Convair* abruptly halted efforts on its losing Kingfish design when the CIA selected the Lockheed A-12 in August 1959 as a high-speed, high-altitude replacement for the U-2 reconnaissance aircraft. Structural test parts, tooling, and raw materials associated with Kingfish were destroyed and sold as scrap. Engineers working on the program were reassigned. Documents were shredded. The CIA officially terminated Convair’s work on Project Gusto—the project code name for the Dragon Lady replacement—in February 1960. The company received a final payment for work related to the program in January 1963.
However, only ten months later, Convair used the predecessor to Kingfish—FISH—as the starting point for design studies for an A-12 replacement.
A team of about fifteen engineers led by Randy Kent worked on the renewed design studies. “We put together an excellent team,” Kent recalled almost fifty years later. “We were assigned a secure area that was dedicated specifically for our project. The work was very important to the company because we thought we were going to be out of business if we didn’t produce. Very few new aircraft programs were out there for us at the time.”
Those working on the A-12 replacement project initially referred to it by an internal billing designation—Work Order 540. The initial studies were divided into four two-month phases that spanned November 1963 through June 1964.
FISH Configuration 234 was the starting point for the Phase 1 studies. This design, its evolution detailed earlier in Part 2 of this series, was finalized in 1959. Configuration 234 was forty-seven feet long and ten feet high at the tail. The aircraft had a wingspan of thirty-seven feet, a wing area of 714 square feet, and a gross weight of 38,325 pounds. Powered by two Marquardt MA24E ramjet engines, the aircraft had a maximum speed of Mach 4 and a range of 3,900 nautical miles.
The initial phase of the A-12 replacement studies focused on parasitic aircraft that were compatible with an expanded version of the B-58 that had a larger tail, beefier and taller landing gear, and a five-foot longer fuselage. The operational radius for launching FISH from the larger B-58 was 2,300 nautical miles.
Supersonic refueling, variable sweep wings, and turbofan ramjet engines were considered in this phase of the studies. Four new configurations were the result.
The first of the configurations, Configuration 234A, was optimized for supersonic aerial refueling. It had a gross weight of 41,850 pounds, a zone range of 3,045 miles, and a post-zone range of 1,885 nautical miles. (Range was split into zone and post-zone legs. Zone was the effective range once the aircraft reached its operational speed and altitude, defined as Mach 4 and 90,000 feet.) Supersonic refueling posed several aerodynamic problems so this configuration was dropped from consideration.
Configuration 234B was a variation of the original 234 except it was refueled at subsonic speeds. The aircraft had a gross weight of 42,710 pounds, a zone range of 3,750 nautical miles, and a post-zone range of 2,000 nautical miles.
While Configuration 234 had two turbojet engines that were hinge-mounted behind the cockpit and inside the fuselage so they could pop out for landings, 234B had three turbo engines mounted on a mechanism behind the cockpit. The mechanism would rise for landings. This configuration showed promise and was carried into the next phase.
Configuration VSF-1 had variable sweep wings. Variable sweep allows the planform and aerodynamic behavior of the aircraft to be changed in flight. The application of variable sweep wings to the designs for an A-12 replacement had much to do with timing. Variable sweep wings were prescribed by the US Air Force in 1960 in the requirements set for the TFX program. General Dynamics won this program in November 1962 with its design for what became the F-111, the first production aircraft with variable sweep wings.
VSF-1 had a gross weight of 43,795 pounds, a zone range of 3,470 nautical miles, and a post-zone range of 2,780 nautical miles. The wings would sweep about fifteen degrees. Like Configuration 234, VSF was powered by two ramjet engines for supersonic flight and by two turbojet engines for subsonic flight. The turbojet engines were stowed internally for supersonic flight with the same approach used for 234B.
Initially, the variable sweep design was discounted for consideration from subsequent phases because the wing pivot thickness exceeded some aerodynamic and space requirements set by the B-58 carrier aircraft. The decision was later reversed.
Configuration FWF-2 incorporated two turbofan ramjet engines. These engines, with turbojet and ramjet modes, allowed the internal turbojets used on the other configurations studied in this phase to be deleted. The result was increased range. FWF-2 had a gross weight of 48,685 pounds, a zone range of 3,900 nautical miles, and a post-zone range of 3,000 miles. This configuration also made the cut.
