Remember when: the X-15 went Hypersonic and served as the basis for the Space Program

October 3rd, 1967, Test pilot "Pete" Knight gave that Ol' Mach Demon the best chase it ever had! William John "Pete" Knight set a world absolute aircraft speed record for manned aircraft when he piloted the X-15A-2 to 4,520 miles per hour, or Mach 6.72, almost seven times the speed of sound.

Key features and facts about the North American X-15:

• Altitude: The X-15 also set altitude records. It reached a maximum altitude of approximately 67 miles (107.8 kilometers) during one of its flights, officially entering space and making its pilots astronauts according to the U.S. definition of space.
• Design: The X-15 was a rocket-powered aircraft with a slender, needle-like fuselage and wings with a relatively small aspect ratio. It was powered by an XLR99 rocket engine, which burned liquid propellants (anhydrous ammonia and liquid oxygen) and produced thrust in the range of 57,000 to 57,850 pounds-force.
• Duration: The X-15 program lasted from 1959 to 1968, with a total of 199 flights. It provided crucial information for the development of future spacecraft and paved the way for human spaceflight.
• Impact on Space Program: The data collected from X-15 flights contributed significantly to the development of the Mercury, Gemini, and Apollo space programs. The knowledge gained about high-speed flight and re-entry was crucial for the safe return of astronauts from space missions.
• Legacy: The X-15 remains one of the most iconic and groundbreaking aircraft in the history of aviation and aerospace research. It contributed significantly to the knowledge and technology needed for the Space Shuttle program and subsequent human space exploration missions.
• Parabolic Flight Path: The X-15 followed a parabolic canon ball type flight path, which involved a steep climb to reach its peak altitude and speed, followed by a descent back to Earth. During this descent, it would gather data on the behavior of the aircraft at high speeds and re-entry conditions.
• Pilots: The X-15 was flown by a select group of highly trained test pilots, including Neil Armstrong (who would later become the first person to walk on the Moon), Joe Engle, and Scott Crossfield, among others, flew the X-15 during its test program.
• Purpose: The X-15 program aimed to gather data and conduct scientific experiments in the upper atmosphere and at hypersonic speeds, which are speeds greater than Mach 5 (five times the speed of sound).
• Research and Experiments: The X-15 conducted numerous experiments and collected valuable data on hypersonic aerodynamics, materials, and control systems. It helped researchers understand the challenges and characteristics of flight at extreme speeds and altitudes.
• Rocket-powered: The X-15 was powered by a rocket engine, specifically the XLR99, which burned a combination of liquid oxygen and anhydrous ammonia as fuel. This engine provided the tremendous thrust needed to achieve high speeds and altitudes.
• Speed and Altitude Records: The X-15 set multiple world records for speed and altitude during its flights. On October 3, 1967, William J. "Pete" Knight piloted the X-15 to a speed of Mach 6.7 (4,520 mph or 7,274 km/h) and an altitude of 102,100 feet (31,120 meters).
• Total Flights: The X-15 completed a total of 199 flights between 1959 and 1968.

Meet the X-15: It Flew At 4,250 Miles Per Hour (It Made History)

 

This aircraft speed record still stands to this date. Knight also became one of only five pilots to earn their Astronaut Wings by flying an airplane to an altitude over 280,500 feet.

Powered by a rocket, the X-15 was air launched from a B-52 to accommodate the large fuel consumption of its rocket engine. Launching from the B-52 at speeds more than 500 miles per hour, the X-15’s rocket engine provided thrust for 80-to-120 seconds of flight, before gliding into landing at speeds of 200mph.

Hypersonic Model - big tanks, pretty in pink, eyes like snoopy

The X-15 with the tail number of 56-6671 which would set the speed record was different than the other two X-15 aircraft at Edwards. It had no exterior markings.

