The Air Force’s 846th Test Squadron at Holloman AFB, N.M., has conducted two recovery tests of hypersonic sleds traveling at about Mach 5, the Air Force Materiel Command (AFMC) said on Oct. 26.

In both tests, testers stopped the two sleds moving at speeds of 5,300 feet per second–3,613 miles per hour–on a 10-mile monorail as part of the Hypersonic Sled Recovery (HSR) effort. That monorail is part of the Arnold Engineering Development Complex Holloman High Speed Test Track (HHSTT), “a unique Department of Defense test asset, as it is the only sled track capable of recovering sleds with test articles from velocities over Mach 5,” per AFMC.

The 846th Test Squadron is executing HSR “to prepare for the increased need for hypersonic test and evaluation in support of the National Defense Strategy,” Daniel Lopez, project manager for the July test, said in an AFMC statement.

“The project is multifaceted and covers development and resurrection of various braking methods, sled designs and thermal protection systems, as well as gaining proficiency in conducting recovered hypersonic missions,” per Lopez.

AFMC said that, before HSR, the last recovered hypersonic missions at the sled track was about two decades ago.

“If a customer needs the test article back for post-test analysis, then it must be recovered on the rail without damage,” AFMC said. “Therefore, recovered hypersonic missions entail using high-speed braking capabilities to slow down and stop the sled on the 9-inch monorail. These types of tests are limited to the monorail because at 10 miles, it’s the longer of the track systems.”

The other, narrow gauge system is 3.8 miles long–too short to account for Mach 5 acceleration and recovery. Some 18 years ago, an unrecovered sled on the narrow gauge system set the world land speed record of Mach 8.4, some 9,465-feet per second, or 6,453 miles per hour, Lopez said.

The next step for HSR is to recover sleds “from Mach 6-plus,” he said.

Hypersonics are a fairly recent jingle in the military’s quest for ever better technology–this time, in the words of Pentagon officials over the last five years, to compete with and counter China and Russia.

Prime among the Air Force efforts is the Lockheed Martin [LMT] AGM-183A Air Launched Rapid Response Weapon (ARRW), which is to be the military’s first hypersonic weapon.

The service requested $399 million in research and development for ARRW in fiscal 2022, including $161 million to buy the first 12 missiles (Defense Daily, May 18). Air Force plans have called for ARRW to achieve an “early operational capability” by the end of fiscal 2022 after a contract award in January, per the Air Force, but that looks unlikely due to recommendations by congressional appropriators.

The House Appropriations Committee’s version of the fiscal 2022 defense funding bill funds the rapid prototyping research and development for ARRW but advises a procurement cut of $44 million, “an amount approximately equal to four missiles, to the request while noting that the rapid prototyping effort intends to provide up to four all-up round missiles as a residual early operational capability,” per the committee’s report on the bill.

The committee report said that “the flight test regimen for the rapid prototyping program has become increasingly delayed and compressed, increasing the concurrency risk to the first production lot of weapons.”

Senate appropriators have advised funding the Air Force request of $238 million for ARRW prototyping but a cut of more than $80 million in the buy of the first dozen missiles.

Brig. Gen. Heath Collins, the Air Force program executive officer for weapons, has said that the Air Force wants to see a successful all-up round ARRW test before the service awards a production contract for Lot 1.

ARRW is to destroy high-value, time-sensitive targets and enable rapid response strikes against heavily defended land targets.