Imagine flying from Sydney to London in few hours. That’s what the Defence Science and Technology Organisation (DSTO) is working on with high-speed or hypersonic flight.
Hypersonic speeds are greater than five times the speed of sound (>Mach 5). When a hypersonic speed reaches level Mach 7, for example, that’s equivalent of travelling at two kilometres a second.
“We are interested in investigating the science and engineering of hypersonic flight, so we have been doing experiments in the range of Mach 5-10,” said Alex Zelinsky, chief defence scientist at DSTO.
“You could use hypersonics for satellite launches, as well as for a military system. But also for civilians, ultimately, because you can imagine [very fast] flight with that. But it takes a long time to develop these things.”
DSTO has been doing hypersonic experiments in Woomera, South Australia and Norway. In 2018, it plans to launch a glider with an air-breathing scramjet engine that will cruise at hypersonic speeds to travel about 200 kilometres in 30 seconds.
The air-breathing engine directly takes air from the outside and mixes it with fuel to get propulsion. It is considered to be one of the most efficient types of engines in the world, but the vehicle has got to be moving quite fast, Zelinsky said.
There are two main things to focus on when developing hypersonic flight, Zelinsky said: Aerodynamics and thermodynamics. Aerodynamics in hypersonics is all about being able to control the vehicle and thermodynamics is managing the heat issues of travelling very fast speeds.
“Hypersonics research is not new; it’s been conducted for 30 or 40 years. But the way the DSTO conducts its work is quite different in terms of experimentation. So we are effectively taking an IT approach. These experimentations would not be possible without IT systems. The whole payload is instrumented with IT systems,” Zelinsky said.
Sensors attached to the air-breathing engine measure the aerodynamic and thermodynamic properties in real time, which is gathered and analysed for insight into how the DSTO should shape its next experiment and to progressively advance the technology each time.
“We use telemetry, which is radio communications, a little antenna dish tracking this vehicle as this 2-stage rocket goes up into space, turns around and comes back down. We are tracking and communicating all the time and getting the megabits of data that are associated with this platform.”
The 2-stage rocket is launched into low orbital space, up to about 250-350 kilometres above the Earth’s surface. Then it’s turned to the ‘angle of attack’ and brought back down to about 20-30 kilometres above the Earth’s surface to do the hypersonic experiment.
That height above the Earth’s surface is where density of air is right to sustain hypersonic propulsion and flight without burning up. The ‘angle of attack’ means carefully aligning the vehicle to its target, because it could end up somewhere else even if it’s a few degrees out, Zelnsky said.
“When it gets to the 20-30 kilometres above the Earth’s surface, we use gravity to accelerate the vehicle to hypersonic speed. What we are doing is we are shooting the vehicle up very high up in the Earth, turning it around and then it just starts accelerating through gravity to get to that Mach 5 to Mach 10 speeds.
“We do the experiment and gather the data. All the data is sent very quickly back down through to the Earth’s station where we capture it, and then the vehicle comes down and returns to Earth with a thud,” he said.
The next experiment is due in November this year, looking at the aerodynamics and thermodynamics, gathering data around the boundary layer or small layer of air close to the surface of the vehicle.
Another experiment will take place in early 2016 where two gliders will do some controlled manoeuvring at 32 kilometres above the Earth’s surface, flying at about Mach 6.
“The idea is to control the vehicle, do a pull up like when you pull out of a steep dive and you lose speed, and then we are going to turn the vehicle around and come back towards a target. The idea is to land or hit a target on the ground. That’s to show that we can control a glider and manoeuvre it at hypersonic speed,” he said.
“The two gliders will have different control strategies,” he added.
Zelinsky said the experiments are to demonstrate the capability of this technology and its potential application in not just Defence but also for commercial airlines in the far future.
“If there is a continuation program it would only happen after we show what’s possible with our experimental technology.”
Dr Allan Paull, who works for DSTO in Brisbane, is also leading the project. The University of Queensland, Boeing, BAE Systems, Lockheed Martin, NASA and the US Air Force Research Laboratory are working in collaboration with the DSTO on hypersonic flight.