Super Hustler was the name given to a series of 1950s-era designs for a manned Mach 4 capable aircraft designed to penetrate into the Soviet Union. This aircraft would have been launched from beneath a B-58 Hustler. The proposed parasite aircraft, one of many design studies associated with Convair’s work on the B-58 program, became the starting point for the company’s contender in a high-stakes competition for a high-altitude, high-speed, stealthy reconnaissance platform.
The competition eventually led to the Lockheed A-12 and SR-71 Blackbird. Super Hustler, in turn, became a starting point for subsequent hypersonic projects at Convair and later General Dynamics, including designs proposed in the 1960s as a replacement for the SR-71. (General Dynamics Fort Worth later became the headquarters for Lockheed Martin Aeronautics Company.)
Super Hustler began in the mid-1950s as highly classified design studies at the Fort Worth Division of Convair. “If anyone asked us what we were working on, we’d say that we worked on a special project—nothing else,” said Randy Kent, who was the propulsion lead for Super Hustler as one of his first jobs at the company.
The Cold War provided the context for most military projects at the time, and the Super Hustler was no exception. With the threat of nuclear war looming, the United States wanted to develop platforms for delivering weapons over strategic distances while penetrating increasingly complex air defenses.
The spectrum of capability and complexity for these platforms was wide. Large conventional propeller-driven manned bombers, like the B-36 Peacemaker, fell at the less complex end of the spectrum. Smaller, faster jet engine-powered manned bombers, such as the subsonic B-47 Stratojet and supersonic B-58, fell in the middle of the spectrum. Orbital vehicles, still under development, fell at the far end of the spectrum. A high-altitude, high-speed bomber would bridge the gap between existing conventional systems and intercontinental ballistic missiles. The bomber would need to fly much faster than existing bombers while still meeting intercontinental range requirements. Super Hustler was Convair’s solution.
The parasitic approach Convair took for Super Hustler can be traced to parasite fighter escort projects done for the B-36. The first of these, conducted by McDonnell Aircraft Corporation in the late1940s, involved launching and recovering the specially designed XF-85 Goblin defensive fighter from a B-36 bomb bay. The program was terminated in 1949 because of the turbulence between the B-36 and the XF-85 and the pilot skill needed to make a successful recovery to the trapeze lowered from the bomb bay. The poor fighter performance characteristics of the XF-85 also supported the cancellation.
Convair was more directly responsible for a B-36 parasite project launched in 1951. The Fighter Conveyor, called FICON, project involved launching and recovering the lone YRF-84F Thunderjet for reconnaissance from a trapeze mounted in the B-36 bomb bay. The B-36 provided the long range, and the YRF-84F provided the speed needed to penetrate defenses to collect the imagery. B-36s modified for FICON were deployed to the 99th Strategic Reconnaissance Wing at Fairchild AFB, Washington, beginning in 1955, where they saw limited service. FICON was phased out of service when the U-2 became operational.
Project Tom-Tom, a mid-1950s Convair project, involved launching and recovering the F-84 from the wingtips of the B-36. Named after two men who worked on the project—Maj. Gen. Tom Gerrity and Convair contract manager Tom Sullivan, Tom-Tom ended in 1956 after only a few attempts at aerial wingtip-to-wingtip hookups were made. Vortices and turbulence near the attach points made such connections very difficult for the pilot of the parasite fighter.
The parasite concept even influenced the origins of the B-58, what would become the mothership for the Super Hustler. Convair was involved in the Generalized Bomber, called GEBO, studies that were conducted by the US Air Force starting in 1946. The studies systematically applied the latest advances in engineering, materials, and aeronautics to the requirements for the Air Force’s next-generation bomber. They resulted in a large array of configurations with varying combinations of wing types and sizes (area, aspect ratio, sweep, etc.) and propulsion systems (number and types of engines). These configurations were evaluated by the US Air Force in terms of range, payload, gross weight, and other factors.
