Fifty-three years ago this month, the USAF/North American XB-70A Valkyrie reached three times the speed of sound for the first time. This historic aviation achievement took place on the 18th anniversary of the breaking of the sound barrier by the USAF/Bell XS-1.
When it comes to legendary aircraft, aviation enthusiasts speak in almost reverent terms about the XB-70A Valkyrie. Indeed, few aircraft have evoked such utter awe or symbolized better the profound majesty of flight than the “The Great White Bird”. Though its flight history was brief, the XB-70A’s influence on aviation has proven to be of enduring worth.
The Valkyrie measured 185 feet in length, had a wingspan of 105 feet and an empty weight of 210,000 pounds. With a GTOW of 550,000 pounds, it was the heaviest supersonic-capable aircraft of all-time. The aircraft was powered by a six-pack of General Electric YJ93-GE-3 turbojets generating more than 172,000 pounds of thrust in afterburner.
To enhance lift-to-drag ratio and directional stability at high Mach number, the Valkyrie was configured with wing tips that could be deflected downward as much as 65 degrees. Each wing tip was the size of an USAF/Convair B-58A Hustler wing panel. To this day, the XB-70A deflectable wing tip is the largest control surface ever used on an aircraft.
The XB-70A was originally intended to be a supersonic strategic bomber. The aircraft’s mission was to penetrate Soviet airspace at Mach 3 and deliver nuclear ordnance from an altitude of 72,000 feet. However, the rapid ascendancy of Soviet surface-to-air missile capability would compromise the type’s military mission before it even flew.
As a consequence of the above, the Valkyrie ultimately became a high-speed flight research aircraft. Only two (2) copies were constructed and flown. Ship No. 1 (S/N 62-0001) made its maiden flight on Monday, 21 September 1964 while Ship No. 2 (62-0207) first took to the air on Saturday, 17 July 1965.
XB-70A Ship No. 1 became the first Valkyrie to reach Mach 3. It did so while flying at an altitude of 70,000 feet on Thursday, 14 October 1965. The flight crew consisted of North American Aviation test pilot Alvin S. White (aircraft commander) and USAF Colonel Joseph Cotton (co-pilot).
The XB-70A aircraft flew all of their flight research missions out of Edwards Air Force Base in California. Between September of 1964 and February of 1969, a total of 129 XB-70A research flights took places; 83 by Ship No. 1 and 46 by Ship No. 2. A total of nearly 253 flight hours was amassed by the aircraft.
The XB-70A Program made significant contributions to high-speed aircraft technology including aerodynamics, aerodynamic heating, flight controls, structures, materials, and air-breathing propulsion. Lessons-learned from its flight research have been applied to numerous aircraft developments including the B-1A, American SST, Concorde and the TU-144.
XB-70A Ship No. 1 survived the flight test program while Ship No. 2 did not. The latter was destroyed in a mid-air collision with a NASA F-104N on Wednesday, 08 June 1966. Today, XB-70A Ship No. 1 can be seen at the National Museum of the United States Air Force at Wright-Patterson Air Force Base in Dayton, Ohio.
Fifty years ago this month, NASA successfully conducted the first manned Apollo Earth-orbital mission with the flight of Apollo 7. This mission was a critically-important milestone along the path to the first manned lunar landing in July 1969.
The launch of Apollo 7 took place from Launch Complex 34 at Cape Canaveral Air Force Station, Florida at 15:02:45 UTC on Friday, 11 October 1968. The flight crew consisted of NASA astronauts Walter M. Schirra, Donn F. Eisele, and R. Walter Cunningham. Their primary goal was to thoroughly qualify the new Apollo Block II Command Module (CM) during 11 days in space.
Apollo 7 was not only the first flight of the Block II CM, but in fact the first manned mission in the Apollo Program. Apollo 7 also featured the first use of the Saturn IB launch vehicle in a manned mission. Apollo 7′s critical nature stemmed from the tragic Apollo 1 fire that took the lives of Virgil I. (Gus) Grissom, Edward H. White II, and Roger B. Chaffee on Friday, 27 January 1967.
The Apollo 1 fire was attributed to numerous deficiencies in the design, construction, and testing of its Block I CM. The Block II spacecraft flown on Apollo 7 was a major redesign of the Apollo Command Module and was in every sense superior to the Block I vehicle. However, it had taken 21 months to return to flight status and the Nation’s goal of a manned lunar landing within the decade of the 1960′s was in serious jeopardy.
