Category X-15 EXTENDING THE FRONTIERS OF FLIGHT

Although 15 pilots were assigned to the X-15 program, only 12 of them actually flew the airplane. Al White was the backup pilot for Scott Crossfield and never needed to take over. Iven Kincheloe was the initial Air Force project pilot, but he died in an accident before the first airplane was delivered. NASA reassigned John Manke to the lifting-body program after the loss of X-15-3, before he was able to fly the X-15. In each of the four groups of government pilots, an equal number came from the Air Force and NASA. The following table shows the pilots in the order of their selection by the program:

There were also plans to allow four Dyna-Soar pilots to fly the X-15 before Robert McNamara canceled that program, and some sources have indicated that Jacqueline Cochran attempted to get permission to fly the X-15 to set the women’s speed and altitude records.-11

Hartley A. Soule was born on 19 August 1904 in New York City. He received a bachelor of science degree in mechanical engineering from New York University in 1927 and joined the staff at Langley in October 1927 after working briefly for the Fairchild Airplane Company in Long Island. Soule concentrated his research on stability and control, and became chief of the Stability Research Division in 1943. He became assistant chief of research in 1947 and assistant director of Langley in August 1952.

Soule was a coinventor of the stability wind tunnel and directed the construction of three other wind tunnels at Langley. He pioneered the use of computing machinery for analytical and data reduction. He was also instrumental in establishing the Pilotless Aircraft Research Division at Wallops Island. Soule became chairman of the Interlaboratory Research Airplane Projects Panel, and in that role he directed research on the Bell X-1 program and was instrumental in managing the early years of the X-15 program. Later he became project director for the Mercury worldwide tracking and ground instrumentation system. Soule retired from NASA on 16 February 1962 and passed away in 1988.

In its own way, the X-15 program was "politically correct," even if the term did not yet exist. Paul Bikle had decided that a NASA pilot should make the first government X-15 flight, but he would later give the honor of performing the first government XLR99 flight to an Air Force pilot. The initial piloting duties were split evenly between one NASA pilot and one Air Force pilot. It seemed only fitting, therefore, that the third government pilot to qualify in the X-15 should be from the Navy.

Forrest Petersen checked out in the airplane while Joe Walker and Bob White conducted the envelope-expansion phase with the XLR11 engine. Like all of the early pilot familiarization flights, Petersen’s first flight would be low and slow, if that describes Mach 2 and 50,000 feet. The flight plan showed Petersen launching over Palmdale, heading toward Boron, turning left to fly back toward Mojave, and making another left turn toward Edwards. The launch went well, but as the airplane approached Boron the upper engine began to fail; soon it stopped altogether. Petersen reported that he "believed erroneously that the lower engine was still running, but the inability to hold altitude, and airspeed variations from values expected for single engine operation forced the pilot to the inevitable conclusion that both engines were shut down." Milt Thompson, who was NASA-1 for the flight, advised Petersen to head directly for Rogers Dry Lake. Petersen arrived at high key with only 25,000 feet altitude, much lower than desired, and Joe Walker tucked a chase plane into formation and coached Petersen through a tight turn onto final. The landing was almost perfect, and Petersen handled the entire incident with his usual aplomb. Petersen’s final report was understated: "Nothing during the flight surprised the pilot with the exception of early engine shutdown." The only Navy pilot was an excellent addition to the team.-1106

It was time for Crossfield to go back to work with the ultimate engine. The first flight attempt of X-15-2 with the XLR99 was on 13 October 1960, but a peroxide leak in the no. 2 APU ended the day prior to launch. Just to show how many things can go wrong on a single flight, there was also liquid-oxygen impingement on the aft fuselage during the prime cycle, manifold pressure fluctuations during engine turbopump operation, and fuel-tank pressure fluctuations during the jettison cycle. Two weeks later, Crossfield again entered the cockpit with the goal of making the first XLR99 flight. More problems with the no. 2 APU forced an abort.

On 15 November 1960, everything went right and Crossfield made the first flight (2-10-21) of X – 15-2 powered by the XLR99. The primary flight objective was to demonstrate engine operation at 50% thrust. The launch was at Mach 0.83 and 46,000 feet, and the X-15 managed to climb to 81,200 feet and Mach 2.97 using somewhat less than half the available power. The second XLR99 flight (2-11-22) tested the engine’s restart and throttling capability. Crossfield made the flight on 22 November, again using the second X-15. During the post-flight inspection of the aircraft and its engine, engineers found that, like most of the ground-test engines, the XLR99 was beginning to shed some of the Rokide coating on the exhaust nozzle.[107]

Despite being fast-paced, the X-15 program was never reckless. As North American prepared X – 15-2 for its next flight during December 1960, AFFTC commander Brigadier General John Carpenter heard rumors about the Rokide coating and called a meeting to discuss the matter. Representatives from the Air Force, NASA, North American, and Reaction Motors were present.

