Sixty-one years ago this month, the United States Army’s Bumper-WAC No. 7 two-stage rocket reached a maximum speed of 8,213 ft/sec (Mach 9). This concluding flight of the Bumper Program was flown from the Long-Range Proving Ground (LRPG) in Florida.
The Bumper Program was a United States Army effort to reach flight altitudes and velocities never before achieved by a rocket vehicle. The name “Bumper” was derived from the fact that the lower stage would act to “bump” the upper stage to higher altitude and velocity than it (i.e., the upper stage) was able to achieve on its own.
The Bumper Program, which was actually part of the Army’s Project Hermes, officially began on Friday, 20 June 1947. The project team consisted of the General Electric Company, Douglas Aircraft Company and Cal Tech’s Jet Propulsion Laboratory. A total of eight (8) test flights took place between May 1948 and July 1950.
The Bumper two-stage configuration consisted of a V-2 booster and a WAC Corporal upper stage. The V-2′s had been captured from Germany following World War II while the WAC Corporal was a single stage American sounding rocket. The launch stack measured 62 feet in length and weighed around 28,000 pounds.
Propulsion-wise, the V-2 booster generated 60,000 pounds of thrust with a burn time of 70 seconds. The WAC Corporal rocket motor produced 1,500 pounds of thrust and had a burn time of 47 seconds.
The flight of Bumper-WAC No. 1 occurred on Thursday, 13 May 1948. This was an engineering test flight in which the WAC Corporal achieved a peak altitude of 79 miles. Unfortunately, the next three (3) flights were plagued by development problems of one kind or another and failed to achieve an altitude of even 10 miles.
Bumper-WAC No. 5 was fired from WSPG on Thursday, 24 February 1949. The V-2 burned-out at an altitude of 63 miles and a velocity of 3,850 feet per second. The WAC Corporal accelerated to a maximum velocity of 7,550 feet per second and then coasted to an apogee of 250 miles. With generation of a very thin bow shock layer and high aerodynamic surface heating levels, this flight can be considered as the first time a man-made flight vehicle entered the realm of hypersonic flight.
Three (3) more Bumper-WAC missions would follow Bumper-WAC No.5. While Bumper-WAC No. 6 would fly from WSPG, the final two (2) missions were conducted from an isolated Florida launch site in July of 1950. The hot, bug-infested Floridian launch location, springing-up amongst sand dunes and scrub palmetto, would one day become the seat of American spaceflight. It was known then as the Long-Range Proving Ground (LRPG). Today, we know it as Cape Canaveral.
Bumper-WAC No. 7 was supposed to be the first rocket fired from the LRPG. However, Bumper-WAC No. 8 got that honor when No. 7 experienced a glitch on the pad. No. 8 was fired at 13:29 UTC on Monday, 24 July 1950. The mission failed when the rocket motor of the WAC upper stage did not ignite.
On Saturday, 29 July 1950, Bumper-WAC No. 7 was launched from the LRPG. The resulting flight achieved the highest kinematic performance of the Bumper Program. The WAC upper stage burned-out at 8,213 ft/sec (Mach 9) and flew 150 miles downrange. The maximum velocity within the atmosphere was more than 3,200 mph – a record for the time.
The Bumper Program successfully demonstrated the efficacy of the multi-staging concept. Bumper also provided valuable flight experience in stage separation and high altitude rocket motor ignition systems. In short, Bumper played a vital role in helping America successfully develop its ICBM, satellite and manned spaceflight capabilities.
While its historical significance, and even its existence, has been lost to many here in the 21st Century, the Bumper Program played a major role in our quest for the Moon. As such, it will forever hold a hollowed place in the annals of United States aerospace history.
Fifty-years ago this week, Mercury Seven Astronaut Vigil I. “Gus” Grissom, Jr. became the second American to go into space. Grissom’s suborbital mission was flown aboard a Mercury space capsule that he named Liberty Bell 7.
The United States first manned space mission was flown on Friday, 05 May 1961. On that day, NASA Astronaut Alan B. Shepard, Jr. flew a 15-minute suborbital mission down the Eastern Test Range in his Freedom 7 Mercury spacecraft. Known as Mercury-Redstone 3, Shepard’s mission was entirely successful and served to ignite the American public’s interest in manned spaceflight.
Shepard was boosted into space via a single stage Redstone rocket. This vehicle was originally designed as an Intermediate-Range ballistic Missile (IRBM) by the United States Army. It was man-rated (that is, made safer and more reliable) by NASA for the Mercury suborbital mission. A descendant of the German V-2 missile, the Redstone produced 78,000 lbs of sea level thrust.