The Apollo 7 crew orbited the Earth 163 times at an orbital altitude that varied between 125 and 160 nautical miles. In that time, they rigorously tested every aspect of their Block II CM. This testing included 8 firings of the Service Propulsion System (SPS) while in orbit. Apollo 7 splashdown occurred in the Atlantic Ocean near the Bermuda Islands at 11:11:48 UTC on Tuesday, 22 October 1968.
The Nation’s Lunar Landing Program overwhelmingly got the unqualified success that it desperately needed from the Apollo 7 mission. The Apollo Block II CM would provide yeoman service throughout the time of Apollo. The spacecraft would also go on to see service in the Skylab and Apollo-Soyuz Test Project programs.
While the technical performance of the Apollo 7 crew was unquestionably superb, their interaction with Mission Control at Johnson Spacecraft Center (JSC) in Houston, Texas was quite strained. The crew suffered from head colds through much of the mission and the food quality was poor. Coupled with Houston’s incessant attempts to cram more tasks into each moment of the mission, Apollo 7 Commander Schirra took charge of his ship and made the ultimate decisions as to what work would be performed onboard the spacecraft.
The flight of Apollo 7 would be Wally Schirra’s last mission in space as he had announced prior to launch. As history records, he holds the distinction of being the only astronaut to have flown Mercury, Gemini, and Apollo space missions.
Interestingly, Apollo 7 was not only Schirra’s last time in space, but it was Donn Eisele’s and Walt Cunningham’s first and last space mission as well. That there is a direct connection between this historical fact and the crew’s insubordinate behavior during Apollo 7 is obvious to the inquiring mind.
Sixty-two 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 descending unit and deploy his personal parachute to complete the emergency egress process. However, such 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 that mark 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.
Sixty-two years ago this month, the USAF/North American F-107A aircraft flew for the first time. The Mach 2-capable fighter-bomber went supersonic on the type’s maiden flight.
The F-107A was designed, developed and tested by North American Aviation (NAA) in the mid-1950’s. With it, the contractor hoped to satisfy Tactical Air Command’s (TAC) need for a front line fighter-bomber. However, Republic Aircraft also had a candidate for the same role; the F-105 Thunder Chief.
The competition between Republic and North American for the TAC fighter-bomber production contract has a story of its own. Suffice it to say here that the competitive effort was (1) extremely close and (2) tinged with political intrigue. In the end, Republic Aircraft reaped the spoils of victory.
Although the F-107A came out on the short end of the stick in the TAC fighter-bomber competition, such did not imply an inferiority in fulfilling the intended role. Indeed, like the Northtrop YF-23’s loss to the General Dynamics YF-22 in the ATF competition of the early 1990’s, North American’s failure to get the nod with the F-107A is still a subject of passionate debate.
The F-107A measured 60.8 feet in length and had a wing span of 36.6 feet. Gross take-off weight was around 41,000 pounds. The aircraft was powered by a single Pratt and Whitney YJ75-P-11 turbojet that produced 15,500 pounds of thrust in military power and 23,500 pounds of thrust in full afterburner.
F-107A longitudinal control was provided by an all-flying horizontal tail. Similarly, an all-flying vertical tail was employed for directional control. Lateral control was provided by a unique 3-segment spoiler-deflector system mounted on each wing. The aircraft was also configured with inboard flaps and leading edge slats for lift augmentation at low speeds.
A unique and prominent feature of the F-107A was its dorsal-mounted air induction system known as the Variable-Area Inlet Duct (VAID). Internally, this unit incorporated a system of adjustable ramps to efficiently decelerate and compress freestream prior to entering the engine compressor face. Ramp deflection scheduling with Mach number was controlled automatically. Ramp boundary layer bleed air was vented from the top of the VAID.
The F-107A carried weapons externally. In addition to wing pylon-mounted stores, the aircraft was designed to carry a single “special weapon” from a semi-submerged recess located on the aircraft ventral centerline. The term “special weapon” means that it was a tactical nuclear bomb. The Sandia-developed store could also be used in combination with a special saddle fuel tank to extend the aircraft’s combat range.