Many of the configurations Convair developed for GEBO studies involved supersonic weapon-delivering parasites launched from the B-36 or B-36 derivatives. After the second GEBO study ended in 1951, Convair had developed an initial design for the world’s first supersonic bomber—the MX-1626, a small delta-wing aircraft with a two-man crew. MX-1626 had three non-afterburning engines, one of which was installed in an expendable ballistic weapons pod. The aircraft was to be carried on and launched from the B-60, a version of the B-36 with swept-back wings and turbojet (and later turboprop) engines. As the design of the MX-1626 evolved, the parasite launch concept was dropped in favor of conventional takeoff and landing aircraft. Long-range requirements would be met by aerial refueling. The design later turned into hardware in the form of the B-58 Hustler.
The actual design origins of Super Hustler can be traced to studies for improving B-58 performance. The first of these studies, which began in 1955, addressed ways to increase target range with minimal modifications to the basic B-58 airframe. The study continued into 1957 and resulted in a configuration with larger GE J79-9 engines, a fuselage length extension, folding wingtips, and side-by-side seating.
A second study, performed simultaneously, looked at ways to create an all-supersonic version of the B-58. The resulting configuration had more extensive changes needed to increase the lift/drag ratio for supersonic flight. The wing was redesigned, and the canopy was made flush with the fuselage. Pratt & Whitney JT-9 engines, later the J-58 engines in the SR-71, were proposed as well. This design had a Mach 2 radius of 3,000 nautical miles, however, which was considered inadequate.
The next phase of these studies involved greater deviations from the basic B-58 configuration. The cruising speed of an all-supersonic version was increased to Mach 3. The more complex design required exotic high-energy fuel and significant aerodynamic changes that involved expensive construction techniques to deal with the high supersonic temperatures. During this phase, aircraft weight grew to 300,000 pounds.
The all-supersonic, Mach 3 design was dropped in favor of a return to a subsonic cruise/supersonic dash design. The new configuration used dual-cycle engines in which the turbojet compressors were bypassed for the Mach 4 dash. The afterburners were mechanically transformed into ramjets. The design incorporated a folding ventral fin for high speeds and a fixed canard, called a linearizer surface, forward of the wing. The increased drag and weight associated with the dual-cycle engines and the overall complexity made this design problematic and led to additional studies.
To reduce drag and still take advantage of ramjet performance, the next configuration (circa August 1957) had four turbojet engines—like the B-58. However, two engines were placed above the wing to make room for two expendable ramjets below the wing. The aircraft was designed for a split mission. The cruise out leg of the mission was at Mach 4 on the ramjets. The return leg was made with the turbojets only. Balance problems and other undesirable features forced designers to abandon this configuration.
The ramjet/turbojet combination was revisited in the next design (circa September 1957), which added expendable rockets to the mix. The rockets, located under the wings on the inside pylons, were used for takeoffs and accelerated the aircraft to supersonic speeds, then fell away. At this point, four ramjets, also under the wings, accelerated the aircraft to Mach 4 for the cruise out and return legs of the mission. A single turbojet engine on the aircraft’s centerline was used for landing. The configuration, which weighed more than 400,000 pounds, was deemed impractical.
The B-58 parasite studies that led directly to the Super Hustler began in earnest in October 1957. The B-58 was designed to carry large external stores—including combinations of fuel tanks, free-fall bombs, powered air-to-surface missiles, and reconnaissance pods. A small manned parasitic supersonic bomber was, in some ways, an extension of this payload capability. Several configurations were drawn to fit under a lower cost stretch fuselage version of the B-58. The supersonic speed of the B-58 would be used to get to the conditions needed to ignite the ramjets.
The latest aerodynamic innovations in wing planform shapes and inlet designs were incorporated in the configuration studies. All of the initial parasite designs were single-stage vehicles designed for Mach 5 cruise and launched from the B-58 carrier at about 2,000 nautical miles from the takeoff base. The parasite would have the range to return to the takeoff base.
Clearing the B-58 landing gear with the parasite’s wing presented a major obstacle for all of the early designs. Gruen Applied Science Laboratory* provided a solution to Convair in the form of a two-stage tandem wing configuration. The front stage, called Baby, carried a single pilot and was powered by one ramjet. The rear expendable stage, called Big Brother, was powered by two ramjets and carried a nuclear warhead. Although the Gruen solution furnished part of the design concept for what eventually became the Super Hustler, it was not sufficiently refined to satisfy the mission requirements.
