chemistry

Reaction Engines

Reaction Engines is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Reaction Engines rather than just read about it. In short: Reaction Engines Limited (REL) was a British aerospace manufacturer founded in 1989 and based in Oxfordshire, England. The company also operated in the USA, where it used the name Reaction Engines Inc.

Key takeaways

Reaction Engines belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Reaction Engines to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Reaction Engines from memory before moving on to harder problems.

Reference excerpt

Reaction Engines Limited (REL) was a British aerospace manufacturer founded in 1989 and based in Oxfordshire, England. The company also operated in the USA, where it used the name Reaction Engines Inc. (REI). REL entered administration on 31 October 2024. Both REL and REI ceased operations and laid off the bulk of their staff.

History and personnel In 1989, Reaction Engines was founded by Alan Bond (lead engineer on the British Interplanetary Society's Project Daedalus), Richard Varvill and John Scott-Scott (the two principal Rolls-Royce engineers from the RB545 engine project). The company conducted research into space propulsion systems, centred on the development of the Skylon re-usable SSTO spaceplane. The three founders had worked together on the HOTOL project, funding for which had been withdrawn the previous year, in 1988. In 2015, BAE Systems agreed to buy a 20% stake in the company for £20.6m as part of an agreement to help develop Reaction Engines' Synergetic Air-Breathing Rocket Engine (SABRE), a hypersonic engine designed to propel the Skylon orbiter. In April 2018, Boeing announced an investment in Reaction Engines, through Boeing HorizonX Ventures, with a $37.3 million Series B funding alongside Rolls-Royce. Rolls-Royce and REL announced a strategic partnership in August 2020, with a £20m investment. In January 2023, the company announced that it had raised a further £40m from backers including the United Arab Emirates Strategic Development Fund. At the end of October 2024, after unsuccessful attempts to raise more money from investors, the company ceased operations, laying off the majority of staff and entering administration.

Research

Skylon

Skylon was a design for a single-stage-to-orbit combined-cycle-powered orbital spaceplane.

SABRE

Skylon, and the SABRE engine by which it was to be powered, were being developed as a private venture which aimed to overcome the obstacles that were imposed on further HOTOL development due to the British government classifying the HOTOL engine as an official secret, and keeping the engine design classified for many years afterward. The company's development effort was focused on developing a ground demonstration of the SABRE air-breathing core, with additional funding gained from the sale of consultancy and spin-off applications from its heat exchanger expertise. In February 2009, the European Space Agency announced that it was partially funding work on Skylon's engine to produce technology demonstrations by 2011. With this funding, Reaction Engines completed a non-frosting sub-zero heat exchanger demonstration program, Bristol University developed the STRICT expansion/deflection nozzle, and DLR completed an oxidiser-cooled combustion chamber demonstration. Reaction claimed this work moved the Skylon project to a TRL of 4/5. In July 2016, at the Farnborough Air Show, Reaction Engines announced £60 million in funds from the UK Space Agency and ESA to create a ground-based SABRE demonstration engine by 2020. Commenting on work undertaken at TF2 in Colorado, in April 2019, Reaction Engines announced that it had successfully tested the precooler technology for supersonic conditions needed to prevent the engine from melting, and in October 2019, Reaction announced that it successfully validated its precooler for hypersonic (Mach 5) conditions.

United States

In January 2014, Reaction entered into a Cooperative research and development agreement (CRADA) with the United States Air Force Research Laboratory (AFRL) to assess and develop SABRE technology. In 2015 AFRL announced their analysis "confirmed the feasibility and potential performance of the SABRE engine cycle". However they felt SSTO as a first application was a very high risk development path and proposed that a Two Stage to Orbit (TSTO) vehicle was a more realistic first step. In 2016 AFRL released two TSTO concepts using SABRE in the first stage: The first 150 feet (46 m) long carrying an expendable upper stage in an underside opening cargo bay capable of delivering around 5,000 pounds (2,300 kg; 2.3 t) to an orbit of 100 nautical miles (190 km), the second 190 feet (58 m) long carrying a reusable spaceplane on its back, capable of delivering around 20,000 pounds (9,100 kg; 9.1 t) to an orbit of 100 nautical miles (190 km). In March 2017, Reaction announced the formation of an American subsidiary, Reaction Engines Inc (REI), led by Adam Dissel in Castle Rock, Colorado. In September 2017, REI announced a contract from DARPA to test a Reaction precooler test article "HTX" at temperatures exceeding 1,000 °C (1,830 °F; 1,270 K), previous precooler tests focusing on frost control having been conducted from ambient temperature.

Other studies

LAPCAT A2

On 5 February 2008, the company announced it had designed a passenger plane to the concept stage. The LAPCAT A2 would be capable of flying, non-stop, halfway around the world at hypersonic speed (Mach 5+). The engine, SCIMITAR, has precooler technology which is somewhat similar to SABRE, but does not have the rocket features, and was optimized for higher efficiency for atmospheric flight.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Reaction Engines

Start with the simplest possible case. Write down what Reaction Engines claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Reaction Engines before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Reaction Engines ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Reaction Engines

In research: Reaction Engines appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Reaction Engines in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Reaction Engines is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1989 establishments in the United Kingdom, Aerospace companies of the United Kingdom, Companies based in Oxfordshire, so understanding it makes those chapters shorter.
In everyday life: Look for Reaction Engines outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Reaction Engines in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Reaction Engines means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Reaction Engines out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Reaction Engines in simple terms?

Why does Reaction Engines matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Reaction Engines?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Reaction Engines.