A total of three (3) F-107A aircraft were built and flown. USAF-assigned tail numbers include 55-5118, 55-5119 and 55-5120. On Monday, 10 September 1956, the No. 1 ship (55-5118) took-off from Edwards Air Force Base on its first flight. NAA Chief Test Pilot Robert Baker, Jr. was at the controls. The aircraft attained a maximum Mach number of 1.03 in a 43 minute flight test.
The F-107A could really scream. The type had a maximum climb rate of around 40,000 feet per minute in full afterburner. The maximum demonstrated Mach number attained by the F-107A was Mach 2.18. Program engineers estimated that by increasing the engine inlet area slightly, the F-107A was capable of reaching approximately Mach 2.4.
The trio of F-107A aircraft flew 272 flight tests that totaled 176.5 hours. Included in this testing was successful separation of a special store prototype at Mach 2. Test pilots of note who flew the F-107A included XB-70A pilot Al White and X-15 pilots Scott Crossfield, Bob White, Jack McKay and Forrest Peterson.
Though it never became a production aircraft, the F-107A contributed in significant ways to aviation progress. Indeed, many future aircraft would greatly benefit from F-107A flight control and air induction technology including the A-5 Vigilante, XB-70A, A-12, SR-71, YF-12A and F-15.
The F-107A was the last of NAA’s fighter aircraft which includes such notables as the P-51 Mustang, the F-86 Sabre and the F-100 Super Sabre. While the F-107A has often been referred to in print as the Ultra Sabre, Ultimate Sabre, Super Super Sabre or such, it was never officially assigned a nickname. Alas, there was never an XF-107A or YF-107A designation either. North American Aviation’s TAC fighter-bomber candidate was simply known as the F-107A.
Today, the No. 1 F-107A (55-5118) is displayed at the Pima Air and Space Museum (PASM) in Tucson, Arizona. The No. 2 ship (55-5119) resides at the USAF Museum at Wright-Patterson Air Force Base in Dayton, Ohio. The No. 3 airplane (55-5120) no longer exists as it was relegated to the status of a fire fighting prop and was ultimately destroyed in that role sometime in 1961 or 1962.
Thirty-three years ago today, the USAF/LTV ASM-135 anti-satellite missile successfully intercepted a target satellite orbiting 300 nautical miles above surface of the Earth. The historic test was the first and only time that an aircraft-launched missile successfully engaged and destroyed an orbiting spacecraft.
The United States began testing anti-satellite missiles in the late 1950′s. These and subsequent vehicles used nuclear warheads to destroy orbiting satellites. A serious disadvantage of this approach was that a nuclear detonation intended to destroy an adversary satellite will likely damage nearby friendly satellites as well.
By the mid 1970′s, the favored anti-satellite (ASAT) approach had changed from nuclear detonation to kinetic kill. This latter approach required the interceptor to directly hit the target. The 15,000-mph closing velocity provided enough kinetic energy to totally destroy the target. Thus, no warhead was required.
The decision to proceed with development and deployment of an American kinetic kill weapon was made by President Jimmy Carter in 1978. Carter’s decision came in the aftermath of the Soviet Union’s successful demonstration of an orbital anti-satellite system.
LTV Aerospace was awarded a contract in 1979 to develop the Air-Launched Miniature Vehicle (ALMV) for the USAF. The resulting anti-satellite missile (ASM) system was designated the ASM-135. The two-stage missile was to be air-launched by a USAF F-15A Eagle executing a zoom climb. In essence, the aircraft acted as the first stage of what was effectively a 3-stage vehicle.
The ASM-135 was 18-feet in length and 20-inches diameter. The 2,600-lb vehicle was launched from the centerline station of the host aircraft. The ASM consisted of a Boeing SRAM first stage and an LTV Altair 3 second stage. The vehicle’s payload was a 30-lb kinetic kill weapon known as the Miniature Homing Vehicle (MHV).
The ASM-135 was first tested in flight on Saturday, 21 January 1984. While successful, the missile did not carry a MHV. On Tuesday, 13 November 1984, a second ASM-135 test took place. Unfortunately, the missile failed when the MHV that it was carrying was aimed at a star that served as a virtual target. Engineers went to work to make the needed fixes.
In August of 1985, a decision was made by President Ronald Reagan to launch the next ASM-135 missile against an orbiting US satellite. The Solwind P78-1 satellite would serve as the target. Congress was subsequently notified by the Executive Branch regarding the intended mission.
