Manpower

By late 1961, most of the people involved in the flight program expected it to end in December 1964. This would allow an orderly investigation of the remaining aero-thermo environment, an evaluation of the MH-96 adaptive control system, and a few follow-on experiments. This was in general agreement with the original 1959 Air Force plan, although it consisted of only 100 flights instead of the anticipated 300 flights.11681

A quick look at the labor required to support the X-15 shows that it was not a small program. The following table counts only government employees, not contractors, in "equivalent" man years, meaning that there may have been more people actually supporting the program than shown, but they were doing so on a less than full-time basis. In general, the Air Force figures consisted of

about 55% civil servants and 45% military personnel. The Air Force paid the civilians an average of $8,370 per annum at the ASD and $7,850 at the AFFTC. The FY65 numbers reflect the period between June 1964 and December 1964 (the government fiscal years at the time ran from 1 July to 30 June).[169]

Organization	FY62	FY63	FY64	FY65	Total
ASD	22	16	11	6	55
AFFTC	170	170	170	85	595
NASA-FRC	420	420	420	300	1,560
Total	612	606	601	391

The next table shows the projected propellant and gas requirements at the same point in the program:[170]

Propellant	FY62	FY63	FY64	FY65	Total
Ammonia (gal)	240,000	240,000	240,000	120,000	840,000
Peroxide (lbs)	420,000	420,000	420,000	210,000	1,470,000
Helium (scf)	5,400,000	5,400,000	5,400,000	2,700,000	18,900,000
Liquid nitrogen (tons)	3,500	3,500	3,500	1,750	12,250
Liquid oxygen (tons)	3,560	3,560	3,560	1,780	12,460

The AFFTC also had a separate budget for support of the X-15 program, including supplies

required for the operation of the NB-52s, other support and chase aircraft, propellant analysis and servicing, instrumentation, data processing and acquisition, photo lab, biomedical support, engineering, and test operations.

X-15 FLIGHT RESEARCH PROGRAM

ЧЬЪЕДКОт ДІКНІ. ІЖЕ. ____ COMMIT TEL

JASA ІГШУ :U£AF

SFERFIY —1

The X-15 program was a joint venture between the Air Force, Navy, and NASA, although the Navy generally played the role of a silent partner. The Air Force developed and paid for the airplanes and operated much of the support infrastructure at Edwards AFB, while NASA flew the airplanes (often with military pilots) and performed the maintenance. This 1961 organizational chart delineates the various interrelationships. In all, it worked well. (NASA)

Additional funds were budgeted for travel. Again, these are only Air Force funds; the equivalent NASA funding could not be ascertained.

	FY62	FY63	FY64	FY65	Total
O&M funds	$1,277,403	$1,277,403	$1,277,403	$638,702	$4,470,911
Travel	$65,000	$59,000	$55,000	$27,000	$206,000

The Adaptive Control System Arrives

20 Dyna-Soar. At the time, Honeywell had tested the system on a McDonnell F-101 Voodoo, but many researchers wanted to get some high-performance experience with the system prior to committing it to space flight on the X-20. When an XLR99 ground test almost destroyed X-15-3, the Air Force seized the opportunity to include a prototype MH-96 when North American rebuilt the airplane.171

The MH-96 was the first command augmentation system with an adaptive gain feature that provided invariant aircraft response throughout the flight envelope. The MH-96 used a rate command control mode whereby a given control-stick deflection would produce a specific rate response for the airplane. For example, a 1-inch pitch stick deflection would result in a 5- degrees-per-second pitch rate, regardless of how far the control surfaces had to deflect to produce that rate. This meant that the response would be the same regardless of airplane speed or flight condition.1721

In a conventional aircraft of the period, the pitch rate response would vary with airspeed. In an airplane with a large speed envelope, such as the X-15, a 1-inch stick deflection with a conventional system could result in such disparate responses as almost none at low speed to an extremely violent one at high speed. The MH-96 was an attempt to cure this. However, nothing comes free. With an invariant response, the pilot lost the "feel" for the airplane; for example, the controls did not become sloppy as it approached a stall. The system automatically compensated for everything right up to the point that the airplane stopped flying. The same problem would confront the first fly-by-wire systems.-11731

The rate-command system eliminated the need to modify the trim settings because of configuration changes, such as deploying the landing gear or flaps. The system also masked any shifts in the center of gravity. In many respects, these were good things because they eliminated mundane tasks that otherwise needed to be accomplished by a pilot who already had his hands full of rocket plane. On the other hand, they eliminated many of the normal cues the pilots used to confirm that certain things had happened, such as the trim change after the landing gear deployed. It took an open mind-and some experience-to get comfortable flying the MH-96.-11741

The MH-96 was potentially superior to the basic flight-control system installed in the other two airplanes, for a couple of reasons. The first was that it was more redundant than the SAS (even after the ASAS was installed), which eliminated many of the concerns of flying to high altitudes. Also, the MH-96 blended the ballistic controls and the aerodynamic controls together beginning at 90,000 feet. The pilot moved the same stick regardless of altitude and the MH-96 decided which controls were appropriate to command the airplane. The MH-96 also offered a few autopilot modes (such as roll hold, pitch-attitude hold, and angle-of-attack hold) that significantly reduced the pilot’s workload during the exit phase.-1751

The system minimized any extraneous aircraft motions by providing much higher damper gains. The pilots appreciated this feature particularly during altitude flights, and X-15-3 was designated the primary airplane for altitude flights. Neil Armstrong had been heavily involved in the development and evaluation of the MH-96 and made the first four evaluation flights with the system.

North American moved the rebuilt X-15-3 from Inglewood to Edwards on 15 June 1961, and finally delivered the airplane, along with the XLR99 and MH-96, to the government on 30 September. After various ground tests were completed, Neil Armstrong attempted to take the airplane for its first flight on 19 December 1961, but a problem with the XLR99 resulted in an abort. The flight (3-1-2) successfully launched the next day, with additional flights on 17 January

and 5 April 1962. As it turned out, the MH-96 worked remarkably well, but Armstrong and others realized the system would require a considerable period of evaluation before researchers could thoroughly understand it. The MH-96 provided good service to the X-15 program until a fateful day in 1967.-176