The US is developing a new type of shape-shifting hypersonic engine, an innovation that may signal a shift in how the US approaches and develops hypersonic weapons amid rising concerns it’s falling behind China and Russia.

This month, The Debrief reported that a morphing hypersonic engine capable of changing form while in flight is being developed at the University of Central Florida (UCF).

The Debrief reports that the engine could be more efficient than current hypersonic engine designs, potentially leading to aircraft designs that can travel anywhere from 5 to 17 times the speed of sound.

The report notes that the university research team received a grant from the US Naval Research Laboratory to design a morphing hypersonic engine to solve some of high-speed air travel’s biggest challenges.

Currently, the most popular engines for hypersonic flight are scramjets, which can take in air at supersonic speeds and use it in the combustion cycle to generate incredibly high speeds. However, it notes that many of these scramjets are lacking in efficiency and performance.

The Debrief says that the UCF team has in response developed an “aerothermodynamic” model for a morphing scramjet engine that is currently in the experimental testing stage.

The same news report notes that a morphing hypersonic engine would enable flying from New York to Los Angeles in 30 minutes, with long-term goals of hypersonic travel for high-performance military vehicles, rapid emergency alert response and high-speed commercial travel.

Engine performance has been one of several major stumbling blocks hounding the US hypersonic weapons program, which has led to concerns that the US has already been overtaken by its near-peer competitors, China and Russia.

Bloomberg recently reported that the US Army has announced that it will not meet its four-year-old goal to deploy a hypersonic weapon in the last two weeks of this month.

Bloomberg states that this marks the second consecutive year that the Pentagon will miss an intended date to field its first operational hypersonic weapon.

The report says that the US Army has requested US$944 million for continued hypersonic research and development and $ 157 million for procurement for fiscal 2024.

Excessively complex designs, such as the two-stage Air-Launched Rapid Response Weapon (ARRW) that the US Air Force has since abandoned, may be needlessly complicated by requiring the proper integration of multiple subsystems. This approach leads to an increased risk of potential points of failure and requires more tests for design validation.

Despite those setbacks, the US is hard at work developing hypersonic engines with its allies and exploring other applications of hypersonic technology beyond missiles.

According to an Asia Times report in April 2022, Hypersonix, an Australian firm, has claimed that it can 3D-print a hypersonic engine within three weeks. This technology could give the US the necessary means to develop its hypersonic weapons at higher speed.

The Hypersonix scramjet engine was presented to senior US officials last month and can be 3D-printed using special alloys resistant to high temperature, high pressure, corrosion and oxidation. However, the high temperature-resistant composites needed are not readily available in Australia, creating an urgent need for their in-country development and production.

Unlike more complex US designs, Hypersonix’s engine has a fixed geometry and no moving parts that could potentially fail. The scramjet engine takes in atmospheric oxygen, reducing weight by 60% compared to rockets.

Aside from developing a new type of hypersonic engine with Australia, the US is exploring the applications of hypersonic technology on sophisticated aircraft.

For instance, Asia Times reported in March 2023 that the US and Australia had announced plans to develop a hypersonic aircraft, with the US Department of Defense (DOD) selecting Hypersonix to develop a high-speed aircraft to test hypersonic technologies.

The aircraft will support America’s Hypersonic and High-Cadence Airborne Testing Capabilities (HyCAT) program to alleviate strain on government testing facilities. The HyCAT represents a paradigm shift in hypersonics from weapons to aircraft.

Hypersonix’s DART AE aircraft uses a hydrogen-fueled scramjet engine to reach Mach 7. It tests high-speed platforms, sensors and control systems, providing data for hypersonic spy planes. Leidos was awarded a $334 million contract to develop a larger air-breathing hypersonic system for multiple missions.

Furthermore, Asia Times reported in December 2022 that the US has begun developing a new intelligence, surveillance and reconnaissance (ISR) hypersonic vehicle, which some analysts believe is the successor to the Cold War-era SR-71 Blackbird spy plane.

The classified Mayhem program, which includes work at Wright-Patterson Air Base in Ohio and other potential testing sites, is expected to deliver the SR-72 hypersonic system capable of multiple missions by October 2028.

The aircraft will reportedly be powered by a turbine-based combined cycle (TBCC) powerplant scheme, allowing it to take off from conventional runways and reach the necessary airspeed for its scramjets to kick in.

NASA is currently funding a validation of a previous Lockheed study that proposed the development of the SR-72. The SR-72 is designed to operate at Mach 6, enabling it to conduct ISR operations over enemy territories before their air defenses can react. The study found that the SR-72 could achieve speeds up to Mach 7 by combining turbine and ramjet technologies.

While there are concerns that the US has already been overtaken in hypersonic missile technology by China and Russia, the US may be taking a wider view of the emerging technology.

Asia Times has noted the US is focusing on developing capabilities that it needs for warfare rather than engaging in a tech race with its near-peer adversaries.

Although Russia has been using hypersonic weapons in the ongoing Ukraine war, the weapons have had no noticeable effect on the course of the conflict. This suggests that the implications of hypersonic weapons, often referred to as game-changers, may be overhyped.

Low-cost weapons can produce similar results as high-end hypersonic ones, with the former being more accessible. Existing air defenses do not fully protect against slower, older cruise and ballistic missiles.

It is unlikely that an attacker would opt for mounting nuclear warheads on expensive hypersonic missiles if US missile defenses already cannot stop a nuclear attack involving hundreds of conventional ballistic missiles.

The same logic would apply if the US initiated a full-scale nuclear attack on its adversaries, which could explain why the US is not interested in matching China and Russia’s hypersonic missile arsenals and is seemingly seeking other hypersonic applications.