Post by Blackbird on Aug 10, 2004 14:24:44 GMT -5
Reports of plans for a high-performance piloted replacement for the SR-71 date back more than a decade. In 1979 it was reported that a:
"... Mach 4, 200,000-ft.-altitude aircraft that could be a follow-on to the Lockheed SR-71 strategic reconnaissance vehicle in the 1990s has been defined by the Air Force Aeronautical Systems Division and Lockheed."
As previously noted, reports of the existence of a successor to the SR-71 surfaced repeatedly during the debate over termination of the SR-71. Subsequent observations of mysterious aerial phenomena have been connected with the 1988 reports that Aurora was a Mach 6 stealthy reconnaissance aircraft that was being developed to replace the SR-71.
Noted aerospace analyst Wolfgang Demisch, of First Boston Company, suggested that the $10 billion program would result in the production of about 30 aircraft. More recently, Kemper Security analyst Lawrence Harris concluded that Lockheed was involved in a:
"... hypersonic replacement for the Mach 3 plus SR-71 reconnaissance aircraft. Circumstantial evidence suggests that this project has been underway since 1987 and that a first flight occurred in 1989... Aurora could be operational in 1995, six years after the probable first flight."
This analysis suggested that the total development costs for Aurora might range from $4.4 billion to $8 billion, with the procurement of 24 aircraft costing an additional $10 billion to $24 billion.
According to another report, by mid-1992:
"... Aurora was being flown from a base in the Nevada desert to an atoll in the Pacific, then on to Scotland to refuel before returning to the US at night. Specially modified tanker aircraft are being used to top up Aurora's tanks with liquid methane fuel in mid-air... The US Air Force is using the remote RAF airbase at Machrihanish, Strathclyde, as a staging point... The mystery aircraft has been dropping in at night before streaking back to America across the North Pole at more than six times the speed of sound... An F-111 fighter bomber is scrambling as the black-painted aircraft lands, flying in close formation to confuse prying civilian radars."
The rationale used most frequently by the Department of Defense for the SR-71's termination was financial. The Blackbird's operation and maintenance costs were very high. According to some reports, the SR-71's O&M costs were nearly $710- million in FY-90 and FY-91. Furthermore, they argued, imaging satellites could now conduct worldwide surveillance more efficiently and less expensively than manned reconnaissance aircraft.
Independent aerospace analysts, however, deflated this argument somewhat by pointing to the unique advantages aircraft bring to the reconnaissance arena. Aircraft, for example, are inherently flexible and unpredictable. Though not as fast as satellites, they can fly lower and the interval between over the horizon arrival and time-over-target is just as short. Aircraft have a wide choice of routes, so tracking ships are unlikely to see it on the way in. Application of low observable technology could further reduce warning time. Thus, it appears plausible that aircraft may still have a role in global reconnaissance.
Another analyst has considered the possibilities of "Aurora's" characteristics and capabilities. A long-range reconnaissance follow-on to the SR-71 would be a blended delta with 75 degree leading-edge sweep and retractable low-speed foreplanes. It would be powered by two regenerative air-turboramjet (RATR) engines of 180 kN sea-level static thrust. It would carry a crew of two and use a synthetic aperture radar with real-time datalink for reconnaissance. It is suggested that this type of platform could be very responsive, much more easily maintainable than the SR-71 and could deliver imagery of most points of interest within six hours of the decision to go. A speed between Mach 5 and Mach 6 and a cruising altitude of 40 kilometers would make the aircraft invulnerable to any current missile system.
The Public Record
Beginning in the mid-1980s, the Air Force and NASA have supported a number of studies of aircraft that are consistent with accounts of the Aurora project. Although these studies have not been linked to actual development efforts, they provide some insight into the potential configuration and capabilities of Aurora.
In 1985 McDonnell Douglas conducted studies of a Mach 5, 12,000 km range 305 passenger HSCT (hypersonic commercial transport) powered by regenerative ATR (air turboramjet) engines. Initial research led to claims that this type of aircraft was not only feasible, but remarkably efficient. According to these studies, a ramjet was the best option at Mach 5, and that methane was the preferred fuel. Hydrogen was also considered, but it takes up to five times as much space. If the large HSCT was scaled down to the dimensions of an SR-71, the aircraft could have a range of approximately 10,000 miles with a crew of two and a 1 ton sensor suite.
Lockheed's renowned Skunk Works has been the incubator of several programs that could evolve, or could already have evolved, into an SR-71 replacement. Presently, Lockheed engineers are reportedly studying the development of a liquid methane- fueled aircraft that could penetrate enemy airspace in order to perform reconnaissance missions.
