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First Reusable Space Vehicle

Thirty-six years ago this week, the Space Shuttle Columbia completed the second orbital space mission of the Space Shuttle Program. Designated STS-2, the mission marked the first reuse of a space vehicle for manned orbital flight.

America’s early manned spacecraft – Mercury, Gemini and Apollo – were single-flight vehicles. That is, a new spacecraft was required for each space mission. This was appropriate for meeting the aims of the early space program which concentrated on getting America to the moon before the end of the 1960’s.

The concept of space vehicle reusability came into vogue with the introduction of the Space Transportation System (STS). The original goal of the STS was to provide frequent and routine access to space via a fleet of Space Shuttle vehicles. For the STS to achieve economic viability, this meant flying a Space Shuttle once every two weeks. History records that this projected flight rate was much too optimistic.

The Space Shuttle vehicle was ultimately configured as a 3-element system consisting of (1) a winged orbiter, (2) a pair of solid rocket boosters (SRB’s) and (3) an external tank (ET). Both the orbiter and the SRB’s were designed to be reusable. The ET would be the only disposable element of the system since higher costs would be incurred in the recovery and refurbishment of this piece of flight hardware than in simply using a new one for each flight.

The Space Shuttle was designed to haul large payloads; on the order of 60,000 and 50,00 lbs into and out of orbit, respectively. With a maximum landing weight of 230,000 lbs, the Space Shuttle Orbiter needed wings to generate the required aerodynamic lift force. Wings were needed to satisfy the Orbiter’s 1,100-nm entry cross range requirement as well.

Following the successful first flight (STS-1) of the Space Shuttle Columbia in April of 1981, preparations began immediately to ready the Orbiter for its equally monumental second flight. The STS-2 flight crew would consist of Commander Joe Henry Engle and Pilot Richard Harrison Truly. STS-2 would be the first orbital spaceflight for both men.

On Thursday, 12 November 1981, the Space Shuttle Columbia lifted-off at 15:09:59 UTC from Cape Canaveral’s LC-39A. Ascent flight was nominal and Columbia was placed into a 125-nm x 120-nm orbit. At this point, Columbia became the first manned spacecraft to achieve Earth-orbit twice. It was an extra special occasion for Richard Truly inasmuch as it was his 44th birthday.

Engle and Truly anticipated 5-days in orbit with their celestial steed. However, one of Columbia’s three fuel cells failed early-on and the mission was reduced to just over two days. Nonetheless, the crew achieved 90 percent of the mission’s goals. They even remained awake during a scheduled sleep period to exercise the new Canadian Remote Manipulator System (RMS).

On Saturday, 14 November 1981, Columbia and her crew successfully completed STS-2 by landing on Rogers Dry Lake at Edwards Air Force Base, California. Main gear touchdown occurred at 21:23:11 UTC. Joe Engle flew the entire reentry manually. He holds the distinction of being the only pilot to manually fly a lifting space vehicle all the way from orbit to landing. Engle completed a total of 29 Programmed Test Input (PTI) aerodynamic maneuvers in the process.

STS-2 was a monumental success. Columbia became the first space vehicle to be reused for manned orbital space operations. Other Orbiters would follow including Challenger, Atlantis, Discovery, and Endeavor. The final mission of the Space Shuttle Program (STS-135) was flown by Atlantis in July 2011.

As a footnote, Joe Engle went on to command one more Space Shuttle mission in 1985 (STS-51I). He retired from the USAF in November of 1986. Richard Truly served as Commander of STS-8 in 1983. That mission featured the first night launch and landing of the Space Shuttle. Richard Truly also served as NASA Administrator from May of 1989 to May of 1992.

Posted in Aerospace, History

X-15: Beyond Mach 6

Fifty-six years ago today, the USAF/NASA/North American X-15 became the first manned aircraft to exceed Mach 6. United States Air Force test pilot Major Robert M. White was at the controls of the legendary hypersonic flight research aircraft.

The North American X-15 was the first manned hypersonic aircraft. It was designed, engineered, constructed and first flown in the 1950’s. As originally conceived, the X-15 was designed to reach 4,000 mph (Mach 6) and 250,000 feet. Before its flight test career was over, the type would meet and exceed both performance goals.