Shepard’s suborbital trajectory resulted in an apogee of 101 nautical miles (nm). With a burnout velocity of 7,541 ft/sec, Freedom 7 splashed-down in the Atlantic Ocean 263 nm downrange of its LC-5 launch site at Cape Canaveral, Florida. Shepard endured a maximum deceleration of 11 g’s during the reentry phase of the flight.
Mercury-Redstone 4 was intended as a second and confirming test of the Mercury spacecraft’s space-worthiness. If successful, this mission would clear the way for pursuit and achievement of the Mercury Program’s true goal which was Earth-orbital flight. All of this rested on the shoulders of Gus Grissom as he prepared to be blasted into space.
Grissom’s Liberty Bell 7 spacecraft was a better ship than Shepard’s steed from several standpoints. Liberty Bell 7 was configured with a large centerline window rather than the two small viewing ports featured on Freedom 7. The vehicle’s manual flight controls included a new rate stabilization system. Grissom’s spacecraft also incorporated a new explosive hatch that made for easier release of this key piece of hardware.
Mercury-Redstone 4 (MR-4) was launched from LC-5 at Cape Canaveral on Friday, 21 July 1961. Lift-off time was 12:20:36 UTC. From a trajectory standpoint, Grissom’s flight was virtually the same as Shepard’s. He found the manual 3-axis flight controls to be rather sluggish. Spacecraft control was much improved when the new rate stabilization system was switched-on. The time for retro-fire came quickly. Grissom invoked the retro-fire sequence and Liberty Bell 7 headed back to Earth.
Liberty Bell 7’s reentry into the Earth’s atmosphere was conducted in a successful manner. The drogue came out at 21,000 feet to stabilize the spacecraft. Main parachute deployed occurred at 12,300 feet. With a touchdown velocity of 28 ft/sec, Grissom’s spacecraft splashed-down in the Atlantic Ocean 15 minutes and 32 seconds after lift-off. America now had both a second spaceman and a second successful space mission under its belt.
Following splashdown, Grissom logged final switch settings in the spacecraft, stowed equipment and prepared for recovery as several Marine helicopters hovered nearby. As he did so, the craft’s new explosive hatch suddenly blew for no apparent reason. Water started to fill the cockpit and the surprised astronaut exited the spacecraft as quickly as possible.
Grissom found himself outside his psacecraft and in the water. He was horrfied to see that Liberty Bell 7 was in imminent peril of sinking. The primary helicopter made a valiant effort to hoist the spacecraft out of the water, but the load was too much for it. Faced with losing his vehicle and crew, the pilot elected to release Liberty Bell 7 and abandon it to a watery grave.
Meanwhile, Grissom struggled just to stay afloat in the churning ocean. The prop blast from the recovery helicopters made the going even tougher. Finally, Grissom was able to retrieve and get himself into a recovery sling provided by one of the helicopters. He was hoisted aboard and subsequently delivered safely to the USS Randolph.
In the aftermath of Mercury-Redstone 4, accusations swirled around Grissom that he had either intentionally or accidently hit the detonation plunger that activated the explosive hatch. Always the experts on everything, especially those things they have little comprehension of, the denizens of the press insinuated that Grissom must have panicked. Grissom steadfastly asserted to the day that he passed from this earthly scene that he did no such thing.
Liberty Bell 7 rested at a depth of 15,000 feet below the surface of the Atlantic Ocean until it was recovered by a private enterprise on Tuesday, 20 July 1999; a day short of the 38th anniversary of Gus Grissom’s MR-4 flight. The beneficiary of a major restoration effort, Liberty Bell 7 is now on display at the Kansas Cosmosphere and Space Center. The spacecraft’s explosive hatch was never found.
As for Gus Grissom, ultimate vindication of his character and competence came in the form of his being named by NASA as Commander for the first flights of Gemini and Apollo. Indeed, Grissom and rookie astronaut John W. Young successfully made the first manned Gemini flight in March of 1965 during Gemini-Titan 3. Later, Grissom, Edward H. White II and Roger B. Chaffee trained as the crew of Apollo 1 which was slated to fly in early 1967. History records that their lives were cut short in the tragic and infamous Apollo 1 Spacecraft Fire of Friday, 27 January 1967.
Fifty-six years ago this month, the USAF/Republic XF-84H experimental turboprop fighter took to the air for the first time. The test hop originated from and recovered at Edwards Air Force Base, California.