Each gave his opinion, which was that it appeared safe to continue. Carpenter dismissed the meeting but asked Scott Crossfield and Harrison Storms to stay. During this session he questioned Crossfield on his feelings about making the flight given the condition of the engine. Scott did not show any concern and indicated he was willing to go ahead with the flight. Carpenter excused Crossfield but asked Storms to stay.-1108

Storms recalled, "When we were alone, General Carpenter asked my opinion. I told him that earlier this day on my arrival at Edwards that I had inspected the thrust chamber in question and did not have any great concerns. Yes, some of the insulation was gone, but not to any great extent and the individual areas were small. It had not all been lost in one area, but the loss was fairly evenly well distributed over the entire area. Further, it certainly had not caused any negative comments from the manufacturer or their test engineers. The General’s comment was, ‘Very well, we will make it a joint decision to proceed with the flight.’ … Seriously, there is a point to be made here. That is, there is a very fine line between stopping progress and being reckless. That the necessary ingredient in this situation of solving a sticky problem is attitude and approach. The answer, in my opinion, is what I refer to as ‘thoughtful courage.’ If you don’t have that, you will very easily fall into the habit of ‘fearful safety’ and end up with a very long and tedious-type solution at the hands of some committee. This can very well end up giving a test program a disease commonly referred to as ‘cancelitis,’ which results in little or no progress." It was an excellent observation, and is as applicable today as it was in 1960.[109]

With the blessing of Carpenter and Storms, North American conducted the third and final XLR99 demonstration flight (2-12-23) using X-15-2 on 6 December 1960. Crossfield successfully accomplished the engine-throttling, shutdown, and restart objectives. This marked the last X-15 flight for North American Aviation and Scott Crossfield. The job of flying the X-15 was now totally in the hands of the government test pilots. Crossfield, the engineer, transferred to testing the Hound Dog cruise missile and then to the Apollo program.-1110

After this flight, the program established a work schedule that would allow an early XLR99 flight with a government pilot using North American maintenance personnel. Bob White would make the flight as early as 21 December 1960, assuming North American could accomplish the necessary maintenance work in time. This included replacing the engine, which had suffered excessive chamber coating loss; installing redesigned canopy hooks and a reinforced vertical stabilizer; rearranging the alternate airspeed system; and relocating the ammonia tank helium pressure regulator into the fixed portion of the upper vertical. The company made good progress until engineers found a pinhole leak in the chamber throat of the replacement engine during a ground run. Although Reaction Motors considered the leak acceptable, it became increasingly worse during a subsequent test. Since a spare XLR99 was not available, the program canceled the flight and established a schedule to deliver the aircraft to the government prior to another flight. As a result, North American formally delivered X-15-2 to the Air Force and turned the airplane over to NASA on 7 February 1961. On the same day, X-15-1 was returned to the North American plant for conversion to the XLR99, having completed the last XLR11 flight (1-21-36) of the program the day before with Bob White at the controls.-111

The first two years of the flight program showed five major reasons for flight cancellations: problems with the APUs and their fuel system, XLR11 problems, propellant system (less engine) difficulties, weather, and heating and ventilation troubles. When the ultimate engine came on line, the top five reasons changed slightly to XLR99 problems, propulsion system (less engine) difficulties, miscellaneous, problems with the APU and its fuel system, and stable platform failures. It was not surprising that the engine became a major source of delays, since the XLR99 was a major leap forward in rocket engine technology and growing pains were to be expected. Many of the propulsion-system problems were a direct result of the XLR99, such as some plastic seal materials being incompatible with anhydrous ammonia. Although the XLR99 was performing satisfactorily in flight, by the end of December 1960, maintenance personnel had discovered ammonia leaks in the thrust chambers of three engines. Reaction Motors dispatched technicians to Edwards to correct the problems while the Air Force, NASA, North American, and Reaction Motors all looked for a cause.112

Major Robert M. White flew the last XLR11 flight of the program (1-21-36) on 7 February 1961. This was the fastest XLR11 flight, reaching 2,275 mph and Mach 3.50. Six months earlier White had gone to 136,500 feet using the XLR11s. Bob White holds the distinction of being the first man to fly Mach 3, Mach 4, Mach 5, and Mach 6, and the first pilot to fly to 200,000 feet and 300,000 feet, all in the X-15. (NASA)

From the beginning of the X-15 flight program in 1959 until the end of 1960, seven pilots had made 31 flights with the first two airplanes. The NB-52s had carried the two X-15s 55 times, including two scheduled captive flights and 22 aborted launch attempts. However, X-15-1 was experiencing an odd problem. When the pilot started the APU, the hydraulic pressure was either slow in coming up or dropped off out of limits when he moved the control surfaces. The solution to the problem was found after researchers placed additional instrumentation on the hydraulic system. The bootstrap line that pressurized the hydraulic reservoir was freezing, causing a flow restriction or stoppage. Under these conditions the hydraulic pump would cavitate, resulting in little or no pressure rise. The apparent cause of this problem was the addition of a liquid-nitrogen line to cool the stable platform. Since North American had installed the nitrogen line adjacent to the hydraulic lines, it caused the Orinite hydraulic oil to freeze. The solution was to add electric heaters to the affected hydraulic lines, since there was not enough room in the side tunnel to separate the lines sufficiently to prevent the problem.

