Notable Military Jet Engines

As a special tribute this Veterans Day, we decided to have a look at some of the most notable engines that have been used to propel military vehicles throughout history.

PW F135

Kicking off our list is the Pratt & Whitney 135 turbofan engine. The pride and joy of Pratt & Whitney’s military engine lineup, the 135 powers the US Military’s F35 Lightning II. Presently, two variants of the F135 are used in several different variants of the F35, although it should be noted that the F135 was developed specifically for the F35. The 3 engine variants are known as the F135-PW-100, the F135-PW-600, and the F135-PW-400, each for a different application of the F35. The 100 variant is used in the conventional take off and landing F35A, the 600 is used in the F135B for short take off and vertical landing F35B, and the 400 uses salt corrosion-resistant materials for the Naval variant F35C.

A Lockheed Martin F35A in fight, and an F35C taking off from the USS Abraham Lincoln

The F135 is capable of 28,000 lbf of thrust with the afterburner capability pushing thrust all the way to a whopping 43,000 lbf of thrust, making the Lightning II a supersonic STOVL aircraft suited to a wide variety of applications, as seen in the above illustrations. At the heart of the Pratt F135 are 3 fan stages, 6 compressor stages, and 3 turbine stages. In the STOVL variant, the F135-600 uses the same core components, but is also coupled to a drive shaft which connects the engine to the lift fans which were originally developed by Rolls-Royce, and give the Lightning the ability to hover, perform short distance takeoffs, and vertical landings.

A Royal Air Force RAF F35B Lightning II performing a vertical landing on a Royal Navy carrier.
A Royal Air Force RAF F35B Lightning II performing a vertical landing on a Royal Navy carrier.

The F35 by Pratt & Whitney and in turn the F35 Lightning II by Lockheed Martin represent the cutting edge in military aviation, and are the centerpieces of Pratt and Lockheed respectively. The Lightning variants and this line of turbofan engines will be in service with several branches of the US military and its allies around the world for the foreseeable future, with more iterations of the F135 to come. Read More


This is an excerpt from a technical paper, presented at the ASME Turbo Expo 2020 online conference and written by Leonid Moroz, Maksym Burlaka, Tishun Zhang, and Olga Altukhova. Follow the link at the end of the post to read the full study! 


The attempts to simulate transient and steady-state sCO2 cycles off-design performance were performed by numerous authors [1], [2], [3], [4], and [5]. Some of them studied the dynamic behavior of regulators, some studied different control strategies or off-design behavior in different scenarios, which definitely has certain utility in the development of the reliable technology of sCO2 cycle simulation. Nevertheless, they used rather simplified models of components, especially turbomachinery and heat exchangers, which are of crucial importance to correctly simulate cycle performance.

The authors of this paper attempted to apply the digital twin concept to a simulation of off-design and part-load modes of the sCO2 bottoming cycle considering real machine characteristics and performance, which nobody tried to apply in this area.

On IGTC Japan 2015, SoftInWay Inc. has published a paper “Evaluation of Gas Turbine Exhaust Heat Recovery Utilizing Composite Supercritical CO2 Cycle”. The paper considered combinations of different bottoming sCO2 cycles for a specific middle power gas turbine. It mainly studied the advantages of different types of sCO2 cycles to increase the power production utilizing GTU waste heat.

The present paper is a further study based on that so the Cycle 2 [6] from that previous paper was selected as the sCO2 bottoming PGU layout in the present paper for subsequent analysis. The cycle is a combination of recompression cycle and simple cycle which offers 16.13 MW as output. GE LM6000-PH DLE gas turbine, was used as the heat source for bottoming PGU. According to GE official brochure [7], the GE LM6000 offers 40 MW to over 50 MW with up to 42% efficiency and 99% fleet reliability in a flexible, compact package design for utility, industrial and oil and gas applications. GE LM6000-PH DLE provides 53.26 MW output with exhaust temperature at 471 ℃ and exhaust flow at 138.8 kg/s. (This information came from GE products specification from 2015. It appears that GE continuously modifying the parameters of its turbines along with the naming of different modifications. Therefore, today’s parameters and configuration names might be slightly different comparing to 2015) Exhaust gas pressure was assumed to be 0.15 MPa. These parameters were taken to analyze the bottoming PGU and are presented below in TABLE 1.


