Scout X-1 was an American expendable launch system and sounding rocket which was flown seven times between August 1960 and October 1961. Four orbital and three suborbital launches were made, with four of the launches resulting in failures. The Scout X-1 was similar to the Scout X test vehicle which was launched in April 1960, however it had live second and fourth stages, as opposed to the battleship versions used on the Scout X. It also featured an improved first stage, using an Algol 1B instead of the earlier Algol 1A used on the Scout X. All seven launches occurred from Launch Area 3 at the Wallops Flight Facility. The maiden flight was a suborbital test of the rocket's systems, and was conducted successfully on 2 July 1960, with the rocket launching at 00:04 GMT. Following this, a suborbital radiation experiment was successfully launched on 4 October. The first orbital launch attempt, with the S-56 satellite, was made on 4 December, and ended in failure after the second stage malfunctioned. On 16 February 1961, a Scout X-1 successfully placed Explorer 9, a reflight of the failed S-56, into Earth orbit, in the first successful orbital launch to be conducted by a Scout rocket. The next launch attempt on 30 June carried the S-55 satellite, but this did not reach orbit because the third stage failed to ignite. A reflight of S-55, Explorer 13, was launched on 25 August, but reached a lower than planned orbit, and was unusable. The final flight of the Scout X-1 was made on 19 October, carrying plasma and aeronomy research payloads on a suborbital trajectory. This launch was successful. Several derivatives of the Scout X-1 were also flown. The United States Navy developed the Blue Scout, which was a three-stage sounding rocket, and the Blue Scout II which was almost identical to the Scout X-1. The Scout X-1A, a five-stage variant of the Scout X-1, was used for a single suborbital launch in March 1962. It featured an improved first stage, and a NOTS-17upper stage.