Some problems defied all efforts to fix them. For example, North American tested the APU and its fuel system for many hours on an exact replica of the airplane installation. Yet, over the course of the program, the APUs caused more schedule delays and cancellations than any other system. One of the major problems was a critical pressure switch. Although the switch had been thoroughly (and correctly) qualified by the vendor, the program had to replace it by the dozen. Even with improvements, the switch continued to be a problem.-113

Paul Bikle closed the year by saying that he was generally pleased with the progress made: "The data coverage within this envelope has been fairly complete in the areas of performance, flight dynamics, control, and structural loads, but somewhat limited in structural heating due to the low heating rates encountered." Bikle cautioned, however, that the short duration and transient nature of each flight had generally precluded the acquisition of extensive or systematic measurements under selected flight conditions, as was possible with conventionally powered aircraft.-114-

On 13 October 1960, the government established the Aeronautics and Astronautics Coordinating Board (AACB) to coordinate various activities between the Department of Defense and NASA. The deputy administrator of NASA and the assistant secretary of the DDR&E served as cochairmen of the AACB; initially this meant Hugh Dryden and Herbert F. York, respectively. In an indirect way, the Research Airplane Committee that was created in 1954 to manage the X-15 program fell under the auspices of the AACB. However, given that the X-15 program existed prior to the creation of the AACB, the board had little direct impact on the program. The Research Airplane Committee continued to function much as it always had until sometime in 1965.[375]

The AACB Aeronautics Panel began discussing the issue of continued funding for the X-15 in early 1966. Charles W. Harper from NASA made a good case for continuing Air Force funding for the X-15 since both the HRE and delta-wing projects were of potential value to the Air Force as well as to NASA. Both projects were part of a joint national hypersonics program organized in May 1965 by John Becker from NASA Langley and R. E. Supp from the Air Force Systems Command. Becker and Supp made a presentation to the Aeronautics Panel on 13 June 1966 showing that the HRE and delta-wing projects would be the principal users of the X-15 after the end of 1967, although a number of other experiments also continued. After a brief discussion, the Aeronautics Panel endorsed these projects and recommended that the AACB develop a cost-sharing plan that would allow the X-15 program to continue.-1376

The next meeting of the AACB on 5 July 1966, in fact, would influence the X-15 program greatly, but not the way the Aeronautics Panel had expected. Instead, the meeting essentially defined the date the X-15 program would end. In rejecting the recommendation of the Aeronautics Panel, the AACB indicated that the two most important approved Air Force experiments (20 and 24) would conclude at the end of 1967, and the AACB saw little need for continued Air Force support of the program past that date. Beginning on 1 January 1968, the program would become the

responsibility of NASA exclusively.13771

Rather quickly, however, it became apparent that the planned completion of the two Air Force experiments would run well into 1968. Consequently, at the 24 August 1967 meeting of the AACB, the participants attempted to work out some compromise that would allow the X-15 program to continue. The agreement changed little on the surface. From a monetary perspective, NASA agreed to begin funding the sustaining engineering contracts the Air Force maintained with North American, Reaction Motors, and the other original contractors. Both agencies concluded it was easier to allow the Air Force contracts to continue than to terminate them and restart them as NASA contracts. Instead, NASA would reimburse the Air Force for the cost of the contracts. The FRC agreed to continue its maintenance responsibilities for the airplanes and most of their systems, while the AFFTC agreed to continue maintenance of the carrier aircraft, rocket engines, and other systems it had been responsible for.13781

The largest change was the dissolution of the Research Airplane Committee that had guided the X-15 program since the signing of the original 1954 memorandum of understanding. The X-15 Joint Operations Committee and the X-15 Joint Program Coordinating Committee that had reported to the Research Airplane Committee would now report to the Aeronautics Panel of the AACB.13791

All in attendance agreed the X-15 program would continue at least through the middle of 1968. How long the program would continue after that depended upon the status of the Air Force experiments and the NASA funding situation. On 26 October 1967, the Air Force and NASA signed a new memorandum of understanding, replacing the original 1954 MoU that had governed the X – 15 program for 13 years. Charles W. Harper (NASA deputy associate administrator for the Office of Advanced Research and Technology) worked with Thomas C. Muse (assistant director OSD,

DDR&E) to get the new agreement signed by Dr. John S. Foster (director, DDR&E) and Dr. Robert C. Seamans, Jr. (NASA deputy administrator). The new MoU reestablished Air Force responsibility for X-15 costs, and spelled out the specific responsibilities of the two organizations. However, instead of ending with a statement of national priority, the new MoU contained the ominous proviso, "funds permitting." To most NASA managers, this meant that NASA would still have to face up to the total funding of the X-15 program as soon as the last two Air Force experiments ended.13801

Charles Harper and his boss at the Office of Advanced Research and Technology, Mac Adams, made one last effort to find funds for the program during the fall of 1967. They solicited help from the NASA Office of Manned Spaceflight (OMSF) because both the HRE and the delta-wing projects would produce new technology for the Space Shuttle. The attempt failed, however, because the OMSF was already having trouble promoting the space shuttle concept and did not want to add to its problems by supporting a potentially attractive-sounding alternative.13811

The accident involving Mike Adams underscored the concerns long expressed privately by Paul Bikle and others regarding the high costs and risks associated with extending the X-15 program. In the discussions that followed the accident, Bikle convincingly speculated on the enormous costs of the HRE flight program involving years of delay in getting started, malfunctions, and repairs. In December 1967, the Air Force and NASA both agreed to abandon the HRE flight program and to terminate the X-15 program at the end of 1968. On 13 March 1968 the Air Force announced that it would allow its X-15 funding to expire at the end of the year, but that it would continue to support flight tests to the "completion of Air Force IR [241 and WTR [201 experiments."13821

