Convair KINGFISH
Encyclopedia
The Kingfish reconnaissance aircraft
design was the ultimate result of a series of proposals designed at Convair
as a replacement for the Lockheed U-2
. "Kingfish" competed with the Lockheed A-12 for the Project Oxcart mission, and lost out to that design in 1959.
would be between 18 months and two years. After overflights began and the Soviets demonstrated the ability to track and attempt to intercept the U-2, this estimate was adjusted downward. In August 1956, Richard Bissell reduced the number to six months.
To extend the useful life of the U-2, the CIA started Project Rainbow
, which added various countermeasures to confuse the Soviet radars and make planning an intercept more difficult. The anti-radar methods developed under Rainbow consisted of, first, a diffusing coating for the fuselage, and, second, a series of wires strung along the fuselage and the wing edges that were supposed to cancel out radar reflection from the airframe by "broadcasting" a similar return but out-of-phase. Several Rainbow-equipped flights were made, but the Soviets proved able to track the aircraft regardless. The weight of the equipment also had the side-effect of lowering the aircraft's maximum cruise altitude, making it more vulnerable to interception. Rainbow was canceled in 1958.
as much as possible. High-altitude flight would still be useful to avoid interception by aircraft, but did little to help against missiles. By reducing the RCS, the radars guiding the missiles would have less time to track the aircraft, complicating the attack.
In August 1957 these studies turned to examining supersonic
designs, as it was realized that supersonic aircraft were very difficult to track on radars of that era. This was due to an effect known as the blip-to-scan ratio
, which refers to the "blip" generated by an aircraft on the radar display
. In order to filter out random noise from the display, radar operators would turn down the amplification of the radar signal so that fleeting returns would not be bright enough to see. Returns from real targets, like an aircraft, would become visible as multiple radar pulses all drawn onto the same location on the screen, and produced a single brighter spot. If the aircraft is moving at very high speeds, the returns would be spread out on the display. Like random noise, these returns would become invisible.
Kelly Johnson
of Lockheed presented the Archangel I design, which could cruise at Mach 3 for extended periods in order to take advantage of blip/scan spoofing, although it was not designed for reduced RCS. Convair proposed a parasite aircraft
that was launched in the air from a newer version of the B-58 Hustler
that was then being studied. The Navy introduced a submarine-launched inflatable rubber vehicle that would be lifted to altitude by a balloon, boosted to speed by rockets, and then cruise using ramjet
s. Johnson was asked to provide a second opinion on the Navy design, and the committee arranged to meet again shortly.
At the next meeting, in September 1958, the designs had been further refined. Johnson reported on the Navy concept and demonstrated that it would require a balloon a mile wide for launching; the submission was then dropped. Boeing
presented a new design for a 190 feet (57.9 m) long liquid hydrogen
powered inflatable design. Lockheed presented several designs; the Lockheed CL-400 Suntan looked like a scaled-up F-104 Starfighter
powered by wingtip-mounted hydrogen-burning engines, the G2A was a subsonic design with a low radar cross-section, and the A-2 was a delta wing
design using zip fuel
–powered ramjets. Convair entered their parasite design, slightly upgraded and now intended to fly at Mach 4.
For Project Gusto, the concept had been simplified and reduced to a single aircraft. Code-named FISH or First Invisible Super Hustler, the aircraft was based on a lifting body
design that bears some resemblance to the Asset
of a few years later. It differed in having the nose taper down to a flat horizontal line instead of the rounded delta of the ASSET, and the fuselage was not as large at the rear. Two vertical control surfaces were placed on either side of the fuselage at the rear, and a small delta wing
covered about the rear third of the aircraft. It was to be powered by two Marquardt
RJ-59 ramjet
s during the cruise phase, providing a cruise speed of Mach 4 at 75000 ft (22,860 m), climbing to 90000 ft (27,432 m) as it burned off fuel. In order to handle the intense heat generated by skin friction at these speeds, the leading edges of the nose and wings were built of a new "pyroceram" ceramic material, while the rest of the fuselage was made of a honeycomb stainless steel
similar to the material for the proposed XB-70 Valkyrie
. After completing its mission, the aircraft would return to friendly airspace, slow, and then open intakes for two small jet engines for the return flight at subsonic speeds.
Lockheed's entry had also changed during the research phase. Their original submission was the Archangel II (A-2), another ramjet-powered design, but one that was ground-launched using large jet engines.
