stood for “Fiasco.”

The WAC Corporal

In December 1944, the Ordnance Corps asked the Jet Propulsion Labs (the name adopted by GALCIT in November of 1943) to perform a study of the feasibility of developing a high-altitude sounding rocket capable of carrying 25lbs of meteorological instruments to an altitude of 100,000 feet. Frank Malina, Homer Joe Stewart, and some members of their staff prepared a proposal for submission in three days, and they received the go ahead for the WAC Corporal in early 1945.

Some said WAC was named after the Army’s Women’s Auxiliary Corps, while others said it stood for “Without Attitude Control” which was more nearly correct. They had considered putting in a gyroscope to stabilize the missile in flight, but the weight was more than they wanted to accept. Instead, Malina and Stewart calculated that, if the WAC Corporal were launched from a tower at high enough speed, it wouldn’t deviate much from vertical flight and, after all, it was to be a sounding rocket.

The WAC Corporal was 12 inches in diameter and 194 inches long, consisting of an acid/aniline propellant system capable of 1,500lbs thrust for 45 seconds and a booster consisting of a Tiny Tim rocket, which had a thrust of 50,000lbs for 0.6 seconds. The Tiny Tim booster and the WAC Corporal were launched vertically from a 100ft tower, which would stabilize the rocket until it exited the tower at about 400ft per second. The launch tower was located at the new White Sands Proving Ground. WAC Corporal burnout would occur at about 80,000ft and the missile would rise on up to over 200,000 feet or a little under 40 miles altitude.

The WAC Corporal program sponsor was Col. B. S. Mesick of the Ordnance Corps; missile development and technical phases of the firing program were directed by Dr. Frank J. Malina of JPL; flight test data was obtained by the Aberdeen Proving Ground personnel under the supervision of Dr. L.A. Delasso; weather instruments and radiosonde equipment were operated under the supervision of Maj. K.S. Jackson of the Signal Corps; and scheduling of firing tests and maintenance of safety were the responsibility of Lt. Col. Harold R. Turner, first Commanding Officer of WSPG. Ground Support Equipment (GSE), was provided by Aerojet Engineering Corp., and missile assembly was accomplished by Douglas Aircraft Corporation.

As an example of the simplicity of things in the early days, the program consisted of four phases:

Phase I: Tiny Tim with a lead nose cone for ballast;
Phase II: Tiny Tim with a pipe full of cement simulating the WAC Corporal weight and shape;
Phase III: Tiny Tim and a partially charged acid/aniline WAC Corporal;
Phase IV: Tiny Tim with the full up WAC Corporal system.

The first flight of Tiny Tim (and the first rocket flight from WSPG) took place at 10 a.m. on September 26, 1945. Two more Tiny Tim flights were launched on the same day and the fourth took place the following morning. Two rockets of the Phase II type were fired on September 27 and 28. Two rockets of the Phase III variety were fired on October 1 and 2, followed by six rockets of the full WAC Corporal configuration, which were fired between October 11 and October 25, 1945. Some of them reached 230,000ft in altitude, as estimated by JPL and the Army, although the Proving Ground was not well instrumented at that time. In summary, fourteen rockets in the WAC Corporal family were launched in the first month of missile operations at WSPG.

Von Karman had told the Army’s Ordnance Research chief Major General Gladeon M. Barnes that JPL planned a series of improved missiles up to the rank of Colonel, but they would stop there “because that is the highest rank that works.” Actually, they encountered enough problems that it was 15 years before they got up to the Sergeant missile.

The Corporal

At the end of the war, Army interest shifted from the Army Air Corps and JATO rockets to Army Ordnance and long-range ballistic missiles. Even before the first German V-2s had hit London during the war, Army Ordnance was generally aware of what was going on and they wanted GALCIT to begin research on the problems of building and controlling such a rocket.

During the War, Caltech operated two rocket projects. One eventually became JPL and the other was the Eaton Canyon project for the Navy. The Eaton Canyon project developed the barrage rockets used with good success in the Pacific War. Several thousand rockets were manufactured for the Navy, and shortly before the end of the war in the Pacific, the project selected what is now Inyokern as a desert site for research and testing. At the end of the war, Caltech decided to give the Eaton Canyon project to the Navy but to keep JPL. Inyokern became NOTS, the Naval Ordnance Test Station, and JPL concentrated on supporting the Army.

By 1949, the Russians had detonated their own atomic bomb, the Cold War was heating up and the Korean War was not far off. JPL had developed the Private, the Tiny Tim, the WAC Corporal described earlier, and the Corporal research vehicle, a liquid fueled ballistic missile with a 100-mile range.