The turbojet-powered XF-84H was a variant of Republic Aviation’s F-84 Thunderstreak. An Allison XT40-A-1 turboprop engine, rated at 5,850 hp, served as the power source for this novel aircraft. The XT40 drove a variable-pitch, 3-blade, 12-foot diameter propeller at 3,000 rpm. Thrust level was changed by varying blade pitch.
Owing to its high rotational speed and large diameter, the outer 2 feet of the XF-84H propeller saw supersonic velocities. The shock waves that emanated from the prop produced a deafening wall of sound. The extreme sound level produced intense nausea and raging headaches in ground crewmen. As a result, the XF-84H was dubbed the “Thunderscreech”.
The prop wash from the aircraft’s powerful turboprop necessitated the use of a T-tail to keep the horizontal tail and elevator in clean air flow. The engine’s extreme torque was partially countered by differential deflection on the left and right wing flaps and by placement of the left wing root air intake a foot ahead of the right intake.
A pair of XF-84H prototype aircraft (S/N 51-17059 and S/N 51-17060) was built by Republic Aviation. The first flight of an XF-84H took place on Friday, 22 July 1955 at Edwards Air Force. The flight was made by Republic test pilot Henry G. “Hank” Beaird, Jr. in Ship No. 1 (S/N 51-17059). The flight was cut short by a forced landing.
A total of twelve (12) test flights were made in the two Thunderscreech prototypes; eleven (11) in Ship No. 1 and one (1) in Ship No. 2. Total flight time accumulated by these experimental airframes was 6 hours and 40 minutes. The majority of flights experienced forced landings for one reason or another.
The XF-84H suffered from reduced longitudinal stability and poor handling qualities. The aircraft was also plagued by frequent engine, hydraulic system, nose gear and vibration problems. Faced with the type’s obvious non-viability, USAF opted to cancel the XF-84H Program in September of 1956.
Historical records indicate that the XF-84H reached a top speed of 520 mph during its brief flight test life. This figure was a full 120 mph short of the aircraft’s design speed. Nonetheless, the XF-84H held the speed record for single-engine prop-driven aircraft until Monday, 21 August 1989. On that date, a specially modified Grumman F8F Bearcat established the existing record of 528.33 mph.
Twenty-nine years ago today, the Space Shuttle Columbia landed at Edwards Air Force Base to successfully conclude the fourth orbital mission of the Space Transportation System. Columbia’s return to earth added a special touch to the celebration of America’s 207th birthday.
STS-4 was NASA’s fourth Space Shuttle mission in the first fourteen months of Shuttle orbital flight operations. The two-man crew consisted of Commander Thomas K. Mattingly, Jr. and Pilot Henry W. Hartsfield who were both making their first Shuttle orbital mission. STS-4 marked the last time that a Shuttle would fly with a crew of just two.
STS-4 was launched from Cape Canaveral’s LC-39A on Sunday, 27 June 1982. Lift-off was exactly on-time at 15:00:00 UTC. Interestingly, this would be the only occasion in which a Space Shuttle would launch precisely on-time. The Columbia weighed a hefty 241,664 lbs at launch.
Mattingly and Hartsfield spent a little over seven (7) days orbiting the Earth in Columbia. The orbiter’s cargo consisted of the first Getaway Special payloads and a classified US Air Force payload of two missile launch-detection systems. In addition, a Continuous Flow Electrophoresis System (CFES) and the Mono-Disperse Latex Reactor (MLR) were flown for a second time.
The Columbia crew conducted a lightning survey using manual cameras and several medical experiments. Mattingly and Hartsfield also maneuvered the Induced Environment Contamination Monitor (IECM) using the Orbiter’s Remote Manipulator System (RMS). The IECM was used to obtain information on gases and particles released by Columbia in flight.
On Sunday, 04 July 1982, retro-fire started Columbia on its way back to Earth. Touchdown occurred on Edwards Runway 22 at 16:09:31 UTC. This landing marked the first time that an Orbiter landed on a concrete runway. (All three previous missions had landed on Rogers Dry Lake at Edwards.) Columbia made 112 complete orbits and traveled 2,537,196 nautical miles during STS-4.
The Space Shuttle was declared “operational” with the successful conduct of the first four (4) shuttle missions. President Ronald Reagan and First Lady Nancy Reagan even greeted the returning STS-4 flight crew on the tarmac. However, as history has since taught us, manned spaceflight still comes with a level of risk and danger that exceeds that of military and commercial aircraft operations. It will be some time before a manned space vehicle is declared operational in the desired sense.
Fifty-three years ago this week, the United States Army Nike Hercules air defense missile system was first deployed in the continental United States. The second-generation surface-to-air missile was designed to intercept and destroy hostile ballistic missiles.
