Beyond the Clouds in No Time

We can all agree that airplanes are cool, and rockets are awesome, but when combined, the result is even better! Besides getting engineers to jump up and down for this revolutionary concept, Reaction Engines Ltd applied it to an actual SABRE engine concept.

SABRE stands for Synergistic Air-Breathing Rocket Engine and one typically does not associate “Air-Breathing” with “Rocket.” which makes this engine a one of a kind to reach new heights (literally). Let’s dig into the geeky technical specs of the engine while going through some quick history of this revolutionary single stage to orbit propulsion system.

SABRE Engine
Source: Reaction Engines

SABRE is an evolution of Alan Bond's series of liquid air cycle engine (LACE) and LACE-like designs that started in the early/mid-1980s under the HOTOL project. Upon termination of HOTOL funding, Bond formed Reaction Engines Ltd. SABRE is currently being developed for hypersonic flights and runs on a combined cycle; the precooled jet engine configuration is used in the air-breathing phase of the flight until air becomes scarce and speed critical. From this moment on the engine switches to its close cycle rocket mode to bring the Skylon airplane to orbit (2 engines are mounted on the aerospace plane).

The air-breathing mode (below Mach ~5 and about 25 km altitude which is about 20% of the orbital velocity and altitude, respectively) works almost like a regular jet with one major difference being the apparition of a new component, first discussed in 1955; the air precooler which is placed behind the translating axisymmetric shock inlet cone that slows the air to subsonic speeds inside the air-breathing engine using 2 shock reflections. The precooler is “capable of cooling incoming air (without liquefying it, from around 1000°C) to −150°C (−238°F), to provide liquid oxygen (LOX) for mixing with hydrogen to provide jet thrust during atmospheric flight before switching to tanked LOX when in space." This precooler also allows a considerable reduction of the thermal constraints of the engine which then requires “weaker” and much lighter materials that are a necessity when reaching orbital velocities and altitudes. With compressors working more efficiently with a colder fluid, and the incoming air already highly compressed from the flight speed and shock waves, the fed pressure in the combustion chamber is around 140 atm. When in rocket mode, the inlet cone is closed and liquid oxygen and liquid hydrogen are burned from on-board fuel tanks for the remaining 80% of velocity and climb required to reach orbit.

Source: Reaction Engines

On a very recent note, feasibility studies conducted by the U.S. Air Force Research Laboratory were successfully passed in 2015.

Although the application of the SABRE engine is destined for orbital use, its cousin (Scimitar) has been designed for the environmental-friendly A2 hypersonic (top speed higher than Mach 5) passenger jet for 300 rushed passengers (about 3 times more than the Concorde) under the LAPCAT (Long-Term Advanced Propulsion Concepts and Technologies) study founded by the European Union.

When dealing with such high speeds, noise becomes a real constraint and flying above inhabited areas is restricted, which is why specific aerial routes are designed. According to Alan Bond, the A2 design could fly subsonically from Brussels International Airport into the North Atlantic, reaching Mach 5 across the North Pole and over the Pacific to Australia in about 4.6 hours, with a price tag similar to what you would pay for business class these days. This speed would heat the body of the craft so that windows are not an option because the appropriate thickness would represent a considerable weight. It is therefore thanks to flat panel displays showing images that you would be able to enjoy the scenery.

Blog - plane 2

When one talks about high-velocity flight it is difficult not to think of the French Concorde that operated between 1976 and 2003 and could travel at Mach 2.04 (limited by thermal constraints due to the material used) using the Scramjet technology; scramjet standing for “supersonic combustion ramjet”. This allowed a New York City to Paris flight in less than 3.5 hours instead of 8 hours with a conventional jet.

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The principle of this technology is to compress air with shock waves under the body of the aircraft before injecting the fuel (the Concorde’s intake ramp system can be seen on the figure on the right).

Due to the high inefficiency of this technology at low speeds, afterburners are used from take-off until reaching the upper transonic regime.

Keeping in mind that the heating of the Concorde’s body due to friction could make it expand by as much as close to a foot, it becomes easy to understand one of the reasons why high altitudes (scarcer air and therefore lesser aerodynamic resistance) are chosen for such high flight velocities; the Concorde cruising altitude was around 56,000 ft and would be decreased when sun radiation levels were becoming too high. On a side note you can keep an eye out at Charles de Gaulle airport in Paris (France) for a Concorde displayed outside.

Oh and did I forget to mention that the turbomachinery parts on the SABRE engine are currently being designed in the AxSTREAM suite??

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Turbochargers in Formula 1

The history of turbochargers in Formula 1 is pretty fascinating. Turbochargers were initially introduced in 1905, applied to large diesel engines in the 1920’s and found their way into commercial automobiles in 1938. However, it took a few more decades for the turbochargers to be used in Formula 1 car racing.

When Renault decided to enter the sport in 1977, they started their engines based on the novel turbocharger concept. As one would expect, their first design suffered from constant reliability problems through all the races it competed in. As Renault focused their development entirely on the engine, the car’s aerodynamics worsened; it suffered a huge turbolag under acceleration, and when the boost finally triggered the tires were not able to handle it [1]. “So the engine broke and made everyone one laugh”, Jean-Pierre Jabouille, the driver, admitted in an interview. At the time, everyone was looking at the turbo engines as something that no one would ever hear about again.

MMR, twin turbocharged GT500 V8 engine, from Mustangs Daily [3].
MMR, twin turbocharged GT500 V8 engine, from Mustangs Daily [3].
From theJUDGE13 [2].
From theJUDGE13 [2].