The digital twin (DT) concept is the developing technology that allows simulation of object behavior during its life cycle or in specified time due to changing ambient conditions, for example. The DT is applicable for performance tuning, digital machine building, healthcare, smart cities, etc [8] that allows decreasing the time and costs of development and optimize the object on the developing stage. GE has raised DT concepts for power plants to continually improves its ability to model and track the state of the plants [9].

In the context of this paper, DT is a simulation system comprised of physicist-based models organized in a special algorithmic structure that allows simulating the behavior of sCO2 PGU under alternating ambient conditions and grid demands.

The DT in this study was created utilizing AxSTREAM® Platform, which includes multiple software tools. The following software tools were utilized in this study: AxCYCLE™ was used to perform cycle thermodynamic calculation; solution generator in AxSTREAM® helped with finding possible machine geometry with given boundary conditions when performing preliminary design for compressors and turbines at design point; parameters and performance of turbomachinery including mass flow rate, pressure, power, efficiencies, etc. were calculated by Meanline/Streamline solver in AxSTREAM® for design and off-design conditions; AxSTREAM NET™ is a 1D system modeling solver and it was introduced here to simulate performance of heat exchangers (HEX) and pressure drop in the pipes involved in the cycle; AxSTREAM ION™ was used to integrate all modules and tools together in one simulation system. Read More

Performance Testing of Axial Compressors

Performance testing is a key part of the design and development process of advanced axial compressors.  These are widely used in the modern world and can be found in nearly every industry, and include the core compressor for aeropropulsion turbofan engines, as well as aeroderivative gas turbine engines for power generation.  An example of this are the turbine engines shown in Figure 1 and 2, which feature an industrial gas turbine and a high bypass ratio turbofan engine with a multistage high-pressure core compressor. The development time of these machines can involve numerous expensive design-build-test iterations before they can become an efficient and competitive product. This places a great importance on the accuracy of the data taken during the performance tests during the development of the compressor since the test data taken is often used to anchor the loss models within the design tools. Modern axial compressors typically have high aerodynamic loadings per stage for improved system efficiency and requires precise aerodynamic matching of the stages to achieve the required pressure ratio with high efficiency. Variable geometry inlet guide vanes and stators in the first few stages are typically required to provide acceptable operability while maintaining high efficiency and adequate stall margin.

Industrial gas turbine for power generation.
Figure 1. Industrial gas turbine for power generation. Source
Figure 2. Turbofan engine for aeropropulsion.
Figure 2. Turbofan engine for aeropropulsion. Source

Performance Testing of Axial Compressors

Axial compressors all undergo a thorough design and development phase in which performance testing is vital to their ultimate success as a product. Performance testing during the development phase of these high-power density machines can ensure that the design meets the specified requirements or can identify a component within the turbomachine which falls short of its expected performance, and may require further development, and possible redesign. Performance testing can also ensure that the unit can meet all the conditions specified and not merely the guaranteed condition. Aerodynamic performance testing multistage axial compressors during the early part of development is often done in phases. The development test program is planned and executed with a design of experiments approach and includes varying the air flow and shaft rotational speed as well as the variable geometry schedule in order to fully characterize the compressor. In the first phase, the front block of the compressor is built and tested at corrected (referenced) air flow rate, inlet pressure, temperature and shaft rotational speed. Instrumentation includes utilizing traditional rakes and surveys at the exit, to obtain spanwise distributions of pressure, temperature, and flow angles. Testing in phases is typically done for two reasons. Read More

The History of Turbochargers, Part 2

Hello! And welcome back for part 2 of our series on “A Brief History of the Turbocharger”. To read part 1, which compares superchargers and turbochargers, and explains the early history of turbochargers and forced induction from the turn of the century through to World War 1, click here. Having covered all of that, let’s pick up from where we left off!