The historic satellite takedown mission occurred on Friday, 13 September 1985. USAF F-15A (S/N 77-0084), stationed at Edwards Air Force Base, California and code-named Celestial Eagle, departed nearby Vandenberg Air Force Base carrying the ASM-135 test package. Major Wilbert D. Pearson was at the controls of the Celestial Eagle.
Flying over the Pacific Ocean at Mach 1.22, Pearson executed a 3.8-g pull to achieve a 65-degree inertial pitch angle in a zoom climb. As the aircraft passed through 38,000-feet at Mach 0.93, the ASM-135 was launched at a position 200 miles west of Vandenberg. Both stages fired properly and the MHV intercepted the Solwind P78-1 satellite within 6-inches of the aim point. The 2,000-lb satellite was completely obliterated.
In the aftermath of the stunningly successful takedown of the Solwind P78-1 satellite, USAF was primed to continue testing the ASM-135 and then introduce it into the inventory. Plans called for upwards of 112 ASM-135 rounds to be flown on F-15A aircraft stationed at McChord AFB in Washington state and Langley AFB in Virginia. However, such was not to be.
Even before the vehicle flew, the United States Congress acted to increasingly restrict the ASM-135 effort. A ban on using the ASM-135 against a space target was put into effect in December 1985. Although USAF actually conducted successful additional ASM-135 flight tests against celestial virtual targets in 1986, the death knell for the program had been sounded.
In the final analysis, a combination of US-Soviet treaty concerns, tepid USAF support, and escalating costs killed the ASM-135 anti-satellite effort. The Reagan Administration formally cancelled the program in 1988.
While the ASM-135 effort was relatively short-lived, the technology that it spawned has propagated to similar applications. Indeed, today’s premier exoatmospheric hit-to-kill interceptor, the United States Navy SM-3 Block IA anti-ballistic missile, is a beneficiary of ASM-135 homing guidance, intercept trajectory and kinetic kill weapon technologies.
Sixty-two years ago to the day, the rocket-powered USAF/Bell X-2 aircraft established a new altitude record when the vehicle soared to 126,200 feet above sea level. This historic accomplishment took place on the penultimate mission of the type’s troubled 20-flight aeronautical research program.
The X-2 was the successor to Bell’s X-1A rocket-powered aircraft which had recorded maximum speed and altitude marks of 1,650 mph (Mach 2.44) and 90,440 feet, respectively. The X-2 was designed to fly beyond Mach 3 and above 100,000 feet. The X-2’s primary mission was to investigate aircraft flight control and aerodynamic heating in the triple-sonic flight regime.
The X-2 had a gross take-off weight of 24,910 lbs and was powered by a Curtis-Wright XLR-25 rocket motor which generated 15,000-lbs of thrust. Aircraft empty weight was 12,375 lbs. Like the majority of X-aircraft, the X-2 was air-launched from a mothership. In the X-2’s case, an USAF EB-50D served as the drop aircraft. The X-2 was released from the launch aircraft at 225 mph and 30,000 feet.
The day was Friday, 07 September 1956. The pilot for the X-2 maximum altitude mission was USAF Captain Iven Carl Kincheloe, Jr. Kincheloe was a Korean War veteran and highly accomplished test pilot. He wore a partial pressure suit for survival at extreme altitude.
While the dynamic pressure at the apex of his trajectory was only 19 psf, Kincheloe successfully piloted the X-2 with aerodynamic controls only. The X-2 was not configured with reaction controls. Mach number over the top of the trajectory was supersonic (approximately Mach 1.7).
Kicheloe’s maximum altitude flight in the X-2 (S/N 46-674) would remain the highest altitude achieved by a manned aircraft until August of 1960 when the fabled X-15 would fly just beyond 136,000 feet. However, for his achievement on that late summer day in 1956, the popular press would refer to Iven Kincheloe as the “First of the Space Men”.
Forty-three years ago this month, the USAF/NASA/Martin X-24B became the first lifting body to perform an unpowered precision landing on a concrete runway. The feat was pivotal to convincing NASA officials that landing the Space Shuttle Orbiter in an unpowered state was operationally feasible.
Early Space Shuttle Orbiter operational concepts featured the use of a pair of turbojets to provide a powered landing capability. These air breathing engines were to be internally stowed just below the Orbital Maneuvering System (OMS) pods. The turbojets would be deployed and started once the Orbiter had decelerated to high subsonic flight speeds.
