August 13, 1964

MEMORANDUM for Chief, Research Division

Subject: Preliminary Results of X-15 flight 1-49-77

The X-15 flight 1-49-77 was flown June 30, 1964. John B. McKay was the pilot.

A maximum velocity of 4890 ft/sec, and a maximum altitude of 99,600 ft were attained during the flight. The powered portion of the flight was 83 seconds. The total X-15 flight time was 11.44 min.

The launch conditions were as follows:

SAS: Hi-Lo-Hi (8-4-8)

ASAS: "Armed"

BCS: "On"

RAS: "Off"

Auto cutoff: "Off"

Heading vernier: "Standby"

Ventral fin: "Off"

The launch lake was Delamar #1. The launch heading was 214° magnetic.

At drop a maximum b of 7° was observed on the T/M, however, the pilot did not notice such a b. The inertial platform failed at drop causing the pilot to elect to follow an alternate climb profile. This accounts for the lower than planned maximum altitude.

A time history of flight 1-49-77 is shown as figure 2.

B. Mission Objectives
 

This flight was planned and executed for the purpose of continuing the Phase II optical degradation experiment, and, also, as an altitude buildup for the pilot.

Because of the inertial platform failure, the objectives of this flight were not realized.

C. Stability and Control
 

The failure of the inertial platform left the pilot with no roll or pitch reference except the horizon. During the climb portion of the flight, the pilot was required to look outside the airplane for a reference to keep the wings level.

The selection of an alternate profile by the pilot eliminated the need for "BCS" control since dynamic pressure was never less than 250 pounds per square foot. The pilot estimates that approximately two thirds of the flight was spent at this dynamic pressure. Thus, it was required to maintain full back stick (dh = -35°) to maintain a reasonable flight profile. According to pilot McKay, even down to 250 q the airplane felt like it had a lot of aerodynamic control."

The pilot used the q meter as his primary flight instrument. The inertial platform failure did not affect the operation of the q meter.

The rate of descent at landing was 4.3 ft/sec at a touchdown angle of attack of 11°. dh » 6° at main gear touchdown. At nose gear touchdown dh = -12°, but was reduced to -8° after the rebound. The maximum main gear load was 8600 pounds.

D. Handling Qualities
 

The most adverse control task encountered by the pilot during the flight was the pushover from climbout. Pilot ratings for this condition were:

q f y

2 2 2

The pushover maneuver occurred at approximately 46 seconds after launch.

The pilot workload was high during climbout because of the effort required to maintain horizon contact. The difficult pilot task prevented the pilot from manually selecting the correct V/H settings for the KS-25 experiment.
 

The pilot altitude buildup objective was not accomplished because of the alternate climb profile used. As a result, the pilot obtained no experience controlling with the BCS control system.

Since the V/H ratio used for camera adjustments, with the KS-25 camera experiment, was locked at launch conditions, it is doubtful that any usable data were obtained.

The objectives of this flight were not realized, but the techniques used by the pilot to cope with the inertial platform failure will be useful for X-15 flight planning purposes.
 

Aerospace Engineer