Following World War 1, and the work of Dr. Sanford Alexander Moss, Alfred Büchi, who had created the first true turbocharger, had continued innovating following the failure of his first design. By 1925, he had a working turbocharger design that consistently and reliably worked (1).

Following this breakthrough, the turbocharger saw its first commercial application on ten-cylinder diesel engines. Since diesel engines are typically built to withstand the high-pressures required by their operating conditions, the pressures generated by using forced induction are easily accommodated. As a result of adding the turbochargers, the engines upped their horsepower ratings from 1750HP, all the way to a whopping 2,500HP. (1)

The Hansestadt Danzig, one of the German ships fitted with the 10 cylinder turbodiesel engine described above
The Hansestadt Danzig, one of the German ships fitted with the 10 cylinder turbodiesel engine described above. (

For Büchi, this was a great achievement, as it marked the first commercial application of a machine that he had first begun working with more than 20 years prior. For the turbocharger, however, this was just the beginning. Read More

A Brief History of the Turbocharger – Part 1

Turbochargers are one of the more common turbomachines out there today! As everyone is making efforts to lower carbon dioxide emissions in automobiles, and the automotive OEMs engage in a “horsepower war”, the turbocharger will likely continue to grow in popularity for both civil and commercial uses.

But how did these machines get so popular? That’s what we’ll be exploring in this blog miniseries! Today’s blog will introduce the concept of the turbocharger, and the beginnings of its development around the turn of the 20th century.

Turbocharging engines and the idea of forced induction on internal combustion engines are as old as the engines themselves. Their intertwined history can be traced back to the 1880’s, when Gottlieb Daimler was tinkering with the idea of forced induction on a “grandfather clock” engine. Daimler was supposedly the first to apply the principles of supercharging an engine in 1900, when he mounted a roots-style supercharger to a 4-stroke engine.

The birth of the turbocharger, however, would come 5 years later, when Swiss engineer Alfred Büchi received a patent for an axial compressor driven by an axial turbine on a common shaft with the piston of the engine. Although this design wasn’t feasible at the time due to a lack of viable materials, the idea was there.

Turbochargers vs Superchargers

What idea was that, exactly? And how did it differ from supercharging?

I think it’s important to quickly go over the basic differences between turbocharging and supercharging. Both offer “forced induction” for piston engines. A naturally aspirated engine simply will draw in atmospheric air as the intake valve opens, and the piston travels down to bottom dead center. A forced induction engine, pushes more air into the cylinder than what the dropping of the piston would pull in, allowing more air to be combusted, and thus generating more power and efficiency. While turbochargers and superchargers are both forced induction , how superchargers and turbochargers go about compressing that air is different. Superchargers are driven by the engine themselves, typically via a belt or gear. This uses some of the engine’s available horsepower, but doing so provides more horsepower back to the engine. The compressors can be either positive displacement configurations (such as a Roots or Twin-Screw), or a  centrifugal supercharger.

supercharger configurations
A very helpful image of the 3 kinds of superchargers, courtesy of

Turbochargers, as mentioned before, use the air from the exhaust of the engine to drive a turbine, and the work of the turbine is transmitted on a common shaft to a compressor. The most common configuration is a radial turbine driving a centrifugal compressor similar to the one above in the supercharger diagram. However, there are other configurations ,seen in larger examples, such as an axial turbine driving a centrifugal compressor. Read More

Micro Gas Turbines in Trains and Railroad Technology

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Welcome to this latest (and sadly, last) entry in the Micro Gas Turbines in Transportation series! Today, we’ll be having a quick look at micro gas turbines and their larger siblings, specifically the history of how they have been used in railroad locomotion and  what the future holds for micro turbines and railroad technology. We’ll also consider the advantages and disadvantages of using them to drive trains.

Rail transportation has been around in one form or another for longer than you might think. There are examples of wheeled carts running on fixed roads and tracks that prevented any deviation being used since the 6th century BC in ancient Greece.