The Gruen two-stage solution was followed by a series of numbered Convair configurations from November through December 1957.
The first post-Gruen configuration, labeled Configuration 101, featured a manned stage with a flat top and a 210 square-foot wing with three-degree negative incidence angle. The engine inlet was a scoop type located forward of the pilot, who flew in a prone position. A small windshield was located just forward and below the pilot’s head position. The expendable stage was little changed from the Gruen design. The gross weight of both stages was 32,860 pounds, with the manned stage weighing 16,370 pounds.
Configuration 102 involved a variation of the expendable stage creating negative incidence effect in the wing to improve aerodynamic performance. Square ramjets were introduced to clean up the intersection of surfaces between the two stages and to minimize base drag. The wing area of the expendable stage was 300 square feet. The expendable stage, which carried 15,000 pounds of fuel, had a gross weight of 27,800 pounds.
Configuration 103 added a second crewmember in side-by-side position (both still prone) in a crew compartment seventy inches wide and forty inches tall. The wing area remained the same (210 square feet). The upper and lower fuselage was reshaped to take advantage of lift effects. (A diminishing body—volume from fore to aft—over the top side of the wing created a negative pressure field; an enlarging body under the wing created a positive pressure field.) The gross weight increased to 16,670 pounds.
Configuration 104A decreased the fuselage width of the manned stage to sixty-one inches across and forty inches high. The gross weight was decreased to 16,430 pounds. The wing area remained the same. Fuel for the manned stage is listed as 8,100 pounds. Configuration 104G introduced several changes to the manned stage. The ramjet had a squared exhaust nozzle to match the expendable stage. The fuel capacity increased to 9,700 pounds, and the gross weight increased to 18,300 pounds.
Square ramjets were dropped for the manned stage in Configuration 105 because of manufacturing problems. The crew was reduced to one person in a seated position. The increased fuselage depth needed for this new crew position/size was offset by a narrower width. Configuration 106B added drop tanks to the expendable stage. Fuel capacity reached 13,750 pounds, and gross weight reached 25,200 pounds (expendable stage only).
Super Hustler configurations to this point assumed a derivative of the B-58 as a carrier aircraft. The derivative, called B-58B, had an extended fuselage that provided a 100 inch longer wheelbase than a B-58A. Though the Air Force authorized the development, design, and testing of the B-58B in October 1958, uncertainty surrounding this model improvement forced the design team to assume the B-58A as the carrier. The B-58B was subsequently canceled in July 1959.
Given the decreased wheelbase dimensions of the B-58A, clearing the nose landing gear became an even larger design issue. Configuration 110 addressed the limitation in the front manned stage with twin parallel bodies that straddled the front gear of the B-58A. One crewmember was located in each body.
The twin-body approach was deemed impractical. So Convair designers began investigating ways to fold the nose to fit the space limitations created by the B-58’s extended gear (and gear swing). The nose would be unfolded before the parasite launched and after the B-58’s landing gear retracted. The movable nose would also act as a control surface.
Pilot vision over the nose at landing was another issue for the parasite. High-Mach flight required a flush canopy. Slower speeds required for landing raised the angle of attack. Several approaches for allowing the pilot to see over the nose were studied. These included a nose that rotated ninety degrees on the roll axis, remote cameras that allowed the pilot to see the runway on a screen in the cockpit, and a tilting crew compartment that created the needed viewing angle over the nose. Instead, designers chose to put a pivoting hinge in the middle of the manned stage to provide downward vision for landing, similar to the canting nose later seen on the Concorde. The pivot point was placed just behind the crew compartment. The entire forward fuselage would pivot down twenty degrees for landings. Configuration numbering is undefined for these changes.
Configuration 118 offered above- and below-fuselage wing position options for the expendable stage. The high-wing position was chosen in December 1957.
Convair first briefed the Super Hustler concept to the Air Force in January 1958 in Palm Springs, California. Meeting notes taken by Bob Widmer, who was chief of design for Convair at the time, label the reception as “enthusiastic.” The audience included Lt. Gen. Clarence Irvine, the deputy commander of Air Materiel Command for Production and Weapon Systems. Convair was asked to consider speeds greater than Mach 4 and designs that had a flat bottom.