North American built a trio of X-15 airframes; Ship No. 1 (S/N 56-6670), Ship No. 2 (56-6671) and Ship No. 3 (56-6672). The X-15 measured 50 feet in length, had a wing span of 22 feet and a GTOW of 33,000 lbs. Ship No. 2 would later be modified to the X-15A-2 enhanced performance configuration. The X-15A-2 had a length of 52.5 feet and a GTOW of around 56,000 lbs.

The Reaction Motors XLR-99 rocket engine powered the X-15. The small, but mighty XLR-99 generated 57,000 pounds of sea level thrust at full-throttle. It weighed only 910 pounds. The XLR-99 used anhydrous ammonia and LOX as propellants. Burn time varied between 83 seconds for the stock X-15 and about 150 seconds for the X-15A-2.

The X-15 was carried to drop conditions (typically Mach 0.8 at 42,000 feet) by a B-52 mothership. A pair of aircraft were used for this purpose; a B-52A (S/N 52-003) and a B-52B (S/N 52-008). Once dropped from the mothership, the X-15 pilot lit the XLR-99 to accelerate the aircraft. The X-15A-2 also carried a pair of drop tanks which provided propellants for a longer burn time than was possible with the stock X-15 flight.

The X-15 employed both aerodynamic and reaction flight controls. The latter were required to maintain vehicle attitude in space-equivalent flight. The X-15 pilot wore a full-pressure suit in consequence of the aircraft’s extreme altitude capability. The typical X-15 drop-to-landing flight duration was on the order of 10 minutes. All X-15 landings were performed deadstick.

On Thursday, 09 November 1961, USAF Major Robert M. White would fly his 11th X-15 mission. The X-15 and White had already become respectively the first aircraft and pilot to hit Mach 4 and Mach 5. On this particular day, White would be at the controls of X-15 Ship No. 2. The planned maximum Mach number for the mission was Mach 6.

At 17:57:17 UTC of the aforementioned day, X-15 Ship No. 2 was launched from the B-52B mothership commanded by USAF Captain Jack Allavie. Bob White lit the XLR-99 and pulled into a steep climb. Mid-way through the climb, White pushed-over and ultimately leveled-off at 101,600 feet. XLR-99 burnout occurred 83 seconds after ignition. At this point, White was traveling at 4,093 mph or Mach 6.04.

On this record flight, the X-15 was exposed to the most severe aerodynamic heating environment it had experienced to date. Decelerating through Mach 2.7, the right window pane on the X-15’s canopy shattered due to thermal stress. The glass pane remained intact, but White could not see out of it. Fortunately, he could see out of the left pane and made a successful deadstick landing on Rogers Dry Lake at Edwards AFB.

For his Mach 6+ flight, Bob White was a recipient of both the 1961 Collier Trophy and the Iven C. Kincheloe Award. The year before, White had received the Harmon Trophy for his X-15 flight test work. He would go on to fly the X-15 to a still-standing FAI altitude record of 314,750 feet in July of 1962. For this accomplishment, White was awarded USAF Astronaut Wings.

Bob White flew the X-15 a total of sixteen (16) times. He was one (1) of only twelve (12) men to fly the aircraft. White left X-15 Program and Edwards AFB in 1963. He went on to serve his country in numerous capacities as a member of the Air Force including flying 70 combat missions in Viet Nam. He returned to Edwards AFB as AFFTC Commander in August of 1970.

Major General Robert M. White retired from the United States Air Force in 1981. During his period of military service, he received numerous decorations and awards including the Air Force Cross, Distinguished Service Medal, Silver Star with three oak leaf clusters, Legion of Merit, Distinguished Flying Cross with four oak leaf clusters, Bronze Star Medal, and Air Medal with 16 oak leaf clusters.

Bob White was a true American hero. He neither sought nor received much notoriety for his many accomplishments. He served his country and the aviation profession well. Bob White’s final flight occurred on Wednesday, 17 March 2010. He was 85 years of age.

Posted in Aerospace, History

Gemini XII

Fifty-one years ago this month, NASA’s pioneering manned spaceflight program, Project Gemini, was brought to a successful conclusion with the 4-day flight of Gemini XII. Remarkably, the mission was the tenth Gemini spaceflight in 20 months.

Boosted to Earth orbit by a two-stage Titan II launch vehicle, Gemini XII Command Pilot James A. Lovell, Jr. and Pilot Edwin E. “Buzz” Aldrin, Jr. lifted-off from Cape Canaveral’s LC-19 at 20:46:33 UTC on Friday, 11 November 1966. The flight was Lovell’s second trip into space and Aldrin’s first.