The Nike Program was a United States Army project to develop a missile capable of defending high priority military assets and population centers from attack by Soviet strategic bombers. Named for the Greek goddess of victory, the Nike Program began in 1945. The industrial consortium of Bell Laboratories, Western Electric, Hercules and Douglas Aircraft developed, tested and fielded Nike for the Army.
Nike Ajax (MIM-3) was the first defensive missile system to attain operational status under the Nike Program. The two-stage, surface-launched interceptor initially entered service at Fort Meade, Maryland in December of 1953. A total of 240 Nike Ajax launch sites were eventually established throughout CONUS. The primary assets protected were metropolitan areas, long-range bomber bases, nuclear plants and ICBM sites.
Nike Ajax consisted of a solid-fueled first stage (59,000 lbs thrust) and a liquid-fueled second stage (2,600 lbs thrust). The launch vehicle measured nearly 34 feet in length and had a ignition weight of 2,460 lbs. The second stage was 21 feet long, had a maximum diameter of 12 inches and weighed 1,150 lbs fully loaded. The type’s maximum speed, altitude and range were 1,679 mph, 70,000 feet and 21.6 nautical miles, respectively.
The Nike Hercules (MIM-14) was the successor to the Nike Ajax. It featured all-solid propulsion and much higher thrust levels. The first stage was rated at 220,000 lbs of thrust while that of the second stage was 10,000 lbs. The Nike Hercules airframe was significantly larger than its predecessor. The launch vehicle measured 41 feet in length and weighed 10,700 lbs at ignition. Second stage length and ignition weight were 26.8 feet and 5,520 lbs, respectively.
Nike Hercules kinematic performance was quite impressive. The respective top speed, altitude and range were 3,000 mph, 150,000 feet and 76 nautical miles. This level of performance allowed the vehicle to be used for the ballistic missile intercept mission. Most Nike Hercules missiles carried a nuclear warhead with a yield of 20 kilotons.
The first operational Nike Hercules systems were deployed to the Chicago, Philadelphia and New York localities on Monday, 30 June 1958. By 1963, fully 134 Nike Hercules batteries were deployed throughout CONUS. These systems remained in the United States missile arsenal until 1974. The exceptions were batteries located in Alaska and Florida which remained in active service until the 1978-79 time period.
Like Nike Ajax before it, Nike Hercules had a successor. It was originally known as Nike Zeus and then Nike-X. This Nike variant was designed for intercepting enemy ICBM’s that were targeted for American soil. The vehicle went through a number of iterations before a final solution was achieved. Known as Spartan, this missile was what we would refer to today as a mid-course interceptor.
In companionship with a SPRINT terminal phase interceptor, Spartan formed the Safeguard Anti-Ballistic Missile System. The American missile defense system was impressive enough to the Soviet Union that the communist country signed the Anti-Ballistic Missile (ABM) Treaty 3 years before Safeguard’s deployment. Though operational for a mere 3 months, Safeguard was depostured in 1975. This action brought to a close a 30-year period in which the Nike Program was a major player in American missile defense.
Ten years ago this month, the first NASA X-43A airframe-integrated scramjet flight research vehicle was launched from a B-52 carrier aircraft high over the Pacific Ocean. The inaugural mission of the HYPER-X Flight Project came to an abrupt end when the launch vehicle departed controlled flight while passing through Mach 1.
In 1996, NASA initiated a technology demonstration program known as HYPER-X (HX). The central goal of the HYPER-X Program was to successfully demonstrate sustained supersonic combustion and thrust production of a flight-scale scramjet propulsion system at speeds up to Mach 10.
Also known as the HYPER-X Research Vehicle (HXRV), the X-43A aircraft was a scramjet test bed. The aircraft measured 12 feet in length, 5 feet in width, and weighed close to 3,000 pounds. The X-43A was boosted to scramjet take-over speeds with a modified Orbital Sciences Pegasus rocket booster.
The combined HXRV-Pegasus stack was referred to as the HYPER-X Launch Vehicle (HXLV). Measuring approximately 50 feet in length, the HXLV weighed slightly more than 41,000 pounds. The HXLV was air-launched from a B-52 mothership. Together, the entire assemblage constituted a 3-stage vehicle.
The first flight of the HYPER-X program took place on Saturday, 02 June 2001. The flight originated from Edwards Air Force Base, California. Using Runway 04, NASA’s venerable B-52B (S/N 52-0008) started its take-off roll at approximately 19:28 UTC. The aircraft then headed for the Pacific Ocean launch point located just west of San Nicholas Island.