Up until the late 18th Century, however, railroads were rather limited in what they could be used for, since there was no way of mechanically propelling the vehicles used. Rather, these railroads relied on humans, animals, or gravity to move the carts along the tracks. This changed when in 1784, the great Scottish inventor James Watt created and patented the first steam engine locomotive which was an improvement of a steam engine designed by Thomas Newcomen. Following this invention, engineers in the UK working on different projects such as Richard Trevithick and his development of the first high-pressure steam engine would lead to the first uses of locomotive-hauled railway. His invention would be used in Wales on a short 9 mile run from an iron-works in Penydarren to the Merthyr-Cardiff canal.(2)  On February 21st, 1804, the first trip took place on this railway using only steam propulsion.(2) However it wasn’t until George Stephenson’s creation paved the way for public use of steam engines like those created by James Watt on the rails, and in the coming years rail travel would play an important role not just in the United Kingdom but in the United States as well. This raises the question, where and when did turbines and turbomachinery come into play in rail travel?

George Stephenson's Locomotion 1 –
George Stephenson’s Locomotion 1 – image courtesy of Chris55 / CC BY-SA

Believe it or not, gas turbines in trains were being experimented with long before Frank Whittle and Hans von Ohain were designing them to take to the skies. As far back as 1861, the year that Abraham Lincoln became president of the United States, patents were being filed for a turbine that utilized ambient air mixed with combustion gasses to drive a turbine. As seen in patent 1633, Marc Antoine Francois Mennons created an engine that included all of the components needed in a modern gas turbine engine. It was called a “caloric engine” and it had a compressor (called a ventilator), combustion chamber (using ambient air and burned wood or coke), and a turbine to create work from the combustion gasses as well as a pre-heater (which he called a regenerating apparatus).(3)

Read More

Charles Parsons and His Contribution to Engineering

Welcome to this special edition of the SoftInWay blog! While we at SoftInWay are known for helpful articles about designing various machines, retrofitting, and rotordynamics, we believe it is also important to examine the lives of some of the men and women behind these great machines.

The compound steam turbine is one of the greatest inventions, not just in turbomachinery but around the world. Once it was introduced to the marine industry, the steam turbine exploded in popularity as a means of allowing ships to travel faster and farther than ever before. It would go on to become a critical part in the naval arms race that preceded the First World War. The steam turbine not only revolutionized marine and naval propulsion, it became one of the best ways to generate electricity. After its inception, the steam turbine became one of the best ways to reliably generate power on a large scale, and make electricity the regular utility that it is today. But who invented the modern steam turbine?

Sir Charles Parsons
Image courtesy of Wikimedia

Sir Charles Algernon Parsons, (1854 – 1931), is the inventor of the modern steam turbine. The work he undertook in his life had a massive impact on the world, continuing the legacy of James Watt by bringing steam technology into the modern era. Born on June 13th 1854 into an Anglo-Irish family, Sir Charles Parsons was born into a well-respected family with roots in County Offaly, Ireland. In fact the town now known as Birr was then known as Parsonstown, from the early 1600’s through to 1899. Parsons was the sixth son of the 3rd Earl of Rosse, and had a family lineage that had made great strides in the areas of military, political, and physical science. The family’s castle in Birr, which is still owned by the Parsons family and is the permanent residence of the 7th Earl of Rosse, was a rendezvous for men of science during the childhood of Sir Charles. Suffice it to say, there was no better place for a future-engineer to grow up. He alongside his brothers would receive private tutorship from Sir Robert Ball and Dr Johnstone Stoney, famous Irish astronomer and physicist, respectively. Read More

Engineering Luke Skywalker’s X-34 Landspeeder

Today, landspeeders we look at!


Landspeeders belong to the “repulsorlift” transport class, like the podracers we looked at last year, and travel above a world’s surface (up to 2 meters) without contact (very useful on swampy lands like Dagobah). Landspeeders are the successors to the hanno speeder which was mainly used as a racing vehicle with many Tatooine natives still using them to race in the Boona Eve Classic today.

