47 Years Ago Today: The Fastest Manned Aircraft Flight Ever.

By Tom Demerly for ALERT 5.

Air Force test pilot William J. “Pete” Knight with X-15 aircraft number 56-6671. This photo was before Knight’s speed record flight when the X-15 received a white, heat-resistant coating. Photo Credit: NASA.

It flew at nearly Mach 7, seven times the speed of sound and twice the speed of a rifle bullet. The speed record it set 47 years ago today still stands today.

It flew so high its pilots earned Air Force astronaut wings: 280,500 feet or 53.1 miles above the earth.

It pioneered technologies that were used on the SR-71 Blackbird, the space shuttle and the reusable spacecraft in Richard Branson’s future Virgin Galactic passenger space program.

And it killed test pilots in an era before redundant flight control systems and modern safety protocols for hypersonic flight.

It was the North American X-15. Today is the 47th anniversary of its fastest ever manned, powered flight.

The X-15 could be the most ambitious and successful flight test program in aviation history. Apollo astronauts flew it. It challenged the paradigms of aerospace design well beyond the limits of any prior program, including Chuck Yeager’s sound barrier busting Bell X-1. The X-15 program sits alongside the Wright Flyer as an aviation milestone. So much progress was made so quickly in the face of such great risk with such rudimentary technology that no other development program, with the exception of the Apollo missions, has come close.

10:30 Hr.s Local, Tuesday, 3 October, 1967. Edwards Air Force Base, Mojave Desert, California.

After the awkward and tedious process of donning his pressure suit, Air Force test pilot William J. “Pete” Knight, clambers up a custom made ladder and lowers himself into the cramped cockpit of X-15A-2 aircraft number 56-6671. Half a dozen men helped Knight get ready for his flight this morning, testing life support equipment and helping him into his bulky pressure suit. His first astronaut type flight helmet attached to his pressure suit didn’t work with his aircraft communications system, so technicians have replaced it with a backup pressure suit helmet. Communication checks are normal now.

The X-15A-2 rocket plane is mounted between the number 5 engine and the fuselage under the right wing of “Balls 8”, a massive Boeing NB-52B mothership. Today it’s flown by Air Force Col. Joe Cotton and Lt. Colonel Bill Reschke Jr. The launch aircraft has a sprawling 185-foot wingspan and eight jet engines. It was originally a B-52 strategic bomber built for dropping hydrogen bombs on the Soviet Union if the Cold War ever got hot. The bizarre pairing of aircraft, the little X-15 nestled under the right wing of the giant silver and red B-52, is parked at the beginning of runway 04R/22L, a 3 mile long × 300 foot wide strip of reinforced concrete with an additional unpaved 2 miles for emergencies. Other than the sounds of vehicles coming and going it is quiet and still at Edwards Air Force Base in the wide expanse of the Mojave Desert.

The record setting X-15A-2, aircraft number 56-6671, with its unusual white heat resistant ablative coating and giant anhydrous ammonia tanks under its fuselage.

This X-15 is different than the only other two aircraft of the same type. The other two X-15’s are painted black and have a yellow NASA band on their vertical stabilizer with U.S. Air Force markings on the fuselage and wings.

The X-15 Pete Knight is strapping himself into is an “X-15A-2”. It has no exterior markings. It is covered with a milky white ablative coating to resist heat and carries a pair of giant anhydrous ammonia tanks under its fuselage. The rocket plane is made of a special, ultra strong alloy called “Inconel-X”. As Inconel-X heats up it actually becomes stronger. The X-15A-2 burns a volatile mixture of deadly ammonia and liquid oxygen as fuel. When ignited, its single XLR99 engine burns 7 tons of fuel in just over a minute and generates half a million horsepower, nearly 60,000 pounds of thrust. By comparison a modern day F-16 fighter generates about 30,000 pounds of thrust in full afterburner.

Today’s flight profile has one objective: speed. It is an attempt to set a maximum manned-flight speed record. The X-15 will be a piloted projectile blasting through a violent acceleration from 500 MPH to nearly 5,000 MPH in only 75 seconds. Six times the speed of sound. On the downside of this flight profile the X-15A-2 will decelerate so violently that a rearward-facing crash pad is installed in the canopy, in front of the pilot, so Pete Knight’s helmet can slam into something soft as the friction of the atmosphere slows the plane after its explosive fuel burns out.

An original graphic showing both the speed record profile with the flight beginning in Utah and the altitude record flights with their higher profiles.

Test pilot Pete Knight is hot inside the X-15A-2 cockpit. The desert sun in the Mojave is unrelenting. The cockpit is pressurized with nitrogen gas and Knight is breathing oxygen fed to him through his spacesuit. In an emergency Knight needs to get the X-15A-2 below mach 4 and 120,000 feet to use his rudimentary ejector seat to escape. His chances of surviving an ejection in that corner of the performance envelope are slim. Outside that envelope, where the X-15A-2 will fly today, they are zero.