At 20:43 UTC, the HXLV fell away from the B-52B mothership at 24,000 feet. Following a 5.2 second free fall, the rocket motor lit and the HXLV started to head upstairs. Disaster struck just as the vehicle accelerated through Mach 1. That’s when the rudder locked-up. The launch vehicle then pitched, yawed and rolled wildly as it departed controlled flight. Control surfaces were shed and the wing was ripped away. The HXRV was torn from the booster and tumbled away in a lifeless state. All airframe debris fell into the cold Pacific Ocean far below.
The mishap investigation board concluded that no single factor caused the loss of HX Flight No. 1. Failure occurred because the vehicle’s flight control system design was deficient in a number of simulation modeling areas. The result was that system operating margins were overestimated. Modeling inaccuracies were identified primarily in the areas of fin system actuation, vehicle aerodynamics, mass properties and parameter uncertainties. The flight mishap could only be reproduced when all of the modeling inaccuracies with uncertainty variations were incorporated in the analysis.
The X-43A Return-to-Flight effort took almost 3 years. Happily, the HYPER-X Program hit paydirt twice in 2004. On Saturday, 27 March 2004, HX Flight No. 2 achieved scramjet operation at Mach 6.83 (almost 5,000 mph). This historic accomplishment was eclipsed by even greater success on Tuesday, 16 November 2004. Indeed, HX Flight No. 3 achieved sustained scramjet operation at Mach 9.68 (nearly 7,000 mph).
The historic achievements of the HYPER-X Program went largely unnoticed by the aerospace industry and the general public. For its part, NASA did not do a very good job of helping people understand the immensity of what was accomplished. Even the NASA Administrator appeared different to the scramjet program. While he attended an X-Prize flight by Scaled-Composites’ SpaceShipOne right up the street at the Mojave Spaceport, he did not see fit to attend either of that year’s historic scramjet flights that originated right down the street at Edwards Air Force base.
However, it was the loss of the Space Shuttle Columbia on STS-107 in February of 2003 that doomed HX even before the program’s first successful flight. Everything changed for NASA when Columbia and its crew was lost. The agency’s overriding focus and meager financial resources went into the Shuttle Return-to-Flight effort. NASA’s aeronautical and access-to-space arms were especially hard hit.
If timing is everything as some insist, then the HYPER-X Program was really the victim of bad timing. It is both intriguing and distressing to ponder what would have been the case if HX Flight No. 1 had been successful. The likely answer is that at least one of the anticipated follow-on scramjet flight research programs (i.e., X-43B, X-43C, and X-43D) would have been developed and flown. Thanks to Murphy’s ubiquitous influence, we’ll never know.
Sixty-three years ago this month, the USAF/Northrop YB-49 Flying Wing came apart during a test flight that originated at Muroc Air Force Base. Among the five crew members who perished in the aviation mishap was famed test pilot USAF Captain Glen W. Edwards.
The USAF/Northrop YB-49 heavy bomber prototype first flew in October of 1947. The aircraft was a jet-powered derivative of the propeller-driven XB-35. Both of these legendary aircraft were flying wing designs pioneered by visionary aircraft designer Jack Northrop.
Traditionally, interest in a flying wing aircraft stems from its inherently-high lift, low drag and hence high lift-to-drag ratio characteristics. These attributes make a flying wing ideal for the strategic bombing mission where large payloads must be carried long distances to the target. In addition, the type’s low profile and swept wings contributed to its low radar cross-section.
The same configurational features that give flying wing aircraft favorable performance also present stability and control issues and adverse handling qualities. The lack of a traditional empenage requires that all flight controls be placed on the wing itself. This leads to significant aerodynamic coupling that affects aircraft pitch, yaw and roll motion.
The YB-49 had a wing span of 172 feet, a length of 53 feet and a height of 15 feet. Gross take-off weight was approximately 194,000 lbs. Fuel accounted for roughly 106,000 lbs of that total. Power was supplied by eight (8) Allison/General Electric J35-A-5 turbojets. Each of these early-generation powerplants was rated at a mere 4,000 lbs of sea level thrust.
The YB-49 design performance included a maximum speed of 495 mph, a service ceiling of 45,700 feet and a maximum range of 8,668 nautical miles. The aircraft was designed to carry a maximum bomb load of 32,000 lbs. The strategic bombing mission would be flown by a crew of seven (7) including pilot, co-pilot, navigator, bombardier and gunners.
A pair of XB-35 airframes were modified to the YB-49 configuration. Ship No. 1 (S/N 42-102367) first took to the air on Tuesday, 21 October 1947. The maiden flight of Ship No. 2 (S/N 42-102368) occurred on Tuesday, 13 January 1948. Both flights originated from Hawthorne Airport and recovered at Muroc Air Force Base.
