The Aerobee was not the only replacement for the aging V-2’s. The Naval Research Laboratory needed a large sounding rocket with more capacity and altitude capability. It was also clear that experience in large rocket design would be of value for future missile development. Originally named Project Neptune, the Viking would be the highest flying US-built rocket for years to come. Eventually, it would serve as the first stage for the first US satellite attempt.
The Viking would take on the role of the V-2 in high altitude research, but it would be of a quite different design. Aside from the difficulty of attempting to clone the V-2, The V-2 had stability problems. It was stable only with a ton of payload, and even then it would tumble freely or at high altitudes after engine burnout. The Viking was to trade payload weight for altitude, and stability during measurements was desirable.
The design that emerged was a long, slender vehicle, steered by gimballing of its alcohol and liquid oxygen burning engine. It could boost 400 pounds of instruments as high as 136 miles, as demonstrated by the seventh and final flight of this design.