"The sleek aircraft would cruise at Mach 5 (3,350 mph) speed at a maximum altitude of about 100,000 feet. The aircraft would be made primarily of titanium with its outer edges constructed of Inconel, a heat-resistant stainless steel. At Mach 5 speed the leading edges of the air-frame would glow red above 1,000 degrees Fahrenheit. Power for this futuristic airplane would come from four turbo-ramjets. The engines would operate as turbojets at low speeds, but at higher speeds the compressor and turbine would be overridden so the engines would operate as ramjets."
Other aircraft designs that would fly between Mach 4 and Mach 8, fueled by hydrocarbon or liquid hydrogen are also being considered. And in the mid-1980s, Lockheed proposed a Mach 7-8 "transatmospheric vehicle" or TAV as an SR-71 replacement. Intriguingly enough, the name "Aurora" was also used in conjunction with this proposal.
In 1986, the Directorate for R&D Contracting, Wright-Patterson Air Force Base, issued an RFP for aircraft propulsion integration technology.
"... The purpose of the proposed investigation is to develop an improved foundation for manned aircraft air-breathing propulsion integration technology in the Mach 4 to 6 regime."
Under an Air Force contract, Boeing Military Airplane Co. designed an interceptor capable of sustaining supersonic speeds. It was reported that wind tunnel tests would be conducted under a 26 month $572,000 follow-on contract. This effort also included detailed studies of aircraft subsystems. Similar studies were conducted by Lockheed and General Dynamics.
Keeping an aircraft sufficiently cool during extreme speeds is a primary challenge of hypersonic flight. According to studies done by General Dynamics and Boeing, an aircraft travelling at between Mach 5.5 and Mach 6 would have an average skin temperature of approximately 1100-1300 degrees Fahrenheit.<66> One potential solution incorporated in the Air Force studies, also being explored by researchers at NASA's Langley Research Center and Wright-Patterson Air Force base, is the use of Methylcyclohexane (MCH) as both the fuel and the thermal management medium of the vehicle.
MCH has several advantages over other possible hydrocarbon or cryogenic fuels. Unlike standard hydrocarbon fuels, MCH has a very high capacity to absorb heat prior to combustion, up to 1800 Btu per pound of fuel, which is ten times the capacity of most hydrocarbon fuels.<68> Cryogenic Methane and Hydrogen have high heat absorbtion capacities as well, but their use as an aviation fuel is limited by the logistical difficulties of handling, storage and fuel boil off.
"... Mach 4, 200,000-ft.-altitude aircraft that could be a follow-on to the Lockheed SR-71 strategic reconnaissance vehicle in the 1990s has been defined by the Air Force Aeronautical Systems Division and Lockheed."
As previously noted, reports of the existence of a successor to the SR-71 surfaced repeatedly during the debate over termination of the SR-71. Subsequent observations of mysterious aerial phenomena have been connected with the 1988 reports that Aurora was a Mach 6 stealthy reconnaissance aircraft that was being developed to replace the SR-71.
Noted aerospace analyst Wolfgang Demisch, of First Boston Company, suggested that the $10 billion program would result in the production of about 30 aircraft. More recently, Kemper Security analyst Lawrence Harris concluded that Lockheed was involved in a:
"... hypersonic replacement for the Mach 3 plus SR-71 reconnaissance aircraft. Circumstantial evidence suggests that this project has been underway since 1987 and that a first flight occurred in 1989... Aurora could be operational in 1995, six years after the probable first flight."
This analysis suggested that the total development costs for Aurora might range from $4.4 billion to $8 billion, with the procurement of 24 aircraft costing an additional $10 billion to $24 billion.
According to another report, by mid-1992:
"... Aurora was being flown from a base in the Nevada desert to an atoll in the Pacific, then on to Scotland to refuel before returning to the US at night. Specially modified tanker aircraft are being used to top up Aurora's tanks with liquid methane fuel in mid-air... The US Air Force is using the remote RAF airbase at Machrihanish, Strathclyde, as a staging point... The mystery aircraft has been dropping in at night before streaking back to America across the North Pole at more than six times the speed of sound... An F-111 fighter bomber is scrambling as the black-painted aircraft lands, flying in close formation to confuse prying civilian radars."
The rationale used most frequently by the Department of Defense for the SR-71's termination was financial. The Blackbird's operation and maintenance costs were very high. According to some reports, the SR-71's O&M costs were nearly $710- million in FY-90 and FY-91. Furthermore, they argued, imaging satellites could now conduct worldwide surveillance more efficiently and less expensively than manned reconnaissance aircraft.
