USA and China getting close to flying Hypersonic demo airplanes

Lockheed Martin plans to build the fly the first prototype of a mach 6 SR-72 hypersonic plane as early as 2018. the SR-72 will be a strike and reconnaissance aircraft that tops Mach 6.

Hypersonic technologies, including a combined cycle propulsion system that blends a rocket engine and a supersonic jet engine, are now sufficiently advanced to allow the planned SR-72 project to begin.

China’s Turbo­aided rocket­ augmented ram/scramjet combined cycle

China is looking to free jet test a Turbo­aided rocket­ augmented ram/scramjet combined cycle (TRRE) engine later this year.
Concept combines three main propulsion systems—turbine, rockets, ram/scramjets—in just two main ducts.
Capable of operations from zero to Mach 6+, with targeted top speed in Mach 10 range

China’s TRRE engine is similar to several earlier combined ­cycle concepts, including the Trijet proposed by Aerojet Rocketdyne in 2008, the TRRE incorporates the three main propulsion systems in just two main ducts. The TRRE consists of a turbine, liquid oxygen/kerosene­liquid­fueled rockets and a kerosene­fueled ram/scramjet combined with a common inlet and exhaust and is designed to operate from a standing start to Mach 6+. The turbine, which operates from take­off to Mach 2, is housed in an upper low­speed duct, while the ramjet and rockets are located in the lower high­speed duct. Two rockets are mounted in the duct; an aft­mounted rocket for transonic acceleration and mode transition, and a main rocket mounted farther forward in the duct for flame stabilization during acceleration through to scramjet transition at Mach 6.

Results show that the TRRE engine can reconcile the demands of high thrust at lower Mach numbers and high specific impulse at a Mach number of 6.0.

* Best aspect of the TRRE is that it can solve the problems of an RBCC at low thrust and low speed by using the turbine engine for takeoff and landing as well as low­ speed flight
* solves the problem of the TBCC transition thrust ‘pinch,’ and can achieve a high specific thrust from Mach 3 to Mach 10.

Numerical test results of the TRRE prototype show it can “operate in the full flight envelope of Mach 0­6+ and have demonstrated the integrated high­ and low­speed channels work cooperatively

China is working towards a flying hypersonic demonstrator. The turbine will likely be based on the WS­15, a super­cruising turbofan under development by Xian Aero Engine Corp. for later production versions of the twin­engine Chengdu J­20 stealth fighter. However, even though the initial batch of J­20s entered service early this year with the People’s Liberation Air Force, they are believed to be powered by an interim variant of the Russian­made Saturn AL­31 rather than the WS­15.

Work on the WS-15 has been delayed by quality control issues with relatively recently developed areas of advanced engine technology for China, specifically single­crystal superalloy turbine blades and powder metallurgy superalloy turbine disks.

Before 2025, China will select a mature turbine hypersonic engine.

Phase three of China’s hypersonic plane program will go from 2025 to 2030. China will focus on development and integration of an advanced high­speed turbine engine into the TRRE. Program success will also hinge on parallel breakthroughs in “the operation of the scramjet at higher Mach numbers, particularly in technology areas such as the adjustable combustion chamber ramjet suitable for a wide range of work.

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