Post by Blackbird on Aug 10, 2004 16:00:02 GMT -5
There is also the possiblity that the SR-71 follow-on was hidden in plain sight. The program to develop what is called the National Aerospace Plane (NASP), designated the X-30, had its roots in a highly classified, Special Access Required, Defense Advanced Research Projects Agency (DARPA) project called Copper Canyon, which ran from 1982 to 1985. Originally conceived as a feasibility study for a single-stage-to-orbit (SSTO) airplane which could take off and land horizontally, Copper Canyon became the starting point for what Ronald Reagan called:
"...a new Orient Express that could, by the end of the next decade, take off from Dulles Airport and accelerate up to twenty-five times the speed of sound, attaining low earth orbit or flying to Tokyo within two hours..."
The next stage of the program, called Phase 2, with Copper Canyon being Phase 1, was intended to develop the technologies for a vehicle that could go into orbit as well as travel over intercontinental ranges at hypersonic speeds. There were no commitments to undertake Phase 3, the actual design, construction and flight testing of the aircraft. The decision to undertake Phase 3 based on the maturity of the requisite technologies, originally planned for 1990, was currently been postponed until at least April of 1993.
There were six identifiable technologies which are considered critical to the success of the project.<3&g; Three of these "enabling" technologies are related to the propulsion system, which would consist of an air-breathing supersonic combustion ramjet, or scramjet. A scramjet is designed to compress onrushing hypersonic air in a combustion chamber. Liquid hydrogen is then injected into the chamber, where it is ignited by the hot compressed air. The exhaust, consisting primarily of water vapor, is expelled through a nozzle to create thrust. The efficient functioning of the engine is dependent on the aerodynamics of the airframe, the underside of which must function as the air inlet mechanism and the exhaust nozzle. Design integration of the airframe and engine are thus absolutely critical to project success. The efficient use of hydrogen as a fuel for such a system is another crucial element in the development of the X-30.
Other enabling technologies include the development of advanced materials including various composites and titanium-based alloys which maintain structural integrity at very high temperatures. The enormous heat loads associated with hypersonic flight, sometimes in excess of 1,800 degrees fahrenheit, will necessitate the development of active cooling systems and advanced heat-resistant materials.
Although the NASP effort was announced by President Reagan in his State of the Union address, much of the project remains shrouded in secrecy. Indeed, the paucity of publicly available information on this project is remarkable, given the scope of the effort to date. This very high level of classification derives at least in part from the core technological innovation that was the genesis of the X-30 project.
Prior analyses of scramjet propulsion systems had concluded that they would only be able to achieve speeds of about Mach 8. At this speed, the thrust emerging from the rear of the plane would be balanced by the heat generated by atmospheric drag and the high temperature of the air as it entered the front of the engine. Thus limited to a maximum speed that was only one-third the orbital velocity of Mach 25, a scramjet-propelled vehicle would need rocket motors to achieve the remaining speed needed to reach orbit. Analyses concluded that such a vehicle would be heavier and more complicated that a conventional rocket.
However, the Copper Canyon project discovered that higher speeds could be achieved through the imaginative use of active thermal management. By circulating, and thus heating, the scramjet's hydrogen propellant through the skin of the vehicle prior to injection into the engine, energy generated through atmospheric drag was added to the thrust of the scramjet, enabling it to accelerate beyond the Mach 8 thermal barrier. Initially, there was optimism that this active thermal management approach would permit speeds of up to Mach 25 using air- breathing engines alone, eliminating the need for rocket propellants to achieve orbit.
X-30 NASP
The mass saved by eliminating the final rocket propellants had to be balanced, however, against the mass of the active thermal management system. This system became more complex and massive at higher speeds. At some point, the additional mass of the thermal management system needed to continue the acceleration of the air breathing scramjet would become greater than the mass of the rocket motors and propellant needed to continue the ascent to orbit.