The committee didn't find either entry particularly interesting, and when the B-58B was canceled by the Air Force in 1959, the entire "Fish" concept was put in jeopardy. There was some design work on converting the existing A-model Hustlers as "Fish" carriers, but the aircraft appeared to have limited capabilities for launching the "Fish", and the Air Force was unwilling to part with any of their bombers anyway. The committee asked both companies to return with another round of entries powered by the Pratt & Whitney J58
turboramjet.
, while other portions used a variety of materials selected for low radar reflection, including fiberglass
. The new engines reduced the cruise speed to Mach 3.2 compared to the "Fish"'s Mach 4.2, but range was increased to about 3,400 nm (6,300 km).
In August 1959 the teams met again to present their latest designs. Lockheed had produced an aircraft similar to the "Kingfish", the A-11, but it was more "conventional" in layout. Although the A-11 had somewhat better performance than "Kingfish", the panel generally preferred Convair's design due to its much lower RCS. Johnson expressed skepticism of Convair's claimed RCS, and complained that they had given up performance to achieve it: "Convair have promised reduced radar cross section on an airplane the size of A-12. They are doing this, in my view, with total disregard for aerodynamics, inlet and afterburner performance."
In the end it was not performance that decided the outcome; during the U-2 project Lockheed had proven its ability to design advanced aircraft in secret, on-time, and under-budget. In contrast, Convair had massive cost overruns with the B-58 and no secure facility similar to the Skunk Works. Lockheed promised to lower the RCS in a modified version of the A-11 known as the A-12, and that sealed the deal. The A-12 entered service with the CIA in the 1960s, and was slightly modified to become the Air Force's SR-71.
The CIA continued studies into even higher performance aircraft, and studied replacing the A-12 under Project Isinglass
. Isinglass focused on a new design blending features of the General Dynamics F-111
and "Kingfish." The new design aimed to produce a new reconnaissance aircraft capable of reaching up to Mach 5 at an altitude of 100000 ft (30,480 m). The CIA felt that the extra performance would not be enough to protect it from missile systems already capable of attacking the A-12, and nothing came of the project.
Ironically, the entire idea of spoofing radars through their blip/scan turned out to not work. Among other effects, it was discovered that the engine ejectors produced significant reflections. Lockheed proposed adding cesium to the jet fuel to create a cloud of ions that would help mask this effect. Additionally, since the entire idea relied on problems in the radar display systems, upgrades to these systems could render the entire concept moot. In the end, the A-12 was considered too vulnerable and was only flown over secondary nations like Vietnam
. The failure of the A-12's attempts to avoid radar was proven when the Vietnamese proved able to track the A-12 with some ease, even firing on it on several occasions and causing minor damage on one occasion in 1967.
Reconnaissance aircraft
A reconnaissance aircraft is a manned military aircraft designed, or adapted, to carry out aerial reconnaissance.-History:The majority of World War I aircraft were reconnaissance designs...
design was the ultimate result of a series of proposals designed at Convair
Convair
Convair was an American aircraft manufacturing company which later expanded into rockets and spacecraft. The company was formed in 1943 by the merger of Vultee Aircraft and Consolidated Aircraft, and went on to produce a number of pioneering aircraft, such as the Convair B-36 bomber, and the F-102...
as a replacement for the Lockheed U-2
Lockheed U-2
The Lockheed U-2, nicknamed "Dragon Lady", is a single-engine, very high-altitude reconnaissance aircraft operated by the United States Air Force and previously flown by the Central Intelligence Agency . It provides day and night, very high-altitude , all-weather intelligence gathering...
. "Kingfish" competed with the Lockheed A-12 for the Project Oxcart mission, and lost out to that design in 1959.
Problems with the U-2
Before the U-2 became operational in June 1956, CIA officials had estimated that its life expectancy for flying safely over the Soviet UnionSoviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
would be between 18 months and two years. After overflights began and the Soviets demonstrated the ability to track and attempt to intercept the U-2, this estimate was adjusted downward. In August 1956, Richard Bissell reduced the number to six months.
To extend the useful life of the U-2, the CIA started Project Rainbow
Project Rainbow
Project Rainbow was the name given by the CIA to a research project aimed at reducing the radar cross section of the Lockheed U-2 to reduce the chance that it would be detected and tracked by Soviet radars during its overflights of the USSR.-Early Flights:...
