Rocket and missile system

Rocket and missile system, any of a variety of weapons systems that deliver explosive warheads to their targets by means of rocket propulsion. Rocket is a general term used broadly to describe a variety of jet-propelled missiles in which forward motion results from reaction to the rearward ejection of matter (usually hot gases) at high velocity. The propulsive jet of gases usually consists of the combustion products of solid or liquid propellants. In a more restrictive sense, rocket propulsion is a unique member of the family of jet-propulsion engines that includes turbojet, pulse-jet, and ramjet systems. The rocket engine is different from these in that the elements of its propulsive jet (that is, the fuel and oxidizer) are self-contained within the vehicle. Therefore, the thrust produced is independent of the medium through which the vehicle travels, making the rocket engine capable of flight beyond the atmosphere or propulsion underwater. The turbojet, pulse-jet, and ramjet engines, on the other hand, carry only their fuel and depend on the oxygen content of the air for burning. For this reason, these varieties of jet engine are called air-breathing and are limited to operation within the Earth’s atmosphere.

For the purposes of this article, a rocket engine is a self-contained (i.e., non-air-breathing) propulsion system of the type described above, while the term rocket refers to any free-flight (unguided) missile of the types used since the beginning of rocketry. A guided missile is broadly any military missile that is capable of being guided or directed to a target after having been launched. Tactical guided missiles are shorter-ranged weapons designed for use in the immediate combat area. Long-range, or strategic, guided missiles are of two types, cruise and ballistic. Cruise missiles are powered by air-breathing engines that provide almost continuous propulsion along a low, level flight path. A ballistic missile is propelled by a rocket engine for only the first part of its flight; for the rest of the flight the unpowered missile follows an arcing trajectory, small adjustments being made by its guidance mechanism. Strategic missiles usually carry nuclear warheads, while tactical missiles usually carry high explosives.

Military Rockets

Early history

There is no reliable early history of the “invention” of rockets. Most historians of rocketry trace the development to China, a land noted in ancient times for its fireworks displays. In 1232, when the Mongols laid siege to the city of K’ai-feng, capital of Honan province, the Chinese defenders used weapons that were described as “arrows of flying fire.” There is no explicit statement that these arrows were rockets, but some students have concluded that they were because the record does not mention bows or other means of shooting the arrows. In the same battle, it is reported, the defenders dropped from the walls of the city a kind of bomb described as “heaven-shaking thunder.” From these meagre references some students have concluded that by 1232 the Chinese had discovered black powder (gunpowder) and had learned to use it to make explosive bombs as well as propulsive charges for rockets. Drawings made in military documents much later show powder rockets tied to arrows and spears. The propulsive jet evidently added to the range of these weapons and acted as an incendiary agent against targets.

In the same century rockets appeared in Europe. There is indication that their first use was by the Mongols in the Battle of Legnica in 1241. The Arabs are reported to have used rockets on the Iberian Peninsulain 1249; and in 1288 Valencia was attacked by rockets. In Italy, rockets are said to have been used by the Paduans (1379) and by the Venetians (1380).

There are no details of the construction of these rockets, but they were presumably quite crude. The tubular rocket cases were probably many layers of tightly wrapped paper, coated with shellac. The propulsive charge was the basic black powder mixture of finely ground carbon (charcoal), potassium nitrate (saltpetre), and sulfur. The English scientist Roger Bacon wrote formulas for black powder about 1248 in his Epistola. In Germany a contemporary of Bacon, Albertus Magnus, described powder charge formulas for rockets in his book De mirabilibus mundi. The first firearms appeared about 1325; they used a closed tube and black powder (now referred to as gunpowder) to propel a ball, somewhat erratically, over varying distances. Military engineers then began to invent and refine designs for both guns and rockets.

By 1668, military rockets had increased in size and performance. In that year, a German colonel designed a rocket weighing 132 pounds (60 kilograms); it was constructed of wood and wrapped in glue-soaked sailcloth. It carried a gunpowder charge weighing 16 pounds. Nevertheless, the use of rockets seems to have waned, and for the nxt 100 years their employment in military campaigns appears to have been sporadic.

