Over the last five years Rolls-Royce say it has been pioneering ‘world-first’ technology that will contribute to the UK’s next-generation Tempest fighter jet programme.

In what it describes as “an aim to be more electric, more intelligent and to harness more power”, Rolls-Royce say it has recognised that any future fighter aircraft will have unprecedented levels of electrical power demand and thermal load; all needing to be managed within the context of a stealthy aircraft.

“Before the launch of the Tempest programme, Rolls-Royce had already started to address the demands of the future. Back in 2014, the company took on the challenge of designing an electrical starter generator that was fully embedded in the core of a gas turbine engine, now known as the Embedded Electrical Starter Generator or E2SG demonstrator programme.”

Conrad Banks, Chief Engineer for Future Programmes at Rolls-Royce said:

“The electrical embedded starter-generator will save space and provide the large amount of electrical power required by future fighters. Existing aircraft engines generate power through a gearbox underneath the engine, which drives a generator. In addition to adding moving parts and complexity, the space required outside the engine for the gearbox and generator makes the airframe larger, which is undesirable in a stealthy platform.”

The firm say that phase two of this programme has now been adopted as part of Rolls-Royce’s contribution to the Tempest programme.

Click to enlarge.

“As part of this journey, the company has been continuously developing its capabilities in the aerospace market, from gas turbine technologies through to integrated power and propulsion systems. The goal being to provide not only the thrust that propels an aircraft through the sky, but also the electrical power required for all the systems on board as well as managing all the resulting thermal loads. Rolls-Royce is adapting to the reality that all future vehicles, whether on land, in the air or at sea will have significantly increased levels of electrification to power sensors, communications systems weapons, actuation systems and accessories, as well as the usual array of avionics.”

The launch of phase one of the E2SG programme saw significant investment in the development of an integrated electrical facility – a test facility where gas turbine engines can be physically connected to a DC electrical network.

“The launch of the second phase of the project in 2017 saw the inclusion of a second electrical generator connected to the other spool of the engine. It also included an energy storage system in the electrical network and the ability to intelligently manage the supply of power between all these systems. The two-spool mounted electrical machines allows, by combination of operation as either a motor or a generator, the production of a series of functional effects on the engine, including the transfer of power electrically between the two spools.”

Team Tempest Future Combat Air System concept.

As part of the E2SG programme, Rolls-Royce say it is investigating the feasibility of using dual spool generation to influence the operability, responsiveness and efficiency of the engine. Another key technology under development is the Power Manager intelligent control system, which uses algorithms to make real time intelligent decisions about how to supply the current aircraft electrical demand while optimising other factors including engine efficiency to reduce fuel burn or engine temperature to extend component life.

A third phase of testing is likely to include a novel thermal management system being integrated with the overall system, as well as more electric engine accessories.

The company also intends to showcase a full-scale demonstrator of an advanced power and propulsion system. There will be new technologies in all parts of the gas turbine, including twin spool embedded generation to higher power levels, an advanced thermal management system, an energy storage system tailored to the expected duty cycle of the future fighter and an intelligent power management system which will be able to optimise the performance of both the gas turbine and the power and thermal management system.

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Peter E

All sounds good stuff. Aero engines remains an area where we are alongside the Americans and have a genuine edge on the Russians and Chinese.

Elsewhere I did read about the possibility of bolting the pre-cooler from SABRE on the front of an EJ200, but maybe that is not seen as relevant to the Tempest programme, or was found to be not such as good idea as it sounds, when they looked at it closely. I guess building a new engine core with improved electricity generation still doesn’t preclude that though.


The RR engine embedded generator has shown it streamlines the whole engine package, thus taking up less airframe space. This may be a possible problem of trying to fit the pre-cooler to a fighter sized aircraft i.e. the packaging. Reaction Engines use the Sabre engine’s fuel of liquid hydrogen to cool the pre-cooler’s cooling medium which is liquid Helium. So if we wanted to get the same efficiencies we need to find somewhere to fit a radiator for the cooling medium and then re-cool that medium before it goes back through the pre-cooler. You could put the radiator in the… Read more »

Peter E

So they will almost certainly be looking at it, but it may not be quite ready at scale for Tempest in that project’s proposed timescales. Sensible risk management would be to go with what we have by the design cut-off date.

Sounds like the eventual SABRE-Plane will make one hell of a penetrating medium bomber though.