Like almost every Gemini mission before it, Gemini XII was not a glitch-free spaceflight. For instance, when the spacecraft’s rendezvous radar began acting oddly, the crew had to resort to sextant and chart to complete the last 65 nautical miles of the rendezvous with their Agena Target Vehicle. But, overcoming this and other obstacles served to provide the experience and instill the confidence needed to meet the truly daunting challenge that lay ahead; landing on the Moon.

Unquestionably, Gemini XII’s single most important contribution to the United States manned space effort was validating the notion that a well-trained astronaut could indeed do useful work in an Extra-Vehicular Activity (EVA) environment. The exhausting and dangerous EVA experiences of Gene Cernan on Gemini IX and Dick Gordon on Gemini XI brought into sharp focus the challenge of performing even seemingly simple work assignments outside the Gemini spacecraft.

Buzz Aldrin performed a trio of EVA’s on Gemini XII. Two of these involved standing in his seat with the hatch open. The third involved a tethered EVA or space walk. On the latter, Aldrin successfully moved about the exterior of the Gemini-Agena combination without exhausting himself. He also used a special-purpose torque wrench to perform a number of important work tasks. Central to Aldrin’s success was the use of foot restraints and auxiliary tethers to anchor his body while floating in a weightless state.

Where others had struggled and not been able to accomplish mission EVA goals, Buzz Aldrin came off conqueror. One of the chief reasons for his success was effective pre-flight training. A pivotal aspect of this training was to practice EVA tasks underwater as a unique means of simulating the effects of weightlessness. This approach was found to be so useful that it has been used ever since to train American EVA astronauts.

Lovell and Aldrin did many more things during their highly-compressed 4-day spaceflight in November of 1966. Multiple dockings with the Agena, Gemini spacecraft maneuvering, tethered stationkeeping exercises, fourteen scientific experiments, and photographing a total eclipse occupied their time aloft.

On Tuesday, 15 November 1966, during their 59th orbit, a tired, but triumphant Gemini XII crew returned to Earth. The associated reentry flight profile was automated; that is, totally under the control of a computer. This feat was yet another first and vital accomplishment for Project Gemini. Splashdown occurred in the West Atlantic Ocean at 19:21:04 UTC.

While Gemini would fly no more, both Lovell and Aldrin certainly would. In fact, both men would play prominent roles in several historic flights to the Moon. Jim Lovell flew on Apollo 8 in December 1968 and Apollo 13 in April 1970. And of course, Buzz Aldrin would walk on the Moon at Mare Tranquilitatis in July 1969 as the Lunar Module Pilot for Apollo 11.

Posted in Aerospace, History

Faster Than a Speeding Bullet

Fifty years ago this month, USAF Major William J. “Pete” Knight piloted the fabled USAF/North American X-15A-2 hypersonic flight research aircraft to a record speed of 4,520 mph – roughly a mile and a quarter per second. This is about 50 percent faster than the highest speed ever attained by a “speeding bullet”.

North American’s original X-15 production run consisted of three (3) aircraft. The X-15A-2 was a rebuild of the 2nd airframe (S/N 56-6671) which had been severely damaged during an emergency landing at Mud Lake, Nevada in November of 1962.

The rebuilt aircraft was configured with a pair of droppable propellant tanks that allowed the type’s XLR-99 rocket engine to operate 60 seconds beyond the stock X-15’s 80-second burn time. Among other modifications, the aircraft also carried a pylon-mounted dummy ramjet in the ventral region of the aft fuselage.

With the addition of the external propellant tanks, the X-15A-2 was really a three-stage vehicle. The first stage was the NASA NB-52B mothership which launched the X-15 at Mach 0.82 and 45,000 feet. The second stage consisted of the propellant-laden external tanks which were jettisoned at Mach 2.0 and 70,000 feet. The third stage was the X-15A-2 with its entire internal propellant load.

Due to the increased speed of the X-15A-2, the aircraft was covered with Martin MA-25S ablator to protect it from the higher aerodynamic heating loads. The baseline ablator was pink in color and gave the X-15A-2 a rather odd appearance. Fortunately, application of a white wear/sealer over the ablator gave the aircraft a more dignified look.