Phase 1 included several exploratory studies. The first, which concerned aerial refueling in a supersonic wake, related specifically to Configuration 234A. Convair also studied the effects of heat on fuel in fuel tanks, tow concepts for accelerating parasitic aircraft, and a Mach 6 parasite powered by propane. Labeled Configuration HV-1, the gas-powered hypersonic parasite would be added to the list of designs carried into the next phase.
Phase 2, which ran from 13 January to 13 March 1964, expanded the design envelope to cover new parasite configurations, including unmanned parasites. Though Kingfish was never referenced, nonparasitic designs, called self-accelerators, were also considered in this phase.
Configuration 234B, while retaining its basic design, went through more rigorous structural analyses and became known as the Fixed Wing, or FWF, series. FWF-2 evolved into FWF-2C, which had a gross weight of 54,500 pounds, a zone range of 3,900 nautical miles, and a post-zone range of 2,560 nautical miles. Its cruising speed increased to Mach 4.3. Development cost and weight for the turbofan ramjet engines, however, cut this configuration from further consideration.
Configuration HV-1 evolved into HV-2. The Mach 6 design had a gross weight of 54,620 pounds, a zone range of 3,720 nautical miles, and a post-zone range of 1,680 nautical miles. This configuration was also cut from further consideration due to the amount of development time it would require for the compressed gas engine and fuel storage.
The first unmanned parasite was called Configuration UMP-1. With no landing gear, a gross weight of 16,300 pounds, a zone range of 5,000 nautical miles, and a post-zone range of zero nautical miles, this configuration could be launched from an unmodified B-58. The aircraft would transmit information to a ground station in flight and then destroy itself at sea.
The variable sweep Mach 4 VSF-1 evolved into the Mach 5 VSF-4. This aircraft had a gross weight of 47,020 pounds, a zone range of 4,000 nautical miles, and a post-zone range of 2,320 nautical miles. The zone altitude was listed as 95,000 feet. The design had three turbojet engines that would pop out behind the cockpit for landings.
One self-accelerator design was studied in this phase. Called Configuration SA-1, the aircraft had a gross weight of 88,780 pounds, a pre-zone range of 3,380 nautical miles, a zone range of 4,020 nautical miles, and a post-zone range of 4,290 nautical miles. The aircraft was powered by two TF30 turbofan ramjet engines. Engine development cost was listed as a downside, but the approach would be further refined in Phase 3.
Phase 2 also included four exploratory studies. The first study involved using the X-15 as a parasite for the B-58A. A second study involved parasite towing at speeds from Mach 0.5 to Mach 2. A third study involved using ramjets boosted by solid rocket motors. The fourth, and last, study involved using a higher energy-density hydrocarbon fuel for increasing range.
Configuration VSF-4, the variable sweep wing Mach 5 parasite, became the focus for Phase 3. Convair designers were also directed to assess configurations with very low radar cross sections.
Phase 3 began with an evaluation of alternatives to the modified B-58 as a launch platform for VS-4. The first alternative consisted of attaching the second stage of a SCOUT rocket to the underside of VSF-4 and air-launching the parasite/rocket combination from a B-52. The Lockheed D-21 drone would later be launched in this manner. SCOUT, an acronym for Solid Controlled Orbital Utility Test, was the first US-built solid-fuel rocket capable of launching a satellite into a 500-mile orbit. The second alternative consisted of ground launching VSF-4 atop the first stage of an LGM-30 Minuteman I missile. The Minuteman I was a three-stage, solid rocket-powered intercontinental ballistic missile designed to deliver nuclear warheads.
These launching alternatives led to a variable-sweep, self-accelerator version of VSF-4, which was called Configuration SA-2S. This configuration was an enlarged version of VSF-4 powered by two Pratt & Whitney J52 turbojet engines for takeoff and cruise. A solid rocket, the first stage from a SCOUT rocket, was used to accelerate the aircraft to supersonic speeds necessary to start its two Marquardt ramjet engines.