As the NASP effort began, analysis suggested that this transition speed, at which rocket propulsion would be more efficient than continued scramjet operations, would be quite high, above Mach 20. Although this fell short of the initial promise of Copper Canyon, it nonetheless suggested that a scramjet vehicle might offer superior performance compared to conventional rockets. Over time, however, as the complexity of the active thermal management system was better appreciated, estimates of the transition speed declined to below Mach 17. This diminished performance significantly reduces the attractiveness of scramjet propulsion compared with all-rocket vehicles.
Though the protection of this technological principle may explain part of the secrecy surrounding the NASP program, studies of the missions that such a vehicle might perform remain even more closely held.
Defining the mission of NASP to attract maximum support and funding has been a tricky business for program proponents. Original cost projections of $3.1 billion dollars have more than tripled, now at approximately $10 Billion total cost for the development of a pair of single-stage-to-orbit vehicles.
A decision to undertake Phase 3 flight testing would have brought total program costs up to as much as $17 billion. The target date for the first test flight of the X-30 was pushed back to the 2000-2001 period, 11 years behind schedule and 500% over budget. Many years and a further $10 to $20 billion would have been required for the development of an operational vehicle. Funding this significant increase in a time of general budget cutting is not easy, and program cost overruns and delays in scheduling have made the project less attractive to many supporters.
Though the X-30 was originally touted by the Reagan administration for its civilian commercial applications and as a possible follow-on to the Space Shuttle for NASA, the funding structure of the program tells another story. The Department of Defense was scheduled to fund approximately 80% of the project, or $2.65 out of $3.33 billion over the 8 years of the original project. Budget allocations come primarily from the Air Force, which has seen NASP as potentially having a range of military missions.
The mystery remains of what military mission would justify this level of effort. Or perhaps there is no mystery at all. The X-30 may have been the purloined letter of military aircraft, an SR-71 follow-on hidden in plain sight. This would certainly jibe with the statement of Senator John Glenn, noted earlier and repeated here,
"...what you are talking about on that system, I know what you are talking about. That is many years down the road and is still a very speculative system..."
Such a possibility would also explain the tenacious position of Congressman Dave McCurdy, the only member of Congress at the time to sit on both the Armed Services Committee and the Space and Technology Committee. From 1989 through 1992, McCurdy fought hard for continued funding for and Air Force involvement in NASP.
"...a new Orient Express that could, by the end of the next decade, take off from Dulles Airport and accelerate up to twenty-five times the speed of sound, attaining low earth orbit or flying to Tokyo within two hours..."
The next stage of the program, called Phase 2, with Copper Canyon being Phase 1, was intended to develop the technologies for a vehicle that could go into orbit as well as travel over intercontinental ranges at hypersonic speeds. There were no commitments to undertake Phase 3, the actual design, construction and flight testing of the aircraft. The decision to undertake Phase 3 based on the maturity of the requisite technologies, originally planned for 1990, was currently been postponed until at least April of 1993.
There were six identifiable technologies which are considered critical to the success of the project.<3&g; Three of these "enabling" technologies are related to the propulsion system, which would consist of an air-breathing supersonic combustion ramjet, or scramjet. A scramjet is designed to compress onrushing hypersonic air in a combustion chamber. Liquid hydrogen is then injected into the chamber, where it is ignited by the hot compressed air. The exhaust, consisting primarily of water vapor, is expelled through a nozzle to create thrust. The efficient functioning of the engine is dependent on the aerodynamics of the airframe, the underside of which must function as the air inlet mechanism and the exhaust nozzle. Design integration of the airframe and engine are thus absolutely critical to project success. The efficient use of hydrogen as a fuel for such a system is another crucial element in the development of the X-30.
Other enabling technologies include the development of advanced materials including various composites and titanium-based alloys which maintain structural integrity at very high temperatures. The enormous heat loads associated with hypersonic flight, sometimes in excess of 1,800 degrees fahrenheit, will necessitate the development of active cooling systems and advanced heat-resistant materials.
