Viking (rocket)


The Viking rocket series of sounding rockets were designed and built by the Glenn L. Martin Company under the direction of the U.S. Naval Research Laboratory. Twelve Viking rockets flew from 1949 to 1955.

Origins

After World War II, the United States experimented with captured German V-2 rockets as part of the Hermes project. Based on these experiments the U.S. decided in 1946 to develop its own large liquid-fueled rocket design, to be called Neptune but changed to Viking. The intent was to provide an independent U.S. capability in rocketry, to continue the Hermes project after the V-2s were expended, and to provide a vehicle better suited to scientific research. The Navy, in particular, needed a vehicle to study the atmosphere and learn how to predict bad weather which would affect the fleet.
The V-2 would tumble in the rarefied atmosphere at high altitudes. Having been designed as a weapon, the V-2 carried a large payload, approximately one ton of high explosive. This was more than was considered necessary for the scientific instrument payload of a high-altitude research rocket, but in the case of the V-2, used for research, most of the payload was lead ballast required for stable flight, limiting the potential speed and altitude that could be reached with the smaller payloads typically needed for early scientific investigations.
The NRL, partly at the instigation of the American Rocket Society, chose to build the advanced sounding rocket. Milton Rosen, head of the Viking project, credits rocket pioneer Robert Goddard, the ARS, the California Institute of Technology and the V-2 for the "profound influence" they had on the design of the rocket.
The Viking was the most advanced large, liquid-fueled rocket being developed in the U.S. at the time.

Design features

The Viking was roughly half the size, in terms of mass and power, of the V-2. Both were actively guided rockets, fueled with the same propellant, which were fed to a single large pump-fed engine by two turbine-driven pumps. The Reaction Motors XLR10-RM-2 engine was the largest liquid-fueled rocket engine developed in the United States up to that time, producing and of thrust. Isp was and respectively, with a mission time of 103s. As was also the case for the V-2, hydrogen peroxide was converted to steam to drive the turbopump that fed fuel and oxidizer into the engine. As its V-2 counterpart, it also was regeneratively cooled.
Viking pioneered important innovations over the V-2. One of the most significant for rocketry was the use of a gimbaled thrust chamber which could be swiveled from side to side on two axes for pitch and yaw control, dispensing with the inefficient and somewhat fragile graphite vanes in the engine exhaust used by the V-2. The rotation of the engine on the gimbals was controlled by gyroscopic inertial reference; this type of guidance system was invented by Robert Goddard, who had partial success with it before World War II intervened. Roll control was by use of the turbopump exhaust to power RCS jets on the fins. Compressed gas jets stabilized the vehicle after the main power cutoff. Similar devices are now extensively used in large, steerable rockets and in space vehicles. Another improvement was that initially the alcohol tank, and later the LOX tank also, were built integral with the outer skin, saving weight. The structure was also largely aluminum, as opposed to steel used in the V-2, thus shedding more weight.
Vikings 1 through 7 were slightly longer than the V-2, but with a straight cylindrical body only in diameter, making the rocket quite slender. They had fairly large fins similar to those on the V-2. Vikings 8 through 14 were built with an enlarged airframe of improved design. The diameter was increased to 45 in, while the length was reduced to 13 m, altering the missile's "pencil shape." The fins were made much smaller and triangular. The added diameter meant more fuel and more weight, but the "mass ratio", of fueled to empty mass, was improved to about 5:1, a record for the time.

Flight history

All except Viking 4 were flown from White Sands, New Mexico.
The first launch, of Viking 1, on 3 May 1949 came after a very prolonged and trying period of ground firing tests, and attained an altitude of. The altitude was limited by a premature engine cut-off, eventually traced to steam leakage from the turbine casing.
Viking 2, flown 6 September 1949, also suffered early engine cut-off for the same reason as Viking 1; it reached only.
Viking 3, 9 February 1950, suffered from instability in a redesigned guidance system, and had to be cut off by ground command when it threatened to fly outside the range. Altitude was again only.
Viking 4, on 11 May 1950, launched from the deck of the USS Norton Sound near the Equator, reached a peak altitude of, almost the maximum possible for the payload flown, in a nearly perfect flight. Guidance system was reverted to that of Vikings 1 and 2.
Viking 5, 21 November 1950 reached. Engine thrust was about 5% low, or altitude would have been slightly higher.
Viking 6, 11 December 1950, suffered catastrophic failure of the stabilizing fins late in powered flight, with loss of attitude control, and associated very large drag. Altitude was therefore only.
Viking 7, 7 August 1951, reached altitude to beat the old V-2 record for a single-stage rocket. This was the highest and last flight of the original airframe design.
Viking 8, 6 June 1952, first rocket of improved airframe design, lost when it broke loose during static testing, and flew to before ground commanded cut-off.
Viking 9, 15 December 1952, reached altitude in the first successful flight of the improved airframe design.
Viking 10. The engine exploded on first launch attempt 30 June 1953. The rocket was rebuilt and was flown successfully 7 May 1954, to.
Viking 11 rose to on 24 May 1954, an altitude record for a Western single-stage rocket up to that time. Earth photography and re-entry vehicle test.
Viking 12 was flown 4 February 1955, for re-entry vehicle test, photography, and atmospheric research. It reached. The National Air and Space Museum contains a full-size cutaway reconstruction of Viking 12, built from original blueprints.
Two additional Viking airframes, similar to Vikings 9 through 12, were flown as test vehicles for Project Vanguard. Both were launched from Cape Canaveral, on 8 December 1956 and 1 May 1957, and were designated Vanguard TV0 and Vanguard TV1 respectively.

Achievements

While the underlying motivation for the Viking Project clearly had a national defense component, since it was a US Navy program, it nevertheless established a number of early space exploration landmarks, some technological and some scientific.
Peaceful space travel and space exploration were clearly important objectives that energized many of the higher level instigators even of the German V-2 rocket program, which was funded by the German Army entirely for military purposes. Viking was probably the most ambitious program up to its time, which had significant objectives that were essentially scientific, accompanied by a desire to explore and advance rocket technology for more ambitious peaceful space exploration goals such as artificial earth satellites.
Technological advances pioneered by Viking included the following:
Among its scientific achievements, firsts up to their time, were:
Through the Viking flights, NRL was first to measure temperature, pressure, density, composition and winds in the upper atmosphere and electron density in the ionosphere, and to record the ultraviolet spectra of the Sun.

Viking into Vanguard

The success NRL achieved in this series of experiments encouraged laboratory scientists to believe that, with a more powerful engine and the addition of upper stages, the Viking rocket could be made a vehicle capable of launching an earth satellite. This led to NRL's three-stage Project Vanguard vehicle which launched the second US satellite. Two later rockets in the Viking series, Vanguard TV0 and TV1, substantially similar to Vikings 8 through 12, were used as suborbital test vehicles during Project Vanguard, before the first Vanguard vehicle became available for test as Vanguard TV2, in the fall of 1957.