A little over a month later, on November 15, 1967, USAF test pilot, Major Michael J. Adams will die when his X-15 enters a violent spin at mach 5 and disintegrates under crushing G-loads. Wreckage is strewn over 60 miles and two states. He is remembered as the first fatality of the U.S. space program.

Desert memorial to USAF test pilot, Major Michael J. Adams, killed in an X-15 accident on 15 November, 1967 just after Pete Knight’s speed record.

Knight communicates with ground control and the crew of his NB-52B mothership over his radio as he prepares for his record setting mission. Checklists are read and verified, engines on the NB-52B are started and the aircraft taxis heavily onto the long runway with a following group of crash, fire and support trucks trailing behind. Two chase planes, a “Century Series” F-104 Starfighter and an F-100 Super Saber, prepare to take off to follow and observe the mission until separation. A second set of chase aircraft will be in the air to receive the X-15A-2 as it decelerates back toward Edwards for landing at the end of the flight. Two sets of chase aircraft are needed, one pair at the start of the flight and one at the end. Nothing in the air can follow the X-15A-2 through its flight, not even a missile. Nothing is fast enough.


The sky is brilliantly clear, arcing dark blue up into a vaulting space that seems to dare the test pilot strapped into the milk white missile-plane. It is a deadly empty space where physics are a cruel arbiter. The “surly bonds of earth” are comfortable and safe by comparison. The vast test range where the mission is being flown covers three states, Utah, Nevada and California. Knight will hurtle across these states in a blur only seconds long covering well over a mile per second.

The take-off roll is long and oddly slow looking. The NB-52B wallows into the air with an unusual flight attitude, black smoke settling rearward from its screaming engines. Knight is a passenger inside the X-15A-2 for the moment, calmly reviewing procedures and checklists and re-checking his flight profile and navigational range card strapped to the right leg of his spacesuit. It is about 13:40 local time.

The climb to launch altitude takes time. Chase aircraft close in on the NB-52B/X-15A-2 pairing in preparation to conduct visual checks of flight control actuations prior to launch. A local NOTAM, or Notice to Airmen restricts all civilian air traffic from the area.

The white X-15A-2 is not as attractive as its black predecessors. It looks almost like a mock-up, not a real aircraft, since the paint appears blotchy and hastily applied. The giant ammonia tanks look like an afterthought strapped to the pasty missile-plane. Despite all the planning, training and preparation the X-15A-2 looks more like something preparing for a crash test than the threshold of a new aviation speed record.

Even with meticulous preparation, planning and checks the X-15 missions were often filled with unexpected incidents. On an earlier flight, test pilot Scott Crossfield’s X-15 cockpit filled with smoke while it was still mated to the NB-52A. Almost immediately after radioing the crew inside the NB-52A mother ship about the smoke in his cockpit, Crossfield’s radio in the X-15 went dead. The implication of a burning X-15 filled with highly explosive ammonia and liquid oxygen attached to the wing of a B-52 caused the crew to consider dropping the X-15, not knowing if Crossfield was still alive or already incinerated in a deadly cockpit fire that would touch off a massive explosion any second. Crossfield told the NB-52A crew earlier, if there was any question, “Drop me”, since “There is one of me, and four of you.” Oddly, the smoke in Crossfield’s cockpit cleared and the radio began functioning again. The mission proceeded as normal.

This rare photo taken through the canopy of one of the chase planes shows Pete Knight’s X-15A-2 before launch as it vents expanding gases from ascending to altitude. Notice the experimental scramjet housing mounted under the rear of the aircraft. This would burn and fall off the aircraft during the flight.

The central risk of the X-15 concept, especially when it was chasing altitude records, was that it crossed from atmospheric flight to non-atmospheric near space flight. Those two regimes are vastly different. One has air, the other doesn’t. In the atmosphere aircraft steer by using control surfaces over which air moves. Move part of the flight control surface as air is moving over it, and the plane moves. In near-space the rules change entirely. There is, effectively, no atmosphere or air moving over flight control surfaces. The aircraft uses miniature rockets mounted in the nose and tail to control its yaw, pitch and roll. In 1967, it was an imprecise science. In the atmosphere the stubby wings and small control surfaces of the X-15 had little purchase. In near space they had none.

Once at drop altitude of 45,000 feet final checklists and systems checks were completed. There was a countdown. The X-15 was released at precisely 14:31:50.9 local time. It dropped at a slight angle from under the wing of the NB-52A, quickly rolled level, dropped further then ignited its engine.

A brilliant white contrail lanced forward of the lumbering NB-52A and the supersonic chase planes struggled to try to keep pace with the X-15. They were quickly left behind. The white trail traced a curve upward, upward, vaulting away into the western sky. Blue sky gave way to black. And there was a concussive explosion.