, which added various countermeasures to confuse the Soviet radars and make planning an intercept more difficult. The anti-radar methods developed under Rainbow consisted of, first, a diffusing coating for the fuselage, and, second, a series of wires strung along the fuselage and the wing edges that were supposed to cancel out radar reflection from the airframe by "broadcasting" a similar return but out-of-phase. Several Rainbow-equipped flights were made, but the Soviets proved able to track the aircraft regardless. The weight of the equipment also had the side-effect of lowering the aircraft's maximum cruise altitude, making it more vulnerable to interception. Rainbow was canceled in 1958.
Replacing the U-2
As early as 1956 Bissell had already started looking for an entirely new aircraft to replace the U-2, with an emphasis on reducing the radar cross sectionRadar cross section
Radar cross section is a measure of how detectable an object is with a radar. A larger RCS indicates that an object is more easily detected.An object reflects a limited amount of radar energy...
as much as possible. High-altitude flight would still be useful to avoid interception by aircraft, but did little to help against missiles. By reducing the RCS, the radars guiding the missiles would have less time to track the aircraft, complicating the attack.
In August 1957 these studies turned to examining supersonic
Supersonic
Supersonic speed is a rate of travel of an object that exceeds the speed of sound . For objects traveling in dry air of a temperature of 20 °C this speed is approximately 343 m/s, 1,125 ft/s, 768 mph or 1,235 km/h. Speeds greater than five times the speed of sound are often...
designs, as it was realized that supersonic aircraft were very difficult to track on radars of that era. This was due to an effect known as the blip-to-scan ratio
Blip-to-scan ratio
In radar systems, the blip-to-scan ratio, or blip/scan, is the ratio of the number of times a target appears on a radar display to the number of times it could have been seen...
, which refers to the "blip" generated by an aircraft on the radar display
Radar display
Modern radar systems typically use some sort of raster scan display to produce a map-like image. In the past, notably during the early days of radar development, such displays were difficult to produce for a number of reasons. Several different display types were developed during this...
. In order to filter out random noise from the display, radar operators would turn down the amplification of the radar signal so that fleeting returns would not be bright enough to see. Returns from real targets, like an aircraft, would become visible as multiple radar pulses all drawn onto the same location on the screen, and produced a single brighter spot. If the aircraft is moving at very high speeds, the returns would be spread out on the display. Like random noise, these returns would become invisible.
Project Gusto
By the autumn of 1957 so many ideas had been submitted that Bissell arranged for the formation of a new advisory committee to study the concepts, led by Edwin Land under the designation Project Gusto. The committee first met in November to arrange for submissions. At their next meeting, on 23 July 1958, several submissions were studied.Kelly Johnson
Clarence Johnson
Clarence Leonard "Kelly" Johnson was an aircraft engineer and aeronautical innovator. As a member and first team leader of the Lockheed Skunk Works, Johnson worked for more than four decades and is said to have been an "organizing genius"...
of Lockheed presented the Archangel I design, which could cruise at Mach 3 for extended periods in order to take advantage of blip/scan spoofing, although it was not designed for reduced RCS. Convair proposed a parasite aircraft
Parasite aircraft
A parasite aircraft is a component of a composite aircraft which is carried, and air launched by, a mother ship aircraft.The first use for parasite aircraft was in 1916, when the British used a Bristol Scout, flying from a Felixstowe Porte Baby, a giant flying boat of its time. This eventually...
that was launched in the air from a newer version of the B-58 Hustler
B-58 Hustler
The Convair B-58 Hustler was the first operational supersonic jet bomber capable of Mach 2 flight. The aircraft was designed by Convair engineer Robert H. Widmer and developed for the United States Air Force for service in the Strategic Air Command during the 1960s...
that was then being studied. The Navy introduced a submarine-launched inflatable rubber vehicle that would be lifted to altitude by a balloon, boosted to speed by rockets, and then cruise using ramjet
Ramjet
A ramjet, sometimes referred to as a stovepipe jet, or an athodyd, is a form of airbreathing jet engine using the engine's forward motion to compress incoming air, without a rotary compressor. Ramjets cannot produce thrust at zero airspeed and thus cannot move an aircraft from a standstill...
s. Johnson was asked to provide a second opinion on the Navy design, and the committee arranged to meet again shortly.