NASA allocated $1,500,000 for X-15 operations in FY68, with the Air Force contributing another $777,000. It appeared the program could save $150,000 by not returning X-15A-2 to flight status, and by flying a minimum number of other flights using X-15-1. The first six months of 1969 would require approximately $400,000 to catalog and dispose of spare parts, ground equipment, and prepare the two remaining vehicles for shipment to museums. The X-15 program would transfer some parts and ground equipment to other programs, and scrap the remainder.-138^

1968 FLIGHT PERIOD

The X-15 program would only fly another eight missions. During 1968, Bill Dana and Pete Knight took turns flying X-15-1. However, even within NASA, not everyone was certain the flights were worth the risk and $600,000 cost.-1384

X-15A-2 returned to Edwards on 27 June 1968. On 15 July, a series of nondestructive load and thermal tests began on the instrumented right wing in the FRC High Temperature Loads Calibration Laboratory. The airplane would remain grounded forever.-1385

Nevertheless, during the first part of 1968 the AFFTC and FRC worked together to see if there was sufficient interest to extend the program. By October 1968, they had surveyed the current users of the airplane and potential future researchers, and found some programs that could likely benefit from the X-15 being available. Two of the Air Force experiments (20 and 24) might need more time, especially the WTR launch monitoring, which would require extraordinary luck to get the X-15-1 and an ICBM in the air at the same moment. The groups investigating the impingement heating on the last flight of X-15A-2 also would have been happy to keep that airplane flying, since they had little other means of conducting experiments to understand the problem.-1385

Technically, NASA had already canceled the HRE flight program, but most everybody acknowledged that the ramjet experiments could also benefit from flight testing. However, NASA was a bit gun-shy after the bad experience on X-15A-2, and the flight ramjet development was running well behind schedule. Several other programs within the defense community were studying advanced propulsion concepts (ramjets, turbo-ramjets, or similar engines), and most of them potentially could have used the X-15 as a platform if it was still flying. There was even some talk about reviving the delta-wing concept that had been canceled after the loss of X-15-3.-1387

Despite this minor interest, in the end the AFFTC report concluded that "no known overpowering technological benefits will be lost if [the X-15] program ends on 31 December 1968." It noted that there was a firm requirement for the completion of the two Air Force experiments, and that "many USAF/USN technological activities [were] underway or planned for the Mach 4-6 regime," but the report failed to identify any specific requirements for the use of the small black airplanes.

It noted that "the future value of the X-15 as a hypersonic test capability should be more evident by mid-late 1969" and that the "option to use X-15 resources after 1969 should be protected."[388]

Bill Dana completed the 199th—and as it turned out the last-X-15 flight, reaching Mach 5.38 and 255,000 feet on 24 October 1968. The program made 10 attempts to launch the 200th flight, but maintenance and weather problems forced cancellation every time. The attempt on 12 December actually got airborne (1-A-142), but the X-15 inertial system failed before launch. On 20 December 1968, things looked dismal, but everybody geared up for an attempt. Bill Dana began taxiing an F-104 for a weather flight, but John Manke noted that snow was falling-at Edwards! Manke recalled Dana before he took off and canceled the mission. Later that afternoon, technicians at the FRC demated X-15-1 from the NB-52A for the last time. After nearly 10 years of flight operations, the X-15 program ended.[389]

By the end of the program, the two remaining airplanes were tired. In absolute terms, they were still young airframes-just 10 years old and with only about 10 flight hours each. The total free – flight time for all three airplanes was only 30 hours, 14 minutes, and 57 seconds. Even counting all the time spent under the wing of the two NB-52s, the total barely reached 400 hours. Despite early Air Force estimates of 300-500 flights, that had not been the original idea. Bob Hoey remembers asking North American project aerodynamicist Edwin W. "Bill" Johnston how long North American expected the airplanes to last. Johnston responded that the company had "expected that each airplane would only see 5 or 6 exposures to the design missions [i. e., Mach 6 or 250,000 feet]." They did much better.[390]

The X-15s accumulated much more flight time than most of the high-performance X-planes, and the environment they flew in was certainly extreme. They frequently experienced dynamic pressures as high as 2,000 psf, and as low as (essentially) 0 psf. The airframes endured accelerations ranging from -2.5 g to over +8.0 g. Temperatures varied from -245°F to over 1,200°F. It had been a rough life.

