Flight 3-25-42 was flown by Milton O. Thompson on January 16, 1964, to obtain heat transfer data with the sharp upper vertical fin and to evaluate damper off controllability of X-15-3. An instrumentation power failure occurred 32 seconds after launch and with the exception of the positions and forces oscillograph, no data was recorded internally until the difficulty was corrected 40 seconds later. Heat transfer data was to have been obtained during this interval. Approximately ten seconds of heat transfer data appears to have been recorded following the power failure. Other systems appear to have functioned normally throughout the flight.

The launch configuration for this flight was MH-96 adaptive, R.C. "OFF," BCS "OFF," Heading vernier to standby, and lower ventral "OFF." The launch was made in the vicinity of Hidden Hills on a magnetic heading of 212.2° at an altitude and a velocity of approximately 44,000 feet and 720 feet per second, respectively. The maximum altitude and velocity attained during the flight was approximately 71,000 feet and 4750 feet per second. The maximum dynamic pressure was approximately 1640 psf.

The flight request was accomplished essentially as planned. The powered flight duration was 91.6 seconds with 70.3 seconds at 100% thrust. The longitudinal acceleration at thrust reduction and burnout was approximately -1.7 "g". At launch, the pilot commanded a steady - da input of approximately 7 degrees. The aircraft rolled approximately 6.3 degrees right (b» -5.3°) following launch. Intermittently during the boost phase, the pilot applied a steady 1 degree right rudder and the aircraft had rotated to a heading of 216.7° at burnout. The speed brakes were fully opened 15 seconds after thrust reduction and were retracted 40 seconds after burnout. Pilot ratings during the heating portion of the flight were:

q 2.5 , f 2.5 , y 2.5 .

After burnout, the pilot switched the yaw damper off and performed a right and a left rudder pulse. The roll damper was then switched off and the pilot performed roll and rudder pulses. The pilot indicated that with the roll and yaw dampers off, the aircraft was still damped and appeared more stable than the simulator. The pilot indicated the control task following pulse inputs would be rated as:

Yaw damper only off q 2.5 , f 2.5 , y 3 .

Roll and yaw dampers off q 2.5 , f 3 , y 3 .

The roll and yaw dampers were reset to adaptive for the remainder of the flight.

Coming out of the turn, the speed brakes were opened to 25 degrees by steps and were closed during final approach. Immediately prior to touchdown, the speed brakes were opened full. The touchdown was at a rate of sink of approximately 4.3 feet per second and occurred 1425 feet south of the 2-mile marker. Main gear load at touchdown was 7300 lb. The landing disengage switch was utilized during the landing and the servos were centered and locked approximately .1 seconds after main gear touchdown. The pilot pushed forward on the stick approximately .25 seconds after main gear touchdown and the main gear left the ground 190 feet after initial touchdown. The main gear touched down for the second time after approximately 20 feet. Nose gear touchdown occurred approximately 42 feet later and the main gear lifted off for a third time 144 feet after nose gear touchdown. The final main gear touchdown occurred approximately 470 feet after the initial main gear touchdown. The slideout distance was approximately 5700 feet. Total flight duration was 496.3 seconds (8.27 minutes).
 
 

James R. Welsh

Aerospace Engineer