What is hypersonic flight?

Systems Engineer
Hypersonic flight is the ability to fly at exceptionally high speeds - exceeding Mach 5. At Mach 6, we are flying at around 2km per second. That is 7,200km per hour.

At this speed, six times the speed of sound, we would cover the 655km between Adelaide and Melbourne in about 6 minutes.

Potential advantages of hypersonic flight are numerous, including reduced travel times and improved space access. Our expertise in engineering complex systems is working to realise these benefits, while positioning us to understand and respond to future threats.
We are demonstrating our capability in flight vehicle design and testing, and creating technologies to overcome the many technical challenges associated with hypersonic flight.
Friction from the atmosphere exposes the airframe to extreme temperatures. We need materials and strategies to cope with the high temperature, which threaten to melt and warp the structure.
To counter drag, we seek propulsion systems that are efficient and effective at high speed. We currently rely on traditional rocket engines to provide thrust above Mach 3 to 4. These are generally unsophisticated and inefficient. 
Flow pressure ellipse
Vehicle motion at hypersonic speed is fast, unstable and difficult to control. We struggle to accurately predict the vehicle behaviour in this flight regime. Navigation and guidance laws fight against sensor errors, unusual trajectories and aggressive manoeuvres.
To address these difficulties, our first step is to understand the hostile environment hypersonic vehicles see in flight. By actually flying vehicles at high speeds we learn about the realities of the hypersonic environment, and improve our predictions. Flight testing is both thrilling and terrifying. After launch it is too late to rectify deficiencies.

The thrill when it is successful is unparalleled.

Collaborating with partners around the world, including Defence Science & Technology Group and The University of Queensland in Australia, and the Air-Force Research Labs and Boeing Phantom Works in the US, we are working to ensure that high speed flight tests are successful. To do this, we carefully design and verify each vehicle before flight.
On the ground, in the years leading up to the flight tests, we work to predict the vehicle performance in flight and attempt to replicate the extreme environment. We make extensive use of computational tools to predict structural and thermal effects, and use environmental test facilities to expose the flight vehicles to the expected conditions. We approximate the vehicle behaviour with numerical simulations, and exercise the vehicle hardware through thousands of simulated missions.
The recently concluded HIFiRE program in Australia was a series of hypersonic flight tests. Experimental flight vehicles were built and flown to explore the fundamental science of high speed flight. We gained insight into payload design, avionics, aerodynamics, thermodynamics, materials technology, guidance and control systems and propulsion concepts.
HIFiRe trial
The culmination of the program HIFiRE4, proved our ability to navigate, guide and control a free flying hypersonic glider. We developed a robust autopilot to perform atmospheric re-entry and manoeuvres at hypersonic speeds.
As the BAE Systems scientific lead for this flight, I was delighted that our autopilot helped to deliver a very successful flight test. The autopilot handled large uncertainty in the vehicle behaviour and sensor measurement errors, across a wide range of flight conditions. In my next blog I will share my experience of flight trials – some of the most memorable moments in my life.
BAE Systems colleagues in the UK are also progressing an exciting hypersonics project, working with Reaction Engines to accelerate its development of SABRE™ – a new aerospace engine class that combines both jet and rocket technologies with the potential to revolutionise hypersonic flight and the economics of space access.
The working partnership draws on our extensive aerospace technology development, engineering and commercial expertise and will provide Reaction Engines with access to critical industrial, technical and capital resources to progress towards the demonstration of a ground based engine – a key milestone in the development of the technology.

I see great scope for the Australian and UK based projects to share our experiences in high-speed flight technologies, exploring opportunities to capitalise on our international capabilities.

Leveraging technology and capability between our international groups will deliver great benefit, and help us pursue overlapping international opportunities, for example in hypersonic flight, trusted autonomy and space activities.
top Systems Engineer
Andrew George Systems Engineer 3 May 2018