At the next meeting, in September 1958, the designs had been further refined. Johnson reported on the Navy concept and demonstrated that it would require a balloon a mile wide for launching; the submission was then dropped. Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...
presented a new design for a 190 feet (57.9 m) long liquid hydrogen
Liquid hydrogen
Liquid hydrogen is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.To exist as a liquid, H2 must be pressurized above and cooled below hydrogen's Critical point. However, for hydrogen to be in a full liquid state without boiling off, it needs to be...
powered inflatable design. Lockheed presented several designs; the Lockheed CL-400 Suntan looked like a scaled-up F-104 Starfighter
F-104 Starfighter
The Lockheed F-104 Starfighter is a single-engine, high-performance, supersonic interceptor aircraft originally developed for the United States Air Force by Lockheed. One of the Century Series of aircraft, it served with the USAF from 1958 until 1969, and continued with Air National Guard units...
powered by wingtip-mounted hydrogen-burning engines, the G2A was a subsonic design with a low radar cross-section, and the A-2 was a delta wing
Delta wing
The delta wing is a wing planform in the form of a triangle. It is named for its similarity in shape to the Greek uppercase letter delta .-Delta-shaped stabilizers:...
design using zip fuel
Zip fuel
Zip fuel, also known as high energy fuel , is any member of a family of jet fuels containing additives in the form of hydro-boron compounds, or boranes. Zip fuels offered higher power density than conventional fuels, helping extend the range of jet aircraft, a major problem for the military...
–powered ramjets. Convair entered their parasite design, slightly upgraded and now intended to fly at Mach 4.
FISH
Convair's parasite design was derived from the Super Hustler concept which Convair had proposed to the Air Force. The original version had been a two-part design, the rear portion being an unmanned booster powered by a pair of ramjets, and the front portion a manned aircraft with a single ramjet. The Super Hustler could either be launched from under a B-58 bomber or from a ground trailer using a booster rocket. For the air launch, the Super Hustler would be carried to a speed of Mach 2 at 35000 ft (10,668 m), and released. All three ramjets would fire for "boost", after which the rear portion would fall away. The unmanned booster could also be used as a weapon, if armed.For Project Gusto, the concept had been simplified and reduced to a single aircraft. Code-named FISH or First Invisible Super Hustler, the aircraft was based on a lifting body
Lifting body
A lifting body is a fixed-wing aircraft configuration in which the body itself produces lift. In contrast to a flying wing, which is a wing with minimal or no conventional fuselage, a lifting body can be thought of as a fuselage with little or no conventional wing...
design that bears some resemblance to the Asset
ASSET (spaceplane)
-Winged Gemini:In the mid-1960s, McDonnell proposed a variant of the Gemini capsule which retained the original spacecraft's internal subsystems and crew compartment, but dispensed with the tail-first ballistic reentry, parachute recovery and water landing....
of a few years later. It differed in having the nose taper down to a flat horizontal line instead of the rounded delta of the ASSET, and the fuselage was not as large at the rear. Two vertical control surfaces were placed on either side of the fuselage at the rear, and a small delta wing
Delta wing
The delta wing is a wing planform in the form of a triangle. It is named for its similarity in shape to the Greek uppercase letter delta .-Delta-shaped stabilizers:...
covered about the rear third of the aircraft. It was to be powered by two Marquardt
Marquardt
Marquardt Corporation was one of the few aeronautical engineering firms that was dedicated almost solely to the development of the ramjet engine. Marquardt designs were developed through the 1940s into the 1960s, but the ramjet never became a major design and the company turned to other fields in...
RJ-59 ramjet
Ramjet
A ramjet, sometimes referred to as a stovepipe jet, or an athodyd, is a form of airbreathing jet engine using the engine's forward motion to compress incoming air, without a rotary compressor. Ramjets cannot produce thrust at zero airspeed and thus cannot move an aircraft from a standstill...
s during the cruise phase, providing a cruise speed of Mach 4 at 75000 ft (22,860 m), climbing to 90000 ft (27,432 m) as it burned off fuel. In order to handle the intense heat generated by skin friction at these speeds, the leading edges of the nose and wings were built of a new "pyroceram" ceramic material, while the rest of the fuselage was made of a honeycomb stainless steel
Stainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
similar to the material for the proposed XB-70 Valkyrie
XB-70 Valkyrie
The North American Aviation XB-70 Valkyrie was the prototype version of the proposed B-70 nuclear-armed deep-penetration strategic bomber for the United States Air Force's Strategic Air Command...
. After completing its mission, the aircraft would return to friendly airspace, slow, and then open intakes for two small jet engines for the return flight at subsonic speeds.