In addition, NASA tested the airplanes-a lot. After each flight, NASA removed, disassembled, and thoroughly checked almost every system. Then each was reinstalled and tested some more. If the technicians noted any anomalies they made the appropriate repairs and retested. Milt Thompson wrote, "[M]y personal opinion is that we wore the airplanes out testing them in preparation for flight." The space shuttle would suffer much the same fate.[391]

It is interesting to note that although the X-15 is generally considered a Mach 6 aircraft, only two of the three airplanes ever exceeded Mach 6, and then only four times. On the other hand, 108 flights exceeded Mach 5 (not including the four Mach 6 flights), accumulating 1 hour and 25 minutes of hypersonic flight. At the other end of the spectrum, only two flights were not supersonic (one of these was the first glide flight), and 14 others did not exceed Mach 2. It was a fast airplane. Similarly, there were only four flights above 300,000 feet (all by X-15-3), but only the initial glide flight was below 40,000 feet.[392]

During the summer of 1961, the Air Force ASD and NASA Headquarters proposed a new initiative to use the X-15 to carry scientific experiments that were unforeseen when John Becker conceived the aircraft in 1954. For instance, researchers at the FRC wanted to use the X-15 to carry high – altitude experiments for the proposed Orbiting Astronomical Observatory, while others wanted to carry a hypersonic ramjet for air-breathing propulsion studies. Of particular interest was the ability of the X-15 to carry experiments above the attenuating effects of the atmosphere.-180

On 15 August 1961, the Research Airplane Committee signed a memorandum of understanding (MoU) to form the X-15 Joint Program Coordinating Committee with Air Force and NASA representatives as cochairmen. The MoU included the following statements:^

1. The X-15 is a program of national importance undertaken in accordance with the terms of a Memorandum of Understanding dated 23 December 1954 among the Department of the Air Force, Department of the Navy, and the NACA (now the NASA). It is recognized that the X-15 flight research program will soon complete the initial phase of flight research.

2. It is necessary that an optimum follow-on research program be formulated to insure maximum benefit to the national objectives accrue from the research program.

3. An X-15 Joint Program Coordinating Committee with the NASA and USAF representatives in the role of co-chairman is hereby assigned the responsibility to formulate the optimum follow-on research program for the X-15. The program will be transmitted to the participating departments through normal channels and will be jointly reviewed by HQ [Headquarters] USAF and the NASA RAPL [Research Airplane Project Leader (Hartley Soule)] prior to submittal to the Research Airplane Committee.

4. The X-15 Joint Program Coordinating Committee is recognized by the Research Airplane Committee as the focal point of the subject project for continuous evaluation and formulation of program objectives for approval of the Research Airplane Committee. The establishment of a Joint Program Coordinating Committee is not intended to change the functions or responsibility of the NASA FRC-AFFTC Flight Test Steering Committee [later called the X-15 Joint Operations Committee].

The initial cochairs of the X-15 Joint Program Coordinating Committee were Lieutenant Colonel E. F. Pezda, chief of the X-15 project office at the ASD, and Paul Bikle from the FRC. The committee held its first meeting on 23-25 August 1961, during which the scientific community suggested over 40 experiments as suitable candidates. Hartley Soule and John Stack proposed separating the experiments into four groups.-182!

• Group I consisted of desirable experiments that did not require special aircraft modifications or special flight profiles. It was also initially limited to experiments that could be prepared within three to four months of approval.

• Group II consisted of experiments that required "appreciable aircraft modifications" or a relatively long lead time for preparation.

• Group III was a holding area for experiments that were not well defined.

• Group IV included experiments that supported other programs (such as the Dyna-Soar or Apollo).

By November 1961, a long list of possible experiments had been divided among the first three groups; the fourth group was not populated pending coordination with other programs. The X-15 Joint Program Coordinating Committee met four more times (9 May 1962, 7-8 January 1963, 18 September 1963, and 16 October 1963), and initially forwarded proposals for 28 experiments to the Research Airplane Committee for approval. The committee subsequently approved at least three other proposals for implementation, and it appears that several others were assigned experiment numbers; however, the nature or purpose of some of them is unknown.-183!

Mike Adams flew the X-15 for 13 months from 6 October 1966 until 15 November 1967, making seven flights. All of these were with the XLR99 engine and he reached Mach 5.59, a maximum speed of 3,822 mph, and an altitude of 266,000 feet. Adams died on flight 3-65-97.

Michael James Adams was born on 5 May 1930 in Sacramento, California, and enlisted in the Air Force on 22 November 1950 after graduating from Sacramento Junior College. Adams earned his pilot’s wings and commission on 25 October 1952 at Webb AFB, Texas. He served as a fighter- bomber pilot in Korea, flying 49 missions during four months of combat service. For 30 months Adams served with the 613th Fighter-Bomber Squadron at England AFB, Louisiana, and for six months he served rotational duty at Chaumont Air Base in France.-12

In 1958 Adams received a bachelor of science degree in aeronautical engineering from Oklahoma University. In 1962, after 18 months of astronautics studies at the Massachusetts Institute of Technology (MIT), Adams attended the Experimental Test Pilot School at Edwards, where he won the Honts Trophy for being the best in his class. He subsequently attended the Aerospace Research Pilot School (ARPS), graduating with honors on 20 December 1963, and was assigned to the Manned Spacecraft Operations Division at Edwards AFB in the Manned Orbiting Laboratory program. During this time he was one of four Edwards aerospace research pilots to participate in a five-month series of NASA Moon-landing practice tests conducted by the Martin Company in Baltimore, Maryland.