The 19th century

A revival commenced late in the 18th century in India. There Hyder Ali, prince of Mysore, developed war rockets with an important change: the use of metal cylinders to contain the combustion powder. Although the hammered soft iron he used was crude, the bursting strength of the container of black powder was much higher than the earlier paper construction. Thus a greater internal pressure was possible, with a resultant greater thrust of the propulsive jet. The rocket body was lashed with leather thongs to a long bamboo stick. Range was perhaps up to three-quarters of a mile (more than a kilometre). Although individually these rockets were not accurate, dispersion error became less important when large numbers were fired rapidly in mass attacks. They were particularly effective against cavalry and were hurled into the air, after lighting, or skimmed along the hard dry ground. Hyder Ali’s son, Tippu Sultan, continued to develop and expand the use of rocket weapons, reportedly increasing the number of rocket troops from 1,200 to a corps of 5,000. In battles at Seringapatam in 1792 and 1799 these rockets were used with considerable effect against the British.    The news of the successful use of rockets spread through Europe. In England Sir William Congreve began to experiment privately. First, he experimented with a number of black-powder formulas and set down standard specifications of composition. He also standardized construction details and used improved production techniques. Also, his designs made it possible to choose either an explosive (ball charge) or incendiary warhead. The explosive warhead was separately ignited and could be timed by trimming the fuse length before launching. Thus, air bursts of the warheads were feasible at different ranges.

Congreve’s metal rocket bodies were equipped on one side with two or three thin metal loops into which a long guide stick was inserted and crimped firm. Weights of eight different sizes of these rockets ranged up to 60 pounds. Launching was from collapsible A-frame ladders. In addition to aerial bombardment, Congreve’s rockets were often fired horizontally along the ground.

These side-stick-mounted rockets were employed in a successful naval bombardment of the French coastal city of Boulogne in 1806. The next year a massed attack, using hundreds of rockets, burned most of Copenhagen to the ground. During the War of 1812 between the United States and the British, rockets were employed on numerous occasions. The two best-known engagements occurred in 1814. At the Battle of Bladensburg (August 24) the use of rockets assisted British forces to turn the flank of the American troops defending Washington, D.C. As a result, the British were able to capture the city. In September the British forces attempted to capture Fort McHenry, which guarded Baltimore harbour. Rockets were fired from a specially designed ship, the Erebus, and from small boats. The British were unsuccessful in their bombardment, but on that occasion Francis Scott Key, inspired by the sight of the night engagement, wrote “The Star Spangled Banner,” later adopted as the United States national anthem. “The rockets’ red glare” has continued to memorialize Congreve’s rockets ever since.

In 1815 Congreve further improved his designs by mounting his guide stick along the central axis. The rocket’s propulsive jet issued through five equally spaced holes rather than a single orifice. The forward portion of the guide stick, which screwed into the rocket, was sheathed with brass to prevent burning. The centre-stick-mounted rockets were significantly more accurate. Also, their design permitted launching from thin copper tubes.  Maximum ranges of Congreve rockets were from one-half mile to two miles (0.8 to 3.2 kilometres), depending upon size. They were competitive in performance and cost with the ponderous 10-inch mortar and were vastly more mobile.

The next significant development in rocketry occurred about the middle of the 19th century. William Hale, a British engineer, invented a method of successfully eliminating the deadweight of the flight-stabilizing guide stick. By designing jet vents at an angle, he was able to spin the rocket. He developed various designs, including curved vanes that were acted upon by the rocket jet. These rockets, stabilized by means of spin, represented a major improvement in performance and ease of handling.  Even the new rockets, however, could not compete with the greatly improved artillery with rifled bores. The rocket corps of most European armies were dissolved, though rockets were still used in swampy or mountainous areas that were difficult for the much heavier mortars and guns. The Austrian Rocket Corps, using Hale rockets, won a number of engagements in mountainous terrain in Hungary and Italy. Other successful uses were by the Dutch colonial services in Celebes and by Russia in a number of engagements in the Turkistan War. Hale sold his patent rights to the United States in time for some 2,000 rockets to be made for the Mexican War, 1846–48. Although some were fired, they were not particularly successful. Rockets were used in a limited way in the American Civil War (1861–65), but reports are fragmentary, and apparently they were not decisive. The U.S. Ordnance Manual of 1862 lists 16-pound Hale rockets with a range of 1.25 miles.  In Sweden about the turn of the century, Wilhelm Unge invented a device described as an “aerial torpedo.” Based upon the stickless Hale rocket, it incorporated a number of design improvements. One of these was a rocket motor nozzle that caused the gas flow to converge and then diverge. Another was the use of smokeless powder based on nitroglycerin. Unge believed that his aerial torpedoes would be valuable as surface-to-air weapons against dirigibles. Velocity and range were increased, and about 1909 the Krupp armament firm of Germany purchased the patents and a number of rockets for further experimentation.