The moment of launch for Pete Knight and X-15A-2 number 56-6671. Knight will free fall away from the launch aircraft before firing his rocket motor.

The sound barrier is broken when a succession of shockwaves accumulate on the nose of a projectile. Or aircraft. When they are compressed enough, the explosion happens. Like the crack of a bullet. There are often two sonic booms. In this case, there is no record. But over the next 75 seconds Pete Knight accelerates past the sound barrier- and keeps on accelerating. Mach 2…3…4… There is no secondary sonic boom as Mach speed accumulates. No dramatic acknowledgement of a new speed frontier being crossed.

Mach 5.

Five tons of anhydrous ammonia and liquid oxygen have burned in a barely controlled explosion 15 feet behind Knight’s ejector seat. Two tons remain.

Mach 5.5.

A by-product of speed in the atmosphere is friction, and a by-product of friction is heat. Pete Knight’s X-15A-2 begins to melt. The leading edge of the wings glow at over a thousand degrees. Even at high altitude the air molecules can’t get out of the way fast enough to dissipate heat. So chunks of Knight’s X-15 begin to burn and fall off. Big chunks. During flight, shock waves burn through the leading edge of the lower ventral fin igniting a series of small fires in the engine housing. Near the explosive nitrogen tanks.

Mach 6.

Knight already has the throttle advanced to the forward stop. One of two things will happen; he will complete his fuel burn and set a new speed record by a massive margin…

He passes through Mach 6.5.

Or, he will disintegrate as the accumulation of heat causes a massive structural failure of his airframe that will result in an instantaneous explosion of any unburned fuel. It’s unlikely much wreckage will be found.

Mach 6.6.

A big part of the X-15A-2’s ventral fin ignites and burns completely through. It flies off the aircraft, tracing a bright, burning arc to the desert floor.

Mach 6.7.

Fuel burn complete. Flight profile nominal. Powered flight terminated, ballistic flight initiated. Knight is still alive and at the controls of the world’s fastest glider. The X-15A-2 had reached its maximum velocity, a new manned flight speed record by a huge margin. It arcs over the Nevada-California border, over a mile a second, leading edges still glowing from heat. Accumulated heat detonates the separation charges on the dummy scramjet carried for test purposes. It explodes away from the X-15A-2 over Edwards bombing range as Knight decelerates through Mach 1 and 32,000 feet, more charred junk toppling to earth. Knight continues to descend, burning fragments dropping off the aircraft as he flies. The relentless forces of physics reel in ambition once again. But only after history is made.

Somewhere east of Edwards Air Force Base the second set of recovery chase aircraft find Knight as he descends and decelerates to enter the landing profile. The X-15A-2 is charred. There are visible holes burned through the ventral tail. Would the landing gear still function? Had the single nose wheel tire melted from the heat? The rear landing gear on the X-15 was a pair of stubby, ski-like skids designed for one-time use.

A long telephoto shot of Pete Knight landing the charred X-15A-2 at the end of the record setting flight.

Knight extends his nose wheel, landing skids, speed brakes and sets flaps for landing. A chase pilot confirms that the landing gear appear intact. He touches down at 14:40:07 local time on Rogers Dry Lakebed runway 17/35. A billowing plume of dust erupts behind his two rear skids as the X-15A-2 slides to a stop on the 7.5-mile long runway. The flight lasted 8 minutes and 16 seconds and covered over 213 miles of the western United States. Knight’s rocket engine only burned for a fraction more than 2 minutes and 20 seconds of the flight.

William J. “Pete” Knight’s speed record remained unbroken by any winged craft until the space shuttle Columbia’s reentry from space on April 14, 1981. His speed record still remains intact for a non-orbital aircraft.

Pete Knight had become the fastest pilot to fly inside the atmosphere in powered, controlled flight. A record that officially remains today.

Fire crews extinguish the fire under the X-15A-2 after Knight’s landing.

The massive achievement of the X-15 program, both speed and altitude records, would pave the way to the moon and the space shuttle program. Its technology dividend is truly immeasurable, touching everything from the GPS constellation to cell phone communications and even the idea of civilian space travel.

Knight was awarded the Harmon International Aviator’s Trophy in 1969 for his record setting flight by then-President Lyndon Johnson. Following his test flight program in 1968 Bill Knight transferred to an active combat unit and flew 253 combat missions over Vietnam in the supersonic F-100 Super Sabre. For Knight, flying the Super Sabre after the X-15 must have felt like going from a dragster to a dump truck.

Pete Knight’s X-15A-2 the day after the record setting flight. The burned sections of the aircraft, missing scramjet housing and disintegrated lower stabilizer are visible.

Pete Knight left the Air Force and began a political career in 1984. He eventually became the first ever elected Mayor of Palmdale, California. Under Knight’s term Palmdale was the fastest growing city in the United States. He was later elected as a Republican Senator for the 17th District of California.