In July 1966 Adams came to the X-15 program with 3,940 hours of total flight time, including 2,505 hours in single-engine jets (primarily the F-80, F-84F, F-86, F-104, F-106, and T-33) and an additional 477 hours in multiengine jets (primarily the F-5, T-38, and F-101). Unfortunately, Mike died during flight 3-65-97 on 15 November 1967, and The Air Force posthumously awarded Adams an astronaut rating for his last flight in X-15-3, which had attained an altitude of 266,000 feet (50.38 miles). In 1991, the Astronaut Memorial at the Kennedy Space Center in Florida added Adams to its list of astronauts who had been killed in the line of duty.

Harrison A. "Stormy" Storms, Jr., was born in 1915 in Chicago, Illinois. He attended Northwestern University and graduated with a master of science degree in mechanical engineering in 1938. Storms then attended the California Institute of Technology (Caltech), earning a master of science degree in aeronautical engineering. At Caltech he studied under Theodore von Karman and worked in the wind tunnels at the Guggenheim Aeronautical Laboratory (GALCIT).

In 1940, Storms went to work on the P-51 Mustang at North American Aviation, where he developed a reputation as an expert on wind flow and high-speed aircraft. He subsequently worked on the F-86 and F-100 jet fighters. In 1957, Storms became vice president and chief engineer of the Los Angeles Division, where he led the development of the XB-70 bomber. In 1959, he became vice president for program development, in charge of the development of the Apollo spacecraft. Between 1961 and 1967, he served as president of the Space and Information Systems Division, an organization that peaked at more than 35,000 employees in 1965. Storms took the brunt of the blame for the Apollo 1 fire and stepped out of the public eye, although he continued as a company vice president. The AIAA honored him with the 1970 Aircraft Design Award. Storms died in Los Angles in July 1992.[25]

In mid-1955 the Soviet Union and the United States separately announced intentions to orbit satellites as part of the 1957 International Geophysical Year. Nevertheless, when the Soviet Union launched the first Earth artificial satellite-Sputnik (later called Sputnik 1)-on 4 October 1957, the event created a stir among the popular press. The seeming lack of response by President Dwight D. Eisenhower further antagonized the fourth estate and soon the American people as well. However, it was the 1,100-pound Sputnik 2 that ultimately caused the administration to take action, since it graphically portrayed the capability of Soviet launch vehicles and, directly, their ICBM program.

The Soviet achievements damaged American scientific and technological prestige, and the satellite was widely regarded as a threat to national security. Robert Gilruth later wrote, "I can recall watching the sunlight reflecting off the Sputnik 1 carrier rocket as it passed over my home on the Chesapeake Bay, Virginia. It put a new sense of value and urgency on the things we had been doing."1130!

Over a year before, the Air Force had begun Project HYWARDS (Hypersonic Weapon and Research & Development Supporting System) to design a successor to the X-15. Researchers considered this round III of the research airplane program. Round I had been the X-1 and D-558 series, while round II consisted of the X-15. The goal of round III was to design a vehicle capable of achieving at least Mach 12 and perhaps as much as Mach 18. HYWARDS is outside the scope of this history, but it created an enormous debate between researchers at Ames and Langley, and between the NACA and the Air Force. The Air Force soon combined HYWARDS with the remaining work on BoMi/RoBo and other projects into the Boeing X-20 Dyna-Soar program. Ultimately, the experimental research conducted for HYWARDS and Dyna-Soar, combined with the flight results from X-15, formed the technical foundation for the development of a space shuttle.

Although HYWARDS was the next logical step in the progressive effort to fly a man into space, other programs, such as Project 7969, were under way concurrently. The organizations that proposed these programs intended then to put a man into space as soon as possible, mainly as a publicity ploy, and offered little in the way of a long-term solution to space flight. The X-15 figured into some of these programs, and at least two proposals for orbital X-15s were made during 1957 and 1958 (see the "X-15B" section for more details).

In the meantime, the NACA Executive Committee met in its regular annual session on 10 October 1957, less than a week after the launch of Sputnik. Interestingly, the committee did not discuss the Soviet satellite at any length. But the NACA Committee on Aerodynamics met on 18-20 November 1957 aboard the aircraft carrier USS Forrestal (CVA-59) and paid a great deal of attention to crafting a response to Sputnik. The committee noted that "[t]he big question to be answered now is how can these views [on accelerating space research] be put across to the NACA and to the Government in order that the NACA be recognized as the national research agency in this field, and be provided with the necessary funds… the NACA should act now to avoid being ruled out of the field of space flight research." The committee suggested highlighting the hypersonics program in general and the X-15 program specifically in order to make that case.-1131!

This threw a great deal more attention onto the X-15 program than it was ready for. North American was making good progress with its development effort, but the first airframe was still almost a year away from being completed. The XLR99 engine was much further away.

