A new hypersonic spy plane, capable of flying up to six times faster than the speed of sound, is being developed by aerospace giant Lockheed Martin Corp., according to company officials.

The new aircraft, known as the SR-72, is the unmanned successor to Lockheed's SR-71 Blackbird, a twin-engine, two-seater, supersonic aircraft that was developed in the 1960s. The company's new spy plane will be able to fly twice as fast as the Blackbird and three times faster than current fighter jets, accelerating to Mach 6, which is six times the speed of sound, or more than 3,500 mph (5,600 km/h).

The hypersonic SR-72 also will be able to fly to any location within an hour, which could be revolutionary for the military, said Brad Leland, Lockheed Martin's program manager for hypersonics. [In Photos: The 10 Fastest Military Airplanes]

"Hypersonic is the new stealth," Leland told Reuters. "Your adversaries cannot hide or move their critical assets. They will be found. That becomes a game-changer."

Furthermore, Lockheed is designing the spy plane using existing technology, which could help the company develop a prototype in five or six years for under $1 billion, he added.

Lockheed is aiming to fly a missile to demonstrate the new technology as early as 2018, and Leland said operational SR-72s could be in service by 2030, according to Aviation Week, which was first to report on the new project.

"What we are doing is defining a missile that would have a small incremental cost to go at hypersonic speed," Leland told Reuters.

The SR-72 is being developed by Skunk Works, Lockheed's California-based advanced research program that previously worked on the SR-71 Blackbird and the famed U-2 spy plane.

The hypersonic SR-72 will feature a two-phase propulsion system, which uses a basic jet turbine to accelerate the plane to Mach 3. Lockheed is collaborating with rocket and missile propulsion manufacturer Aerojet Rocketdyne to incorporate this turbine with an air-breathing, supersonic ramjet engine to propel the vehicle from standstill to Mach 6.

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The new spy plane will build upon Lockheed's previous experimental hypersonic programs, such as the Hypersonic Technology Vehicle 2, or HTV-2, which was developed as part of the Defense Advanced Research Projects Agency's (DARPA's) Falcon Project.

In 2011, the unmanned, arrow-shaped HTV-2 glider reached Mach 20 and controlled itself for approximately three minutes, before crashing into the Pacific Ocean. During the flight, surface temperatures on the vehicle reached 3,500 degrees Fahrenheit (1,930 degrees Celsius), which is hotter than a blast furnace capable of melting steel.

The SR-72's predecessor, the SR-71 Blackbird, could accelerate to Mach 3.3 (more than 2,200 mph, or 3,540 km/h) at an altitude of 80,000 feet (24,400 m). The Blackbird made its first flight in December 1964, and was flown by the U.S. Air Force until 1998. The two-seater aircraft was capable of outracing potential threats during reconnaissance missions, including being able to accelerate and out-fly surface-to-air missiles if it was detected.

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