Hi Peter, “design cut-off date.” If only the Services / MoD would recognise that engineers need a stable design brief to have any chance of delivering to time and cost. Flexibility can be designed in up to a point, but constantly changing requirements cannot be designed for. So hopefully they will accept that the risk is too great and keep focused on getting Tempest mk1 into production on time and to a reasonable budget. Note I say ‘reasonable budget’ I do not expect it to come in on budget because the cost will inevitably be overly optimistic on account that… Read more »


By the way, what happened to TSR1? Was there one?
Was the TSR2 likely to have been given a name?

On topic. Nice diagrams, but is this likely to be of use to say the Chinese? All these ideas eventually get out onto the public domain. Are other countries working on it?


Believe it or not the TSR.1 was the Fairey Swordfish….T stood for Torpedo


I often wondered what was the TSR1 – Swordfish! Amazing aircraft, saw off at least 1 replacement the Baracuda. Shame the TSR.2 didn’t have the same record. Lets hope Tempest does…


It’s all very well having a glossy diagram of the embedded generator (which may not be truthfully factual to the design). But without material specifications, you will still need to research the materials or try and steal the specifications from Rolls Royce. The Chinese are having massive issues with their domestically produced fighter engines. Their WS10 is a copy of the AL31 that they reverse engineered when Ukraine old them the Su27/33 prototype, that they then turned in to the J15 naval fighter. This engine had very poor acceleration which caused a number of crashes. But the main issue with… Read more »


I guess industrial espionage… well plain old espionage… becomes important.


Fair do’s. It’s what the Soviets did to the Nene engine we sold to them in the late ’40s, which they promised to use only in civilian aircraft and then built that well known passenger plane the Mig-15 around it.


You’re predicating this on a desire to install a full Sabre pre-cooler. Thats not necessary. And in fact it would not be desirable. The Typhoon and Tempest are not designed for hypersonic speeds, they’re not going to be utilising the pre-cooled oxygen as a fuel. The objective of installing a pre-cooler would be help manage the thermal loads and reduce IR signature, it wouldn’t necessarily increase speed or range by a major amount. As the aircraft wouldn’t be travelling hypersonically the air temperature would also be far, far lower. It could therefore be dramatically smaller, even to the extent that… Read more »


My thoughts to and posted above before reading your comment. I would think directing precooled air to cool the high pressure blades and the generator would yield benefits.


No, I am not suggesting the full Sabre installation i.e. fuelled on hydrogen and oxygen, but just the installation of the pre-cooler fitted to a gas turbine/turbo-jet burning regular avtur. There are a number of methods used to increase a gas turbine’s or turbojet’s power. Apart from increasing the efficiency of the blades and combustion chamber, you can play with the by-pass ratios and compression ratios, these only gets you so far. The best method is to increase the amount of air being forced into the engine. This is the value of the pre-cooler, it significantly cools the air thus… Read more »


I thought perhaps a much smaller precooler could be used to cool the high pressure blades and assist with thermal management and efficiency. The Tempest electrical systems could benefit from cooling especially give the power requirements of direct energy weapons.

George Royce

I was just about to say this. Integrating the SABRE pre-cooler technology into a new generation Rolls-Royce engine would completely change the game if all goes well.

Rupert Chandler

Very difficult to believe there won’t be any cross fertilisation from Sabre given it has to be seen as relevant in terms of GEN6 aircraft. Theres nothing that the SABRE technology offers that wouldn’t be very useful. Also all parties involved have an interest in SABRE.

Nigel Collins

As I touched upon in an earlier thread, would it not make sense to design an early Tranche 1 version of Tempest using the current airframe and install new the RR engine? Given that we need to upgrade Typhoons earlier models at some point, this would make a great deal of sense, not least for the purpose of testing and the fact that we may not have the US as a guaranteed ally in future conflicts. Many of you on here will no that I have been a very strong advocate for self-reliance rather than depend on others to come… Read more »

Peter E

One would imagine that after ground testing the new engine, one or more prototype airframes will be ordered. Depending on timelines, I guess you could have interim steps of either the new airframe with an old engine, or the new engine shoe-horned into a Typhoon. But given the cost and complexity of either of those compromises, they might just go straight to the new/new demonstrator, if timelines allow.

Nigel Collins

Exactly Peter E, as I’ve mentioned previously.