Flight testing of the YB-49 quickly confirmed the type’s performance promise. Demonstrated performance included a top speed of 520 mph and a maximum altitude of 42,000 feet. On Monday, April 26, 1948. On that date, the aircraft remained aloft for 9.5 hours, of which 6.5 hours were flown at an altitude of 40,000 feet.
The low point in YB-49 flight testing came on Saturday, 05 June 1948. On that fateful day, YB-49 Ship No. 2 crashed to destruction in the Mojave Desert northwest of Muroc Air Force Base. The entire crew of five (5) perished in the mishap. These crew members included Major Daniel N. Forbes (pilot), Captain Glen W. Edwards (co-pilot), Lt. Edward L. Swindell (flight engineer), Clare E. Lesser (observer) and Charles H. LaFountain (observer).
The cause of the YB-49 mishap was never fully determined. In descending from 40,000 feet following a test mission, the aircraft somehow exceeded its structural limit. The outer wing panels failed and the rest of the aircraft tumbled out of control, struck the ground inverted and immediately fireballed. Whether the incident was related to wing stall, spin or some such other flight control issue will never be definitively known.
YB-49 Ship No. 1 continued to fly after the loss of its stable mate. However, it too met an unkind fate. On Wednesday, 15 March 1950, the aircraft was declared a total loss following a non-fatal high-speed taxiing mishap. Several months later, all of Northrop’s flying wing contracts with the government were unexpectedly cancelled. Incredibly, the Wizards of the Beltway ultimately ordered that all Northrop-produced flying wing variants be cut-up for scrap.
Despite its performance, the YB-49 was too far ahead of its time. The aircraft did not exhibit good handling qualities and thus was not a good bombing platform. It needed the type of computer-based, multiply-redundant autopilot that is standard equipment on today’s aircraft.
Happily, the performance merits of the flying wing concept would be fully exploited with the introduction of the USAF/Northrop B-2 Advanced Technology Bomber (ATB). This aircraft first flew on Monday, 17 July 1989. Its subsequent success is now history. A host of new technologies converged to finally made the flying wing concept viable. Not the least of which is the aircraft’s multiply-redundant flight control system.
Finally, we note that 30-year old Captain Glen W. Edwards was a rising star in military flight test circles at the time of his death. In tribute to his aviation skills and in memory of a life cut short, Muroc Air Force Base was officially renamed on Tuesday, 05 December 1950. Since that day, it has been known as Edwards Air Force Base.
Sixty-two years this week, the No. 2 USAF/Northrop X-4 experimental flight research aircraft took to the air for the first time. The flight of the second X-4 prototype originated from and recovered at Muroc Air Force Base, California.
The USAF/Northrop X-4 was an early X-plane designed to explore the flight characteristics of a swept-wing, tailless aircraft in transonic flight. It came into being as a result of recent Air Force studies which indicated that a tailless configuration might alleviate or eliminate instability issues associated with supersonic flight. The X-4’s external configuration was similar to that of the German Me163 Komet and the British De Havilland DH.108 Swallow.
The USAF contracted with the Northrop Aircraft Company in June of 1946 to construct and perform initial flight testing of two (2) X-4 aircraft. Northrop received the sole-source contract principally because of the company’s vast experience with flying-wing aircraft. Notable examples include the N-1M, XP-79B, XP-56 and the fabled B-35 heavy bomber.
The X-4 was a physically small airplane. As such, it received the nickname Bantam. It measured 23.25-feet in length and had a wing span of 26.75-feet. The wing leading edge sweep angle was 40.5-degrees. Gross take-off weight was 7,820 lbs. Power was provided by a pair of Westinghouse J30-WE-9 non-afterburning turbojets. Each powerplant had a sea level thrust rating of a paltry 1,600-lbs.
Due to the absence of a horizontal tail and an associated elevator, the X-4 was configured with wing-mounted elevons (combined elevator and aileron). These surfaces provided both pitch and roll control. The type’s split trailing edge flaps were used for low-speed lift enhancement as well as speed brake control. Aircraft directional control was provided via a standard vertical tail-mounted rudder.
The No. 1 X-4 aircraft (S/N 46-676) first flew on Wednesday, 15 December 1948 at Muroc Air Force Base, California. Northrop test pilot Charles Tucker was at the controls. The X-4’s first mission revealed that the aircraft was slightly unstable in pitch. Moving the center-of-gravity forward by 3-inches corrected this problem on subsequent X-4 flights.
