The "Saturn insulation" experiment exposed various types of insulation material from the Saturn launch vehicles to the hypersonic environment. Some documentation shows this as experiment #41. The X-15-3 made at least five flights with pieces of Saturn insulation material. By flying the material on the X-15, researchers could examine it after a flight, which was not possible with the expendable Saturn boosters. Generally, researchers installed variable-thickness panels on the upper speed brakes with two thermocouples on the left side, and seven thermocouples, two static-pressure transducers, and one pitot probe on the right side. They also installed additional constant-thickness insulation panels on the lower speed brakes with two thermocouples on the right side and seven thermocouples on the left side. NASA installed a camera in the right wing-tip pod to look at the upper speed brakes, and a second camera in the left pod pointed at the lower speed brakes. Some of the tests were decidedly unsuccessful. For instance, NASA applied Saturn insulation to the upper left speed brake on the aborted flight attempt on 31 October 1967 (3-A – 96); the bond failed and the insulation came off during the captive flight. Researchers replaced the insulation before Mike Adams’s fatal flight (3-65-97).
The test of insulation for the Saturn launch vehicles is usually heralded as one of the X-15’s contributions, but in reality the tests were minimal and concentrated more on the adhesives behind the insulation. Here the Saturn insulation is installed on the upper speed brakes of X-15-3 on 31 October 1967, just before its last flight. Note the tail cone box behind the speed brakes. (NASA)
After X-15-3 was lost, NASA transferred the experiment to X-15-1. Researchers installed 16-
mm movie cameras in each wing pod to photograph the insulation on the upper speed brakes, and installed 18 thermocouples in the speed brakes themselves. Several flights carried the insulation until the end of the program, although sometimes it was on the lower speed brakes (and other times on both).-1205!
Since these tests were conducted fairly late in the Saturn development program (1966-1967), it is unlikely that any unexpected information was gained. More probably, the researchers just achieved final confirmation of the material’s ability to withstand high dynamic pressures without losing its thermal properties.