While air breathing propulsion would give the Orbiter a loiter and go-around capability, the drawbacks were significant. Jet fuel would have to be carried into and out of earth orbit. The weight of this fuel and the turbojets would severely penalize Orbiter payload capability. Further, the system would increase both the complexity of and cost to Shuttle operations.
As the Shuttle Program grappled with the development of a powered landing capability for the Orbiter, the NASA DFRC flight test community made what appeared to be a rather bold claim. The Orbiter could simply glide all the way to touchdown and land dead-stick. After all, X-planes had been doing so safely and without incident since the late 1940’s.
A leading proponent of unpowered Shuttle landings was NASA DFRC test pilot John Manke. He was convinced that the Orbiter could routinely and safely conduct unpowered precision landings on a concrete runway. If true, the Orbiter could land anywhere a 15,000-foot concrete runway was located.
Manke proposed that the X-24B (S/N 66-13551) lifting body be employed to conduct unpowered precision landings on Runway 04/22 at Edwards Air Force Base. He and fellow test pilot USAF Lt. Col. Michael V. Love practiced low lift-to-drag precision landings using F-104 and T-38 aircraft in preparation for the demonstrations.
On Tuesday, 05 August 1975, John Manke successfully made the first-ever unpowered precision landing of an aircraft on a concrete runway. The X-24B main gear touched-down exactly at the aimpoint situated 5,000 feet down Runway 04/22. On Wednesday, 20 August 1975, Mike Love duplicated the feat.
Following the successful unpowered precision landings with the X-24B lifting body, John Manke was quoted as saying: “We now know that concrete runway landings are operationally feasible and that touchdown accuracies of ±500 feet can be expected.” NASA Space Shuttle Program management concurred and officially adopted the unpowered precision landing concept.
History records that thirty-one years of Orbiter flight operations confirmed the wisdom of that long-ago decision.
Fifty-five years ago today, NASA chief research pilot Joseph A. Walker flew X-15 Ship No. 3 (S/N 56-6672) to an altitude of 354,200 feet. This flight would mark the highest altitude ever achieved by the famed hypersonic research vehicle.
Carried aloft by NASA’s NB-52A (S/N 52-0003) mothership, Walker’s X-15 was launched over Smith Ranch Dry Lake, Nevada at 17:05:42 UTC. Following drop at around 45,000 feet and Mach 0.82, Walker ignited the X-15’s small, but mighty XLR-99 rocket engine and pulled his ship into a steep vertical climb.
The XLR-99 was run at 100 percent power for 85.8 seconds with burnout occurring around 176,000 feet on the way uphill. Maximum velocity achieved was 3,794 miles per hour which translates to Mach 5.58 at the burnout altitude. Following burnout of the XLR-99, Walker’s X-15 gained an additional 178,200 feet in altitude as it coasted to apogee.
Joe Walker went over the top at 354,200 feet (67 miles). Although he did not have much time for sight-seeing, the Earth’s curvature was strikingly obvious to the pilot as he started downhill from his lofty perch. Walker subsequently endured a hefty 5-g’s of eyeballs-in normal acceleration during the backside dive pull-out. The aircraft was brought to a wings-level attitude at 70,000 feet. Shortly after, Walker greased the landing on Rogers Dry Lake at Edwards Air Force Base, California.
The X-15 maximum altitude flight, in which the aircraft’s design altitude was exceeded by more than 100,000 feet, lasted 11 minutes and 8 seconds from drop to nose wheel stop. In that time, Walker and X-15 Ship 3 covered 305 miles in ground range. This mission was Ship No. 3’s 22nd flight and the 91st of the legendary X-15 Flight Research Program.
For Joseph Albert Walker, the 22nd of August 1963 marked his 25th and last flight in an X-15 cockpit. The mission qualified him for Astronaut Wings since he had exceeded the 328,000 foot (100 km) FAI/NASA standard set for such a distinction. However, it would be more than four decades after his historic mission that Walker would be officially be recognized as an astronaut. In a special ceremony conducted at NASA’s Dryden Flight Research Center on Tuesday, 23 August 2005, Joe Walker was posthumously awarded his Astronaut Wings.