Convair conducted several additional Super Hustler presentations in 1958. The audiences, which were at the highest levels of command, included Gen. Jimmy Doolittle (then special assistant to Air Force Chief of Staff); Gen. James Douglas (Air Force Secretary); Dr. Hugh Dryden (director of the National Advisory Committee for Aeronautics, the predecessor to NASA); Gen. Curtis LeMay (Air Force Vice Chief of Staff); and Gen. Thomas White (Air Force Chief of Staff).
Feedback from the briefings influenced the design. Configuration 119, for example, had the requested flat bottom, which acted as a precompression surface for the engine inlet. The two-person crew compartment measured sixty-four inches wide and forty-four inches high. The crew was seated in a semi-supine position (based on a recommendation by Air Research and Development Command). The manned stage from Configuration 119 carried into Configuration 121, which became a baseline for the program.
A highly detailed system description was prepared by Convair at this point in the configuration evolution. Dated 3 March 1958, the report consisted of seven large individually bound volumes: a summary of the weapon system; design features and structure; aerodynamics; stability and control; navigation, weapon delivery, reconnaissance, and decoy; propulsion and thermodynamics; and operation and ground support.
The introduction listed six design requirements for the aircraft: Mach 4 to 6 cruise capability; 5,000 nautical mile operating radius; 1961–1963 operational time frame; Class C warhead delivery (weapon load for the aircraft was listed as 3,400 pounds); two-man, side-by-side crew; and minimum size to fit the B-58 and to allow mobile launching and economy of production.
The manned stage was forty-seven feet long with a D-shaped cross section forty-five inches high and sixty-four inches wide. The gross weight for the manned stage was 20,190 pounds. The aircraft weighed 9,120 pounds empty.
The two-person crew sat side by side. The forward section of the manned stage contained an electronics bay and a nose gear. The forward section also contained a movable nose used for trim. The nose could be retracted when it was on the B-58. The aft fuselage of the manned section contained an equipment bay, fuel tank, ramjet engine, turbojet engine, and landing skids. The GE J85 turbojet engine, used for landing, was installed in the lower aft section ahead of the Marquardt MA24F ramjet engine. Fuel could be transferred between stages for balancing the aircraft in flight.
The manned stage retained the twenty-degree pivoting nose for landing. The hydraulic actuator lowered the forward section for approaches and landings. The actuator also functioned as shock absorber for landings.
The two-man crew consisted of a pilot and a bombardier/navigator. The crew stations had dual flight controls. Seating position was reclined forty-five degrees to minimize the height of the compartment. The glass portion of the cockpit enclosure was shielded with metal covers during high-speed flight. Indirect vision was provided by a closed circuit television system.
The expendable stage was almost forty-nine feet long with a maximum diameter of forty-six inches. Gross weight for the expendable stage was 25,700 pounds. Empty weight was 7,400 pounds.
The forward section of the expendable stage contained a fuel tank and a warhead bay with stabilizing skirts that would be opened when the warhead was released from the rest of the expendable section. The aft section contained another fuel tank, a top-mounted wing, and two Marquardt MA24F ramjet engines snuggled beneath the wing adjacent to the body.
The wingspan for the manned stage was just under nineteen feet. Wing area was 278 square feet. The leading edge sweep was seventy-five degrees. The wingspan for the expendable stage was just over twenty-three feet. Wing area was 242 square feet. The leading edge sweep was thirty-five degrees.
The manned stage had hydraulically actuated elevons, control flaps, and rudders for control surfaces. The expendable stage had hydraulically actuated elevons and rudders only. Landing skids were used for the main gear because the temperatures created by Mach 4 to 6 speeds were too high for pneumatic tires. A conventional high-pressure tire was used for the nose landing gear because it would be stowed in a cooled electronic bay.