Independent aerospace analysts, however, deflated this argument somewhat by pointing to the unique advantages aircraft bring to the reconnaissance arena. Aircraft, for example, are inherently flexible and unpredictable. Though not as fast as satellites, they can fly lower and the interval between over the horizon arrival and time-over-target is just as short. Aircraft have a wide choice of routes, so tracking ships are unlikely to see it on the way in. Application of low observable technology could further reduce warning time. Thus, it appears plausible that aircraft may still have a role in global reconnaissance.
Another analyst has considered the possibilities of "Aurora's" characteristics and capabilities. A long-range reconnaissance follow-on to the SR-71 would be a blended delta with 75 degree leading-edge sweep and retractable low-speed foreplanes. It would be powered by two regenerative air-turboramjet (RATR) engines of 180 kN sea-level static thrust. It would carry a crew of two and use a synthetic aperture radar with real-time datalink for reconnaissance. It is suggested that this type of platform could be very responsive, much more easily maintainable than the SR-71 and could deliver imagery of most points of interest within six hours of the decision to go. A speed between Mach 5 and Mach 6 and a cruising altitude of 40 kilometers would make the aircraft invulnerable to any current missile system.
The Public Record
Beginning in the mid-1980s, the Air Force and NASA have supported a number of studies of aircraft that are consistent with accounts of the Aurora project. Although these studies have not been linked to actual development efforts, they provide some insight into the potential configuration and capabilities of Aurora.
In 1985 McDonnell Douglas conducted studies of a Mach 5, 12,000 km range 305 passenger HSCT (hypersonic commercial transport) powered by regenerative ATR (air turboramjet) engines. Initial research led to claims that this type of aircraft was not only feasible, but remarkably efficient. According to these studies, a ramjet was the best option at Mach 5, and that methane was the preferred fuel. Hydrogen was also considered, but it takes up to five times as much space. If the large HSCT was scaled down to the dimensions of an SR-71, the aircraft could have a range of approximately 10,000 miles with a crew of two and a 1 ton sensor suite.
Lockheed's renowned Skunk Works has been the incubator of several programs that could evolve, or could already have evolved, into an SR-71 replacement. Presently, Lockheed engineers are reportedly studying the development of a liquid methane- fueled aircraft that could penetrate enemy airspace in order to perform reconnaissance missions.
"The sleek aircraft would cruise at Mach 5 (3,350 mph) speed at a maximum altitude of about 100,000 feet. The aircraft would be made primarily of titanium with its outer edges constructed of Inconel, a heat-resistant stainless steel. At Mach 5 speed the leading edges of the air-frame would glow red above 1,000 degrees Fahrenheit. Power for this futuristic airplane would come from four turbo-ramjets. The engines would operate as turbojets at low speeds, but at higher speeds the compressor and turbine would be overridden so the engines would operate as ramjets."
Other aircraft designs that would fly between Mach 4 and Mach 8, fueled by hydrocarbon or liquid hydrogen are also being considered. And in the mid-1980s, Lockheed proposed a Mach 7-8 "transatmospheric vehicle" or TAV as an SR-71 replacement. Intriguingly enough, the name "Aurora" was also used in conjunction with this proposal.
In 1986, the Directorate for R&D Contracting, Wright-Patterson Air Force Base, issued an RFP for aircraft propulsion integration technology.
"... The purpose of the proposed investigation is to develop an improved foundation for manned aircraft air-breathing propulsion integration technology in the Mach 4 to 6 regime."
Under an Air Force contract, Boeing Military Airplane Co. designed an interceptor capable of sustaining supersonic speeds. It was reported that wind tunnel tests would be conducted under a 26 month $572,000 follow-on contract. This effort also included detailed studies of aircraft subsystems. Similar studies were conducted by Lockheed and General Dynamics.
Keeping an aircraft sufficiently cool during extreme speeds is a primary challenge of hypersonic flight. According to studies done by General Dynamics and Boeing, an aircraft travelling at between Mach 5.5 and Mach 6 would have an average skin temperature of approximately 1100-1300 degrees Fahrenheit.<66> One potential solution incorporated in the Air Force studies, also being explored by researchers at NASA's Langley Research Center and Wright-Patterson Air Force base, is the use of Methylcyclohexane (MCH) as both the fuel and the thermal management medium of the vehicle.
MCH has several advantages over other possible hydrocarbon or cryogenic fuels. Unlike standard hydrocarbon fuels, MCH has a very high capacity to absorb heat prior to combustion, up to 1800 Btu per pound of fuel, which is ten times the capacity of most hydrocarbon fuels.<68> Cryogenic Methane and Hydrogen have high heat absorbtion capacities as well, but their use as an aviation fuel is limited by the logistical difficulties of handling, storage and fuel boil off.