In an odd footnote Knight wrote legislation in California called “Proposition 22” that banned same-sex marriage. But one of Knight’s sons, David, was gay. David Knight defied his father and married his same-sex partner during a loophole period of the law in San Francisco. Proposition 22 was later repealed in California after being judged unconstitutional.

Air Force Test Pilot, speed record holder and decorated combat fighter pilot William J. Knight died in 2004 at the age of 74. His manned, atmospheric speed record still stands. That we know of.

The actual X-15A-2 flown by Knight was restored after the flight and returned to the original black paint scheme but never flown again. It is now an artifact in the Air Force Museum at Wright-Patterson AFB in Dayton, Ohio.

The X-15A-2 that remains the world’s fastest aircraft ever flown, restored with its original black paint scheme, on display at the Air Force Museum at Wright-Patterson AFB, Dayton, Ohio.

175 thoughts on “47 Years Ago Today: The Fastest Manned Aircraft Flight Ever.

  1. Neil Armstrong was an x15 pilot. He was a naval aviator as was commander forrest Peterson. Neil went on to the moon. Cdr. Peterson eventually promoted to admiral and was commanding officer of nuclear aircraft carrier, USS enterprise.


    1. I served aboard Enterprise under Capt. “Pete” Peterson. He was one of the finest Naval Officers I ever knew.


  2. I would like to fill in a few details about the X-15 program, just for the record.

    It was a part of the high speed aircraft test program that had it origins in the D-558 which in turn led to the “X” series. The X-I was followed by various “X” vehicles leading up to the X-15 which was to provide the ultra high Mach flights to provide various data including temperature as precursors to the Space Shuttle. It was obvious from the beginning that the very high Mach flights would be highly newsworthy. The Air Force, being the contractor, had specified limits upon the manufacturer so that upon delivery of the vehicle the glamor and publicity could be reaped by the Air Force, and it would then be delivered to NACA Edwards for the planned test program. This restriction was a source of frustration to North American and its chief test pilot, Scott Crossfield, as it was also to the NACA chief test pilot at Edwards, Joe Walker.

    As Director of the US Navy Test Pilot School, I took graduating classes on tours of industry. We were visiting North American the manufacturer. In conversation with Scott Crossfield and Joe Walker, we mutually deplored this “hogging” of the publicity and devised a plan to thwart it and provide for the normal delivery of the vehicle to NACA Edwards.

    At the time I was a US member of the Flight Test Panel for AGARD with NATO. In that role, by boss was Hugh Dryden, the head of NACA. Scott and Joe and I decided to get NACA to issue an invitation to the USAF, the Navy, and the High Speed Flight Test Station at Edwards to each provide pilots for the X-15 test program. I thus contacted my boss, Hugh Dryden, and the plan was explained to him. He agreed as did the Navy Deputy Chief of Operations for Air. In anticipation of receipt of the invitation, I convened a selection board to select the Navy pilot and we picked Forrest Peterson with Alan Shepard being the back up. It was a foregone conclusion that Joe Walker would be the pilot from NACA.

    The invitations were issued and Forrest Peterson and Joe Walker were nominated. After a delay of about two weeks, the USAF, realizing that they had been out-maneuvered, tendered their nomination. The program thus proceeded as originally planned. Forrest Peterson later told me that they piloted the craft in rotation and there was no publicity “hogging”.

    signed. L. M. “butch” Satterfield, Captain US Navy, retired.

    Liked by 3 people

    1. Thank you very much for these details “Butch”. We appreciate you reading and your insights. This is stuff we can’t can’t learn from book and internet research so it is particularly welcome. Many thanks! Tom D.


      1. Tom,
        This is fascinating to read since my Dad, Raun Robinson, was one of the two co-assistant chief engineers on the X-15 at North American Aviation. I really only knew of the test flights conducted by North American before NASA took it over and broke the speed and the height records. My Dad went onto other Projects like the B-70 and the B-1.
        Melinda Robinson


    2. Great info Butch. The whole thing was a thriller. BTW..you may have been my instructor in T28s at Whiting field in 1962 / 63.


    3. Butch…Thanks for the added history. An often overlooked fact is that Scott Crossfield was a Naval Aviator during WWII and was very proud of that. v/r Pete


  3. I was 19 in the air force as a ground support person “AGE”. I was told to deliver a MD-3 ground generator and a Ma1a air start cart to aircraft “BALLS EIGHT” on the flight line. Being young and dumb and really young and dumb, I asked “what in the heck is a balls eight”, I was informed that it was the last 3 digits in the tail number now get out there and deliver. Me smart now!!!!!!!!!!!!