K.T. Keller, a former president of the Chrysler Corporation, was selected by the Secretary of Defense to be his “Guided Missile Czar.” His job was to review existing missile developments and to initiate appropriate action in response to a National Security Council study, NSC-68, which called for a vast rearmament program as part of the U.S. global strategy. The outbreak of the Korean War made it politically and financially possible to implement the program.

At about the same time, Army Ordnance asked JPL to convert the Corporal research vehicle into a ballistic missile capable of carrying a 1,000lb warhead 100 miles with good accuracy using the guidance system developed by General Electric for the Hermes program.

Some years later, Dr. William H. Pickering, who became head of JPL, described the problems they had to solve as follows:

1) how to guide the missile;
2) how to get the missile into production and;
3) how to design it so that Army troops could use it.

He went on to say that, “As far as Problem 1, guidance, was concerned, I remember telling Louie Dunn (the Director of JPL) that, with Frank Lehan and Bob Parks, we would probably need to hire about another half dozen engineers to do the job. I slightly underestimated! Problem 2, production, taught us the facts of life. Just because we had built and launched a number of research vehicles, we did not have a production design and we did not know how to work with industry. Problem 3, troop training, was also one we did not appreciate.”

The Army selected the Firestone Tire and Rubber Company to build the air-frame and mechanical parts of the missile. They had no experience in this field, but they subsequently assembled a group to build and factory test the missiles. The design of the system was sufficiently fluid at the time that the Army later awarded Firestone a modification contract to modify the production missiles on a separate production line. Motorola was selected to re-engineer and build the airborne command system, and the Gilfillan Company was selected to modify the SCR 584 radar system for the ground portion of the guidance system.

In spite of all the companies and organizations involved, a system was put together, produced, tested, launched by Army personnel at White Sands and deployed overseas. The missile was 47ft in length, 30in in diameter, and weighed 11,000lbs at launch.

A Corporal Battalion was made up of 250 men in a firing battery and a headquarters service battery. It was equipped with two operational launchers, guidance radar equipment van, Doppler equipment van, an acid tank truck, an aniline tank truck, shipping containers on a flatbed trailer, missile erectors and servicers, high pressure air compressors with compressed air bottles, electrical generators, missile checkout vans, and warhead vans, all in addition to personnel vehicles and personnel support vehicles. The many different types of equipment and men to operate them contributed to making the Corporal a not very militarily useful system. Still, it was our first missile system deployed overseas.

Army Field Forces and Ordnance both sent personnel to JPL for training so that when the production missiles arrived at WSPG there would be a cadre of Army personnel to conduct the Engineering (Ordnance) and User (Field Forces) test program. Some of the Army Field Forces trained personnel also established and operated the training school at Ft. Bliss, Texas. The Army Field Forces Artillery Board Number 4 provided personnel at WSPG to assist in writing the Engineer/User test plans and to add the User perspective to the plans.

More than 120 officers and men of the British 47th Guided Weapons Regiment of the Royal Artillery were flown from their base at Kirkham, Hampshire, England. They encamped at a desert outpost at White Sands Missile Range in 1958 to train and operate a series of Corporal missiles prior to the completion of a British missile range in the Hebrides Islands off the coast of Scotland.

Corporal was in many ways a “pathfinder” system. It was a “telescoped” program, as production at Firestone and Gilfillan was awarded before the design was finalized by JPL. Logistic support and spare parts responsibility was assigned to Redstone Arsenal, Alabama where the personnel were accustomed to working with artillery rounds rather than the complexity of guided missiles. The design and development process at JPL was administratively handled through a contract with Caltech in Pasadena, California, but they didn’t have security clearances to know what was being developed by JPL in Arroyo Seco for Army Ordnance. Considering all of the learning that was going on with the Corporal program, it is surprising that it ever reached the point where it could be deployed overseas, yet it was deployed in England, Italy, France, and West Germany.

Because of the Corporal’s questionable reliability under tactical conditions and its obvious logistical problems, it is probable that The London Times wanted to refer to its deployment in the same manner in which it referred to some other NATO decisions in the early 1950s, i.e., “Its deployment would create the maximum amount of provocation with the minimum amount of deterrent effect.” However, there was a whole lot of learning going on, and it led to the Sergeant program, a more successful and militarily significant successor to the Corporal.