Nevertheless, the media-and indeed, some within the NACA and military-saw the X-15 as the most promising American response to Sputnik. The North American plant in Inglewood, which was clearly visible from the Los Angeles International Airport, soon sported a huge "Home of X-15" neon sign and articles began to appear in periodicals ranging from popular newsstand magazines to serious industry journals. It was a spotlight the X-15 program was ill prepared to handle.-1132

Nevertheless, the publicity probably made some aspects of the X-15 program somewhat easier, particularly securing funding at a time when the program was seriously over budget. In his essay on the 1961 Collier trophy, W. D. Kay wrote:232

After the launch of Sputnik 1 in 1957, interest in the [X-15] project on the part of the military, political leaders, and the public at large grew rapidly… media coverage of the first flights was the most intense ever seen at Edwards, and even led to some public relations mix-ups between NASA and the Air Force. Once the first Mercury flights were underway, public attention shifted to the events at Cape Canaveral. This might, however, have ultimately worked to the [X-15] program’s benefit. A major contributor to the X-15’s success over the long run was its emphasis on incremental development and its use in highly specialized scientific and technical research. As experience with many later space projects… has shown, the general public tends to lose interest in such "routine" undertakings rather quickly. In short, it appears the X-15 got a needed boost of public fanfare at precisely the right point in its history-the later development and early flight test stage-and then became regarded as a low-key effort worthy of only occasional interest just as it was entering its less "flashy" research phase. These shifts in external perception probably could not have been planned any better.

Scott Crossfield might not completely agree that the program wanted the publicity, especially as he spent too many hours in an uncomfortable MC-2 full-pressure suit in the hot desert sun providing encouragement for the technicians working to get the X-15 ready for its first glide flight. Overall, however, events probably turned out as well as anybody could have expected.

There were a variety of proposals (some legitimate, most not) to use the X-15 to put a man into orbit before the Soviets. However, there was a flaw with all of these ideas: the lack of a suitable booster. The ICBMs then under development had two significant problems. First, none had the "throw weight" to launch a complicated lifting reentry vehicle, be it an X-15 derivative or one of the round III concepts under study at Ames, Langley, or Wright Field. Second, the early ICBMs did not work very well; they tended to blow up.

During the late 1950s and early 1960s, the value of a human pilot and redundant systems in space vehicles was a matter of some controversy. There was, and continues to be, a great debate on the relative merits of piloted vehicles versus automated ones. Because it had many similarities to early spacecraft, the X-15 became the subject of several evaluations and studies to determine whether the general design approach taken concerning redundancy and control were appropriate.-1146!

The AFFTC conducted one of these evaluations during late 1961. The basic approach of the study was to perform a detailed flight-by-flight engineering analysis of each problem or failure that occurred for the 44 free flights, plus an additional 2 captive flights and 30 aborts, made through 1 November 1961. For each problem, researchers assessed the action taken by the pilot or redundant system with regard to its impact on mission success and vehicle recovery. The researchers then compared the results with those that would be obtained on a hypothetical unmanned and/or non-redundant X-15.147

The researchers strictly adhered to several important ground rules during the evaluation and documented every problem, whether it seemed significant or not. The researchers conservatively assessed the benefits of the pilot-in-the-loop and redundancy to avoid any glorification of either of these elements.-148! The researchers also attempted to minimize conjecture, especially in the case of the hypothetical unmanned X-15. For instance, the researchers did not credit a pilot with detection or corrective action that some other element would definitely have provided in his absence. Likewise, he was not marked down for detrimental effects that would have been the same without a pilot. The study used a similar assessment scheme for redundancy. Finally, for the hypothetical unmanned X-15, the study assumed no changes to systems or components other than removing all redundant systems and substituting relatively simple and reliable present-day systems in their place.149

The results were not surprising. Of the 44 free flights conducted up to that time, researchers considered 43 successful as flown.150! Computed as an airplane that carried a pilot but no redundant systems, only 27 would have been successful. The number fell to 24 with redundancy but without a pilot, and to only 23 with no redundancy or pilot. The study noted that 19 flights were completely trouble – free, so they would have been successful in any of the three configurations. Significantly, the evaluation showed that the majority of times the mission was not

successful, the aircraft would have been lost. In fact, in the case of a piloted but non-redundant X-15, the study showed that 14 aircraft would have been lost in 44 missions.-1151

Around the same time, The Boeing Company conducted a similar study that analyzed the first 60 flights of the Bomarc surface-to-air missile. This large unmanned missile was designed to be relatively non-redundant in order to keep its manufacturing costs low.-1152 The Boeing study compared the actual flight results with a theoretical piloted Bomarc that incorporated a level of redundancy mostly equivalent to the X-15. Thus, the Boeing study was roughly the inverse extrapolation of the AFFTC X-15 evaluation, and the results bore an amazing similarity. For the X-15, the total mission success rate had been approximately 98%, which compared well to the computed 97% rate for a piloted and redundant Bomarc. Conversely, for both the actual Bomarc and the theoretical unmanned, non-redundant X-15, the total mission success rate was an identical 43%. This lent credibility to the idea that, with the current state of the art, it was still important to include a pilot in the loop.-153

In November 1968, William P. Albrecht and Vincent N. Capasso inspected X-15A-2, which had been in storage at the FRC since the completion of the thermal tests. The engineers determined what work would be needed to prepare the aircraft for display in a museum, or to return it to flight status if necessary. As the airplane stood, it was missing control surfaces, most of its cockpit displays, and the removable right outer wing panel. All of the pieces were stored nearby.[393]

A cursory inspection of the airplane showed signs of minor corrosion in unprotected areas, and the engineers believed the aircraft needed "a thorough inspection for corrosion with cleaning and repainting as required. A lubrication would be accomplished at the same time to protect moving surfaces…. This would take two men approximately 2 to 4 weeks to accomplish."*394

To restore the vehicle to flight status, the engineers believed three to four months of work would be required, including installing the engine plumbing, control surfaces, actuators, and SAS pump. All of the wiring would have to be checked and the hydraulic system would need servicing. In addition, the instrument panel would have to be installed and the landing gear made flight-ready.