  4. I worked for Colonel Pete Knight in 1979 when he was SPO Director of the Fighter/Attack SPO at Wright-Patterson AFB. I was a Captain who had been ‘fired’ for figuring out how to use unmanned aircraft (early drones) to beat the Warsaw Pact in Europe. He understood the politics that revolved around the decision to ignore the potential of the UAVs and put all their eggs in the manned A/C basket. Even with the proposed 27 Wings of Fighters, NATO still lost. With the UAVs the war came to a screeching halt in 8 hours with the Pact not far across the border. Colonel Knight was not PC but he was beyond being touched, so they put up with him until he retired. He was a good boss, a fine officer and a great stick.

    Liked by 1 person

  5. And the nonsense never ends:
    ” Near the explosive nitrogen tanks.”

    As Nitrogen constitutes 78% of the air that we breath I guess we’re lucky we don’t explode all the time.


    1. It’s the tanks that are explosive, not the nitrogen. If the tanks were to lose integrity, they would vent gas “explosively,” aided by the atmospheric heating of the aircraft. Not all explosions involve fire.


      1. I think the author mis-spoke when he wrote about nitrogen tanks exploding. I think he meant to say anhydrous ammonia tanks – which would be highly explosive….yikes.


  6. I was9 yrs old, Lt. JAMES USNr (my dad) said to go out side and LISTEN , History is being made. Thanks DAD and to ALL who made it possible .


  7. I worked on the development of the rocket engine as an instrumentation technician in Denville N.J. We worked 12 hour shifts, seven days a week for a whole year. We had several not so successful runs and in one with big brass observers blew the corrugated roof off the test shed. At a distance of a mile from the test sight the sound level was 120 decibels I was told. This was a very secret project, but no big secret to the people living near by.

    Liked by 1 person

    1. Neat. Where in Denville, and what company? I lived in Rockaway years later, ’77 to ’83. My father put in a career as a mech engineer at Curtiss-Wright in Fairfield and Lodi. He installed the props on the first C130 to test fly at Edwards.


      1. The company was Thiakol, I hope I spelled that right, it has been a long time ago. As to where in Denville, it was not in town proper but on top of a hill outside of town where the test stand was located which included a control center bldg. and a pond which affectionately was called ammonia lake. The engine exhaust on the stand aimed to the center of the pond and I remember the lake water was orange colored from the ammonia. The engine burned ammonia and Lox (liquid oxygen). The propellant pump used 90 percent hydrogen peroxide and pumped both liquid oxygen and ammonia into the engine at something in the range of 400 PSI. The engine fired in three sequences, a first or primer stage and a second and then a third and final stage. This was the very first and perhaps only throttleable liquid rocket engine. The throat of the engine was 9 inches in diameter if memory serves and the inner wall of the engine was lined with Rokite coated tubes that acted to vaporize the fuel.

        The big trick on run was to finally be able to get the main propellant valves to open. The problem they were having is that the bakelite terminals were wired by an outside agency. I discovered that they were using a wire stripper that nicked the wires causing the connection to break under the intense vibration. So I rewired and secured the terminals in silastic rubber. It was then that we were able to meet the test specs for the first time. How little things can cause gigantic problems.


    2. Was the company Reaction Motors? They were later bought byThiakol. My dad worked on the development of the rocket engine as well.


  8. As a retired Aeronautical Engineer, I can only assume that the record breaking event of the X-15 is attributable to The Engineers, (without a mention0 whose ingenuity and brilliance made it all possible Without engineers there would be no Pilots, nor indeed any form of driver, anywhere!!


    1. For sure Keith, the engineers aren’t dashing and daring and so they are not credited with much, but no matter, as we know that without the brain power we would still be watching the Wright Bros. flying their machine at Kitty Hawk. I went on from Senior Technician to Field Engineer to Senior Engineer and finally at Memorex to Development Engineering Manager and even managed to squeeze in a couple of patents along the way. We sure had fun in those days being a part of the Silicon Gulch club.


    2. Mr. Goodrum, My Dad Raun Robinson was one of the co-assistant chief engineers on the X-15 at North American Aviation, along with Roland “Bud” Benner under Charlie Feltz the head of engineering at North American. There is a wonderful book by Richard Tregaskis called X-15 The Diary: The Story of America’s First Space Ship. I couldn’t agree with you more that all of the speed records and the height records etc. wouldn’t be possible without the foresight and creative problem solving of the numerous engineers who contributed, some 200 or more, at North American.


