ROCKETS IN THE HIGH DESERT

In June 1959, the $450,000 Rocket Engine Test Facility at Edwards AFB came on line to provide local testing of the XLR99, although it would be almost a year before an XLR99 was available to use in it. This test facility provided a capability for engine checkout and pilot and maintenance – crew familiarization, as well as limited development firings. There were two test areas with a large blockhouse between them that contained various monitoring equipment and provided safe shelter for the ground crew during engine runs. During the early portion of the program, Reaction Motors used one area to test uninstalled engines, while the Air Force fired engines installed in one of the X-15s in the other area. Several "pillboxes" were also located near each area that provided shelter for other ground crews so that they could observe the operation of the engine.78

ROCKETS IN THE HIGH DESERT

In preparation for the X-15 program, the Air Force constructed the Rocket Engine Test Facility at Edwards AFB to provide local testing of the XLR99. There were two test areas, each capable of supporting an X-15 during engine tests. For most of the flight program, the XLR99 had to be fired prior to every flight attempt, leading several engineers to complain they were testing the engines to death. Later in the program an engine could fly a second flight if no anomalies had occurred on the first. (U. S. Air Force)

In December 1959, the Air Force formally approved the XLR99 for flight in the X-15. Reaction Motors delivered a ground-test engine to Edwards at the end of May 1960, and the first flight engine at the end of July. Initially, the Air Force procured 10 flight engines, along with six spare injector-chamber assemblies. Later, the Air Force procured one additional flight engine. However, in January 1961, shortly after the first XLR99 test flight, only four engines were available to the flight program while Reaction Motors was assembling four others for delivery later in 1961. Reaction Motors continued to use four engines for ground tests, including two flight engines. Three of these engines were involved in tests to isolate and eliminate vibrations at low power levels, while the fourth investigated extending the Rokide loss that was affecting the life of the thrust chamber.-1791