The cockpit windscreens are covered, with small oval viewing windows for the pilot, making the plane look a bit like Snoopy from the Peanuts comic strip. It is covered with a milky white Martin MA-25 ablator to protect it from the higher aerodynamic heating loads.  An ablator is a coating that provides thermal protection, while being slowly consumed during the heat dissipation process. The original ablator applied to this X-15 was pink in color and gave the plane a rather odd appearance.

Fortunately, an application of a white sealer coating over the pink gave the aircraft a more proper look.  It also carried a pair of giant anhydrous ammonia tanks under its fuselage. These huge droppable propellant tanks allowed the  XLR-99 rocket engine to operate 60 seconds beyond the stock X-15’s 80-second burn time to give that extra kick.  Among other modifications, the aircraft also carried a pylon-mounted dummy ramjet in the ventral region under the aft fuselage which gathered hypersonic aerodynamic data for a future hypersonic missile.

The North American X-15 was an iconic experimental aircraft that holds the distinction of being the fastest manned aircraft ever built. It was developed in the 1950s and 1960s as part of a joint program between NASA (then NACA, the National Advisory Committee for Aeronautics) and the U.S. Air Force. The primary purpose of the X-15 program was to conduct research and gather data on high-speed flight, aerodynamics, and the effects of extreme speeds and altitudes on both the aircraft and the human pilot.

The X-15 was an experimental aircraft developed in the 1950s and 1960s by  North American Aviation for NASA and the U.S. Air Force. It was designed to explore hypersonic flight and reach altitudes and speeds that no other aircraft had achieved at the time. It laid the groundwork for future advancements in aerospace engineering and space exploration.

The X-15 program was a groundbreaking and instrumental part of the early space and aviation research efforts in the United States. It pushed the boundaries of human flight and paved the way for future high-speed and high-altitude aircraft and spacecraft development.

Research

Many research reports and papers were generated as a result of the X-15 program. However, NACA (National Advisory Committee for Aeronautics) transitioned into NASA (National Aeronautics and Space Administration) in 1958, so the reports related to the X-15 flights are typically associated with NASA rather than NACA.

Here are a few examples of NASA research reports and publications related to the X-15 program:

1. NASA SP-60 Series: This series includes a collection of reports titled "X-15 Research Results." These reports provide detailed information on various aspects of the X-15 program, including flight data, experiments conducted, and the aircraft's performance. The scientific papers can also be found using google scholar.
   

2. NASA Technical Reports Server: NASA maintains an online repository of technical reports and publications. You can search for X-15-related reports by using keywords like "X-15" or "X-15 research results" on the NASA Technical Reports Server (NTRS) website.

3. NASA Historical Documents: NASA's history office also maintains a collection of historical documents related to the X-15 program. These documents may include reports, photographs, and other materials related to the program's history.

4. Scientific Journals: Some of the research conducted during the X-15 program was published in scientific journals. You can search for X-15-related research articles in aerospace and engineering journals using google scholar.

Key Personnel on the Ground who put the ship in the air

A commemorative look back at the X-15 program 30 years after the first flight gives some insigt to how things happened. See also Design Challenges. The NASA X-15 program office was run by Paul Bikle, who was the Chief of the Advanced Research Projects Division at NASA's High-Speed Flight Station (later NASA's Armstrong Flight Research Center) in Edwards, California. Bikle was responsible for the overall management and direction of the X-15 program, from its inception to its completion in 1968.

The key design leads at the contractors were:

• North American Aviation (NAA):
  • Charles Feltz (Chief Project Engineer)
  • Bud Benner (Assistant Project Engineer)
  • Ron Robinson (Assistant Project Engineer)
• Reaction Motors Division of Thiokol Chemical Corp. (engine contractor):
  • Bob Fields (Power Plant Engineer)
  • John Gibb (Regulators and Relief Valves Expert)

These individuals were responsible for the design and development of the X-15 aircraft and its rocket engine. They worked closely with NASA engineers to ensure that the X-15 met all of the program's requirements.