  9. I was up in Nevada on a dry lake, sitting in a helicopter, as a rescue crew if something went wrong, when this flight took place. We were in radio contact and could hear the flight developments. When the RTB was received, it was wonderful.
    I had met “Speedy Pete” and he was a Gentleman in addition to being a Professional. Later, I was at WPAFB on the F-16 SPO and met him again. He was a Full Colonel and still the same “great & Humble GUY”

    I also knew Major Michael Adams, and was very sad when he died in that X-15 crash. At that time, NASA blamed the crash on pilot error, which I doubted very much. I had witnessed TO-MANY ABORTED test flights by NASA due to mechanical/systems failures that aborted, at the takeoff point — that they had to have known about before leaving the ramp. As a chopper pilot 1st, we covered most all takeoffs and landing with a photographer on board to record that portion of the flight. I WAS NOT IMPRESSED WITH NASA!!!
    ED HEFT, USN Test Pilot School Graduate. Retired LtCol USAF 1979


  10. I with you John! tooting ones horn is why Al Gore invented the internet. I think my tax dollars fly out of my wallet at mach 6.6 mph I was never my Moms hansom little soldier working for uncle Sam So I guess it’s time to retire to the waiting room!
    P.S. that museum in Dayton OH. is fantastic, the X-15 is a great monument to pure thought and my hard earned tax dollars Wonder what aeronautical engineers, technicians and rescue crews make per hour? Hey nice job guys Thanks


    1. Sorry, pal, but Al Gore never claimed to have invented the internet. But as a senator, when most other senators thought computers were some dumb machine that used punch cards, he was key to getting the political backing and funding that allowed development of the internet. In fact the nation does owe him a bit of gratitude for that.


  11. So now most Senators [democrats] think that computers are really smart and can forecast that we are all threatened by the “latest WMD” global warming or climate change, in case earth turns out to be cooling? lol, send money, you gullible taxpayers, so we can study the problem and how to “fix it”… sorry, i’m not buying that nor your implication that politicians are smarter now…


  12. I think I read some place that the X-15 crashed because of those stupid tape type instruments. At the time it seemed that both the military and the airlines were all lined up to shift to vertical tape instruments. Right in the middle of this, if my memory serves me rightly, the L-1011 was thinking about making all the instruments that type. But the video of Adam’s instrument panel showed that it was impossible to keep up with situation awareness when more then two tapes got out of the sweet spot. The L-1011 had tape instruments for engine data but old steam gauges for flight instruments.


  13. Were the ammonia tanks ejected during the flight? If so, when? They aren’t there in the post-flight photos. Do tell. Awesome article. Thanks!


  14. This is a great story, and should be told. Thank you Tom Demerly. I don’t know how something so great can degenerate to such petty mudslinging. Grow up people, this is the type of thing that makes this country great!


  15. As Doug above raised a question about anhydrous ammonia tanks, it occurred to me that even
    after running empty of liquid they remained to be an explosion threat due to remaining fumes.
    It would make perfect sense to eject them. It could be that the mounting pods burned off , as
    they did on the scram jet. The picture of Colonel Pete Knight’s X-15A-2 on final, shows the tanks missing.


    1. Anhydrous anmonia would need oxygen to ignite, At that altitude there wouldn’t be enough available oxygen to burn a candle. We worked around the test stand in clouds of ammonia, a virtual fog and never experienced an ignition. These clouds of ammonia vapor are of course, poisionous and we were supposed wo wear rebreathers (filters), but they proved more cumbersome than what they were worth and so when a cloud of ammonia vapor came your way you just held your breath until it passed as there was always at least a gentle movement of the air. To my knowledge, the only problem we had from time to time were the mechanics getting peroxide on their hands. Seemed like someone always had white spots on thier hands. Of course gloves would solve that problem but interfere with feel. Small nuts and bolts must be felt with the hands and I always felt sorry for the mechanics laying on thier backs under the engine changing out components after a run.

      Liked by 1 person

      1. WOW, loved the ‘play-by-play’ descriptions. Mister Knight was ‘one brave individual’.


      2. They used LOX for the oxidizer. (liquid oxygen)
        NH3 is fertilizer. In todays rocket engines, they use liquid Hydrogen as the fuel. It is less dense than HN3 and is more powerful.


  16. Great article and a nice read. I have been a longtime fan of the US Space program and have always considered the X-15 to truly be our first actual space vehicle and those brave men who flew it above the 50 mile point to be the first US astronauts. The fact that they flew suborbital missions is irreverent as the first two Mercury missions were suborbital as well.

    But while I would agree that Major Michael J. Adams could be said to be the first US Space casualty while flying an actual mission, 20 months earlier on February 28, 1966, Astronauts Elliot See Jr. and Charles Bassett, the prime crew for Gemini 9, were tragically killed when their T-38 trainer jet crashed while attempting to land at the McDonnell Space Center in St. Louis, Mo. McDonnell was the builder of the Gemini space capsule. So perhaps they should be remembered as the first causalities of the US Space program.

    I state this only in honor of their memory and sacrifice…and not to take away at all from what is a fine article that I enjoyed reading.


    1. And as a correction, I meant to say …”those brave men who flew it above the 50 mile point to be among the first US astronauts…”


  17. This is to Edward Heft. You probably knew my brother, Gen George Monahan at the F-16 SPO, who guided that great program along.