SA-2S had a takeoff weight of 92,000 pounds, a pre-zone range of 2,100 nautical miles, a zone range of 4,000 nautical miles, and a post-zone range of 2,700 nautical miles. It cruised at Mach 5 and 95,000 feet. Fuel weight was 37,600 pounds. The aircraft was 87.5 feet long and 16.7 feet tall. The wingspan was 35.0 feet with the wings swept for high-speed flight. Wingspan was 60.3 feet with the wings extended for low-speed flight. Several turbojets and booster rockets, some under development, were studied as alternative powerplants to improve performance.
A preliminary program schedule indicated a first flight date four years after program approval. An accelerated seven-month follow-on program that covered configuration development, wind tunnel tests, structural testing, and radar cross section tests was proposed at a cost of $1.6 million in then-year dollars. Several non-accelerated options were also offered.
Configurations LCS-1 and SUB-6 responded to the request to investigate designs with very low cross sections. These designs relaxed range, speed, and altitude requirements to minimize radar cross section. LCS-1 was a Mach 3 fixed-wing, twin-tail, flat-bottom design with a single inlet on top of the fuselage. The bifurcated inlet wrapped around a centerline cockpit and supplied air to two Curtiss-Wright TJ70 turbojet engines.
LCS-1 was 86.0 feet long, had a wingspan of 70.0 feet, and a wing area of 2,730 square feet. The stealthy design made use of radar absorbing material. LCS-1 had a gross weight of 75,500 pounds, a pre-zone range of 3,750 nautical miles, a zone range of 3,750 nautical miles, and a post-zone range of 3,800 nautical miles. The configuration was recommended for further study.
SUB-6 was a subsonic (Mach 0.77) design that looked like a stealthy version of the U-2. The aircraft had a wingspan of 195 feet. Like the LCS-1, SUB-6 had a bifurcated inlet located on the top side of the fuselage. Also like the LCS-1, SUB-6, was powered by two TJ70 turbojet engines. The aircraft had a gross weight of 60,000 pounds. Its pre-zone, zone, and post-zone ranges were all 2,200 nautical miles. The configuration was dropped from further study because its low speed and low cruising altitude (80,000 feet) made it vulnerable to potential threats.
As in previous phases, Phase 3 included several exploratory studies. The improved range properties of high-density hydrocarbon fuel were verified in tests. Camera window temperature tests were further refined. A variable wing area sail wing with winglets was also studied.
A budget status chart at the end of the report for Phase 3 indicated that Work Order 540 would run through July 1965 with an overall budget of $165,000, and approximately $110,000 had been spent for the first three phases. However, no status reports beyond Phase 3 were found in researching this article. The gap, however, is covered by follow-on design work that was initiated in August 1964. The results of this work were presented to Air Force Systems Command in March 1965 in a report titled Manned Hypersonic Vehicle Study.
The Manned Hypersonic Vehicle study summarized the work done in the previous phases for Mach 4 to 6 designs and then addressed two classes of Mach 6 to 12 hydrogen-powered designs. The first class, called Early Availability, consisted of vehicles with conventional propulsion systems, including currently available turbojets and subsonic combustion ramjets. The second class, called Later Availability, consisted of vehicles with advanced propulsion systems, including advanced turbojets and supersonic combustion ramjets.
None of the designs were B-58 parasites, which is not surprising since Secretary of Defense Robert McNamara formally announced the retirement of the B-58 program in late 1965.
Three design approaches were presented for the Early Availability category. They were based on three variations of the same reconnaissance mission concept—a pre-zone leg at subsonic speeds and medium altitudes that covered at least 2,000 nautical miles from the area to be reconnoitered; a zone leg at maximum altitude and super- or hypersonic cruising speed that covered 4,000 nautical miles; and a post-zone leg at subsonic speed that returned the vehicle to the home base or a safe base in another location.
The first design approached the mission with a boost-glide vehicle. This design, called Configuration R-3, had a maximum speed of Mach 9 and a maximum altitude of 130,000 feet. Powered to max speed and altitude by a liquid hydrogen/liquid oxygen rocket booster with thrust of 190,000 pounds, it then glided for the remainder of the time in the reconnaissance zone. Subsonic propulsion for pre- and post-zone operations was provided by a single Bristol Siddeley 100/8 turbojet engine.