 No bucks, no buck rodgers.

Paul Bickle did a great job managing this program. The program's total cost, including development and eight years of operations are usually estimated at $300 million in 1969 dollars. Each flight is estimated to have cost $600,000. By the time it became fully operational, the X-15 could be turned around in less than thirty days.

How the Moon Shot ate the Dynasoar and resulted in a Shuttle

Decades before the space shuttle, U. S. Air Force officers and scientists using captured NAZI technology and projecting to use results from the X-15 were working on the Dyna-Soar, a single-pilot, reusable spaceplane that would have been boosted aloft by a Titan rocket.

After 8 years of gestation and 11 years of cultivation, the framework underlying the Johnson administration's decision to cancel Dyna-Soar, America's only hypersonic boost-glide program, in December 1963 illustrates the ebb and flow of an advanced technology program within the administrative and political context of modem American society. The decision to cancel Dyna-Soar had several significant consequences. Most important, it ended, at least temporarily, the Air Force's opportunity to use hypersonic flight for military missions. This is why we are now playing catch up to the Chinese and Russians, who spent the last few decades reading old DoD and NASA documents, and going on from there. The Air Force finally recaptured some of this capability with no man in it with the X-37B UAV still billed as NASA's.

The Air Force's inability to persuade Secretary of Defense Robert S. McNamara and other Department of Defense officials of the wisdom of continuing to build and fly such an advanced trans-atmospheric vehicle represented the single most important reason for the program's cancellation, overshadowing 11 years of evolutionary development. The complex political-economic-administrative relationship between the Eisenhower and Kennedy administrations, the aerospace industry, NASA, and the Air Force in the late 1950s and early 1960s left NASA as the national leader for hypersonic R&D.

Dyna-Soar was not a technological failure. It could have flown on top of Titan III. On the other hand, Dyna-Soar's cancellation marked the collapse of the Air Force's political-economic efforts for a hypersonic boost-glider, illustrating the need for a rapid and clear consensus of purpose, single-minded and politically astute leadership, and the near-term attainment of advanced technology. Once Dyna-Soar was canceled, NASA began to acquire an increasing amount of the Air Force's hypersonic research until its Space Shuttle offered the Air Force another chance for a joint venture equal in scope to Dyna-Soar. However, this time NASA would be the lead organization, and DoD would follow along.

Boeing's X-20 Dyna-Soar was a hypersonic glider in development at the same time as the X-15, and its likely successor. A flat, triangular base with flicked up wing tips and a one-man crew cabin on top, it was designed to launch on a Titan missile, orbit the Earth, then land unpowered on a runway. The Air Force described this gliding landing style as dynamic soaring, hence the name Dyna-Soar. And while the concept was initially conceived in WWII Germany as a way to bomb America from Europe, the U.S. Air Force adopted it as a weapon to possibly bomb the Soviets.

In September 1962, a full scale Dyna-Soar mockup and seven pilots - soon to be astronauts - were unveiled to the public in Las Vegas. But the dream didn't last. By early 1963, it was clear that NASA's success was eclipsing Dyna-Soar. The glider just didn't fit anywhere in the nation's Moon shot, and NASA's dominance in space left little room for an Air Force version. A study weighing the merits of Dyna-Soar with NASA's upcoming Gemini program ended with the latter firmly on top. On Dec. 10, 1963, Robert McNamara formally cancelled Dyna-Soar.

Though the full-scale mockup is as close to a flying Dyna-Soar Boeing ever built, the program did have lasting benefits. While the bureaucratic mess dealt the program blow after blow, the pilots did learn how to fly the small delta wing glider to an unpowered landing as though from orbit. They practiced in simulators and unpowered aircraft with equivalent aerodynamic properties. So when it came time for NASA to develop the space shuttle, results from all the Dyna-Soar studies were readily available. The unflown vehicle convinced the agency that unpowered landings from orbit were the best way forward.

