The Nike Ajax was an American guided surface-to-air missile (SAM) developed by Bell Labs for the United States Army. The world's first operational guided surface-to-air missile, the Nike Ajax was designed to attack conventional bomber aircraft flying at high subsonic speeds and altitudes above . Nike entered service in 1954 and was initially deployed within the United States to defend against Soviet bomber attacks, though it was later deployed overseas to protect US military bases, and was also sold to various allied militaries. Some examples remained in use until the 1970s.
Originally known simply as "Nike", it gained the "Ajax" as part of a 1956 renaming effort that resulted from the introduction of the similarly named Nike Hercules. It was initially given the identifier SAM-A-7 (Surface-to-air, Army, design 7) as part of an early tri-service identification system, but later changed to MIM-3 in 1962.Nike was initially designated SAM-G-7, and later changed to SAM-A-7. Originally the Air Force used A while the Army used G, but the Air Force abandoned the 1947 tri-service designation system in 1951 and the Army took over the A designation.
Technological development during the 1950s quickly rendered the MIM-3 obsolete. It was unable to defend against more capable bombers or multiple targets in formation, and had relatively short range. Even while Nike was being deployed, these concerns led to the contracts for the greatly improved MIM-14 Nike Hercules, which began deployment in 1959. As Hercules developed, the threat moved from bombers to ICBMs, and the LIM-49 Nike Zeus anti-ballistic missile project started to address these. All of the Nike projects were led by Bell Labs, due to their early work in radar guidance systems during World War II.
Part of the Nike Ajax development program designed a new solid fuel rocket motor used for the missile's booster. This had originally been designed for the United States Navy's missiles, and was enlarged for the Nike efforts. The rocket found applications outside the military world as the Ajax missiles were decommissioned in the 1960s. Many sounding rockets used the booster as their first or second stage, and many of those used "Nike" in their name.
History Background The inherent inaccuracy of anti-aircraft artillery means that when shells reach their targets they are effectively randomly distributed in the target area. This distribution is much larger than the lethal radius of any given shell, so the chance that any one shell will damage or destroy its target is very small. Successful anti-aircraft gunnery therefore requires as many rounds to be fired as possible. During the Blitz, British anti-aircraft gunners fired 49,044 shells in January 1941 for 12 kills, almost 4,100 shells per success.Ian White, "The History of Air Intercept Radar & the British Nightfighter", Pen & Sword, 2007, p. 75. German gunners did better against Allied daylight raids, firing an estimated average of 2,800 shells to down a single Boeing B-17 Flying Fortress.
Flying faster means that the aircraft passes through the range of a gun more rapidly, reducing the number of rounds a particular gun can fire at that aircraft. Flying at higher altitudes often has a similar effect, as it requires larger shells to reach those altitudes, and this typically results in slower firing rates for a variety of practical reasons. Aircraft using jet engines roughly doubled the speed and altitude over piston-powered designs, limiting the number of shells so greatly that the chance of hitting the bomber dropped almost to zero. As early as 1942, German flak commanders were keenly aware of the problem, and expecting to face jet bombers, they began developing missiles to supplant their guns.
The western allies maintained air superiority for much of the war and their anti-aircraft systems did not see as much pressure to improve. Nevertheless, by the mid-war period, the US Army had reached the same conclusion as their German counterparts: artillery-based anti-aircraft weapons were no longer useful. Accordingly, in February 1944 the Army Ground Forces sent the Army Service Forces (ASF) a request for information on the possibility of building a "major caliber anti-aircraft rocket torpedo". The ASF concluded that it was too early to tell if this was possible, and suggested concentrating on a program of general rocket development instead.
The introduction of German jet bombers late in 1944 led to a re-evaluation of this policy, and on 26 January 1945 the Army Chief of Ordnance issued a requirement for a new guided missile system. The request was passed to Bell Labs, then a world leader in radar, radio control, and automated aiming systems (see Hendrik Wade Bode).
Project Nike
Bell accepted the challenge, and Project Nike was officially formed on 8 February 1945. The Bell team was given the task of attacking bombers flying at or more,Cagle says , but many other sources put it at 500 or more. at altitudes between , and performing a 3 g turn at . Bell reported back on 14 May 1945 (and a formal report the next day) that such a development was possible. They concluded that:
A supersonic rocket missile should be vertically launched under the thrust of a solid-fuel booster which was then to be dropped; thence, self-propelled by a liquid-fuel motor, the missile should be guided to a predicted intercept point in space and detonated by remote control commands; these commands should be transmitted by radio signals determined by a ground-based computer associated with radar which would track both the target and the missile in flight.