If the airplane went to a museum, the engineers thought that some items (mainly bars to replace the control surface actuators) would have to be fabricated. A rough estimate included three people for a month to prepare the airplane for display, plus time to paint and stencil the exterior.-1395!

Officially, the X-15 program simply "expired" at the end of its authorized funding on 31 December 1968. After the New Year holiday, things began to happen quickly. Between the Apollo program and the increasing tempo of the air war in Southeast Asia, neither NASA nor the Air Force seemed particularly interested in the small black airplanes that were stored in the High – Temperature Loads Calibration Laboratory at the FRC.

On 4 January 1969, officials at Edwards formally requested reassignment instructions for the two remaining X-15 airplanes. A response came on 20 February directing that the "number one X-15 be made available for display in the Smithsonian Museum. The Smithsonian is prepared to receive the X-15 and it may be transported to Andrews as soon as it is ready for shipment. In order to protect the option of any future flight test program, extreme care should be taken in handling the X-15 so that it will not be altered or damaged. The Air Force Museum should retain accountability for the aircraft and reassign it to the Smithsonian for display." A later message directed NASA to transfer X-15A-2 to the Air Force Museum at Wright-Patterson AFB.!396

A meeting on 7 January 1969 at North American discussed how best to dispose of the remaining program assets for which North American still had responsibility. Unlike many programs that require the contractor to account for every pencil purchased with government funds, the X-15 ended much more casually. For instance, the "contractor was advised … that no physical inventory of X-15 assets will be required," and that the North American working inventory would be "accepted by the Air Force as the formal X-15 inventory record." The Air Force justified this casual attitude by noting that "(a) it is a research type program, (b) the last physical inventory was taken less than a year ago, (c) [it is] in the interest of program economy." Nevertheless, North American had to assign class codes (indicating how to dispose of the item) to some 9,000 line items having a monetary value in excess of $6,000,000.[397]

On 18 March 1969, the public affairs officer at the FRC wrote to his counterpart at NASA Headquarters. The opening paragraph was telling: "Sometime this spring, probably May, the number one X-15 will go into the Smithsonian. Because of the haste of the announcements and Apollo 8, the world didn’t seem to care much when the program was concluded last December. I’d like to see if we can’t remind the world about the X-15 and use the Smithsonian as an excuse."!3981

The Smithsonian Institution’s National Air and Space Museum (NASM) had begun its efforts to acquire an X-15 as early as 1962, but nothing was likely to happen as long as the flight program continued. After the funding expired, the Air Force agreed to lend X-15-1 to NASM for two years. NASA partially disassembled X-15-1, loaded it onto a flatbed trailer, and flew it to Andrews AFB inside an Air Force transport. On 13 May 1969, a truck moved X-15-1 from Andrews to the Silver Hill Facility (later the Paul E. Garber Facility) in Maryland. After some minor refurbishment, the Smithsonian installed the X-15 near the original 1903 Wright Flyer on the floor in the north hall of the Arts and Industries building, which housed the NASM at the time. On 7 July 1971, the Air Force officially transferred ownership of X-15-1 to the NASM, which subsequently loaned the airplane to the FAA for display at Transpo 72 in the spring of 1972. The airplane then traveled to the FRC to help commemorate its 25th anniversary. The NASA loan was effective for one year beginning in August 1972, but ultimately was extended until the summer of 1975. The X-15 returned to the Smithsonian for installation in the new NASM building on the mall before it

opened to the public on 1 July 1976. X-15-1 currently hangs in the Milestones of Flight Gallery at the NASM in Washington, D. C.[399]

X-15A-2, completely refurbished after its unhappy experience with the ablative coatings, became the property of the National Museum of the United States Air Force at Wright-Patterson AFB, Ohio. However, prior to the airplane arriving in Ohio, the museum loaned it to the Alabama Space and Rocket Center in Huntsville (now the U. S. Space & Rocket Center). The airplane arrived on a one – year loan on 27 March 1970, although for some reason the Air Force did not installed the right wing while the airplane was in Huntsville. The airplane now sits—in black Inconel finish—in the Presidential and Research & Development Galleries of the National Museum of the United States Air Force. A set of external tanks and a dummy ramjet are part of the display.

The Air Force buried the remains of X-15-3 at an undisclosed location on the Edwards reservation. In 1991 the Astronaut Memorial at the Kennedy Space Center, Florida, added Mike Adam’s name, a tacit reminder of an oft-forgotten manned space program.*400

The two NB-52s remained at Edwards to support the heavyweight-lifting-body program. Not long after the end of the lifting-body program, NASA retired the NB-52A to the Pima Air & Space Museum outside Tucson, Arizona. The NB-52B continued to serve as a carrier aircraft, launching the X-38 and X-43 vehicles, through the beginning of 2005. NASA finally received a B-52H in mid-2005 to serve as a carrier aircraft, but a lack of requirements resulted in the airplane returning to the Air Force in 2006. At the time of its retirement, the NB-52B was the oldest operational (and lowest flight time) B-52 in the Air Force.*401