North American Aviation

North American Aviation, Inc. was a major American aerospace manufacturer that played a significant role in the development of aircraft during the 20th century.

North American Aviation was established in December 1928 as a holding company. Its founder, Clement Keys, intended for it to invest in a range of aviation businesses rather than become another aircraft manufacturer. Its first years were spent buying and selling interests in a number of aviation and airline companies through a series of complicated transactions. The Air Mail Act of 1934, however, forced aviation holding companies to break up (although North American was able to retain Eastern Air Lines until 1938). One of the new companies retained the name North American Aviation. James H. "Dutch" Kindelberger was recruited from Douglas Aircraft as the new company president.

The new North American focused on manufacturing aircraft, and Kindelberger moved the company to southern California, where the weather allowed flying year-round. His strategy was to produce small military training aircraft as he felt that competing with the larger, more-established companies would be difficult. Its first planes, the GA-15 observation aircraft and the GA-16 trainer led to the O-47 and the NA-16 (also called the BT-9), a low-wing monoplane that won the 1934 Army Air Corps trainer competition. The NA-16 was the first in a long line of trainers that would continue for some 25 years. North American's first combat airplane, the BC-1, built in 1937, was based on the NA-16.

With war approaching, North American stepped up aircraft production. In 1940, it opened factories in Dallas and Kansas City, Kansas. From 1938 through 1945, the company produced 43,208 aircraft, more than any other U.S. manufacturer. They became known for producing a range of iconic military aircraft, including:

1. North American P-51 Mustang: This World War II fighter aircraft was one of the most successful and recognized American fighters of the war. It played a crucial role in air superiority in both the European and Pacific theaters.

2. North American B-25 Mitchell: A medium bomber used in various theaters during World War II, including the famous Doolittle Raid on Japan.

3. North American F-86 Sabre: A post-World War II jet fighter that saw extensive service during the Korean War and became one of the most iconic jet fighters of its era.

4. North American T-6 Texan: A trainer aircraft widely used by the U.S. military and other air forces around the world.

North American Aviation, Inc. played a key role in the development of spacecraft during the early years of the space race, producing the X-15 rocket plane, which set numerous speed and altitude records.

It's worth noting that North American Aviation, Inc. went through various mergers and changes in ownership over the years. In 1967 shortly before the end of X-15, it merged with the Rockwell Corporation to become North American Rockwell.

Rockwell was involved with the manned spaceflight program from the former's inception, taking over the agreements NASA had already made with NAA. These included contracts to build the second stage of the Saturn V launch vehicle, also known as S-II, and the Apollo Command and Service Module (CSM).

Later, it became part of Boeing when Boeing acquired Rockwell's aerospace and defense units.

Rocket Engine

The XLR99 powered X-15 on its record breaking flights. It was the first large, throttleable, restartable liquid propellant rocket engine to be used in a piloted vehicle. The engine was used only in the X-15 program, which rocketed humans to the edge of space.

Developed and built by the Reaction Motors Division of Thiokol Chemical Corp., the XLR99 could deliver more than 57,000 pounds of thrust. The engine used liquid oxygen and anhydrous ammonia propellants fed into the engine by turbopumps at a flow rate of more than 10,000 pounds per minute.

At that point in time, state of the art in big rockets was the Redstone, which was burning 75/25 ethyl alcohol/water with LOX in an engine which was largely copied from Werner von Braun's V-2; watering the fuel down was necessary to moderate combustion temperature. While regeneratively cooled, the design of the cooling tubes was not as efficient as it would be in later engines.

Kerosene would "coke up" (polymerize) in regeneratively cooled engines, potentially catastrophically clogging coolant tubes. That problem would eventually be solved by the development of the RP-1 kerosene specification in the mid-50s.