The No. 2 X-4 aircraft (S/N 46-677) took to the skies over Muroc Air Force Base for the first time on Tuesday, 07 June 1949 with Northrop’s Charles Tucker once again doing the honors. The second X-4 prototype’s air worthiness characteristics and handling qualities were found to be entirely satisfactory.
This vehicle was in fact superior to the No. 1 aircraft in several respects. Not the least of which was a better flight instrumentation suite.
A total of 17 pilots flew the X-4. Northrop’s Charles Tucker piloted all 30 of the contractor flights including 10 in the No. 1 ship and 20 in the No. 2 X-4. The remaining 82 flights were all flown in the No. 2 ship by USAF and NACA pilots including such luminaries as Stanley Butchart (NACA), Scott Crossfield (NACA), Pete Everest (USAF), Jack McKay (NACA), Joe Walker (NACA) and Chuck Yeager (USAF).
The X-4 achieved a maximum altitude of 42,300 on Tuesday, 29 May 1951 and a maximum speed of Mach 0.94 on Monday, 22 September 1952. NACA pilot Scott Crossfield, who piloted the most X-4 flights (31), was at the controls in both instances.
The X-4 handled well below Mach 0.87. However, the aircraft exhibited an annoying porpoising in pitch at higher transonic speeds. Nose-down pitch changes also produced a Mach-tuck effect that worsened with increasing Mach number. The X-4 also had a nasty tendency to pitch-up as it approached sonic speed. These issues were all related in one way or another to the type’s unique tailless, swept wing configuration.
The X-4 flight test program officially ended in September of 1953. Of the 112 total flight tests conducted over the program’s 58-month duration, 102 were flown by the No. 2 ship. While the X-4 never flew supersonically, the type’s transonic flight research program revealed that the hoped-for advantages of a tailless aircraft in supersonic flight were specious.
Happily, both X-4 aircraft survived the flight test program intact. X-4 No. 1 (S/N 46-676) is currently on display at the United States Air Force Academy in Colorado Springs, CO. The No. 2 ship can be seen at the National Museum of the United States Air Force located at Wright-Patterson Air Force Base in Dayton, OH.
Forty years ago today, the United States launched the Mariner 9 spacecraft on a mission to Mars. Among other achievements, Mariner 9 would become the first terrestrial spacecraft to orbit another planet other than Earth.
The Mariner Program was a NASA project whose goal was to investigate the planets Mars, Venus and Mercury from space. A total of ten (10) Mariner spacecraft were launched between 1962 and 1973. Seven (7) of these pioneering missions were considered successful. The first interplanetary flyby, the first orbiting of another planet and the first gravity assist maneuver were all accomplished by Mariner spacecraft.
Each Mariner was built around a central bus or housing that was either hexagonal or octagonal in shape. All spacecraft guidance, navigation, propulsion, communication, power and instrumentation systems were contained within or attached to this central bus. Mariner spacecraft were typically configured with a set of four (4) solar panels for power. However, Mariner’s 1, 2 and 10 used just two (2). Cameras were carried by all Mariner space probes with the exception of Mission’s 1, 2 and 5.
Mariner 9 carried a scientific instrumentation package that consisted principally of an imaging system, ultraviolet spectrometer, infrared spectrometer and infrared radiometer. Fully deployed, each pair of solar panels measured 22.6-feet across. These panels provided 800 watts of power at Earth and 500 watts at Mars. Power was stored in a 20-amp-hour nickel-cadmium battery.
Mariner 9 lift-off mass was 2,196 lbs. Propellant useage during the flyout to Mars resulted in a spacecraft mass of 1,232 lbs in Martian orbit. Scientific instrumentation accounted for 139-lbs of the on-rbit mass. Spacecraft propulsion for mid-course corrections and orbital insertion was provided by a 300-lb thrust liquid rocket motor burning monomethyl hydrazine and nitrogen tetroxide. Mariner 9’s 3.28-foot diameter antenna telemetered data back to Earth at rates of 1, 2, 4, 8 or 16 kilobits/second using dual S-band 10 watt and 20 watt transmitters.
Mariner 9 was launched from Cape Canaveral’s LC-36B at 22:23:00 UTC on Sunday, 30 May 1971. An Atlas-Centaur SLV-3C launch vehicle provided the propulsive energy required to climb out of the Earth’s gravity well and send the probe on its way to Mars. It would take Mariner 9 roughly 167 Earth days to travel a distance of 214.85 million nautical miles to the Red Planet.
