(SLIDE 17) Landing Prior to the X-15 flight program there was considerable reservation about the pilots' ability to consistently land a power-off, low lift-drag ratio airplane. The X-15, however, had good handling qualities and large variable deflection speed brakes and it proved easy to land. All the pilots used a circling approach that was commenced at 30,000 to 50,000 feet above the runway and they stayed high on profile until it was assured that they would reach the runway, at which time speed brakes were used to descend onto a nominal glideslope. The landing gear was left retracted, for drag reduction, until the landing flare was complete and the aircraft was in level flight.
X-15 Landing (Slide 17)
There were 196 successful landings in the program, and the two landing accidents that occurred were related to system or structural failures and not to pilot error.
The first accident (SLIDE 18) happened early in the program, when an engine explosion occurred during engine start, and the pilot was forced to land at the launch lake. Not all of the propellants jettisoned; also, the oil in the nose strut had become aerated. Thus, the aircraft was heavyweight and the nose strut did not provide the shock absorption it was designed for. In spite of this, the damage was minor and the airplane was back in the air in three months with a modified nose strut able to handle the landing loads.
X-15 Engine Explosion upon
engine start. (Slide 18)
The next slide (SLIDE 19) shows another landing accident. Once again there was engine failure. Here the fuel was jettisoned but the landing flaps failed to extend. The landing was therefore fast and the high download on the main gear after nosewheel touchdown combined with a faulty weld, caused the left main gear to fail. The aircraft veered sideways and rolled over, damaging the wings; destroying the tail surfaces, and injuring the pilot, who suffered three crushed vertebrae.
X-15 Landing Incident. (Slide 19)
The pilot was back on flying status within six months and was soon back in the X-15 program. The rebuilding of this X-15 will be described later.
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