R-3 had a gross weight of 146,000 pounds and a zone range of 1,100 nautical miles. The variable sweep wings, when extended, gave the aircraft a wingspan of eighty feet. The overall length of the aircraft was 141.8 feet. The sweep angle of the leading edge when not extended was eighty-two degrees.
The second design, called Configuration B-2, approached the mission by air-launching a satellite payload from a rocket-propelled missile pod attached to the underside of a hypersonic carrier. The carrier vehicle had a maximum speed of Mach 8. It was powered by four General Electric J93 engines and one liquid oxygen/JP-fueled rocket motor. The rocket had a thrust of 250,000 pounds. The aircraft was 134.7 feet long with a fixed wing span of 77.8 feet and a sweep angle of sixty degrees. It weighed 299,000 pounds without the pod.
The satellite pod in B-2 was powered by two rockets. The first rocket, which ignited after the pod separated from the carrier at Mach 8, consisted of a two-stage UGM-27 Polaris A2 sea-launched ballistic missile. The second rocket was a forty-inch diameter Thiokol rocket. The combination satellite/missile pod weighed 25,000 pounds.
The third design approached the mission with a cruise vehicle. Called Configuration C-3, this design had a maximum speed of Mach 8 and a zone altitude of 115,000 feet. The twin-tail, fixed-wing aircraft was powered by four Pratt & Whitney advanced TF30 turbofan engines and one Marquardt dual fuel ramjet.
The turbojets would power the aircraft to Mach 3 at which point the ramjets would be ignited and powered by JP-4 fuel, the same fuel used to power the turbojets. Once the aircraft reached 115,000 feet and Mach 8, the ramjets would switch to liquid hydrogen for the duration of the zone leg. The dual-fuel approach allowed the aircraft to be sized smaller than a single-fuel design and to be refueled by existing KC-135 tanker aircraft.
C-3 had a gross weight of 170,000 pounds. It was 158.4 feet long and had a wingspan of 68.4 feet. An alternate configuration, which placed all four turbojets between the twin tails, had a length of 147.9 feet and a wingspan of 68.5 feet.
The Later Availability vehicles were based on engine and structural advances as applied to Configuration C-3. These advances included supersonic combustion ramjets and advanced turbojets. These designs, which were not detailed and not pursued, according to Kent, would be capable of reaching orbital velocities.
Historical context explains why these supersonic and hypersonic designs never lifted off the drawing board. The success of the Lockheed A-12 and SR-71 programs made alternatives unnecessary. Engineers in Fort Worth became more focused on the F-111 program and the earliest stages of the lightweight fighter program. Furthermore, the success of US reconnaissance satellites launched from rockets lessened the need for air-breathing reconnaissance platforms.
The National Aerospace Plane project renewed interest in hypersonic flight in the mid- to late 1980s, with emphasis on high-speed transports and air-breathing, single-stage to orbit launchers. The documents used as source material for these FISH and Kingfish articles were declassified for use on the National Aerospace Plane, or NASP, program. While the NASP project was canceled in 1993, hypersonic studies and research continue to this day within Lockheed Martin Skunk Works, in the form of NASA, ONR, and DARPA projects. The Skunk Works continues to study high-speed aerodynamics, supersonic and hypersonic propulsion, and airframe materials that could apply to future systems.
Dedication: The series, “Super Hustler, FISH, Kingfish, and Beyond,” is dedicated to the late Bob Widmer, who created the design and engineering department at the then-Consolidated Aircraft Fort Worth Division in Texas in 1942.
Sources And Credits: “Beyond Kingfish” is based on several presentations released for the NASP program in 1986. Code One thanks Randy Kent for contributing his firsthand accounts to the article and to Kevin Renshaw for reviewing the article for technical accuracy.
*General Dynamics acquired Convair in 1953. The Fort Worth operation subsequently became known as the Convair Division of General Dynamics. After a corporate reorganization in May 1965, the facility in Fort Worth was called General Dynamics Fort Worth Division. For simplicity’s sake, Convair is used throughout this article.