Mariner 9 entered Mars orbit at 00:18:00 UTC on Sunday, 14 November 1971. This marked the first time that a terrestrial spacecraft had achieved orbit about another planet in our Solar System other than Earth. Initial orbital parameters included an apoapsis of 9,672-nm and a periapsis of 755-nm at an inclination of 64.3 degrees. Interestingly, Mariner 9 arrived ahead of the Soviet Mars 2 space probe despite the latter’s eleven (11) day head start.
A planet-wide dust storm greeted Mariner 9 upon its arrival in Mars orbit. Hence, imaging of the planetary surface did not begin in earnest until late November. However, it was not until mid-January 1972 that the storm had subsided to the point that high quality images could be obtained from orbit.
Mariner 9 ultimately took 7,329 images which covered 100% of the Martian surface. The photos revealed a fascinating planetary topology that featured river beds, craters, extinct volcanoes, mountains and canyons. Mariner 9 discovered Olympus Mons, the largest known extinct volcano in the Solar System. Valles Marineris, a system of Martian canyons measuring 2,170-nm in length, was named after Mariner 9 in tribute to the probe’s significant space exploration accomplishments. Photographed as well were the diminutive Martian moons of Phobos and Deimos.
Upon depletion of its attitude control system propellant supply, Mariner 9’s mission was officially terminated when the spacecraft’s systems were turned-off on Friday, 27 October 1972. Total time spent investigating the Martian environment from orbit was 349-days. Though long silent, the craft remains in orbit around the Red Planet. It is expected to continue to do so through approximately the year 2022.
Forty-seven years ago this month, the No. 1 USAF/North American XB-70A Valkyrie aircraft was officially unveiled to the aviation public in a rollout ceremony conducted at USAF Plant 42 in Palmdale, California. The Great White Bird’s public debut occurred on Thursday, 11 May 1964.
The XB-70A Valkyrie was designed as an intercontinental bomber. Its original mission was to penetrate Soviet airspace and drop nuclear ordinance at Mach 3 and 70,000 feet. However, that mission was cancelled before the type ever flew. It was ultimately relegated to the status of an experimental flight research vehicle.
The XB-70A graced the skies of America between September 1964 and February 1969. It is to this day the largest triple-sonic aircraft ever flown. The aircraft measured 189 feet in length and had wing span of 105 feet. Gross weight topped out at around 540,000 lbs. Over half of that weight (290,000 lbs) was JP-6 jet fuel.
The Valkyrie was powered by six (6) General Electric YJ93 all-afterburning turbojets. These engines were designed to operate in continuous afterburner at Mach 3.2 and 95,000 feet. Total sea level thrust of the “6-Pack” was in excess of 185,000 lbs. The YJ93 was a contemporary of the Pratt and Whitney J58 turboramjet which powered the fabled USAF/Lockheed SR-71 Blackbird.
Only a pair of XB-70A airframes were built and flown; Air Vehicle No. 1 (S/N 62-0001) and Air Vehicle No. 2 (S/N 62-207). Together, these aircraft flew 129 flight tests totaling 252.6 flight hours. Ship No. 1 flew two-thirds of the XB-70A flight tests. The highest Mach number achieved during the XB-70A flight test program was Mach 3.08. This feat was accomplished by Ship No. 2 on Tuesday, 12 April 1966.
XB-70A Ship No. 2 also achieved the highest altitude of the XB-70A Program. Specifically, this aircraft attained a cruise altitude of 74,000 feet on Saturday, 19 March 1966. This mission included 32 minutes of continuous Mach 3 flight.
Eight (8) men flew the XB-70A. This line-up included Alvin S. White and Van H. Shepard of North American, Col Joseph E. Cotton, Lt Col Fitzhugh L. Fulton, Lt Col Emil (Ted) Sturnthal and Maj Carl S. Cross of the United States Air Force, and Joseph A. Walker and Donald L. Mallick of NASA.
The Valkyrie pioneered the use of numerous technologies including exploitation of the NACA Compression Lift Principle, development of honeycomb sandwich structural materials, and use of its fuel as a heat sink. The XB-70A was also used as a testbed for sonic boom research and a myriad of other aerodynamic and aerothermodynamic experiments. The Valkyrie also provided significant support to the ill-fated American Supersonic Transport (SST) effort.
XB-70A Ship No. 2 was lost in a collision with a NASA F-104N Starfighter near Edwards Air Force Base on Wedneday, 08 June 1966. This mishap took the lives of Maj Carl S. Cross and Joseph A. Walker on what is still referred to as the “Blackest Day at Edwards”. Ship No. 1 survived the XB-70 flight test program and is displayed today at the National Museum of the United States Air Force in Dayton, Ohio.
