Viking (rocket)

Viking

Launch of Viking 10 on 7 May 1954
Function	Research sounding rocket
Manufacturer	Glenn L. Martin Company
Country of origin	United States
Size
Height	15 m (49 ft); 13 m (43 ft)
Diameter	81 cm (32 in); 114 cm (45 in)
Stages	1
Capacity
Payload to
Launch history
Status	Retired
Launch sites	White Sands Missile Range, (Vikings 1–3 and 5–12) USS Norton Sound, near the Equator (Viking 4)
Total launches	12
Success(es)	7
Failure(s)	1
Partial failure(s)	4
First flight	3 May 1949
Last flight	4 February 1955
First stage
Engines	Reaction Motors XLR10-RM-2
Thrust	92.5 kN (20,800 lbf) (sea level) 110.5 kN (24,800 lbf) (vacuum)
Specific impulse	179.6 s (1.761 km/s)
Burn time	103 seconds
Propellant	Ethyl alcohol and liquid oxygen

Viking was series of twelve sounding rockets designed and built by the Glenn L. Martin Company (now Lockheed-Martin) under the direction of the U.S. Naval Research Laboratory (NRL). Designed to supersede the German V-2, the Viking was the most advanced large, liquid-fueled rocket being developed in the U.S., returning valuable scientific data from the edge of space between 1949-1955.

Origins[]

After World War II, the United States experimented with captured German V-2 rockets as part of the Hermes program. Based on these experiments the U.S. issued a contract 21 August 1946 to the Glenn L. Martin Company for a series of ten large liquid-fueled rockets. The intent was to provide an independent U.S. capability in rocketry, to continue the Hermes program after the V-2s were expended, and to provide a vehicle better suited to scientific research. Originally dubbed "Neptune," it was renamed "Viking" in 1947 to avoid confusion with the Lockheed P-2 Neptune^[1]:26 Twelve Viking rockets flew from 1949 to 1955.^[1]:25–27

The Viking was the most advanced large, liquid-fueled rocket being developed in the U.S. at the time.^[2]

Design[]

Diagram showing both Viking rocket variants, Vikings 1 to 7 (left) and 8 to 12 (right).

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 (Ethyl alcohol and liquid oxygen), 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 92.5 kN (20,800 lb_f) (sea level) and 110.5 kN (24,800 lb_f) (vacuum) of thrust. Isp was 179.6 s (1.761 km/s) and 214.5 s (2.104 km/s) respectively, with a mission time of 103 seconds. 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.^[3][4]

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 H. Goddard, who had partial success with it before World War II intervened.^[1]:66 Roll control was by use of the turbopump exhaust to power reaction control system (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.^[1]:231

Vikings 1 through 7 were slightly longer (about 15 m (49 ft)) than the V-2, but with a straight cylindrical body only 81 centimetres (32 in) 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 114 centimetres (45 in), while the length was reduced to 13 m (43 ft), 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.^[1]:173

Flight history[]

First model[]

Launch of Viking 4

On 3 May 1949, after two static firings (11 March and 25 April), the first Viking rocket took off from White Sands White Sands Missile Range in New Mexico. Its engine fired for 55 seconds, ten seconds short of the hoped-for maximum of 65, but the rocket flew on course and reached an altitude of 51 mi (82 km) -- deemed a good start to the program.^[1]:84–93 Viking 2, launched four months later, also suffered from premature engine cutoff and only made it to 33 mi (53 km). Both had suffered from leaks in their turbines, the intense heat of the steam breaking the seal of the turbine casing. The solution was to weld the casing shut, there being no reason to access the turbine wheel again after a flight.^[1]:98–102

The fix worked, and Viking 3, launched 9 February 1950 and incorporating an integrated (rather than discrete) oxygen tank, reached 50 mi (80 km) and could have gone higher. However, after 34 seconds of accurately guided flight, the rocket veered westward and threatened to leave the launch range. Range safety triggered charges in the rocket to separate the nose from the engine, and both tumbled to the ground, where they were recovered for analysis.^{[1]:108–114}