World War I and after

In the United States, meanwhile, Robert Hutchings Goddard was conducting theoretical and experimental research on rocket motors at Worcester, Mass. Using a steel motor with a tapered nozzle, he achieved greatly improved thrust and efficiency. During World War I Goddard developed a number of designs of small military rockets to be launched from a lightweight hand launcher. By switching from black powder to double-base powder (40 percent nitroglycerin, 60 percent nitrocellulose), a far more potent propulsion charge was obtained. These rockets were proving successful under tests by the U.S. Army when the Armistice was signed; they became the forerunners of the bazooka of World War II.  World War I actually saw little use of rocket weapons, despite successful French incendiary antiballoon rockets and a German trench-war technique by which a grappling hook was thrown over enemy barbed wire by a rocket with a line attached. Many researchers besides Goddard used the wartime interest in rockets to push experimentation, the most noteworthy being Elmer Sperry and his son, Lawrence, in the United States. The Sperrys worked on a concept of an “aerial torpedo,” a pilotless airplane, carrying an explosive charge, that would utilize gyroscopic, automatic control to fly to a preselected target. Numerous flight attempts were made in 1917, some successful. Because of early interest in military use, the U.S. Army Signal Corps organized a separate program under Charles F. Ketteringin Dayton, Ohio, late in 1918. The Kettering design used a gyroscope for lateral control to a preset direction and an aneroid barometer for pitch (fore and aft) control to maintain a preset altitude. A high angle of dihedral (upward tilt) in the biplane wings provided stability about the roll axis. The aircraft was rail-launched. Distance to target was determined by the number of revolutions of a propeller. When the predetermined number of revolutions had occurred, the wings of the airplane were dropped off and the aircraft carrying the bomb load dropped on the target.

The limited time available to attack the formidable design problems of these systems doomed the programs, and they never became operational.

As World War II approached, minor and varied experimental and research activities on rockets and guided missiles were underway in a number of countries. But in Germany, under great secrecy, the effort was concentrated. Successful flights as high as one mile were made in 1931–32 with gasoline–oxygen-powered rockets by the German Rocket Society. Funds for such amateur activities were scarce, and the society sought support from the German army. The work of Wernher von Braun, a member of the society, attracted the attention of Captain Walter R. Dornberger. Von Braun became the technical leader of a small group developing liquid-propellant rockets for the German army. By 1937 the Dornberger–Braun team, expanded to hundreds of scientists, engineers, and technicians, moved its operations from Kummersdorf to Peenemünde, a deserted area on the Baltic coast. Here the technology for a long-range ballistic missile was developed and tested (see below Strategic missiles).

World War II

World War II saw the expenditure of immense resources and talent for the development of rocket-propelled weapons.

Barrage rockets

The Germans began the war with a lead in this category of weapon, and their 150-millimetre and 210-millimetre bombardment rocketswere highly effective. These were fired from a variety of towed and vehicle-mounted multitube launchers, from launching rails on the sides of armoured personnel carriers, and, for massive bombardments, even from their packing crates. Mobile German rocket batteries were able to lay down heavy and unexpected concentrations of fire on Allied positions. The 150-millimetre Nebelwerfer, a towed, six-tube launcher, was particularly respected by U.S. and British troops, to whom it was known as the “Screaming Meemie” or “Moaning Minnie” for the eerie sound made by the incoming rockets. Maximum range was more than 6,000 yards (5,500 metres). A five-inch rocket with an explosive warhead was developed in Great Britain. Its range was two to three miles. These rockets, fired from specially equipped naval vessels, were used in heavy coastal bombardment prior to landings in the Mediterranean. Firing rates were 800–1,000 in less than 45 seconds from each ship.

A development of the U.S. Army was the Calliope, a 60-tube launching projector for 4.5-inch rockets mounted on a Sherman tank. The launcher was mounted on the tank’s gun turret, and both azimuth (horizontal direction) and elevation were controllable. Rockets were fired in rapid succession (ripple-fired) to keep the rockets from interfering with one another as they would in salvo firing.

Other conventional rockets developed in the United States included a 4.5-inch barrage rocket with a range of 1,100 yards and a five-inch rocket of longer range. The latter was used extensively in the Pacific theatre of war, fired from launching barges against shore installations, particularly just before landing operations (see photograph). The firing rate of these flat-bottom boats was 500 per minute. Other rockets were used for smoke laying and demolition. The United States produced more than four million of the 4.5-inch rockets and 15 million of the smaller bazooka rockets during the war.  As far as is known, Soviet rocket development during World War II was limited. Extensive use was made of barrage, ripple-fired rockets. Both A-frame and truck-mounted launchers were used. The Soviets mass-produced a 130-millimetre rocket known as the Katyusha. From 16 to 48 Katyushas were fired from a boxlike launcher known as the Stalin Organ, mounted on a gun carriage.

