Today, planes no longer fly at supersonic speeds. However, a new engine system is promising even greater speed: hypersonic. In theory, a plane flying at this speed, five times the speed of sound, could travel from London to Sydney in just four hours. It was designed to encompass the fuel efficiency of a jet engine with the speed and power of a rocket.
UK based company Reaction Engines, with backing from Rolls-Royce and Boeing, is working on a new engine that ‘inhales’ air at lower altitudes to allow for greater speed. The project has received extensive funding from the UK government, which is making moves to ensure the UK is seen as an aviation and aerospace hub, regardless of the outcome of Brexit.
The SABRE (Synergetic Air Breathing Rocket Engine) engine is part jet, part rocket, and relies on a pre-cooler heater system. Current jet engines can only travel up to Mach 3, and only under certain conditions. The SABRE engine would be able to travel at Mach 5 in air, and Mach 25 in space, roughly 18,500 miles per hour.
The key differences between this engine system and others are its core, its pre-cooler system, and its thrust chamber.
The most impressive section is the pre-cooler: made of thousands of tiny tubes, providing high surface area and low weight. Each tube is connected to an inlet and outlet which allow for coolant to be injected and removed to facilitate a more efficient cooling process. Impressively, this is all achieved with zero leakage. The pre-cooler cools the air, leading to a high-pressure ration within the engine. This air is then fed into the reaction chamber where it is ignited. When the plane reaches an altitude of 28.5 km, the system switches to a closed-cycle high-performance rocket engine, burning liquid oxygen and hydrogen.
This technology can be applied to traditional jets, increasing speed while also allowing for more effective control of engine temperature. Air comes into the engine at around a thousand degrees, but the cooler brings that temperature down to -150C in less than 1/20th of a second.
The SABRE engine also has the potential to revolutionise spaceflight, due to its horizontal take-off and landing capabilities. Most spacecraft still require a vertical take-off, whereas the SABRE system allows for a more flexible approach, with less infrastructure required to facilitate it.
Thanks to its ability to transition from in-air to space-worthy systems. This allows for the craft to escape the atmosphere without the need for multiple propellant stages. This would make spaceflight immediately more sustainable, reliable, and reusable. It would also reduce infrastructure costs and mission preparation times.
While still in testing, the concept has been approved by the European Space Agency, and the system should begin demonstrations next year.
This engine design may revolutionise both traditional flight and spaceflight, making it faster and more accessible.