U.S. Air Force Sets Mach 5.7 Recoverable Test Speed Record

U.S. Air Force Sets Mach 5.7 Recoverable Test Speed Record
A hypersonic sled travels 6,400-feet per second on a monorail and is recovered as part of the Hypersonic Sled Recovery effort at the Arnold Engineering Development Complex High Speed Test Track at Holloman Air Force Base, New Mexico. This test marked the fastest recovery of a monorail sled in over 30 years. (U.S. Air Force photos)

U.S. Air Force 846th Test Squadron at Holloman Air Force Base, New Mexico, announced that it was able to successfully recover a reusable rocket sled after traveling at a recorded speed of 6,400 feet per second (7022.6 km/h), or just about Mach 5.7 — beyond the hypersonic threshold, during a test.


In late March, the 846th Test Squadron at Holloman Air Force Base, N.M., successfully stopped a reusable sled traveling at 6,400 feet per second on a monorail, making it a historic event for the team’s Hypersonic Sled Recovery, or HSR, effort.

Lt. Col. Paul Dolce, Commander, 846th Test Squadron, congratulated his team on this momentous achievement at the Holloman High-Speed Test Track.

“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 those speeds ever,” Dolce said. “Truly historic in my books! This could not have been done without everyone here who works at the track. 

“These efforts will now setup our future HyTIP [Hypersonic Test and Evaluation Investment Portfolio] runs for success and add a new capability for our hypersonic customers.”

Daniel Lopez, a project manager for the HHSTT, added that he hopes this is a sign of future successful hypersonic recovery tests.

“I echo what Lt. Col. Dolce said,” Lopez said. “Excellent job to the entire team for their hard work and innovation. This just sets the bar that much higher.”

The 846 TS has been responding to a significant increase in demand for hypersonic weapons testing, with a focus on improving its high-speed breaking capability in order to recover sleds for post-test analysis. HHSTT is the only sled track capable of recovering sleds with test articles from velocities over Mach 5.

The track serves as a critical link between laboratory-type investigations and full-scale flight tests by simulating selected portions of the flight environment under accurately programmed and instrumented conditions.

“What you accomplished marked the fastest recovery of a monorail sled in over 30 years. The first time we have recovered a planned reusable sled at those speeds ever,” Lt. Col. Paul Dolce, Commander, 846th Test Squadron, said in a public release. “These efforts will now set up our future HyTIP [Hypersonic Test and Evaluation Investment Portfolio] runs for success and add a new capability for our hypersonic customers.”

Being able to recover reusable sleds traveling at hypersonic velocity is important for the squadron’s Hypersonic Sled Recovery (or HSR) effort. It allows for the collection of critical data after testing is completed, which is particularly important for hypersonic weapons testing.

Holloman High-Speed Test Track (HHSTT)

The Holloman Air Force Base (AFB) in New Mexico houses 59,971 feet long aerospace ground test facility — the longest facility of its type in the world — known as the Holloman High-Speed Test Track (HHSTT) which was first developed in 1947.

The facility provides a platform to test rocket systems, collect data and solve problems that cannot be completed by other means on the ground.

An essential benefit of using a free-floating sled attached to a long test track is that the test platform could be recovered after testing for post-run analysis.

There have been significantly higher speeds recorded at the HHSTT during rocket sled testing. In September 2019, a rocket sled achieved a speed of around Mach 8.6 or 10,619 kmph; however, the test in March 2022 was the highest speed a reusable rocket sled has reached before being successfully recovered.

The HHSTT is the only track capable of recovering sleds that hit hypersonic velocity – speeds of Mach 5 and above – by stopping them via high-speed braking.

Despite this, the majority of tests performed with sleds at the HHSTT, to date, have focused on ‘non-recovered impact testing,’ according to HHSTT project manager Daniel Lopez.

The last time, sleds traveling at hypersonic velocity were stopped, was in the summer of 2021, when two sleds traveling over 5,000-feet per second (5486.4 kmph) were recovered. Before that, nearly two decades had passed since recovered hypersonic missions had been conducted there.

“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 those speeds ever,” said Lt. Col. Paul Dolce, Commander of the 846th Test Squadron, while congratulating his team.

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