    Capt. Jack Monahan, American Airlines,ret.


  18. The tape instruments that were mentioned were made by Lear, Inc. to specs provided by the Government. I was a factory re. for them, they were used in the Mark IV Orbital Space Simulator, also made by Lear.

    I remember Ed Heft, he flew our simulators in the Flight Dynamics Laboratory at Wright Patterson AFB.


  19. I was a 21 year-old goober communications tech the first and only time I went out for an X-15 launch. It was June 8,1966, a day which would change Edwards. The experience of the very early morning work in the darkness pierced by the kleig lights with the hustle and bustle of the professionals was both surreal and exciting for a young troop. Working our way through the B-52 Mothership and the X-15 checking comm at all the stations, assuring our stuff was okay and signing it off left us to head back to our part of the base, still before sunrise.

    Driving our van back skirting the lakebed, our doors were slid back, the Sun just starting to glow over the mountains, and it was all I could do to keep from screaming from pure delight of being there. On my left, came up a NASA F-104, with the pilot waving to us. I didn’t know there was a taxiway there, and maybe there wasn’t. It was Joe Walker, supposedly the best pilot in the Free World, and one I wanted to meet. He waved at us and scooted over to the runway and took off. Joe never came back, colliding with our XB-70 Air Vehicle #2.

    We lost something like a plane a week and a pilot a month in the months I served at Eddies. But that one gave us a real bitch-slapping. It still hurts.


  20. I was a crew chief on an F-104 at Edwards in 1967-68. Major (“Pete”) Knight and Major Adams would, along with other “to be” astronauts, fly the 104 with space type suits on. I recall one day it seemed a bit quiet and eery on the flightline – something was wrong. The word came that Major Adams had died in the X-15. Just a bit earlier, he was riding by, tucked under the wing of a B-52. That was my the first “gut wrenching” experience in knowing the loss of a pilot. I always wondered what became of Pete Knight – it was interesting to see he later went to Vietnam, flying F-100’s.


    1. Did he go with Yeager? Yeager took an F-100 group over to get his star.

      I was in the Comm shop when they came in with the roll-away covered with sheets with the flattened control boxes. I identified the ARC-66 box from Joe’s F-104, and directed them where the others were from.

      I was already on my way to my next assignment when X-15 Flight 198 went down. But I have an excellent example of character in a short story regarding those flights, if they let me put it here.

      Liked by 1 person

  21. Class Act
    It was early 1967, late in my time at Edwards, when the Comm shop foreman called everyone together in the middle of the shop to share a little story with us. It was, in my mind, typical Edwards. He looked like he should have been a British Spy Chief, with his pipe and thoughtful ways, as he related to us how the morning before, R H had gone out on another early Mothership preflight assuming it would be the usual easy checkout, slow ride back, a quiet cup of coffee, and home in the early afternoon (my version of his day): Nope.

    R got the Mothership checked out and on its way, but before he could scamper out, he was informed about a UHF Command Radio problem on the other Mothership. Not good news: Those two were the oldest B-52’s in existence. Just getting to and working with their antiquated electronics was guaranteed to change one’s attitude, and perhaps mental state as well. Good thing I wasn’t on that job: The installation of the bulky WW II-era technology ARC-27 units had none of the improvements for accessibility of the production birds, and these two B-52’s were legendary for being terrible places to work. When combined with the desert heat, memorable experiences were likely.

    It took several hours and three installations of receiver-transmitter units before R could get one that worked, and by then, his Attitude Temperature was a high as the skin of that aluminum tube. Roasting in the ample solar irradiance, it converted all available wavelengths to infrared emissions of heat from all directions, from the air itself. These are kind in moderation, . . . but solar moderation is unavailable in the High Desert

    In this case, the mild-mannered Gentle Airman R H had lost it. Cooked by the heat, tortured by the physical insults of the Mothership, blinded by sweat from repeated installations, Russ was by now short of social graces. At first, everything looked good with the last unit we had in stock, good tuning, good sidetone, . . . but nobody would respond on its primary channel. Calling NASA 1 repeatedly, his anger grew until it overcame everything, and the stream of perfectly-modulated and omni-directionally-transmitted obscenities filled the frequency used for sending communications to the X-15. Doing what he could, and leaving much, much later than expected, R wrote up the situation on the forms and went home.

    Alerted to an early meeting of the maintenance personnel that supported the X-15 missions, R was there the next day at the ridiculous time of 04:30 or 05:00, as they went through the necessary items. At the end of it, an unexpected guest at the maintenance meetings stood up to speak: It was Pete Knight, X-15 pilot and holder of world records.

