Air-Breathing Rocket Engine Gets Funding Infusion

Air-breathing rocket engine. Need we say more?

The technology, which sounds straight out of a science-fiction movie, has enough reality to it for the United Kingdom government to offer $90.62 million (£60 million), in stages, to a company looking to develop the engine.

The money will go to Oxfordshire-based Reaction Engines, which we’ve seen on Universe Today before. They’re also developing an unpiloted and reusable spacecraft called Skylon, which is intended for low Earth orbit after leaving the planet from a conventional runway.

Skylon isn’t flight-ready yet, but so far the project did pass a United Kingdom Space Agency technical assessment. If completed, the UK Space Agency says Skylon is just one of many vehicles that could use this engine, which is called Sabre.

“The unique engine is designed to extract the oxygen it needs for low atmosphere flight from the air itself, paving the way for a new generation of spaceplanes which would be lighter, reusable and able to take off and launch from conventional airport runways,” the agency stated.

The money, stated Reaction Engines founder Alan Bond, will fund  “the next phase in the development of its engine and heat management technology.” More specifically, this is what the company plans to use the funds for:

– Engine technical design work;

– Improving lightweight heat exchanger technology and manufacturing;

– Performing wind tunnel and flight testing of engine components;

– Doing a “ground demonstration” of the engine.

If all stays to schedule, Reaction Engines expects a Sabre prototype will be ready in 2017, with flight tests commencing in 2020.

A cutaway view of the proposed Sabre engine, which is being developed by Oxfordshire-based Reaction Engines. Credit: Reaction Engines
A cutaway view of the proposed Sabre engine, which is being developed by Oxfordshire-based Reaction Engines. Credit: Reaction Engines

The major goal of Sabre is to use hot air entering the engine to obtain the required oxygen for operations, rather than carrying the gas separately on board. The engine is supposed to switch to a “rocket mode” at 26,000 feet in altitude.

“This advantage enables a spaceplane to fly lighter from the outset and to make a single leap to orbit, rather than using and dumping propellant stages on the ascent – as is the case with current expendable rockets,” the UK Space Agency stated.

Reaction Engines promises Skylon would give “reliable access to space” through carrying payloads of up to 15 tonnes, but at only 2% of the cost of more conventional launch vehicles — namely, rockets. It remains to be seen if they will achieve that cost goal, but the funding is welcome news nonetheless for the company.

Source: UK Space Agency

17 Replies to “Air-Breathing Rocket Engine Gets Funding Infusion”

  1. Do they explain how adding the weight and complexity of a hypersonic air intake, usable only during a small part of the ascent (so it still has to carry plenty of oxidizer), helps anything?

    1. It’s lighter than carrying the oxidizer for a pure rocket-powered ascent to that altitude? 🙂

      1. Yes, and that’s important if you want SSTO through conventional runway takeoff. An all-rocket vehicle would require landing gear to heavy, that additional fuel/oxidizer would be required for it, leading to still heavier gear…the case never closes.

        You could still possibly have vertical take-off and landing SSTO, because the fully fueled vehicle sits directly on its frame, and the landing gear never has to bear the fully fueled weight (as was done, for example, with DC-X). An abort situation means jettisoning and/or hovering to burn off fuel before landing…not unusual for aircraft emergencies already.

        You could still have all-rocket horizontal takeoff, but it would require a ‘sled’ capable of supporting the gross-liftoff weight that would be left behind…and in that case, it might as well have its own propulsion to also reduce the actual vehicle weight. (rocket sleds, or other ground accelerators). But now you have greater limitations in launch directions (you need that launch track now, and pretty much must go into orbit in the direction the track is pointing), and have otherwise given up part of conventional runway launch flexibility.

        As with anything else, it’s a matter of engineering philosophy and operational trade-offs.

      2. This is why we need to get bases on the moon. On the moon we can build a linear motor similar to the EMALS being designed for the new aircraft carriers to launch space craft to interplanetary/deep space missions.

        No propellant or launch motors needed, aside for the normal manoeuvring engines, which can
        quite easily be ion based rather than chemical. Plus it can be used to launch minerals mined from the moon to earth orbit for processing.

        Plenty of power on the moon with PV or even, since space and weight won’t be such a big issue, solar thermal would also be an option.

        If we can launch a 40T plane from a carrier at ~200km/h in about 100m, what velocity would a probe to deep space have being launched off a catapult several hundred meters long? What would the travel time for a manned mission to Mars be if it could be launched in this way?

    2. Sort of.

      The usual calculation with a ordinary jet engines (or rockets), then scramjet, then rocket returns negative payload to space.

      But here they don’t use scramjets or rocket, but optimized ordinary jets with an ingenious cooling of air taken from supersonic to subsonic speeds all the way through the jet stages. What they save on having just 1 engine set instead of 3 would presumably make the payload positive.

  2. Hardly what I’d call a rocket engine. It’s closer to the J58 engine that propelled the USAF’s SR-71.

    1. The J58 engine is a turbojet, whereas the SABRE engine is neither a conventional rocket engine nor a jet engine, but a hybrid engine that combines a ramjet(s), a turbo-compressor, and rocket engines.

      1. I did not say that it “functions as a ramjet”, I stated that it combines ramjets in its operation:

        “[…], simply cooling the air needs more liquid hydrogen than can be burnt in the engine core. The excess is expelled through a series of burners – “spill duct ramjet burners” which are arranged in a ring around the central core. These are fed air that bypasses the precooler. This bypass ramjet system is designed to reduce the negative effects of drag resulting from air that passes into the intakes but is not fed into the main rocket engine, rather than generating appreciable thrust.

        However, maybe I should have been more clear!

  3. Do they have shares avable to the public ? Who needs Trident Atomic War head attack systems when you can just send a lump of stone into orbit cheaply and let it do a meteor strike on a target ? Less colateral damage , less danger from storage of war heads , less chance of sensors detecting your subs. More reasons to develop cheap accsess to the mineral wealth of space.

  4. There was a project in the 1980s in the UK called Hotul for an air breathing rocket which got binned by the Thatcher government. It was mostly proposed as a sub-orbital aircraft, Australia in an hour and a half!

    1. Skylon is essentially a descendant of Hotol (which was also meant to be SSTO), with, among other things, better center of gravity characteristics, as explained here:

    2. These are the very same guys who had the door slammed in their faces for a few reasons, one of which was apparently, the official secrets act when they were receiving research grants from the MOD to develop Hotol, they’ve spent the last thirty years developing Skylon the ‘son of Hotol’ and I wish them every success.

  5. Reminds of Fred Whipple’s early jet engine with all the interior tubing? With similar ‘earth shattering’ implications! Lets hope it works….

Comments are closed.