Continue reading “Turbochargers in Formula 1”

Innovation in Aerospace: Aircraft Compressor Design

Aerospace - croppedOur next webinar is on Thursday, April 30th! Are you an engineer involved in the Aerospace Industry and its latest development, a manager interested in improving the performance of your aircraft engines, or a student interested in the future of aerospace and the current climate of the industry? You should attend! During the webinar, we will be taking a close look at the most recent trends and developments of compressors in aircraft engines with a focus on the key factors for the successful development of aircraft engines.

Key factors for the successful development of aircraft engines include technological viability, performance, and re-usability. As one of the industry’s most high-technology products, aircraft engines require innovation in manufacturing and especially in design. They also face the need for continuous development in their technical capabilities in terms of achieving not only higher efficiencies and reliability but also safety and environmental legislation.

Continue reading “Innovation in Aerospace: Aircraft Compressor Design”

Innovative Boost of Larger Internal Combustion Engines

The last few decades have brought with them a dramatic increase in the development and use of turbochargers in automobiles, trains, boats, ships, and aircrafts. There are several reasons for this growth, including rising demand for fuel efficiency, stricter regulations on emissions, and advancements in turbomachinery design. Turbochargers are appearing more and more and are replacing superchargers.



Turbochargers are not the only turbomachinery technology growing in popularity in the marine, automobile, and railroad industries. Organic Rankine Cycles are being applied to take advantage of the exhaust gas energy and boost engine power output. ORCs, a system for Waste Heat Recovery, improve the overall efficiency of the vehicle, train, or boat, and reduce specific emissions.

As the size of the engines we consider increases, there is more heat available to recuperate, and more potential WHR systems to use. For instance, we can consider different combinations of these systems with both non-turbocharged and turbocharged engines. We are able to design and compare engine boost system combinations, with and without a turbocharger, with and without a blowdown turbine, and with and without a WHR system, at the cycle and turbine design levels.

In our upcoming webinar, we will do just that. We will design different combinations for larger ICEs and compare the results. This webinar will also cover introductions to these systems and application examples for supplementary power production systems in the automotive and marine industries.

We hope you can attend! Register by following the link below.

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TBT Webinar: Centrifugal Compressor Design: Can You Really Avoid Choke and Surge?

It’s Throwback Thursday and we are sharing another of our past webinars! This week’s is called Centrifugal Compressor Design: Can You Really Avoid Choke and Surge?


Surge and choke are inherent, sophisticated phenomena in centrifugal compressor operation. They limit the operational range of any centrifugal compressor and cause severe damage to the machine if it is in surge condition. Several books cover the development of centrifugal compressor surge and choke models that can be applied in compressor control systems in order to avoid surge and choke; while these methods focus retroactively, there are some proactive methods that can be applied during the design phase of the machine. Continue reading “TBT Webinar: Centrifugal Compressor Design: Can You Really Avoid Choke and Surge?”

Free Webinar: Maximizing Turbocharger Boost with Advanced Design Features

turbochargerinengineTurbochargers, nowadays, are becoming increasingly common in the internal combustion engines of automobiles in order to improve fuel economy and meet government emission regulations. A turbocharger must provide a designed increase in pressure under load condition (design point) while generating enough power at the low end (loss mass flow region). Internal combustion engine working characteristics, however, prevent a centrifugal compressor from generating enough boost at the low end when radial turbine rotational speed is low. Continue reading “Free Webinar: Maximizing Turbocharger Boost with Advanced Design Features”

Formula 1 Racing is Turbocharged

turbochargerinengineYes, the Formula 1 races have begun. The world is three races in with the fourth Grand Prix scheduled for April 20 in China.  As the world watches in awe at the versatility and speed (let’s face it, the races are all about the cars, right?), engineers marvel at the aerodynamics, energy recovery systems, turbochargers and internal combustion engines (because we love engineering).

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Let’s Talk About Centrifugal Compressors

Centrifugal Compressor Design

We all know by now that no machine is perfect. Turbines have carryover losses, pumps experience cavitation phenomena, and compressors certainly have their fair share of pros and cons. We’re on the hunt for some common design problems – perhaps problems that you have experienced yourself, with centrifugal compressors. We scoured through our technical papers and presentations and searched the web for some. Here’s a list of frequent concerns and questions we ran into: Continue reading “Let’s Talk About Centrifugal Compressors”

At a Glance – Turbochargers


With the ongoing movement toward global environmental protection, regulations related to the exhaust emissions and fuel consumption of automobiles are being strengthened. To cope with these requirements, turbochargers are an effective tool to improve fuel consumption and reduce carbon dioxide emissions, by reducing the engine weight and friction loss.

Since a turbocharger supplies compressed air to an engine, it can reduce the engine displacement relative to an atmospheric engine for the same power. Variable geometry turbochargers, which can control the boost pressure according to the engine operating conditions, are becoming increasingly popular, creating a demand for a centrifugal compressor with a wide and stable operational range. Continue reading “At a Glance – Turbochargers”

What Are Some Factors Affecting Gas Turbine Operation?

Let’s face it, we know the operations of our gas turbines can’t all be perfect, and we’ll run through calculations, feasibility studies and more to pinpoint the exact cause. But before all of that is accomplished, you should keep a list in the back of your mind of what might be causing your loss in performance, based on common factors that affect gas turbine efficiency and more.

Here’s the list. Continue reading “What Are Some Factors Affecting Gas Turbine Operation?”