Nike Hercules
The Nike Hercules, initially designated SAM-A-25 and later MIM-14, was a surface-to-air missile used by U.S. and NATO armed forces for medium- and high-altitude long-range air defense. It was normally armed with the W31 nuclear warhead, but could also be fitted with a conventional warhead for export use. Its warhead also allowed it to be used in a secondary surface-to-surface role, and the system also demonstrated its ability to hit other short-range missiles in flight.
Hercules was originally developed as a simple upgrade to the earlier MIM-3 Nike Ajax, allowing it to carry a nuclear warhead in order to defeat entire formations of high-altitude supersonic targets. It evolved into a much larger missile with two solid fuel stages that provided three times the range of the Ajax. Deployment began in 1958, initially at new bases, but it eventually took over many Ajax bases as well. At its peak, it was deployed at over 130 bases in the US alone.
Hercules was officially referred to as "transportable", but moving a battery was a significant operation and required considerable construction at the firing sites. Over its lifetime, significant effort was put into the development of solid state replacements for the vacuum tube-based electronics inherited from the early-1950s Ajax, and a variety of mobile options. None of these were adopted, in favor of much more mobile systems like the MIM-23 Hawk. Another development for the anti-ballistic missile role later emerged as the much larger LIM-49 Nike Zeus design. Hercules would prove to be the last operational missile from Bell's Nike team; Zeus was never deployed, and Hercules's replacements were developed by different teams.
Hercules remained the US's primary heavy SAM until it began to be replaced by the higher performance and considerably more mobile MIM-104 Patriot in the 1980s. Patriot's much higher accuracy allowed it to dispense with the nuclear warhead, and Hercules was the last US SAM to use this option. The last Hercules missiles were deactivated in Europe in 1988, without ever being fired in a military conflict.
Development and deployment
Project Nike
During World War II, the US Army Air Force concluded that existing anti-aircraft guns, only marginally effective against existing generations of propeller-driven aircraft, would not be effective at all against the emerging jet-powered designs. Like the Germans and British before them, they concluded the only successful defence would be to use guided weapons.As early as 1944 the US Army started exploring anti-aircraft missiles, examining a variety of concepts. They split development between the Army Air Force or the Ordnance Department based on whether or not the design "depend for sustenance primarily on the lift of aerodynamic forces" or "primary on the momentum of the missile". That is, whether the missile operated more like an aircraft or a bullet.
Official requirements were published in 1945; Bell Laboratories won the Ordnance contract for a short-range line-of-sight weapon under Project Nike, while a team of players led by Boeing won the contract for a long-range design known as Ground-to-Air Pilotless Aircraft, or GAPA. GAPA moved to the US Air Force when that branch was formed in 1947. In 1946, the USAAF also started two early research projects into anti-missile systems in Project Thumper and Project Wizard.
In 1953, Project Nike delivered the world's first operational anti-aircraft missile system, known simply as Nike. Nike tracked both the target and the missile using separate radars, compared the locations in a computer, and sent commands to the missile to fly to a point in the sky to intercept the target. To increase range, the missile was normally boosted above the target into the thinner air and then descended on it in a gliding dive. Nike was initially deployed at military bases starting in 1953, especially Strategic Air Command bomber airfields, and general deployment then followed at US cities, important industrial sites, and then overseas bases. Similar systems quickly emerged from other nations, including the S-75 Dvina from the USSR, and the English Electric Thunderbird in the UK.
Ajax and Hercules
Even as the Nike was undergoing testing, planners grew concerned about the missile's ability to attack formations of aircraft. Given the low resolution of the tracking radars available at the time, a formation of aircraft would appear on the radars as a single larger return. Launched against such a formation, the Nike would fly towards the center of the composite return. Given the Nike warhead's relatively small lethal radius, if the missile flew into the middle of the formation and exploded, it would be highly unlikely to destroy any of the aircraft.Improving performance against such targets would require either much higher resolution radars or much larger warheads. Of the two, the warhead seemed like the simplest problem to address. Like almost any thorny military problem of the 1950s, the solution was the application of nuclear bombs. In May 1952, Bell was asked to explore such an adaptation to the Nike. They returned two design concepts.