Lockheed's entry had also changed during the research phase. Their original submission was the Archangel II (A-2), another ramjet-powered design, but one that was ground-launched using large jet engines.
The committee didn't find either entry particularly interesting, and when the B-58B was canceled by the Air Force in 1959, the entire "Fish" concept was put in jeopardy. There was some design work on converting the existing A-model Hustlers as "Fish" carriers, but the aircraft appeared to have limited capabilities for launching the "Fish", and the Air Force was unwilling to part with any of their bombers anyway. The committee asked both companies to return with another round of entries powered by the Pratt & Whitney J58
Pratt & Whitney J58
The Pratt & Whitney J58 was a jet engine used on the Lockheed A-12, and subsequently on the YF-12 and SR-71 Blackbird aircraft. The J58 was a variable cycle engine which functioned as both a turbojet and a fan-assisted ramjet. The J58 was a single-spool turbojet engine with an afterburner...
turboramjet.
Kingfish
After cancellation of the B-58B in mid-1959, Convair turned to a completely new design, similar to their earlier entry in name only. The new "Kingfish" design had much in common with the Convair F-106 Delta Dart, using a classic delta wing layout like most of Convair's products. It differed in having two of the J58 engines buried in the rear fuselage, and twin vertical surfaces at the rear. The intakes and exhausts were arranged to reduce radar cross section, and the entire aircraft had the same sort of angular appearance as the later Lockheed F-117. The leading edges of the wings and intakes continued to use pyroceramPyroceram
Pyroceram is a material developed and trademarked by Corning Glass during the 1950s. Its development has been traced to Corning's work in developing photosensitive glass. Corning credits S...
, while other portions used a variety of materials selected for low radar reflection, including fiberglass
Fiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...
. The new engines reduced the cruise speed to Mach 3.2 compared to the "Fish"'s Mach 4.2, but range was increased to about 3,400 nm (6,300 km).
In August 1959 the teams met again to present their latest designs. Lockheed had produced an aircraft similar to the "Kingfish", the A-11, but it was more "conventional" in layout. Although the A-11 had somewhat better performance than "Kingfish", the panel generally preferred Convair's design due to its much lower RCS. Johnson expressed skepticism of Convair's claimed RCS, and complained that they had given up performance to achieve it: "Convair have promised reduced radar cross section on an airplane the size of A-12. They are doing this, in my view, with total disregard for aerodynamics, inlet and afterburner performance."
In the end it was not performance that decided the outcome; during the U-2 project Lockheed had proven its ability to design advanced aircraft in secret, on-time, and under-budget. In contrast, Convair had massive cost overruns with the B-58 and no secure facility similar to the Skunk Works. Lockheed promised to lower the RCS in a modified version of the A-11 known as the A-12, and that sealed the deal. The A-12 entered service with the CIA in the 1960s, and was slightly modified to become the Air Force's SR-71.
Aftermath
Some small-scale work on the "Kingfish" continued even after the choice of the A-12, in case the A-12 ran into problems. This did not occur, and the "Kingfish" funds soon disappeared.The CIA continued studies into even higher performance aircraft, and studied replacing the A-12 under Project Isinglass
Project Isinglass
|-References:NotesCitationsBibliographyFurther reading-External links :* * *...
. Isinglass focused on a new design blending features of the General Dynamics F-111
General Dynamics F-111
The General Dynamics F-111 "Aardvark" was a medium-range interdictor and tactical strike aircraft that also filled the roles of strategic bomber, reconnaissance, and electronic warfare in its various versions. Developed in the 1960s by General Dynamics, it first entered service in 1967 with the...
and "Kingfish." The new design aimed to produce a new reconnaissance aircraft capable of reaching up to Mach 5 at an altitude of 100000 ft (30,480 m). The CIA felt that the extra performance would not be enough to protect it from missile systems already capable of attacking the A-12, and nothing came of the project.
Ironically, the entire idea of spoofing radars through their blip/scan turned out to not work. Among other effects, it was discovered that the engine ejectors produced significant reflections. Lockheed proposed adding cesium to the jet fuel to create a cloud of ions that would help mask this effect. Additionally, since the entire idea relied on problems in the radar display systems, upgrades to these systems could render the entire concept moot. In the end, the A-12 was considered too vulnerable and was only flown over secondary nations like Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
. The failure of the A-12's attempts to avoid radar was proven when the Vietnamese proved able to track the A-12 with some ease, even firing on it on several occasions and causing minor damage on one occasion in 1967.