Fifty-four years ago today, the fabled North American X-15 hit a speed of 3,590 mph (Mach 5.23) in a flight that reached an altitude of 103,300 feet. While decelerating through Mach 4.2, the nose gear of the aircraft unexpectedly deployed in flight.
The 114th powered flight of the legendary X-15 Program took place on Friday, 14 August 1964. USAF Major Robert A. Rushworth was at the controls of X-15 Ship No. 2 (S/N 56-6671). The mission would be Rushworth’s 22nd flight in the famed hypersonic aircraft.
X-15 drop from the NB-52A (S/N 52-0003) launch aircraft took place over Delamar Dry Lake, Nevada. Seconds later, Rushworth called for 100% power from the X-15’s XLR-99 liquid-fueled rocket engine as he pulled into a steep climb. He subsequently pushed-over and then leveled-off at 103,300 feet.
XLR-99 burnout occurred 80.3 seconds after ignition. At this juncture, the X-15 was traveling at 3,590 mph; better than 5 times the speed of sound. Following rocket motor burnout, the aircraft slowed and began to lose altitude under the influence of weight and aerodynamic drag.
As the Mach meter needle passed through Mach 4.2, Rushworth heard a loud bang from the airframe. The aircraft became hard to control as it gyrated in pitch, yaw and roll. Rushworth was equal to the moment and brought his troubled steed under control. However, the aircraft had an uncommanded sideslip and Rushworth had to use left aileron to hold the wings level.
Gathering his wits, Rushworth realized that the loud bang he heard was very similar to that which occurred when the nose gear was deployed in the landing pattern. Unaccountably, the X-15 nose gear had deployed in supersonic flight. An unsettling confirmation of Rushworth’s hypothesis came when the pilot spotted smoke, quite a bit of it, in the X-15 cockpit.
As Rushworth neared Edwards Air Force Base, chase aircraft caught up with him and confirmed that the nose gear was indeed down and locked. Further, the tires were so scorched from aerodynamic heating that they probably would disintegrate during touchdown on Rogers Dry Lake. They verily did.
Despite his tireless nose gear, Rushworth was able to control the rollout of his aircraft fairly well on the playa silt. He brought the X-15 to a stop and deplaned. Man and machine had survived to fly another day.
Post-flight analysis revealed that expansion of the X-15 fuselage due to aerodynamic heating was greater than expected. The nose gear door bowed or deformed outward more than anticipated as well. Together, these two anomalies caused the gear uplock hook to bend and release the nose gear. Fixes were subsequently made to Ship No. 2 to prevent a recurrence of the nose gear door deployment anomaly.
Rushworth next flew X-15 Ship No. 2 on Tuesday, 29 September 1964. He reached a maximum speed of 3,542 mph (Mach 5.2) at 97,800 feet. The nose gear door remained locked. However, while decelerating through Mach 4.5, Rushworth heard a bang that was less intense than the previous flight. This time, thermal stresses caused the nose gear door air scoop to deploy in flight. While the aircraft handled poorly, Rushworth managed to get it and himself back on the ground in one piece.
Following another redesign effort, Rushworth took to the air in X-15 Ship No. 2 on Thursday, 17 February 1965. He hit 3,539 mph (Mach 5.27) at 95,100 feet. On this occasion, both the nose gear door and nose gear door scoop remained in place. Unfortunately, the right main landing skid deployed at Mach 4.3 and 85,000 feet.
Thermal stresses were once again the culprit. Despite degraded handling qualities with the landing skid deployed, the valiant Rushworth safely landed the X-15. Upon deplaning, he is reported to have kicked the aircraft in a show of disgust and frustration. Unprofessional maybe, but certainly understandable.
Yet another redesign effort followed in the aftermath of the unexpected main landing skid deployment. This was the third consecutive mission for X-15 Ship No. 2 and Rushworth to experience a thermally-induced landing gear or landing skid deployment anomaly. Happily, subsequent flights of the subject aircraft were free of such vexing problems.
Forty-one years ago this month, the Space Shuttle Orbiter Enterprise successfully completed the first free flight of the Approach and Landing Tests (ALT) Program. NASA Astronauts Fred W. Haise, Jr. and Charles G. “Gordon” Fullerton were at the controls of the pathfinder orbiter vehicle (OV-101).