On Tuesday, 03 October 1967, Pete Knight and the X-15A-2 dropped away from the NB-52B (S/N 52-008) at the start of the X-15 Program’s 188th mission. Knight ignited the XLR-99 rocket engine and executed a pull-up followed by a pushover to level flight at a little over 102,000 feet. Aircraft speed at XLR-99 burnout was 4,520 mph (Mach 6.7).

As the aircraft decelerated following burnout, Knight executed a series of pre-planned flight maneuvers to acquire vital aerodynamics data. However, passing through Mach 5.5, he received an indication in the cockpit that a high temperature condition existed in the XLR-99 engine bay.

Knight attempted to jettison the aircraft’s remaining propellants, but to no avail. The jettison tubes were welded shut by whatever was happening in the engine bay. This meant he would land heavier and faster than usual. Fortunately, Knight’s piloting skills allowed him to get the X-15A-2 on to Rogers Dry Lake in one piece.

As flight support personnel inspected the X-15A-2 airframe following Knight’s emergency landing, they were alarmed at what they found. The aft ventral region of the aircraft had incurred significant thermal damage. Further, the dummy ramjet was gone.

As reported in the classic NASA document, TM-X-1669, higher-than-expected aerodynamic heating levels were responsible for the damage to the X-15A-2.

First, shock wave/boundary layer interaction heating on the lower fuselage just ahead of the pylon (1) completely destroyed the ablator in that region and (2) penetrated the Inconel-X airframe structure. This introduced very high temperature air into the X-15 engine bay.

Second, impingement of the dummy ramjet nose shock on the detached bow shock coming off of the pylon produced a shear layer that focused on the pylon leading edge. The resulting heating rates were of sufficient magnitude and duration to both burn away the pylon ablator and burn through the pylon structure. The weakened pylon structural attachment eventually failed and the dummy ramjet departed the main airframe.

Pete Knight will forever hold the record for the fastest X-15 flight. However, the X-15A-2 never flew again. Only 11 more flights remained in the X-15 Program at the time. A lack of time and funding meant that little was to be gained by repairing the thermally-damaged aircraft.

As for the final disposition of the X-15A-2 (S/N 56-6671), the aircraft’s remaining ablator was removed with its external surface cleaned-up and original markings restored. The aircraft now resides in a place of honor at the National Museum of the United States Air Force located at Wright-Patterson AFB in Dayton, Ohio.

Posted in Aerospace, History

Joining the Fleet

Thirty-two years ago this month, the Space Shuttle Atlantis was launched on its maiden spaceflight. Known as Mission STS-51J, the flight made Atlantis the fourth member of the Space Shuttle Orbiter fleet to reach Earth orbit.

Mission STS-51J marked the twenty-first orbital flight of the Space Shuttle Program. The primary objective of Atlantis’ first mission was to deploy a Department of Defense (DoD) satellite payload to geostationary orbit. The all-military crew included Commander Karol J. Bobko, Pilot Ronald J. Grabe, Mission Specialists David C. Hilmers and Robert L. Stewart, and Payload Specialist William A. Pailes.

Although classified at the time, the STS-51J payload is suspected to have consisted of a pair of Defense Satellite Communications System (DSCS) satellites. The function of these Lockheed-developed spacecraft was to provide a secure communications capability in support of vital military installations situated across the globe.

Atlantis was launched from LC-39A at Cape Canaveral, Florida on Thursday, 03 October 1985. Lift-off time occurred at 15:15:30 UTC. The new orbiter was successfully inserted into a near-circular orbit having a mean altitude of 219-nm. Orbital inclination and period were 28.5-deg and 94.2 minutes, respectively.

Following deployment from Atlantis’ payload bay, a single Boeing Inertial Upper Stage (IUS) successfully propelled the pair of DSCS satellites into geostationary orbit. With each satellite weighing 5,760 lbs, the total DSCS-IUS stack tipped the scales at 44,020 lbs.

Atlantis orbited the globe 64 times before returning to Earth on Monday, 07 October 1985. The Orbiter touched-down on Rogers Dry Lake at Edwards Air Force Base, California at 17:00:08 UTC. Total mission time was 97 hours, 44 minutes and 38 seconds. From lift-off to landing, Atlantis and her crew flew a total distance of 1,462,203 nm.

History records that Atlantis flew 33 (24.4%) of the 135 missions flown over the life of the Space Shuttle Program. During an “operational” flight career spanning 1985 to 2011, Atlantis and her crews contributed immensely to American spaceflight. Key among many accomplishments were helping to build the International Space Station (ISS), refurbishing the Hubble Space Telescope (HST), launching of the Magellan Probe to Venus, and launching the Galileo Probe to Jupiter.