With successful tests of the engine and guidance systems conducted (though not on the same missions), Viking was deemed ready for its most ambitious test: shipboard launch from the deck of the USS Norton Sound.^{[1]:108–114} Viking 4 was identical to Viking 3, the first of the series not incorporate design changes to fix a problem on a previous Viking.}^[5]:255 On 10 May, 1950, from a site in the Pacific Ocean between Jarvis Island and Christmas Island, the fourth Viking became the first sounding rocket ever launched from a sea-going vessel. The flight was perfect, reaching 106.4 mi (171.2 km), more than double that reached by Vikings 1 and 3.^{[1]:108–114}

Viking 5, launched 21 November 1950 carried a vast array of photomultiplier tubes, ionization chambers and Geiger counters, for the detection radiation across a wide variety of energies and types. The rocket also carried two movie cameras to take high altitude film of the Earth all the way to its peak height of 108 miles (174 km) as well as Pirani gauges to measure air densities in the upper atmosphere.^{[1]:148, 236} Viking 6, launched 11 December, carried a much lighter payload, but its experiments included a battery of custom built pressure gauges. The rocket underperformed, however, only reaching a maximum altitude of 40 miles (64 km).^{[1]:151–153, 236}

The first generation of Vikings reached its acme of performance with the flight of Viking 7, the sole Viking launch of 1951. Launched 7 August from White Sands, the rocket set a new world altitude record of 136 miles (219 km).^{[1]:167–171, 236}

Second model[]

Viking 9 takes off 15 December 1952

In the late spring of 1952, the Naval Research Laboratory team under the management of Milton Rosen prepared to launch the first second-generation Viking, Viking 8, from White Sands Missile Range in New Mexico. The new Viking design was nearly half-again as wide as its precursor, affording the highest fuel-to-weight ratio of any rocket yet developed. The tail fins no longer supported the weight of the rocket, has had previously been the case. Now, the Viking rocket rested on the base of its fuselage. This allowed the tail fins to be made much lighter, one of many ways the Viking was redesigned to carry a heavier tank without weighing more than the first Viking design.

On 6 June 1952, Viking 8 broke loose of its moorings during a static firing test. After it was allowed to fly for 55 seconds in the hope that it would clear the immediate area and thus pose no danger to ground crew, Nat Wagner, head of the "Cutoff group" delivered a command to the rocket to cease its thrust. 65 seconds later, the rocket crashed 4 miles (6.4 km) or 5 miles (8.0 km) downrange to the southeast.^{[1]:172–181}

With lessons learned from the Viking 8 failure, the successful 9 December static firing of Viking 9 was followed on 15 December by a successful launch from White Sands. The rocket reached an altitude of 135 miles (217 km), roughly the same as that of the first-generation Viking 7, launched in 1950. In addition to cameras that photographed the Earth during flight, Viking 9 carried a full suite of cosmic ray, ultraviolet, and X-ray detectors, including sixteen plates of emulsion gel for tracking the path of individual high energy particles. The experiment package was recovered intact after it had secured measurements high in the Earth's upper atmosphere.^{[1]:185–203}

Viking 10[]

On 25 May 1953, Viking 10, originally planned to be the last of the Vikings, arrived at White Sands Missile Range in New Mexico. A successful static firing on 18 June cleared the way for a 30 June launch date, a schedule that had been made months prior, before the rocket had even left the Glenn L. Martin Company plant where it had been built. At the moment of liftoff, the tail of Viking 10 exploded, setting the rocket afire. Water was immediately flooded into the rocket's base in an attempt to extinguish the fire, but flames continued to burn in the East Quadrant of the firing platform. Half an hour after launch, two of the launch team under manager Milton Rosen were dispatched to put out the fire to salvage what remained of the rocket.

