Australia’s contribution to hypersonic flight

Slow and steady wins the race – especially when it comes to hypersonic flight. Now Australia’s persistence in pursuing high-speed engineering is paying off.

Brisbane-based Hypersonix Launch Systems has received a $2.95 million grant from the Australian government to develop the world’s first fully reusable aircraft capable of traveling at speeds of up to 12 times the speed of sound.

The ultimate goal is an autonomous, multi-mission vehicle that can put satellites into orbit while emitting only water vapor as exhaust fumes.

It has taken decades of effort to get to this point.

The Australian Defence, Science and Technology Group (DST) and the university sector have been working on the technology since 1989, when they conducted their first scramjet ground tests. The HyShot flight test program was launched in 2022. And the HIFiRE 7 hydrogen-powered scramjet flew in 2015.

The new DART CMP drone will be a complete technology demonstration package to be developed in collaboration with the University of Southern Queensland. The core will be a 3D-printed Spartan hydrogen-powered scramjet engine. But this must be mounted on an Australian made airframe with associated control surfaces and flight electronics.

Hypersonic propulsion is a competitive field. More than 100 companies are tackling the technology internationally, but Hypersonix hopes its hydrogen-powered 3D scramjet combination will be a winner.

Now it has caught the attention of the United States after a slew of its own high-speed piloted flight projects failed. Australia’s hypersonic lead is the main contributor to the AUKUS defense technology sharing cooperation framework.

Slim, green machine

Unlike rockets, scramjets extract combustible oxygen from the atmosphere. This reduces the weight they have to carry by about 60%. And the Spartan engine burns hydrogen fuel in a process that emits water vapor, not carbon dioxide, as exhaust gases. If that hydrogen comes from renewable energy sources, the reusable 3D-printed scramjet engine will be particularly “green.”

But hypersonic flight is difficult to achieve. And even harder to maintain.

The scramjet engine itself achieves combustion temperatures of over 1000°C. And the airframe is another challenge, as it has to absorb a lot of stress as well as heat.

dr. Michael Smart, co-founder of Hypersonix, says the advantage of the Spartan engine design is that it has no moving parts, which are potential points of failure. “Instead of having all the spinning blades and compressors, we just use the shock waves and the air itself to create combustion,” he says.

This makes the motor more resilient, reliable and reusable.

Hypersonix Managing Director David Waterhouse adds that the engine can be turned off and on, allowing the craft to “skip the atmosphere” like a pebble over water. This allows the craft to cover significant distances with minimal fuel.

Hypersonix has simulated how its scramjet engine and DART airframe will perform at speeds above Mach 5. It has also been proven through a series of hypersonic shock tunnel tests. Now it needs the right manufacturing technology to put the engine and airframe into practice.

And that’s where the new federal government subsidy comes in handy. It is designed to give Australia the sovereign capacity to produce the advanced materials it needs. This includes modern high temperature oxide-oxide ceramic matrix composites, which promise to be more cost effective than titanium and other high temperature alloys.

Demonstrator

Hypersonix is ​​currently assembling its DART AE 3D printing demonstration vessel. The sequel DART CMP will focus on integrating composite materials.

“AE stands for Additive Engineering (or 3D printing) and is the fully 3D printed version of high temperature alloys already available in Australia,” says Waterhouse.

By using 3D printing, the Spartan engine is both cheaper to build and more resilient thanks to its seamless assembly. It can withstand about 1500°C. And Hypersonix says it only takes three weeks to print a new one.

The autonomous technology demonstrator is intended to fly more than 500 kilometers between Mach 5 and 12. It must also be able to control its speed and flight profile and return to a landing site.

The DART AE will be launched in 2023. The new DART CMP project will start in July.

Professor Peter Schubel, executive director of the Institute for Advanced Engineering and Space Sciences at the University of Southern Queensland, says his team will develop and test the ultra-high temperature composite materials and coatings needed by the new craft.

“Our expertise in liquid casting technologies, automated fiber placement, pultrusion and filament winding capabilities with exotic materials allows us to develop revolutionary structures,” he says.

But not everything about the DART is likely to be custom made. Smart says his hydrogen tank could be a turnkey tank used for hydrogen-powered trucks and heavy vehicles because they are already very resilient.

Much depends on the success of the protesters.

A concept image of the proposed Hypersonix DART CMP autonomous hypersonic vehicle. Credit: Hypersonix Launch Systems

On April 6, Australian Prime Minister Scott Morrison, US President Joe Biden and British Prime Minister Boris Johnson detailed their AUKUS defense technology cooperation plans. Developing hypersonic flight technology was high on that list.

Russia and China are widely believed to have a technological lead in this arena after years of failed US projects. Moscow claims to have used such weapons against targets in Ukraine.

“There is an arms race going on, not necessarily for more numbers, but for more quality,” U.S. Air Force Secretary Frank Kendall said late last year. “It is an arms race that has been going on for quite some time. The Chinese have been very aggressive about it.”



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