Like her other stable mates, Atlantis no longer graces the heavens with her presence. She had the honor (?) of flying the final Space Shuttle mission (STS-135) in July of 2011. Now eternally rooted to the ground, Atlantis resides on public display at NASA’s Kennedy Space Center (KSC) in Florida.

Posted in Aerospace, History

Through the Sonic Barrier

Seventy years ago this week, the rocket-powered USAF/Bell XS-1 experimental aircraft exceeded the speed of sound when it reached a maximum speed of 700 mph (Mach 1.06) at 45,000 feet.

Bell Aircraft Corporation of Buffalo, New York built three copies of the XS-1 under contract to the United States Army Air Forces (USAAF). The aircraft were designed to approach and then fly beyond the speed of sound.

The Bell XS-1 was 31-feet in length and had a wing span of 28 feet. Gross take-off weight was around 12,500 lbs. The aircraft had an empty weight of about 7,000 lbs. Propulsion was provided by a Reaction Motors XLR-11 rocket motor capable of generating a maximum thrust of 6,000 lbs.

On the morning of Tuesday, 14 October 1947, the XS-1 (S/N 46-062) dropped away from its B-29 mothership (S/N 45-21800) as the pair flew at 220 mph and 20,000 feet. In the XS-1 cockpit was USAAF Captain and World War II ace Charles E. Yeager. The young test pilot had named the aircraft Glamorous Glennis in honor of his wife.

Following drop, Yeager sequentially-lit all four XLR-11 rocket chambers during a climb and push-over that ultimately brought him to level flight around 45,000 feet. The resulting acceleration profile propelled the XS-1 slightly beyond Mach 1 for about 20 seconds. Yeager then shutdown the rocket, decelerated to subsonic speeds, and landed the XS-1 on Muroc Dry Lake at Muroc Army Airfield, California.

The world would not find out about the daring exploits of 14 October 1947 until December of the same year. As it was, the announcement came from a trade magazine that even today is sometimes referred to as “Aviation Leak”.

Today, Glamorous Glennis is prominently displayed in the Milestones of Flight hall of the National Air and Space Museum located in Washington, DC. For his intrepid piloting efforts in breaking the sound barrier, Chuck Yeager was a co-recipient of the 1948 Collier Trophy.

Posted in Aerospace, History

Back in the Saddle

Twenty-nine years ago today, the Space Shuttle Discovery and her five man crew landed on Rogers Dry Lake at Edwards Air Force Base to successfully complete the Return-to-Flight (RTF) mission of STS-26. The flight signaled a resumption of the Space Shuttle Program after a 32-month hiatus in manned spaceflight resulting from the Challenger disaster.

Well chronicled is the tragic loss of the Space Shuttle Challenger and its crew of seven on Tuesday, 28 January 1986. Following lift-off at 16:38 UTC from Cape Canaveral’s LC-39B, the launch vehicle disintegrated 73 seconds into flight. The presidentially-appointed Rogers Commission concluded that the primary cause was failure of an O-ring seal in a field joint of the right Solid Rocket Booster (SRB).

While the SRB O-ring failure was the physical cause of the Challenger mishap, the Rogers Commission brought to light a more fundamental and disturbing reason for the tragedy. Specifically, the very decision to launch Challenger on that unusually cold January morning in Florida was fundamentally flawed.

As masterfully delineated in Dianne Vaughan’s “The Challenger Launch Decision”, a culture of deviance with respect to Shuttle flight safety issues had slowly developed at NASA. Pressure to launch, scarce resources and organizational disconnects contributed to NASA management’s blind spot when it came to Shuttle flight safety. The SRB contractor was culpable as well and for the same reasons.

Following redesign and testing of the SRB field joints and the implementation of a myriad of other fixes, NASA prepared to return the Shuttle to flight. The mission was designated as STS-26. To the Space Shuttle Discovery would go the honor of and the responsibility for flying the RTF mission. STS-26 was to be a five day orbital mission.

A five-member crew was selected by NASA to fly STS-26. Each crew member had spaceflight experience. You remember their names. Mission Commander Frederick H. “Rick” Hauck, Pilot Richard O. Covey, and Mission Specialists John M. “Mike” Lounge, George D. “Pinky” Nelson and David C. Hilmers.