The Corporal E Variant

The first Corporal E missile was fired at White Sands in May of 1947; this was the version that was deployed overseas. It was 39ft long, weighed 11,700lbs loaded, and was designed to carry a payload of up to 500lbs a little over 60NM. It was powered by a scaled-up WAC Corporal motor that would deliver 20,000lbs thrust. The first flight was successful, but the second and third were both failures. In the second flight, insufficient thrust was developed so the missile sat on the launcher until enough propellant had been burned to equalize the weight of the vehicle to the thrust, after which it rose briefly, tilted over, and skittered through the boondocks. Some would call it the “rabbit killer.” On the third shot, the motor died after 43 seconds, so it only reached an altitude of 14 miles. In both the second and third shots, the motor’s throat burned through the helical cooling coil, forcing JPL back to the drawing board.

Unlike the design of an airplane, which travels at a fairly uniform rate of speed and at a relatively fixed altitude, missiles are constantly accelerating or decelerating, and much of the flight is at supersonic speeds, a regime of which little was known in the mid-1940s. The atmospheric pressure through which the missile flies may vary from sea level to zero and the vehicle’s weight changes constantly from ignition to burnout, thus changing the relative positions of the center of pressure and the center of gravity, causing control and stability problems. In addition, the mass fraction or ratio of missile dry weight to missile fueled weight has to be high if there is to be any payload capability. So that, in turn, means very lightweight thin structures are required. So little data was available in the early days that designers had to rely on theoretical calculations unsubstantiated by empirical data. Artillery shells and airfoil tests in wind tunnels were about all that was available.

JPL went from a helical cooling coil to an axial cooled motor, cutting the empty motor weight from 450lbs to 125lbs, and design changes of the tanks and plumbing cut the Corporal E weight from an average of 5,356lbs for the first three missiles to 4,353lbs empty weight for the production version. This meant the Corporal E could throw a 1,000lb payload 200 miles, compared to 113 miles for the earlier version. The new version Corporal E was first flown at White Sands on June 7, 1949 and worked successfully.

The Sergeant

Sergeant was a solid propellant, inertia-guided missile, in contrast to the liquid fueled, radio guided Corporal. Designed by JPL from the beginning as a tactical weapon rather than a research vehicle, Sergeant was much more successful as a weapon system. The Army selected the Sperry Corporation to be the industrial contractor early in the program, so they and JPL worked closely together as the design evolved.

The Sergeant gave the Army a rapid response weapon with a minimum of Ground Support Equipment. It was tested at WSPG, just like the Corporal, but it didn’t take nearly as many rounds to validate the reliability or to train the crews because of the simplicity of the solid rather than liquid propellants and of inertial rather than radio guidance. The Engineer/User tests at WSPG were conducted firing from the north end of the range back south into the instrumented sites on the range.

Louis G. Dunn, JPL Director from 1946 to 1954, left JPL to head up the Ramo-Wooldridge Corporation (later to become TRW), before the Sergeant program was complete. Dr. Lee DuBridge, President of Caltech from 1946 to 1969, appointed Dr. William Pickering to be Director of JPL, a position he held from 1954 to 1976.

As an aside, it is interesting to note the similarity of the Corporal/Sergeant evolution and the Titan I/Titan II evolution. Both the Corporal and Titan I were learning programs where facilities had to be constructed, personnel staffs had to be hired to perform the design/development/testing programs, and both were pushing the frontiers at the time: Corporal in the mid-1940s and Titan I in the mid-1950s.

Titan I pioneered staging of large liquid-fueled missiles, but used radio guidance in a manner similar to Corporal. Titan I used a cryogenic oxidizer (LOX) and Rocket Propellant 1 (RP1), both of which had to be loaded on board just prior to launching like Corporal (although Corporal’s propellants were storable acid/aniline, they had to be loaded after erection for launch). Titan I had to be elevated to the surface for launch, all of which made it vulnerable to attack for a considerable period, just like Corporal was always vulnerable to attack, and Titan I was radio guided with ground antennas elevated to send guidance commands until burnout.

Titan II went to storable hypergolic propellants, and inertial guidance where Sergeant had solid propellants with inertial guidance, and Titan II launched from within the silo. All of these factors contributed to making both Sergeant and Titan II more survivable, with quicker reaction times. Both Titan II and Sergeant programs evolved from early learning phases during which organizations and facilities had been built and the research work was done.

The more mature Sergeant and Titan II utilized the staff, facilities, and technical know-how developed to produce very reliable and militarily significant systems. Both programs showed the advantages of greater experience, extensive theoretical analysis, experimental testing, earlier establishment of the industrial teams, and stronger, more experienced customer program offices—in effect, the beneficial results of the earlier “shakedown cruises” or learning phases on Corporal and Titan I.