Their efforts were successful but then were threatened by a slow leak in the propellant tank. The vacuum created by the departing fuel was causing the tank to dimple with the danger of implosion that would cause the rocket to collapse. Lieutenant Joseph Pitts, a member of the launch team, shot a rifle round into the tank, equalizing the pressure and saving the rocket. Three hours after the attempted launch, the last of the alcohol propellant had been drained from Viking 10. The launch team was able to salvage the instrument package of cameras, including X-ray detectors, cosmic ray emulsions, and a radio-frequency mass-spectrometer, valued at tens of thousands of dollars, although there was concern that the rocket was irreparable.

A thorough investigation of the explosion began in July, but a conclusive cause could not be determined. In a reported presented in September, Milton Rosen noted that a similar occurrence had not happened in more than 100 prior tests of the Viking motor. It was decided to rebuild Viking 10, and a program for closer monitoring of potential fail points was implemented for the next launch, scheduled for 1954.^{[1]:204–221} Ten months of salvage, testing, and troubleshooting followed the failed launch.

On 30 June, 1953, the rebuilt rocket was once again ready for launch. A successful static firing took place at the end of April 1954, and launch was scheduled for 4 May. Control issues revealed in the static firing as well as gusty, sand-laden winds caused a delay of three days. At 10:00 AM local time, Viking 10 blasted off from its pad at the White Sands Missile Range in New Mexico, reaching an altitude of 136 mi (219 km) -- a tie with the highest altitude ever reached by a first-generation Viking (Viking 7 on 7 August 1951). Data was received from the rocket for all stages of the flight, and its scientific package, including an emulsion experiment, returned the first measurement of positive ion composition at high altitudes.^{[1]:221–236}

Final flights[]

Viking 12 infrared photo of the Earth taken 4 February 1955

Viking 11, which was ready for erection on 5 May, also had a successful static test and was ready for launch, 24 May 1954. Again, the countdown went without hold, and Viking 11, the heaviest rocket yet in the series, was launched at 10:00 AM. Forty seconds into the flight, several puffs of smoke issued from the vehicle, but these accidental excitations of the rocket's roll jets did no harm. Viking 11 ultimately reached 158 mi (254 km) in altitude, a record for the series, snapping the highest altitude photographs of the Earth to date. Viking 11 carried a successful emulsions experiment, measuring cosmic rays at high altitudes.^{[1]:221–236}

The final Viking flight was that of Viking 12, launched 4 February 1955. Reaching an altitude of 143.5 mi (230.9 km), the rocket's K-25 camera snapped an infrared picture of the Southwestern United States, from the Pacific coast to Phoenix, just after reaching its apogee.^[6]

Legacy and status[]

The Viking series returned a bonanza of scientific information measuring temperature, pressure, density, composition and winds in the upper atmosphere and electron density in the ionosphere, and recording the ultraviolet spectra of the Sun,^[1]:234 The success of the program, at a cost of under $6 million, suggested 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.^[7]:283 The Viking was thus incorporated as the first stage of NRL's three-stage Project Vanguard vehicle which launched the second U.S. satellite. Two later rockets in the Viking series, Vanguard TV-0 (renamed from Viking 13) and Vanguard TV-1, substantially similar to Vikings 8 through 12, were used as suborbital test vehicles during Project Vanguard, before the first Vanguard vehicle, Vanguard TV-2, became available for test in the fall of 1957.^[8]

Viking 12 reconstruction at Smithsonian

The National Air and Space Museum contains a full-size cutaway reconstruction of Viking 12, built from original blueprints and reconstructed from parts recovered from the original rocket. The vehicle was donated by the Martin Marietta Corp in 1976 to the Smithsonian.^[9]

Table of flights[]

^[1]:236

All except Viking 4 were flown from White Sands Missile Range, New Mexico.

See also[]

• Vanguard rocket

References[]