Discovery and her brave crew lifted-off from at 15:37 UTC on Thursday, 29 September 1988 from the very same location that Challenger did; LC-39B at Cape Canaveral, Florida. Millions watched that day. Some were in the big crowds that formed in and around the Cape complex. Most observed the event on television. Many prayed.

All who watched Discovery lift-off that day could not forget the previous Shuttle flight. Indeed, they remembered what happened just after the CAPCOM’s call: “Challenger, go at throttle-up.” (Ironically, Richard Covey was the CAPCOM who made that very call.) Today, they heard a similar call over the Shuttle communications network: “Discovery, go at throttle-up.” A collective breath was held. After throttle-up, Discovery continued all the way to orbit. YES!!!

In comparison with the launch, initial climbout, and ascent into space, the remainder of the mission seemed somewhat anti-climatic. A Tracking and Data Relay Satellite (TDRS) was deployed from Discovery’spayload bay to replace the one lost in the Challenger explosion. A multitude of space experiments was conducted by the crew. Fairly standard stuff. Only deboost, the rigors of reentry and the typical dead-stick landing lay ahead.

Discovery landed on Runway 17 at Edwards Air Force Base on Monday, 03 October 1988. Main gear touchdown occurred at 16:37 UTC. Approximately, 450,000 American’s witnessed Discovery’s landing in person. A few who did had witnessed its launch in person as well.

The emotion that attended Discovery’s landing in October 1988 was simply overwhelming. Indeed, the experience was an integral part of the healing process for a nation that still grieved the loss of Challenger and her crew. A TIME magazine cover page headline the following week excitedly read: “Whew! America Returns to Space” And indeed it had.

Posted in Aerospace, History

Final Flight: Bell X-2

Sixty-one years ago today, the No. 1 USAF/Bell X-2 rocket-powered flight research aircraft reached a record speed of 2,094 mph with USAF Captain Milburn G. “Mel” Apt at the controls. However, triumph quickly turned to tragedy when the aircraft departed controlled flight, crashed to destruction, and Apt perished.

Mel Apt’s historic achievement came about because of the Air Force’s desire to have the X-2 reach Mach 3 before turning it over to the National Advisory Committee For Aeronautics (NACA) for further flight research testing. Just 20 days prior to Apt’s flight in the X-2, USAF Captain Iven C. Kincheloe, Jr. had flown the aircraft to a record altitude of 126,200 feet.

On Thursday, 27 September 1956, Apt and the X-2 (Ship No. 1, S/N 46-674) dropped away from the USAF B-50 mothership at 30,000 feet and 225 mph. Despite the fact that Mel Apt had never flown an X-aircraft, he executed the flight profile exactly as briefed. In addition, the X-2′s twin-chamber XLR-25 rocket motor burned propellant 12.5 seconds longer than planned. Both of these factors contributed to the aircraft attaining a speed in excess of 2,000 mph.

Apt and his aerial steed hit a peak Mach number of 3.2 at an altitude of 65,000 feet. Based on previous flight tests as well as flight simulator sessions, Apt knew that the X-2 had to slow to roughly Mach 2.4 before turning the aircraft back to Edwards. This was due to degraded directional stability, control reversal, and aerodynamic coupling issues that adversely affected the X-2 at higher Mach numbers.

However, Mel Apt was now faced with a difficult decision. If he waited for the X-2 to slow to Mach 2.4 before initiating a turn back to Edwards Air Force Base, he quite likely would not have enough energy and therefore range to reach Rogers Dry Lake. On the other hand, if he decided to initiate the turn back to Edwards at high Mach number, he risked having the X-2 depart controlled flight. Flying in a coffin corner of the X-2’s flight envelope, Apt opted for the latter.

As Apt increased the aircraft’s angle-of-attack, the X-2 departed controlled flight and subjected him to a brutal pounding. Aircraft lateral acceleration varied between +6 and -6 g’s. The battered pilot ultimately found himself in a subsonic, inverted spin at 40,000 feet. At this point, Apt effected pyrotechnic separation of the X-2′s forebody which contained the cockpit and a drogue parachute.

X-2 forebody separation was clean and the drogue parachute deployed properly. However, Apt still needed to bail out of the X-2′s forebody and deploy his personal parachute to complete the emergency egress process. However, it was not to be. Mel Apt ran out of time, altitude, and luck. The young pilot lost his life when the X-2 forebody from which he was trying to escape impacted the ground at a speed of one hundred and twenty miles an hour.

