Viking (rocket) - Design Features

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 propellants (alcohol and liquid oxygen ), which were fed to a single large engine by turbine-driven pumps. The Reaction Motors XLR10 engine was the largest liquid-fueled rocket engine developed in the United States up to that time, producing 89 kN (20000 lbf) of thrust. As was also the case for the V-2, hydrogen peroxide was converted to steam to drive the turbopump that fed fuel and LOX into the engine.

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 gimbals were 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 (about 15 m, 49 ft) than the V-2, but with a straight cylindrical body only 32 in (81 cm) 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 (114 cm), while the length was reduced to 13 m (42 ft), destroying 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.