The bazooka

Beginning in mid-1940, Clarence N. Hickman, who had worked with Robert Goddard during World War I, supervised the development of a refined design of the hand-launched rocket. The new rocket, about 20 inches (50 centimetres) long, 2.36 inches in diameter, and weighing 3.5 pounds, was fired from a steel tube that became popularly known as the bazooka. Designed chiefly for use against tanks and fortified positions at short ranges (up to 600 yards), the bazooka surprised the Germans when it was first used in the North African landings of 1942. Although the rocket traveled slowly, it carried a potent shaped-charge warhead that gave infantrymen the striking power of light artillery. The German counterpart of the bazooka was a light 88-millimetre rocket launcher known as Panzerschreck (“Tank Terror”) or Ofenrohr (“Stovepipe”).

Antiaircraft rockets

During World War II high-altitude bombing above the range of antiaircraft guns necessitated the development of rocket-powered weapons. In Great Britain, initial effort was aimed at achieving the equivalent destructive power of the three-inch and later the 3.7-inch antiaircraft gun. Two important innovations were introduced by the British in connection with the three-inch rocket. One was a rocket-propelled aerial-defense system. A parachute and wire device was rocketed aloft, trailing a wire that unwound at high speed from a bobbin on the ground with the object of snagging the aircraft’s propellers or shearing off the wings. Altitudes as high as 20,000 feet were attained. The other device was a type of proximity fuze using a photoelectric cell and thermionic amplifier. A change in light intensity on the photocell caused by light reflected from a nearby airplane (projected on the cell by means of a lens) triggered the explosive shell.

The only significant antiaircraft rocket development by the Germans was the Taifun. A slender, six-foot, liquid-propellant rocket of simple concept, the Taifun was intended for altitudes of 50,000 feet. The design embodied coaxial tankage of nitric acid and a mixture of organic fuels, but the weapon never became operational.

Aerial rockets

Britain, Germany, the Soviet Union, Japan, and the United States all developed airborne rockets for use against surface as well as aerial targets. These were almost invariably fin-stabilized because of the effective aerodynamic forces when launched at speeds of 250 miles per hour and more. Tube launchers were used at first, but later straight-rail or zero-length launchers, located under the wings of the airplane, were employed. One of the most successful of the German rockets was the 50-millimetre R4M. The tail fins remained folded until launch, facilitatingclose loading arrangements. The U.S. achieved great success with a 4.5-inch rocket, three or four of which were carried under each wing of Allied fighter planes. These rockets were highly effective against motor columns, tanks, troop and supply trains, fuel and ammunition depots, airfields, and barges. A variation on the airborne rocket was the addition of rocket motors and fins to conventional bombs. This had the effect of flattening the trajectory, extending the range, and increasing velocity at impact, useful against concrete bunkers and hardened targets. These weapons were called glide bombs, and the Japanese had 100-kilogram and 370-kilogram (225-pound and 815-pound) versions. The Soviet Union employed 25- and 100-kilogram versions, launched from the IL-2 Stormovik attack aircraft.

Postwar

After World War II, unguided, folding-fin rockets fired from multiple-tube pods became a standard air-to-ground munition for ground-attack aircraft and helicopter gunships. Though not as accurate as guided missiles or gun systems, they could saturate concentrations of troops or vehicles with a lethal volume of fire. Many ground forces continued to field truck-mounted, tube-launched rockets that could be fired simultaneously in salvos or ripple-fired in rapid succession. Such artillery rocket systems, or multiple-launch rocket systems, generally fired rockets of 100 to 150 millimetres in diameter and had ranges of 12 to 18 miles. The rockets carried a variety of warheads, including high explosive, antipersonnel, incendiary, smoke, and chemical.

The Soviet Union and the United States built unguided ballistic rockets for about 30 years after the war. In 1955 the U.S. Army began deployment of the Honest John in western Europe, and from 1957 the Soviet Union built a series of large, spin-stabilized rockets, launched from mobile transporters, given the NATO designation FROG (free rocket over ground). These missiles, from 25 to 30 feet long and two to three feet in diameter, had ranges of 20 to 45 miles and could be nuclear-armed. Egypt and Syria fired many FROG missiles during the opening salvos of the Arab–Israeli War of October 1973, as did Iraq in its war with Iran in the 1980s, but in the 1970s large rockets were phased out of the superpowers’ front line in favour of inertially guided missiles such as the U.S. Lance and the Soviet SS-21 Scarab.