Rocket Sled Track sets recoverable test speed record at Mach 5.8

The U.S. Air Force’s 846th Test Squadron at Holloman Air Force Base, New Mexico, successfully recovered a reusable rocket sled after traveling at a recorded speed of 6,400 feet per second, or roughly Mach 5.8 – beyond the hypersonic threshold – reports the Air Force. This is the first time the squadron has managed to recover a reusable rocket sled after traveling at this speed. The test was conducted at the base’s 10-mile-long Holloman High Speed ​​Test Track (HHSTT) in late March 2022.

While significantly higher speeds were recorded at HHSTT during rocket sled tests – see our previous article with images of a rocket sled traveling at around Mach 8.6 – the March 2022 rocket sled test represents the highest speed a reusable rocket sled has reached before being successfully recovered.

The reusable rocket sled traveled at 6,400 feet per second on a monorail and was recovered as part of the hypersonic sled recovery effort from the high-speed test track at the Engineering Development Complex of Arnold Holloman at Holloman Air Force Base, New Mexico. United States Air Force

The HHSTT is the only track capable of recovering sleds that reach hypersonic speed (i.e. speeds of Mach 5 and above) via high speed braking. Speed ​​testing of various military components has been carried out by the 846th Test Squadron on the HHSTT since the 1950s, while the track itself – which dates from 1949 – has been adapted and extended considerably since then.

Most recently, Air Force engineers implemented a Hypersonic Readiness Program (HSR) in 2020, which focused primarily on fielding a 9-inch hypersonic monorail sled test with braking capability. high speed. The majority of testing done with sleds on the HHSTT to date has focused on “unrecovered impact testing,” according to HHSTT project manager Daniel Lopez. By the summer of 2021, when two sleds traveling at hypersonic speed were successfully recovered from the runway, nearly two decades had passed since recovered hypersonic missions had been conducted there.

At present, the HHSTT is 50,971 feet, or about 10 miles long. As the Air Force reported in late 2021, “Currently, recovered high-speed tests—those of Mach 3 or greater—and rain erosion are limited to one of the 10-mile rails long in a monorail configuration”. Engineers continue to update and improve testing capabilities, including the addition of newly designed bird-hunting sleds for HHSTT in late 2021 to mitigate bird and animal strikes during testing .

A rocket sled is shown just before launch on the Holloman High Speed ​​Test Runway at Holloman Air Force Base, New Mexico. The 9-inch monorail sled was launched under the Hypersonic Readiness program on April 23, 2020. United States Air Force

The ability to recover reusable sleds traveling at hypersonic speed is important to the squadron’s hypersonic sled recovery (or HSR) effort. It allows critical data collection after testing is complete, which is especially important for hypersonic weapons testing. As HHSTT Capability Development Manager Lee Powell pointed out in 2020, the Department of Defense relies on “HHSTT enhancements and test capability” to deliver its nuclear force modernization roadmap, missile defense and hypersonic weapons. “These programs,” he said, “require timely and relevant test data to verify lethality effects, impact survivability, aerothermal and meteorological effects, separation dynamics, system performance guidance, sensor performance and other key performance metrics.”

Hypersonic weapons testing, a top priority for the U.S. military, places extreme stress on test subjects to determine which materials can withstand the heat and stresses of sustained flight at speeds of Mach 5 and above. As Powell points out in the quote above, hypersonic weapons testing is designed to reveal the limits of a weapon’s flight performance and survivability before more expensive and complicated flight testing begins. . This is also true for testing materials and other components that might be used on such a weapon or vehicle.

Another view of the reusable rocket sled tested at the end of March 2022. United States Air Force

Lt. Col. Paul Dolce, commanding officer of the 846th Test Squadron, underscored the historical significance of the feat by congratulating the squadron. “What you accomplished marked the fastest recovery of a monorail sled in over 30 years, and the first time we have recovered a planned reusable sled at these speeds.”

“Truly historic in my books! It couldn’t have been done without everyone working on the track here,” exclaimed Dolce.

“These efforts will now set up our future HyTIP [Hypersonic Test and Evaluation Investment Portfolio] racing to success and adding new capability for our hypersonic customers.”

Daniel Lopez echoed Dolce’s sentiments. “Great job to the whole team for their hard work and innovation. This raises the bar even higher.”

The recent success of the 846th Test Squadron validates its efforts to meet the demands of hypersonic speed testing over the past few years. As more hypersonic weapons tests are performed on the HHSTT, it is likely that recovered hypersonic missions will register even higher speeds.

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