Mel Apt’s flight to Mach 3.2 established a record that stood until the X-15 exceeded it in August 1960. However, the price for doing so was very high. The USAF lost a brave test pilot and the lone remaining X-2 on that fateful day in September 1956. The mishap also ended the USAF X-2 Program. NACA never did conduct flight research with the X-2.

However, for a few terrifying moments, Mel Apt was the fastest man alive.

Posted in Aerospace, Final Flight, History

Hypersonic ASSET

Fifty-four years ago today, the first ASSET flight test vehicle (ASV-1) successfully flew 1,600 nm down the Eastern Test Range (ETR) following launch from Cape Canaveral, Florida. Boosted atop a Thor launch vehicle, the hypersonic glider reached a maximum velocity of 10,900 mph (Mach 12).

The Aerothermodynamic/Elastic Structural Systems Environmental Tests (ASSET) Program was a United State Air Force flight research effort aimed at exploring hypersonic lifting entry. Programmatic objectives included evaluation of hypersonic lifting vehicle (1) reentry aerodynamic and aerothermodynamic phenomena (2) structural design concepts, and (3) panel flutter characteristics and body flap oscillatory pressures.

The basic ASSET vehicle configuration was a 70-deg delta planform wing with highly-radiused leading edges. The windward surface of this wing was flat and had a 10-deg break in slope roughly two-thirds of the way back from the nose. A blunted cone-cylinder combination was raked into the leeward surface of the wing to form the fuselage of the vehicle. The aft portion of the vehicle was terminated with a flat base region.

There were two (2) types of ASSET flight vehicles. The Aerothermoelastic Vehicle (AEV) variant was flown to investigate windward panel flutter characteristics and body flap oscillatory pressures. A pair of these vehicles were flown. Each weighed AEV weighed 1,225 lbs and was launched into a suborbital flight path by a Douglas Thor booster.

The Aerothermodynamic Structural Vehicle (ASV) variant was flown to determine external airframe surface temperature, heat flux and pressure distributions in hypersonic flight. These data were used to evaluate materials and structural concepts under reentry conditions. A quartet of these vehicles were flight tested. Each ASV weighed 1,130 lbs and was boosted by a Thor-Delta launch vehicle.

ASSET vehicles were boosted to altitudes between 168 KFT and 225 KFT depending on mission type. AEV entry insertion velocity was roughly 13,000 ft/sec while that for ASV shots varied between 16,000 and 19,500 ft/sec. ASSET performed hypersonic flight maneuvers via a combination of aerodynamic and propulsive controls. The windward-mounted body flap was the lone aerodynamic control surface while a set of 3-axis attitude control thrusters were located in the vehicle’s base region.

The first flight of the ASSET Program (ASV-1) took place on Wednesday, 18 September 1963. ASV-1 lift-off occurred at 09:39 UTC from Cape Canaveral’s LC-17B. Due to booster availability issues, a Thor DSV-2F launch vehicle was used for this mission rather than the higher energy Thor-Delta DSV-2G. Insertion altitude and velocity were 203,200 ft and 16,125 ft/sec, respectively. The ASV-1 mission was highly successful with the exception that the vehicle was lost when it sunk in the South Atlantic during recovery operations.

ASV-1 represented the first time in aerospace history that a lifting vehicle configuration had successfully flown a double-digit Mach number reentry trajectory. Five (5) more ASSET vehicles would fly before completion of the flight research program. The sixth and last mission occurred on Tuesday, 23 February 1965.

The ASSET Program garnered a wealth of first-ever hypersonic vehicle aerodynamic, aerothermodynamic, aerothermoelastic and flight controls data. This priceless information and the valuable experience gained during ASSET contributed significantly to the design and flight testing of the PRIME SV-5D and Space Shuttle Orbiter.

Strangely, only one of the ASSET flight test articles was ever recovered successfully. In particular, ASV-3 was recovered following its 1,800 nm suborbital flight down the Eastern Test Range on Wednesday, 22 July 1964. The recovered airframe is currently on display at the National Museum of the United States Air Force in Dayton, Ohio.

Posted in Aerospace, History

Strange Wings: XP-56 Black Bullet

Seventy-four years ago this month, flight testing of the USAAF/Northrop XP-56 Black Bullet commenced at Army Air Base, Muroc in California. Northrop Chief Test Pilot John W. Myers was at the controls of the experimental pursuit aircraft.