Although the NASP effort was announced by President Reagan in his State of the Union address, much of the project remains shrouded in secrecy. Indeed, the paucity of publicly available information on this project is remarkable, given the scope of the effort to date. This very high level of classification derives at least in part from the core technological innovation that was the genesis of the X-30 project.
Prior analyses of scramjet propulsion systems had concluded that they would only be able to achieve speeds of about Mach 8. At this speed, the thrust emerging from the rear of the plane would be balanced by the heat generated by atmospheric drag and the high temperature of the air as it entered the front of the engine. Thus limited to a maximum speed that was only one-third the orbital velocity of Mach 25, a scramjet-propelled vehicle would need rocket motors to achieve the remaining speed needed to reach orbit. Analyses concluded that such a vehicle would be heavier and more complicated that a conventional rocket.
However, the Copper Canyon project discovered that higher speeds could be achieved through the imaginative use of active thermal management. By circulating, and thus heating, the scramjet's hydrogen propellant through the skin of the vehicle prior to injection into the engine, energy generated through atmospheric drag was added to the thrust of the scramjet, enabling it to accelerate beyond the Mach 8 thermal barrier. Initially, there was optimism that this active thermal management approach would permit speeds of up to Mach 25 using air- breathing engines alone, eliminating the need for rocket propellants to achieve orbit.
X-30 NASP
The mass saved by eliminating the final rocket propellants had to be balanced, however, against the mass of the active thermal management system. This system became more complex and massive at higher speeds. At some point, the additional mass of the thermal management system needed to continue the acceleration of the air breathing scramjet would become greater than the mass of the rocket motors and propellant needed to continue the ascent to orbit.
As the NASP effort began, analysis suggested that this transition speed, at which rocket propulsion would be more efficient than continued scramjet operations, would be quite high, above Mach 20. Although this fell short of the initial promise of Copper Canyon, it nonetheless suggested that a scramjet vehicle might offer superior performance compared to conventional rockets. Over time, however, as the complexity of the active thermal management system was better appreciated, estimates of the transition speed declined to below Mach 17. This diminished performance significantly reduces the attractiveness of scramjet propulsion compared with all-rocket vehicles.
Though the protection of this technological principle may explain part of the secrecy surrounding the NASP program, studies of the missions that such a vehicle might perform remain even more closely held.
Defining the mission of NASP to attract maximum support and funding has been a tricky business for program proponents. Original cost projections of $3.1 billion dollars have more than tripled, now at approximately $10 Billion total cost for the development of a pair of single-stage-to-orbit vehicles.
A decision to undertake Phase 3 flight testing would have brought total program costs up to as much as $17 billion. The target date for the first test flight of the X-30 was pushed back to the 2000-2001 period, 11 years behind schedule and 500% over budget. Many years and a further $10 to $20 billion would have been required for the development of an operational vehicle. Funding this significant increase in a time of general budget cutting is not easy, and program cost overruns and delays in scheduling have made the project less attractive to many supporters.
Though the X-30 was originally touted by the Reagan administration for its civilian commercial applications and as a possible follow-on to the Space Shuttle for NASA, the funding structure of the program tells another story. The Department of Defense was scheduled to fund approximately 80% of the project, or $2.65 out of $3.33 billion over the 8 years of the original project. Budget allocations come primarily from the Air Force, which has seen NASP as potentially having a range of military missions.
The mystery remains of what military mission would justify this level of effort. Or perhaps there is no mystery at all. The X-30 may have been the purloined letter of military aircraft, an SR-71 follow-on hidden in plain sight. This would certainly jibe with the statement of Senator John Glenn, noted earlier and repeated here,
"...what you are talking about on that system, I know what you are talking about. That is many years down the road and is still a very speculative system..."
Such a possibility would also explain the tenacious position of Congressman Dave McCurdy, the only member of Congress at the time to sit on both the Armed Services Committee and the Space and Technology Committee. From 1989 through 1992, McCurdy fought hard for continued funding for and Air Force involvement in NASP.