"Nike Ajax" used a slightly modified Nike missile, largely a re-arrangement of the internal components, making room for the WX-9 "gun-type" warhead also being developed as an artillery round. The WX-9, like all gun-type designs, was long and thin, originally designed to be fired from an artillery piece, and easily fit within the Nike fuselage.
The competing implosion-type design is considerably more efficient and uses much less nuclear fuel to reach any given explosive power. Bell proposed a much more modified design known as "Nike Hercules" with an enlarged upper fuselage able to carry the XW-7 warhead of up to that wouldn't fit in the existing fuselage. Despite the greatly increased explosive power, the WX-7 was only slightly heavier than the WX-9, about for common XW-7 versions, as opposed to for the XW-9.
At the same time, there were increasing concerns that higher speed aircraft would be able to launch their warheads at the extreme range of the Nike bases. This was a common complaint by the Air Force, who noted that bombers had the ability to attack from as much as while the Nike was only comfortable launching at about. This could be increased even further using stand-off missiles, like those currently under development by all of the nuclear-armed forces for just this reason. A larger Nike with greatly improved range would not only help address this sort of attack, but also allow a single base to defend a much larger area, lowering the overall costs of deploying a widespread defensive system.
As the larger Hercules would be easier to adapt to a longer-range form, the Army selected it as the winning design. Bell began working on the new design in concert with the Nike partners, Western Electric and Douglas Aircraft Company. Instead of the basic W-7, development started on an improved boosted fission design known as W31. This used much less fissile material and was thus considerably less expensive. Developed by Sandia Laboratories in Albuquerque and at Los Alamos, it was given 1A priority by the Joint Chiefs of Staff in March 1953.
Solid fuel
Soon after design work started, the Army requested that the existing liquid fuel engine be replaced with a solid fuel design, for a variety of reasons. Primary among these was that the Ajax fuels were hypergolic, igniting on contact. Due to the nature of these fuels, extreme caution had to be used whenever the missiles were moved or unloaded for maintenance. This was carried out in a protected area behind a large berm, in order to protect the rest of the site from an accidental explosion during fueling. This complexity added enormously to the cost and time required to maintain the missiles.Solid fuel rockets can remain stored for years and are generally very difficult to ignite without an extended period of applied flame. This means they can be manhandled safely and maintained with the rocket motor installed. However, the lower specific impulse of these engines, combined with the requirement for longer range, demanded a much larger fuselage to store the required fuel. Hercules, still known officially as Nike B at this point, grew to become a much larger design. This, in turn, required a much larger booster to loft it. Design of such a booster started, but this was instead solved by strapping together four of the existing Nike boosters to form a cluster known as the XM-42. The only modification to the original M5 engine design was the addition of new holes to bolt them together, creating the M5E.
During this period, some effort was put into a frangible booster for the Ajax. Ajax's boosters were housed in steel tubes that fell near the base, presenting a serious range safety concern. Martin produced the T48E1 and E2 designs for Ajax used a fiberglass casing that was destroyed by small explosives, but this proved overweight and did not boost the Ajax to the required speed. Redstone Arsenal then presented the T48E3 which was somewhat larger and longer to reach reasonable performance, but only at the cost of having to modify all of the Ajax launcher rails. The Army eventually decided not to proceed with any Ajax modifications as Hercules would be arriving shortly anyway. Similar experiments for Hercules boosters led to the XM-61 single-chamber booster, but when the XM-42 cluster proved to be even less expensive than expected, this effort was also dropped.
As part of the upgrade project, the original missile became known as Nike I. On 15 November 1956, the new missile was officially renamed as the Nike Hercules, as part of DA Circular 700-22, while the Nike I became Nike Ajax.
The new design ultimately provided effective ranges on the order of and altitudes ranging from . Minimum range had a ground radius of approximately and an altitude of approximately.