The XP-56 (X for Experimental, P for Pursuit) was an attempt at producing a combat aircraft that had superior speed performance relative to conventional fighter-like airframes of the early 1940’s. Towards this end, designers sought to maximize thrust and minimize weight and aerodynamic drag. The product of their labors was a truly strange aircraft configuration.

The XP-56 was essentially a hybrid flying wing to which was added a stubby fuselage to house the pilot and engine. Power was provided by a single Pratt and Whitney R-2800 radial piston engine driving contra-rotating propellers. A pusher power plant installation was selected in the interest of reducing forebody drag. Gross Take-Off Weight (GTOW) came in at 11,350 lbs.

The XP-56’s wing featured a leading edge sweep of 32 degrees and a span of 42.5 feet. The tiny fuselage length of 27.5 feet necessitated the use of elevons for pitch and roll control. Aft-mounted dorsal and ventral tails contributed to directional stability while yaw control was provided by a rudder mounted in the ventral tail.

Under contract to the United States Army Air Force (USAAF), Northrop built a pair of XP-56 airframes; Ship No. 1 (S/N 41-786) and Ship No. 2 (S/N 42-38353). Top speed was advertised as 465 mph at 25,000 feet while the design service ceiling was estimated to be around 33,000 feet. The XP-56 was a short-legged aircraft, having a predicted range of only 445 miles at 396 mph.

XP-56 Ship No. 1 took to the air for the first time on Monday, 06 September 1943. The scene was Rogers Dry Lake at Army Air Field, Muroc (today’s Edwards Air Force Base) in California. Northrop Chief Test Pilot John W. Myers had the distinction of piloting the XP-56. As described below, this distinction was dubious at best.

Myers actually flew XP-56 Ship No. 1 twice on the type’s inaugural day of flight testing. The first flight was really just a hop in the air. Using caution as a guide, Myers flew only 5 feet off the deck in a 30 second flight that covered a distance on the order of 1 mile. The aircraft registered a top speed 130 mph. While the XP-56 exhibited a nose-down pitch tendency as well as lateral-directional sensitivities, Myers was able to complete the flight.

The XP-56’s second foray into the air nearly ended in disaster. Shortly after lift-off at 130 mph, the XP-56 presented pilot Myers with a multi-axis control problem about 50 feet above the surface of Rogers Dry Lake. The strange-looking ship simultaneously yawed to the left, rolled to the right, and pitched down. Holding the control stick with both hands, it was all the Northrop Chief Test Pilot could do keep the nose up and prevent the XP-56 from diving into the ground.

Myers attempted to throttle-back as his errant steed passed through 170 mph. The anomalous yawing-rolling-pitching motions reappeared at this point, once again testing Myers’ piloting skills to the max. The intrepid pilot was finally able to get the XP-56 back on the ground. Albeit, the landing was more of a controlled crash. All of this excitement took place in about 60 seconds over a two mile stretch of Rogers Dry Lake. John Myers had certainly earned his flight pay for the day.

XP-56 Ship No. 1 was demolished during a take-off accident on Friday, 08 October 1943. Although he sustained minor injuries, Myers survived the incident thanks largely to wearing an old polo helmet to protect his valuable cranium. Following the mishap , Myers said that “the airplane wanted to fly upside down and backwards, and finally did!”

XP-56 Ship No. 2 flew a total of ten (10) flights between March and August of 1944. Northrop test pilot Harry Crosby did the piloting honors this time around. Like Myers, Crosby had his hands full trying to fly the XP56. However, Crosby was able to coax the XP-56 up to 250 mph.

Despite valiant attempts to rectify the XP-56’s curious and dangerous handling qualities, Northrop engineers were never able to satisfactorily correct the little beast’s ills. This, coupled with the facts that the XP-56 (1) did not deliver the promised speed performance and (2) was being eclipsed by rapid developments in aircraft technology, the strange aerial concoction became a faded memory by 1945.

A final thought. Just why the XP-56 was given the nickname of Black Bullet is not clear. Ship No. 1 was bare metal and thus silver in appearance. Ship No. 2 sported a dark grey and green camouflage paint scheme. The Bullet moniker could be in deference to the bullet-like nose of the fuselage. In the final analysis, the name Black Bullet probably just sounded cool and evoked a stirring image of a bullet speeding to the target!

Posted in Aerospace, History
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