So during the development of the XLR99, ammonia had a useful niche -- it gave better performance than 75% alcohol, was more suitable for regenerative cooling than cheap kerosene, and was safer than the hydrazine fuels.

The XLR99 engine had an operating life of one hour, after which it could be overhauled and used again, though operating times twice that long were demonstrated in tests. The XLR99 was theoretically capable of between twenty and forty flights before overhaul. The basic X-15 carried propellants for about 83 seconds of full-power flight, and the X-15A-2 carried enough in its twin orange external tanks for more than 150 seconds of full-power flight.  

Reaction Motors, Inc. (RMI)

Reaction Motors, Inc. (RMI) was formed in 1941.  Its four founders were rocket enthusiasts and members of the American Rocket Society, apparently spurred on by the works of Robert Goddard. RMI developed the rocket motors that powered the first supersonic flight, that of the X-1; the retro rockets for five NASA surveyor lunar soft landers; and prepackaged liquid rocket engines for the U.S. Navy Bullpup A & B air to ground missiles, among many other pioneering programs. RMI became a division of Thiokol Chemical Corporation in 1958 and closed in 1972. 

It is interesting to look back at RMI testing the XLR99 at its facility in Rockaway New Jersey. Even then, NIMBYs complained about rocket noise. Berg v RMI. Things haven't changed much with SpaceX problems at Boca Chica in south Texas. The RMI test facility sits abandoned today.

Accidents and Incidents

Despite the NASA X-15 program’s outstanding success in developing and operating the first manned hypersonic research platform, the program suffered a fatal accident on November 15, 1967, when X-15-3, the only aircraft outfitted with advanced pilot displays and an adaptive flight control system, was lost after entering uncontrolled flight at an altitude of 230,000 feet and a velocity near Mach 5. The pilot, Major Michael J. Adams, was incapacitated by the aircraft accelerations and was killed either during the ensuing breakup or upon ground impact.

In light of mitigating risk to current and emerging manned aerospace vehicles, a comprehensive systems level analysis of the accident was conducted with a focus on the electrical power, flight control, and instrumentation failures that affected not only the vehicle dynamics but substantially impacted the pilot decisions that led to an inevitable loss of control. Insights based on reconstructed flight data as well as analysis and simulation of the X-15’s unique adaptive control system, yielded new conclusions about the reasons for the control system’s anomalous behavior and the system-level interactions and human-machine interface design oversights that led to the accident

William J "Pete" Knight had the "Right Stuff"- End of the Road

William J. "Pete" Knight, (November 18, 1929 – May 7, 2004) a former test pilot who earned his U.S. Air Force astronaut wings flying the X-15 rocket plane, became a California state Senator and died of leukemia at age 74.

He was a leader to the end and a prominent figure in California politics. He served in the California State Senate as a Republican from 1993 to 2004. During his time in the Senate, Knight represented the 17th Senate District, which covered parts of Los Angeles and San Bernardino Counties. He was known for his conservative stance on various issues, including fiscal policy and social matters.

Knight was one of six test pilots selected by the USAF in 1960 to fly the X-20 Dyna-Soar which was slated to become the first winged orbital space vehicle capable of lifting reentries and conventional landings. After the X-20 program was canceled in 1963, he completed astronaut training at the USAF Aerospace Research Pilot School at Edwards Air Force Base, Calif., in 1964 and was selected to fly the X-15.

Two weeks after setting the world speed record, on October 17, he climbed to an altitude of 280,500 feet, over 53 miles above the Earth, earning his astronaut wings from the Air Force.On a previous X-15 test flight, Pete suffered a total electrical failure and complete onboard systems shut down, that occurred while climbing through 107,000 feet at Mach 4.17 on June 29, 1967.

Calmly allowing the plane to continue to its apex altitude of 173,000 feet, he pushed the nose over and flew a purely visual approach to a non eventful landing at Mud Lake, Nevada. For his remarkable feat of airmanship that day, he earned a Distinguished Flying Cross.