August 31, 1965

MEMORANDUM for Chief, Research Division X-15 Project Office

Subject: Preliminary evaluation of X-15 flight 1-56-93

Flight 1-56-93 was flown on August 6, 1965, by Milton 0. Thompson. The launch lake was Delamar and the launch heading was 214° magnetic.

The flight had three research purposes, they were:
 

1. Singer Infrared Scanner

2. Stability and Control

3. SAS Checkout

Flight Summary

Prelaunch - The B-52 outbound track was good. The winds were as predicted and the radar tracking was good. No problems with SAS appeared during the prelaunch checkout.

Postlaunch - No real launch transients were noted. There was very little roll-off and the ball nose operated well. The ground track and profile appeared normal on the radar plot during rotation and the first portion of the "power on" flight. The ground track began to drift off during the boost phase. This heading change was the result of a heavy foot on the rudder.

Shutdown conditions were good. The inertial velocity and altitude were 5150 feet per second and 97,000 feet respectively. The peak altitude was 103,000 feet. The glide phase was really good to 50 miles. At this point the simulator and airplane are quite different. When the map was made speed brakes were used during the glide to Edwards, however, the speed brakes were not used on the flight. The pull up after peak was really nice and the Hdot came down and held as planned. The pitch, although good, was not as well damped in the airplane as it is on the simulator.

The inertial system functioned well during the flight. The velocity and altitude checkpoints were as noted in the simulator.

Experiment Results

1. Singer Infrared Scanner:

No data were obtained by the experimenter on this flight. A broken wire in the plug of the microdot cable made the system inoperative. This problem was internal to the experiment and not part of the aircraft system.

2. Stability and Control:

At about the 50 mile point, the ASAS and the roll and yaw SAS channels were disengaged. A left and then a right roll was performed using about 6° alpha. The velocity was about 3000 feet per second when the maneuvers started and about 2500 feet per second at the end. The pilot rated these maneuvers at about 3 1/2 to 4 in roll and 3 1/2 in yaw. The flight plan called for 8° alpha for these maneuvers but the pilot never did get up to the desired alpha.

3. SAS Checkout

The SAS system was much nicer this time than the last flight. No problems appeared during the prelaunch checkout and the system was normal for the flight.

Conclusions

Flight 1-56-93 was flown according to the planned profile. No problems were noted with the aircraft systems. The problem with the simulator during the glide has been resolved. The problem was in the X-Y plotter.

Because no data was obtained from the Scanner experiment, the flight has been rescheduled.

Utilization of the available oscillograph recorder channels was 93 percent. The data return realized based on the utilization figure was 92 percent. Approximately 89 percent of the usable data was requested by the experimenters and research engineers.
 
 

Paul L. Chenoweth

Research Division

X-15 Project Engineer