The main advantages of SFA projects with an axisymmetric body from the perspective of the creation of this database is the ability to combat missile using conventional rocket technology, which significantly reduces the price of products and allows space-saving arrangement of the internal volume of the carrier, as the abundance of available starting systems. Axisymmetric body allows launch as internal compartments of aircraft (with rotary and catapult launchers) and with external pylons of containers on ships and submarines (submarine), using vertical launch systems type Mk 41.
Company «Boeing» and its subcontractor, the company «Aerojet», under contract with DARPA to develop the project in 1997 hypersonic missile ARRMD by subsequent tactical and technical requirements: the missile must be run outside the act of enemy air defenses with ground installations, ships, submarines and aircraft; range of 750-1000 km; design cruise Mach number = 6; starting weight of about 1000 kg; warhead mass of about 110 kg; possible radial deviation of less than 10 m; flight time to the target at a distance of 750 km less than 7 minutes. Includes the introduction of an inertial guidance system on the march with satellite correction. When you exit the target missile crosses into a steep dive, so that the impact velocity is seeking to 1200 m / s and impact affecting enhanced by the highest kinetic energy missiles. The program was suspended in 2001 DARPA due to the unwillingness of the power plant. But all the results of research and development on missile ARRMD formed the basis adopted in 2002, DARPA and the U.S. Navy ONR center applets HyFly. In the project are participating NASA, center NAW Navy and Applied Physics Laboratory APL Institute. Hopkins developed the main part of the rocket — two-chamber scramjet DCR on ordinary hydrocarbon fuel.
Boeing HyFly — this programm development and evaluation of hypersonic technologies that can form the basis of serial production of relatively cheap hypersonic missile to engage stationary and mobile targets, including a very protected and buried objects such as underground command Fri Company «Boeing» received about $ 116 million on research and development, including the creation of a demo benchmark hypersonic missile and its flight tests. Easy to assemble with an axisymmetric body, the design and development of production which are inherited from the rocket ARRMD (namely, as the front part of the body is quite used titanium piece solution), allows developers to argue that the experimental standard can be rapidly transformed into a missile combat with the latest generation of penetrating warhead and universal basing (ship, submarine, aircraft F-18E / F).
Since the question of a single combat missile deployment, technical requirements for it significantly weakened: it is allowed a certain degree of degradation of the material, failure of the cooling structure, the introduction of only a clay based composites (heat-resistant and light). Should be considered a relatively small price missiles ($ 200 thousand for orders of 3,000 units) and power plant. DCR engine has an estimated specific impulse above 600, length 4.25 m, width 0.5 m greatest design consists of less than 20 parts. Features of the concept of DCR, broadly known since the late 1970s, the two systems are vozduhopoglotiteley and two combustion chambers. One system (two vozduhopoglotitelya) supplies air to subsonic gas generator, in which burned part of ordinary hydrocarbon fuel JP-10. Then enriched fuel gas is mixed with hot coaxial supersonic flow of air from the second system (four vozduhopoglotitelya) accelerates and enters the main combustion chamber. Such a process eliminates the use of highly active additive. Low COP achieves 2200 ° C, because heat-resistant composite materials are used on the basis of titanium and clay matrix. Complex heat exchangers available, and the flight Mach number is not very highest — less than 6.5.
Laboratory APL continues to improve and is ready to show vozduhopoglotiteli combustion efficiency above 90% for M> 6. Possible to avoid appropriate for everyday phenomena locking ramjet at supersonic speed. The engine starts with M = 3.3. Previously, the number M rocket accelerates solid boosters. In the upcoming rocket booster is meant to change THD combined cycle. In June 2007, were carried out successful tests of the motor on the boards and in the wind tunnel at M = 3.5; 4.1; 6.5. Engine consistently worked with about 240 for M = 6. It was quite integrated with the body of the rocket. Measured available thrust was close to the calculated one. Under the contract of «Boeing» and «Aerojet» had to spend 11 test flights, while in the last 8 must be armed with a rocket engine running. In the first 2-trial separation processes perfected with a solid rocket booster from the aircraft carrier F-15E and the start of the accelerator. Then, with a ground launcher using accelerator «Terriers — Orion» was conducted experimental SFA start with the engine on hydrocarbon fuel, is a slider DCR scale of 1: 2. After separation SFA engine worked for about 15 seconds at M = 5.5.
This experience prepared, and executed by the CCA under applets FASTT, which aims to practicing relatively cheap methods scramjet flight tests. In a subsequent test with discharge SFA with F-15E aircraft planned start of full-scale motor DCR SFA and acceleration up to speed, the respective M = 5. In the last test first checks composite SMS from which made the engine and who was elected after extensive experimental research 20 different options. But the flight was unable to get the number of M> 3.5 (September 2007). Specialists office «Aerojet» that conducted the tests, said that fuel supplies were small. Second flight in January 2008 and ended in failure, scramjet does not start, the rocket fell into the ocean in a minute after liftoff. According to official statements, background failures are reduced to manufacturing deficiencies (in the 2nd flight refused fuel pump). In the 3rd test flight July 29, 2010 rocket separated from the aircraft at an altitude of 12,200 m, but the accelerator is not earned, the rocket fell into the ocean.
If the reliability and efficiency of the motor DCR been proven in flight tests, it’s much closer to the realization of projects hypersonic missiles «air — ground.» Missile and sea-based projected length of 6.5 m with a launch mass of approximately 1725 kg and the mass of 91-165 kg warhead. The results of R & D program there HyFly accumulated in the project combat hypersonic missiles «air — ground» and «ship — the land» for the U.S. Navy. This program received the title HyStrike. The main tactical and technical requirements: the maximum range of about 1,100 km for 10.7 minutes at an average speed of 1760 m / s; speed at the end of the route is about 550 m / s. When combat load over 100kg maximum speed at an altitude of approximately 30 000 m should be 1340 m / s (M = 6.5).