Estimates for operating temperatures at Mach 4 were 1150 degrees F for the leading edge and 800 degrees F for body and wing surfaces. Cooling systems, ceramic coatings, or titanium-molybdenum alloy coatings or combinations of these approaches would be needed for leading edges at speeds exceeding Mach 5 because the estimated temperatures exceeded 1600 degrees F. The engine nacelle inlets and ducts presented similar high-temp challenges.
The mission profiles for the aircraft were defined under a variety of launch conditions and with two fuel types. Launch conditions included the B-58 carrier, various altitudes, various distances from the target, and two fuel types (JP and high-energy).
Convair also proposed several options for attaching the Super Hustler to a mobile ground-based rocket launcher. The options included attachment locations, rocket types, and rocket quantities (one and two). The recommended rocket system involved attaching the booster above the aircraft. The g-forces and launch angles involved with this option would require jackknifing the seating position of the crew from a supine position at launch to an upright position (forty-five degrees) for the remainder of the mission.
A standard B-58 carrier mission consisted of releasing from the B-58 at Mach 2 at 36,000 feet. The Super Hustler would quickly accelerate to Mach 4 and climb to 72,000 feet. The expendable stage would separate about 2,000 nautical miles later at 80,000 feet and deliver the weapon. The manned stage then had a range of about 4,500 nautical miles to return to the launching base. It covered this distance in two hours at a Mach 4 cruise speed and at altitudes ranging from 75,000 to 90,000 feet.
Standard approach speed for landing the manned stage was 170 knots with touchdown at 160 knots. The skids, even though assisted by an eight-foot landing chute, still made for ground rolls of 4,000 feet.
The nose section of the manned stage functioned as the escape system. The nose section would separate at the pivot point used for landings. Connections between the two sections would be severed—the front capsule would be accelerated away from the back section with a solid rocket motor. Mechanical skirts would deploy to slow the capsule. A drogue chute would deploy at Mach 0.25 and 20,000 feet followed by the main parachutes. In emergencies over water, the capsule would float nose down. This crew escape system could be seen as a predecessor of the F-111 crew escape module.
Configurations for the Super Hustler continued to evolve through most of 1958. In February, Configuration 124 added another ramjet engine to the manned stage. In April, Configuration 130, added more headroom to the cockpit, without increasing frontal area, by putting two curves on the upper surface. A medium-range version that replaced the expendable stage with an unpowered external store was also explored in April. This version offered training missions without the need to drop powered expendable stages. A biplane variant was drawn in June 1958. This design increased the wing area without having to physically expand the planform.
Aircraft carrier- and submarine-launched versions of the Super Hustler became the subject of study after a meeting with Electric Boat Company in June. At the same time, Convair committed to a year-long, company-sponsored series of wind tunnel tests for four specific configurations of the manned stage: flat top, flat bottom, biplane, and extended fuselage. Each design would be tested with the powered stage and with the unpowered external store that was proposed for a medium-range bomber.
Additional test models included a 1/17th scale force model of the B-58/Super Hustler combination, 1/17th scale pressure model of the B-58/Super Hustler combination, 1/7th scale model of the bomb, 1/9th scale inlet model of the expendable stage, 1/5th scale model of the inlet for the manned stage, and 1/40th scale separation model to investigate the separation from the B-58 carrier. Surface erosion models were also fabricated to test the effects of high temperatures on materials and insulation designs.
In September, Convair proposed using the RS-70 as a carrier aircraft. The RS-70 was to be a strike/reconnaissance version of the North American XB-70 Valkyrie. Shortly after, the company began researching reconnaissance versions of the Super Hustler. Called the Special Purpose Super Hustler, this version of the aircraft was briefed to the US government in November 1958. The response to that briefing came in the form of a series of questions. First on that list: What was the effect of the low-radar visibility requirement on the design of the Special Purpose Super Hustler?
Super Hustler was about to become FISH, the subject of the next article in this series.
* Gruen Labs, located in Long Island, New York, was founded in 1956 by Antonio Ferri, an engineering professor at what was then called Polytechnic Institute of Brooklyn. Ferri was financially backed by the Gruen Watch Company. The facility was later renamed the General Applied Science Laboratories. The lab is now part of Alliant Techsystems and is involved in developing advanced propulsion systems for next-generation aircraft and missiles.