Boeing, USAF show off supersonic bomb firing technology

 Boeing and the US Air Force today said they have tested new technology that for the first time will let military aircraft launch bombs from aircraft moving at supersonic speeds.

Researchers from Boeing Phantom Works and the Air Force Research Laboratory used a rocket sled in combination with what researchers called “active flow control” to successfully release a smart bomb known as MK-82 Joint Direct Attack Munition Standard Test Vehicle (JDAM) at a speed of about Mach 2 from a weapons bay with a size approximating that of the U.S. Air Force B-1 bomber,  Boeing said.

Active flow control is a tandem array of microjets upstream of the weapons bay that, when fired reduces the unsteady pressures inside the bay and modifies the flow outside to ensure the JDAM munition travels out of the bay correctly.Boeing said wind tunnel testing indicated that without active flow control, the JDAM munition would have returned to the bay.

The release of the test vehicle from the rocket sled bay was a bigger challenge than an equivalent release from an aircraft bay at altitude, due to the reduced dynamic pressure, reduced vibration and increased amount of time in which to release a munition, Boeing said.

"As it was, the active flow control microjets reduced the unsteady pressures inside the weapons bay and modified the flow outside the bay to ensure that the test vehicle went out of the rocket sled nose up," said Bill Bower, Boeing Phantom Works program manager in a statement.

Boeing also noted that the rocket sled used to test active flow control was a record setter on its own.  The sled used in the High Frequency Excitation Active Flow Control for Supersonic Weapon Release (HIFEX), at 65,700 pounds, was 26,000 pounds heavier than any sled tested in more than 10 years but was faster by 400 feet per second. In the 57-year history of the Holloman High-Speed Test Track, it was the heaviest sled train to reach Mach 2," Boeing said.

Powered by two pusher sleds, the HIFEX sled achieved thrusts of 438,000 pounds for about 5.9 seconds on the first stage, 575,000 pounds for about 3 seconds on the second stage, and 115,000 pounds for about 3.6 seconds on the third stage. The JDAM test vehicle was dispensed during peak velocity, which was about 2,000 feet per second. The sled train accelerated to more than 13 g's to get to peak velocity, then decelerated at 7.5 g's for more than a mile to stop," the company said.

The test was designed by the U. S. Air Force 846th Test Squadron and the Support Systems unit of Boeing Integrated Defense Systems.

Boeing and the Air Force are looking to use active flow control technology to develop weapon release systems for future U.S. Air Force Global Strike aircraft.

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