Luke Skywalkers Soro Suub Corporation X-34 landspeeder
Figure 1:  Luke Skywalker’s Soro Suub Corporation X-34 landspeeder from the 1977 film – Note, the Soro Suub Corporation was your main go-to landspeeder designer and manufacturer before and during the reign of the Galactic Empire even though it specialized mostly in mineral processing. Image source

Landspeeders are found in both civilian and military applications but due to intergalactic ITAR regulations we will only cover the civil aspect here with a focus on the most famous of them all. If you want to know more about our experience working with military, defense and governmental organizations (whether you area part of the Empire, Rebels, Resistance or Separatists) feel free to contact us.

The Famous X-34

Luke Skywalker’s X-34, with its 6 selectable hover heights, features an engine consisting of 3 air-cooled thrust gas turbines able to reach a top speed of about 155 mph. The side engines are also used for steering although it is not obvious whether this steering is achieved by varying their thrust to be asymmetric or through vectoring of their exhaust. With the X-34 total length being 3.4 meters it helps us estimate the overall dimensions of its engines which are, each, roughly 80 cm long by 30 cm wide. Read More

Micro Turbines in Maritime Transportation

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Hello! Or should I say, welcome aboard! In this edition of micro gas turbines in transportation, we’re going to be looking at micro gas turbines in the marine world. Marine transportation presents its own set of unique challenges not seen in other forms of transportation; although some of the common challenges and hurdles will be seen here too. If you haven’t read the other entries, or the introduction, I highly recommend you do so here.

Out of all the different vehicles and forms of transportation that will be covered in this series, the boat as we know it is one of the oldest ways of getting about. From rowing to sailing to paddle wheels and engines, the boat has a long history of carrying every kind of good and being imaginable. Much like the topic of turbines, marine transportation can take up oceans of information; in fact you might say that it’s a whale of a topic.

Whale Whale Whale
Whale, here we are with another pun. I hope it brightens your day at least! Image courtesy of The Georgia Aquarium

This blog will specifically cover a brief history of motorized marine transportation, where/how micro turbines can be used, and the inherent advantages and disadvantages. Let’s get started!

A Brief History of Engines in Marine Transportation

Steamboats became popular in the 19th Century when the Industrial Revolution was in its early stages. Steam engines like the ones designed by James Watt were used to propel everything from small riverboats like the ones that went up and down the Missouri river, to oceangoing steamships. The engines typically drove a propeller or “screw” or a large paddle wheel like what is commonly seen on a watermill. Different steam engines in different configurations dominated marine transportation throughout the 19th century, and by the turn of the 20th century, large expansion engines began to be utilized for oceangoing ships like the Olympic-class ocean liners as well as warships. Read More

Turbomachinery System and Component Training: Something for Everyone!

Mechanical engineering is an ever-changing field, and we want to be there to help engineers stay ahead of the curve, even while they are flattening it. In that spirit, we wanted to share with you our different training options that are available now. Whether you are looking to brush up on the fundamentals, or evaluate a software platform, this is a great time to train and explore the latest and greatest in turbomachinery engineering.

Without further ado, let’s get into it!

Private Corporate Trainings Online

First and foremost, the best most comprehensive training you can get from SoftInWay is a private session with one of SoftInWay’s lead engineers and your team. Why is this the best training option? A couple of reasons:

  • Courses are entirely customizable: The scope of these private training courses is tailored to your specific needs. Are you looking to learn the fundamentals? Or perhaps you want to expand your team’s R&D capabilities when it comes to turbomachinery, rotor dynamics, and 1D thermal systems? Whatever the application, we’ll work with you to develop a course curriculum which brings the most value to you and your team.
  • One-on-one consultation with our expert engineers on individual projects and challenges. Our engineering expertise ranges from flowpath design on a turbomachine, to rotor dynamics, as well as secondary flows/multiphase flows, and other all-encompassing projects such as liquid rocket engine design.
  • ll registrants get a 1-month license of the relevant AxSTREAM modules. During the class, users will be familiarized with the ins and outs of AxSTREAM, and be able to make use of AxSTREAM’s capabilities for 1 month afterwards.

The class can be as long or as short as you need and scheduled around you and your team. Read More