X-15 OPERATIONS FLIGHT REPORT

FLIGHT NO: 3-58-87 DATE OF REPORT: 5-3-67

PILOT: William H. Dana DATE OF FLIGHT: 4-26-67

CARRIER AIRCRAFT: B-52 #008 LAUNCH LAKE: Silver

ENGINE NO: S/N 103 APU #1 19AN APU #2 25AN

PURPOSE OF FLIGHT: 1. PCM System Checkout

2. Coldwall Heat Transfer
3. Step Panel Heat Transfer
4. Boost Guidance Checkout
5. Tip Pod Accelerometer
6. Sonic Boom Study
7. Horizontal Tail Loads

I. Discussion of Previous Operations A. A major configuration change was accomplished, namely the instrumentation system conversion to PCM. This is discussed in Section III. The aircraft crew, particularly the instrumentation crew, did a fine job with superior effort in getting the aircraft ready within a week of the original schedule date which was set last January. It is to be remembered that many things were added (i.e., longitudinal accelerometer, Millikan camera, boost guidance display wiring, nose gear strain gage wires routing to J-panels, Phase 1 horizontal tail loads and T/C's retained, and conversion of T/C's on inertial systems to thermistors) which were not included in the original schedule. II. Aircraft Configuration Changes A. The tip-pods were ballasted to 96.2 pounds at the aft C.G. limit for the tip-pod flutter analysis. The JPL experiment was left in to evaluate the data recording and system noise, although it was not planned for the package to be extended. Micrometeorite was left in as ballast without a collector.

B. The main landing gear extension loads beef-up was installed. This involved changing to the honeycomb skid bungee configuration and stronger drag links and snubbers with attendant structural beef-up.

C. The blowoff panel and coldwall heat transfer panel modification to the rudder was accomplished by NAA. The rudder from X-15-1 was installed in December for a flight attempt, but was returned to ship 1 when the flight was canceled. The cooling system for the skin friction gage was reinstalled on the modified rudder.

D. An ablative coated LH horizontal was installed in December 1966, for a flight attempt, but was returned to ship 1 when the flight was canceled for wet lakebeds.

E. APU S/N 23AN was removed for 15 hour inspection, S/N 25AN was installed.

F. The sky brightness experiment was removed from the LH aft pod position and replaced by the JPL solar spectrometer.

G. The radio antenna was found to be faulty and was replaced. This explains the radio problems on flight 3-57-86.

H. The left-hand inner canopy glass was changed due to a broken wire on the heater.

I. Experiment 4 was installed for a December flight, and removed when the flight was canceled.

J. APU S/N 13AN was replaced by 19AN for a failed turbine seal.

K. On December 27, 1966, the modification for PCM was started. (Reference item III A). The decision to start rather than wait for the scheduled date in January was based on wet lakebed conditions and requirement for a flight in April 1967 on the coldwall heat transfer experiment.

L. The digital timer was installed, replacing the NASA timer.

M. An adapter was made to utilize a Millikan camera in the RH upper bugeye position to photograph the blow-off panel. The camera will be actuated by a switch on the speed brakes at a frame rate of 400 fps.

N. A longitudinal accelerometer was added to the pilots panel.

O. The Alert computer was returned from Honeywell and installed. It was programmed for boost guidance with appropriate changes in switching on the instrument panel.

P. The nose strut was sent to NAA for strain gaging, and reinstalled after calibration at NAA. This was to investigate loads relative to the two struts bent on ship 1. Meanwhile, to reduce loads, only 10 ply tires, magnesium wheels and aluminum rims will be flown.

Q. Engine S/N 110 was removed in late December 1966 for access. Engine S/N 103 was installed on April 4, 1967.

III. Instrument Configuration Changes A. The instrumentation system was converted to PCM. The entire existing systems, TM and internal recording, were removed with the exception of the airspeed/altitude recorder in the nose and the Parsons tape recorder. The elevator bay wiring was removed to the J panels and rewired to the PCM system. The PCM system consists of six subcommutators, a prime commutator, transmitter and power amplifier, and a digital tape recorder. Various peripheral equipment such as J-boxes and demodulators, was installed along with a new strain gage control box in the engine compartment and some new sensors.

B. The digital timer was installed.

IV. Preflight Events A. APU/BCS runs were accomplished on December 8, 1966. The turbine seal failed on the #l APU and the unit was replaced. (Reference item II J). The run was not repeated as the PCM modification was started.

B. The PCM modification was started on December 27, 1966.

C. Engine, APU, and BCS runs were accomplished on April 10, 1967. The JPL tip pod experiment was operated during the APU run.

D. Engine functional was accomplished on April 15, 1967. The functional was repeated while mated on April 21.

E. An end-to-end PCM demonstration was accomplished on April 17.

F. The aircraft was weighed in a ready-to-mate condition on April 20, 13,930 pounds. The aircraft was mated on second shift to B-52 #008 when the bomber was ready.

G. Flight was canceled on April 21 for weather. Flight was not attempted on April 24 due to no C-130 or helicopter support, or on April 25 due to B-70 flight.

V. Flight Events A. Servicing was accomplished with no problems.

B. After APU start, the ball nose did not immediately start to function. After about 8 minutes of APU operation the ball started functioning and worked properly from that time on. It is felt that a freezing problem existed either from moisture around the ball or of the hydraulic fluid.

C. Due to the above and uncertainties of the status of the checklist, a launch was not made at the first pump idle. As there was sufficient pressurization gases on board the aircraft, a 10 minute turn was made.

D. After the second pump idle launch and good ignition of main chamber a fuel line low light was called out by the pilot. As the fuel pump inlet pressure indicator was reading low, the engine was shut down and a landing made at Silver Lake.

Postflight checks of the aircraft and data revealed that the fuel pump inlet pressure sensing line froze after the first pump run. There is a short section of sensing line which is also common to the low light pressure switch; therefore, there appears to be no problem with the engine or aircraft but rather a freezing of the sensing system causing duplication of erroneous presentation. Rerouting of this line away from the Lox prime line is being investigated.

E. The nose strut was checked after the landing and found to be undamaged.

Approved By: Prepared by:

Perry V. Row Vincent N. Capasso

X-15 Senior Project Engineer X-15 Project Engineer