This was not the only Army missile project at the time; the US Army Air Force was involved in studies of the Ground-to-Air Pilotless Aircraft (GAPA), a slightly longer-range system based on what was essentially a drone aircraft. Bell had been invited to take part in GAPA as well, but declined as they wanted to concentrate on Nike. GAPA was opened to tender, and was picked up by other companies, notably Boeing. This led to a semi-formalized agreement that the Army Air Force and the Ordnance Corps would split development based on whether or not the design "depend[ed] for sustenance primarily on the lift of aerodynamic forces" like GAPA, or "primary on the momentum of the missile" like Nike.
As part of the Key West Agreement, GAPA was handed to the newly formed US Air Force in 1948, when that force evolved out of the Army Air Force."GAPA (Ground-to-Air Pilotless Aircraft)" , Boeing
Building the team
At the ranges and speeds being considered, even a supersonic rocket will take enough time to reach the target that the missile needs to lead the bomber to intercept it. Bell proposed a system using two radars, one tracking the target, and another tracking the missile. An analog computer would calculate the impact point and send guidance signals to the missile encoded in the second radar's signals, and detonate the warhead on command (as opposed to a proximity fuse).
The Ballistics Research Laboratory was asked to calculate the proper warhead shaping to maximize the chance of a hit. Once determined, Picatinny Arsenal would produce the warhead, and Frankford Arsenal would provide a fuse. Douglas Aircraft would provide the missile airframe and carry out aerodynamic studies, while Aerojet would supply a solid fuel rocket booster for launch, and Bell Aircraft would provide a liquid fuel rocket for the upper stage sustainer.
The initial design used a thin upper stage with eight JATO-derived boosters wrapped around its tail. The resulting cluster looked quite boxy at launch time. It was expected that the of booster power would accelerate the missile to supersonic speeds of at the end of a booster phase of 1.8 seconds, increasing almost continuously to about at the end of the liquid engine's firing, then decreasing to during the zooming period.
Early in the program, it was realized that existing radar systems based on the conical scanning method did not supply the performance needed for a high-speed missile. In particular, conical scanning radars required some time to settle on an accurate track. The decision was made to use a monopulse radar system for Nike. Two systems were considered, one using phased signals, and another using signal timing known as the "amplitude null system", with the latter being selected. This study resulted in the development of tunable magnetrons for the 250 kilowatt X-band radars for tracking, and 1000 kilowatt S-band radar for target detection. Experiments demonstrated that the radar return from the missile at high altitudes was limited, and when calls for an extended altitude of were added to the requirements, a transponder was added to the missile to boost the return.
These changes, and many more, were summarized in a 28 January 1946 report. The project called for four rounds of test launches starting in 1946, with the aim of having a production design by 1949.
Testing
The first test firing of a static round was carried out at the White Sands Proving Ground on 17 September 1946 and then returned to Douglas in California for study. The next week an unguided example was launched, and similar tests followed until 28 January 1947, ending the first test series. During one test a missile reached an altitude of 140,000 feet. A second test series followed in September and October 1947, including several improvements in the design in order to address problems with the booster. A further series in 1948, originally planned for 1946, continued to demonstrate problems.
Eventually, the team was forced to give up on the clustered booster concept. Invariably small differences in thrust between the different JATO bottles would lead to significant thrust asymmetries, ones that overwhelmed the stabilizing effect of the fins in spite of them being very large. Instead, the project selected a larger booster being developed by the US Navy's Operation Bumblebee, creating a new version known as the Allegheny JATO T39 2.6DS-51,000. The Navy's similar booster can be seen on the RIM-2 Terrier.
A new series of test firings started in September 1948 but were stopped until May 1949 after modifications were carried out. Funding problems then delayed the program until January 1950. From late January through April another 16 missiles were fired, with much better results.
Accelerating development
During its early development, the Nike project had not been considered very important. A series of events in the late 1940s led to a re-appraisal of the situation, including the Soviet atomic test in 1949, the communist victory in China, and the Berlin Blockade. The June 1950 opening of the Korea War brought all of this to a head and new urgency was given to US defense. In October 1950, US Secretary of Defense Charles E. Wilson appointed Kaufman Keller to the newly created position of Director of Guided Weapons to speed their development.
Keller examined the various ongoing projects and decided that Nike was the best developed. He recommended that development of Nike be accelerated and that an initial production run of 60 launch stations and 1,000 missiles should be completed by 31 December 1952, with continued production of 1,000 a month after that date. In January 1951, Wilson approved the plan, in spite of additional testing being required. A new test series of the proposed production model was carried out starting in October, and on 27 November 1951, Nike successfully intercepted a QB-17 target drone. Twenty-two further tests followed that year. In the new year a new test series started, including a live-fire attack on a QB-17 in April 1952 that was viewed by visiting senior officers.
Production