Developers of the Space Shuttle Orbiter faced the challenge of designing a vehicle capable of flight from 17,500 mph (Mach 28) at entry interface (400,000 ft) to 220 mph (Mach 0.3) at landing. Complicating this task was the fact that the Orbiter flew an unpowered, lifting entry that covered a distance of more than 4,400 nm. Once at the landing site, Shuttle pilots had a single opportunity to land the winged ship.
An Orbiter’s approach to the landing field is quite steep compared to that of a commercial airliner. Whereas the glide slope of the latter is around 2-3 degrees, the Orbiter’s flight path during approach is about 22 degrees below the horizon. Falling like a rock is an apt description of its flight state.
The Space Shuttle Approach and Landing Tests (ALT) involved a series of flight tests intended to verify the subsonic airworthiness and handling qualities of the Orbiter. Conducted at Edwards Air Force Base between February and October 1977, the ALT employed a modified Boeing 747 known as the Shuttle Carrier Aircraft (SCA). The Orbiter Enterprise was attached atop the SCA to hitch a ride to altitude.
The Shuttle ALT consisted of a total of thirteen (13) flight tests; five (5) Captive-Inactive (CI) tests, five (5) Captive-Active (CA) tests and three (3) Free Flight (FF) tests. CI testing was aimed at verifying the handling qualities of the SCA-Orbiter combination in flight. There was no crew was onboard the Orbiter for these tests. CA testing focused on preparing for the upcoming free flight series. A crew flew onboard the Orbiter which remained mated to the SCA.
The ALT Free Flights were where the rubber met the road so to speak. The Enterprise and her crew separated from the SCA at altitudes ranging from between 19,000 and 26,000 ft to test the Orbiter in free flight. Landings were made initially on Rogers Dry Lake (Runway 17) and ultimately on Edwards’ 15,000-ft concrete runway (Runway 22).
The Enterprise was flown in two (2) different configurations. The first involved the use of a tailcone fairing which streamlined the base region of the Orbiter. This increased the Orbiter’s lift-to-drag ratio which decreased the vehicle’s rate of descent. It also reduced the level of buffeting experienced by the SCA’s empennage while the Orbiter rode atop the carrier aircraft.
The second Enterprise configuration flown involved removal of the tailcone. This significantly reduced the Orbiter’s lift-to-drag ratio and correspondingly increased the rate of sink. Indeed, the Orbiter’s descent rate without the tailcone was roughly twice as high as that with the tailcone. Removal of the tailcone also markedly increased the buffet loads sustained by the SCA’s empennage.
ALT Free Flight No. 1 took place on Friday, 12 August 1977. With Fitzhugh L. Fulton, Jr. and Thomas C. McMurtry flying the SCA (N905NA), the Enterprise and her crew of Haise and Fullerton was carried to an altitude of 24,100 ft. At a speed of 310 mph in a slight dive, the big glider cleanly separated from the SCA. Just 321 seconds later, the Orbiter touched-down on Rogers Dry Lake at 213 mph.
ALT Free Flights No. 2-5 were successfully conducted over the next several months. Astronauts Joseph H. Engle and Richard H. Truly flew Enterprise on the second and fourth free flights while Haise and Fullerton manned the Orbiter’s cockpit on the third and fifth missions.
Enterprise flew without the tailcone during the last two ALT flights. As expected, the trip downstairs was rapid. Time of descent from 22,400 ft for Free Flight No. 4 was 154 seconds with a landing speed of 230 mph. Free Flight No. 5 took only 121 seconds to descend 19,000 ft and landed at 219 mph.
ALT Free Flight No. 5 was notable in that (1) the Enterprise made its first landing on concrete and (2) a Pilot-Induced Oscillation (PIO) occurred at initial touchdown. For a few tense moments Command Pilot Haise struggled to keep his skittish steed on the ground. Following several disturbing skips and bounces, the Enterprise finally settled down and rolled to a stop.
The Space Shuttle Approach and Landing Tests (ALT) were a necessary prelude to space for the Orbiter. Indeed, the ALT flights represent the first time that NASA’s new winged reentry vehicle took to the air. Having successfully demonstrated the ability to safely land an Orbiter, the next flight in the Space Shuttle Program would be STS-1 in April 1981. Interestingly, that 2-day mission would come to a successful conclusion when the Columbia landed on Rogers Dry Lake back at Edwards Air Force Base, California.