    It was unusual for a busy pilot to waste his time in maintenance meetings, but Pete stepped up to explain that he came to offer a personal apology to R H for not responding to his repeated, and repeated, and repeated calls for a radio check. It seems Pete was “a little busy at the time”, piloting that rocket-powered projectile through Mach Six, over 4,000 miles per hour, . . . while Russ was shouting in his ear and jamming the channel. Pete came in to tell him: “Loud and clear, R.”

    Instead of a Court Martial, or even a rebuke for H, Pete Knight had the class to show up at some ridiculous time in the alleged morning to give an elbow in the ribs to Russ Henderson, a three-striper radio fixer. That flight established a world record, to be broken later in Pete Knight’s last flight, when he went into space at 4,500 MPH, in an airplane, a record which still stands. But in my eyes, he never exceeded that Act of Class.


  22. I was sitting alert in a F-106, and had a friend who was involved in the X-15 program. He invited me out to see the bird, and to watch a recovery from their mobile unit. I was impressed with the whole thing, but what really got my attention was the landing profile — at least for this flight. He called high key at 50,000 ft and Mach 1.5. From there it was just a 360 degree circle, and he was on the runway. Some bird!


  23. I have to admit that I read every word of every post here and the only thing I wish is that I had read a little slower and had one of those cold gin and vermouth beverages in hand when I started. I felt like I stumbled into a midnite bull session at the Ramstein kitchen at midnite and was allowed to sit at the table next to you guys! Even us Army boys have to admit to flybiys did some amazing things. Thank you!


  24. My Name is Skip Hickey and I was lead flying QualitiesEngineer in the F -15 SPO. Around the time of Critical Design review we discovered that , At around 20 Degrees AOA , the f-15 had a roll reversal problem due to Advers yaw similar to the sImilar to the F-4 with augmentation disengaged. I fely thia was unacceptable because it would lead to departure and spin. I felt that, twith Augmentation off the pilot shgould be able to roll in the correct direction by using the Rudder,
    Our Chief Engineer was Fred Rall and the Chief of Test was Col.Jim Woods. Pete Knight was deputy in the tese office. Now Col. Woods set up a group of pilots called the SAP or Systems Application Panel, chaired by Col. Knight.This was a gropup of about 4 pilots, that had both test and Combat experience. To keep a long story short, I briefed the SAP Panel about the problem, told them all the things we had
    tried to fix the problem and that MCAIR was not interested in pursuing the problem further. Pete Knight stood up after my briefing and said” Hickey, your right and your wrong!!! Pilot’s fly with their feet on the floor.” Fred rall turned to the phone on his desk, called his counterpart at MCAIR and told them the results of our meeting anmd Pete knight’s comments… and that is why we have the Aileron Rudder interconnect and roll washout in the F-15 CAS?hydromechanical control system

    And someday I’ll write about my battle about the flying qualities requirements for the F-15 and how Col. Bob White svved my Job

    It was my great fortune to have worked with these men


  25. I remember that and that time.. I was 25 yr’s old and had just joined the Navy….Remember the SR71 at Sig… the fuel leak on that ramp put me TAD to Ramp Repaire…..Loved it all…Best 30 year’s of my life…And it’s what I stand for today….Great Read…..Master Chief Robert Frost…(ret) Jones, OK.


  26. I served as a Jet Mechanic in the USAF SAC ’66-’70 and have been in Civil Air Patrol for 19 years. I have the opportunity to meet fellow CAP Officer Scott Crossfield, work as a docent on an A-12, Seen SR-71 fly, visit Museums all over the US. Help guide many cadets to careers flying all sorts of planes in the Military.I never get tired of reading stories like this. Thank you


  27. A great article, until the totally extraneous mention of the gay marriage issue – a fact that has absolutely nothing to do with the article and subject matter and serves no purpose.


  28. “X-15A-2 aircraft number 56-6671”

    It would be more correct to say, the X-15A-2, the second of only three built, with USAF serial 56-6671.


  29. Minor quibble , if you define airplane as a vehicle which takes off underits own power and has ability to execute go around after missed approach, X-15 is not an airplane (but neither is Wright flyer!). Then gastest airplane is probably YF-12 which flew before X-15. YF-12 designed with slide rule or so I’m told. I believe external config of X-15 was dictated by NASA?


    1. This was a really great read..thanks to everyone that played a part in the X-15 project..way to go. You have some great stories to tell.


  30. Rembering participation in David Clark MC-2 Full Pressure training for X-15 test pilots while working in Bldg. 248, Area B at Wright-Patterson Air Force Base while a University of Dayton student . Helped Air Force equipment personnel conduct pre-fitcheck and pilots post vacuum chamber training suit checkout.


  31. You describe sonic booms as occurring when the sound barrier is broken, i.e. a moment in time. And how no more sonic booms occurred when higher speeds were reached. This is incorrect. A supersonic plane creates a continual sonic boom as it travels across the ground. You only hear it as a “boom” when it passes over you. People down flight hear it as well, only later when it crosses over them.


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