While much of the hype around hypersonic flight talks of Mach 7 cruise missiles and three-hour airline flights to anywhere, an Australian consortium’s plan to launch small satellites may herald the first commercial hypersonic operation in history, in as little as seven years.
Hypersonix is a company formed by The University of Queensland, engineering consultancy BMT-WBM and UAV company Australian Droid and Robot. The entity will commercialise its SPARTAN technology, partly spawned and tested through the university’s involvement with the Hypersonic International Flight Research Experimentation (HIFiRE) project with partners DST Group, the US Air Force Research Laboratory and Boeing Research and Technology.
SPARTAN (Scramjet Powered Accelerator for Reusable Technology AdvaNcement) is a three-stage satellite launch system with a winged hypersonic vehicle mounted atop reusable booster rockets. On the launch pad, it would be around 24 metres tall and weigh around 26 tonnes.
After launching and boosting the hypersonic vehicle to its ignition speed at high altitude, the expended “fly back” boosters would separate and descend, deploying wings and a propeller to land at a designated site. The second stage winged hypersonic vehicle would then accelerate to around Mach 10, climbing to the edge of the earth’s atmosphere before launching a small piggyback third-stage rocket in to space to deploy its payload. The air-breathing SPARTAN unit would then glide back to earth for refurbishment and reuse.
Engines
The heart of the system is the second stage scramjet (supersonic combustion ramjet) engine, which compresses supersonic airflow through a diffuser before adding fuel and igniting the mixture to produce thrust. With no mechanical compressors the system must be accelerated to supersonic speed by its first stage boosters to acquire the minimum airflow required for ignition. But the lack of mechanical systems also means the engine can operate efficiently at speeds as high as Mach 10 (speeds above Mach 5 are referred to as hypersonic); fast enough to put a small third-stage liquid-fuelled rocket within reach of space.
University of Queensland Centre for Hypersonics Professor Michael Smart said inclusion of the controllable winged hypersonic vehicle as a second stage would bring an unheralded level of flexibility and redundancy. Satellite launches would no longer be a “total success or total loss” prospect.
“The second stage is best thought of as a hypersonic aircraft,” he explained to ADM. “This is not a ‘point and shoot’ where you’re going to dump most of the thing in the ocean and once you press the button it’s going to go wherever it’s going to go. If there are problems with the scramjet it can turn around and fly back and land as a glider. If the booster doesn’t do quite what it needs to do and the orbit’s not right, if we can adjust the orbit.”
And with around 80 per cent of the system reused, SPARTAN could build for reliability rather than expendability, and still potentially halve the cost of a single launch of 150-kilogram payloads such as nanosats to sun synchronous orbit compared with competing “throw away” rocket technology. Hypersonix is aiming for a cost of around US$25,000 per kilogram of payload for a dedicated launch, citing the reusability of the system as critical “when you want to do one launch a week forever”.
Small sats
The company is another new start basing its business case on the fast-growing small satellite revolution, spurred partly by technology advances that mean satellites of less than 10 kilograms in mass can perform useful functions at a cost that may bring them within the reach of individual companies, universities and even well-heeled individuals.
Since the first two nanosats launched in 1998 more than 650 have followed. The 2017 worldwide schedule alone called for 569 launches and US analysts predict the nanosatellite and microsatellite markets will grow from US$890 million in 2015 to around US$2.52 billion by 2020.
“This small satellite revolution that’s going on is amazing. A satellite that used to be the size of your kitchen and weigh 5,000 kilograms, now they can do the same thing in a hundred kilos and a cubic metre. A country like Australia can think about a launch system of that scale; we’re not talking about a program that’s going to cost $10 billion to develop and requires a standing army even just to maintain it.”
Smart sees a commercial market for SPARTAN, but also believes the drastically shortened launch cycle and regularity of SPARTAN launches could also appeal to government agencies and Defence. Small, relatively cheap disposable satellites could perform a multitude of timely functions before simply burning up in the atmosphere, partially replacing the functions of malfunctioning larger satellites while they are repaired or replaced, or offering short-term surveillance and sensing functions over national disasters.
Defence applications
“Defence is very interested in being able to responsively put satellites up,” Smart said. “And by responsive I mean within a week or so of wanting to do something.
“These new small satellites open up so many opportunities, like situations where there’s a terrible bushfire or some natural disaster. It means being able to lob a satellite up, which may only stay in orbit for six months or so and just come down and burn up, not creating space junk.”
Although the science is “95 per cent of the way along”, Hypersonix still faces practical challenges in turning its proven data and subscale test models in to a commercial system, a goal Smart believes can be achieved for around $150 million. Hence the company’s creation.
“We’ve done 30 years of research on the scramjet. So the scramjet is at a point where we know what it needs to look like to work. There’s no new equation that we need to solve, there’s no scientific principle that we need to understand better.
“It’s about putting different technologies together in a practical way that is commercial and where we can launch something much cheaper than our competitors will be able to launch. What it needs now is engineering development, it needs business people involved in it and that’s really the phase where we’re at. And a commercial company is the way to move it along.”
This article first appeared in the February 2018 edition of ADM.