Either way and hopefully with the Tempest airframe, we will be able to boost the performance of the Tranche 3A Typhoons with this technology as well as introducing a world-beating platform, generating interest from other countries and jobs here in the UK.

A perfect opportunity which hopefully will not be sold off!


To get an ‘new’ engine from bench test to flying takes over 10 years. This will not go into Typhoon, it just isn’t going to happen.


There is no point in ‘upgrading’ the Tranche 1 Typhoon’s powerplant. We’d need to update the entire aircraft systems to make it worthwhile, and at that point you may as well have bought a new aircraft.

Nigel Collins

“we will be able to boost the performance of the Tranche 3A Typhoons with this technology as well as introducing a world-beating platform”

Nigel Collins

That’s fours years from now Rudeboy by your estimations. It will take at least four years to get a Tempest demonstration aircraft built to match the engine design providing they have settled on the airframes specifications and we continue to provide the fundings for it. As for installing it on the Tranche 3A Typhoon, this, I would have thought, would be more than possible by 20205? The F35A/B will not be Block 4 ready until 2025, so it makes little sense to continue in investing in a 5th gen aircraft to my mind. “Before the launch of the Tempest programme,… Read more »

Robert blay

No chance we will have a Tempest demonstrator by 2025, the mod hasn’t even released an official requirement for what they want the Tempest program to be. My guess is F35A will replace tranche 1 Typhoons from 2030, and maybe a Tempest design from 2040, and even that is being optimistic.

Nigel Collins

The Franco-German FCAS programme is aiming to have its first test flights of a demonstrator in 2026.

As we appear to be in a more advanced stage than them I can see no reason why not, other than the final design of the airframe, or the government buggering about with the finances.

Wasting precious time when you require sales and allowing the competition to catch up on a project like this makes no sense at all.


We need to be careful freezing the dsign to early we may end up with 5.5 gen aircraft. Which the F35 could match after a few years of upgrades. UK needs to ensure its a true 6th gen aircraft to lock in partners and future sales. Its a fine line you need to go for cutting edge tech but not tech that may be too difficult to bring from the lab to production line, that could cause delays and cost over runs and even kill the program.


Exactly, or probably anything else on them for that matter. And unless there is a perceived uplift in air-breathing threat to the U.K., the current spec of the T1 Typhoons will make them suitable for air policing for decades (air frame hours notwithstanding). It also doesn’t warrant having a ‘tranche 1’ Tempest in this mission. Leave the current ac doing what they’re doing and spend the cash elsewhere.


Hi Nigel,

Flight testing a new engine would be best undertaken seperately to the development of the new airframe if possible so I would expect the new engine to go into an exiting airframe, preferably a twin engined model. This would allow one experimental engine and one old reliable EJ200 for example.

Previous engine programmes have put engines under exec jet or BAC 1-11 wings for initial flight testings. Obviously no good for supersonic testing but good enough to test the all important subsonic parts of the flight envelope.

Nigel Collins

Understood! Exciting times ahead, hopefully in the next few years rather than the late ’20s.

I feel sure we could achieve a T1 Tempest within a five-year timescale given the rate that things appear to be progressing?


I believe the EF2000 had Tornado power plants, the EF2000 was the technology demonstrator for the Typhoon. Taranis is another example which flew with the Adour engine.


Yeh, RB199’s for the Tornado if I remember rightly.


A lot of work / technology initiatives seem to be coming together for this project. One might almost think there had been some preparation work undertaken…



All very encouraging, partner companies and nations coming on board, £2b MoD investment and companies like Roll Royce and Leonardo putting their latest and best tech forward.


Replica was the Plan B option if the F35 didn’t work as expected. Due to the technology that went into generating an incredibly small RCS, it allowed BAe to be a tier 1 partner on the F35 program.


Hi Helions, Interesting article. Switching from airframes to systems as the focus for international partnerships would be a good way forward as it would more closely align with the way the defence industry is develops systems. It could also decouple the procurement system’s insistance that a platform has all new kit from the get go which invariably leads to delays due changes in requirments as everyone tries to keep pace with the latest tech. Systems have a completely different life cycle to platforms with computer / silicon tech going obscolescent in anything from 5 to 10 years whilst platforms such… Read more »


The extra electrical generation will come in handy for onboard laser weapons.

Nigel Collins

Agreed JohnHartley, One of the reasons for its design.


Interesting, I did see anything in the image above that would indicate the engine would incorporate variable bypass technology. Perhaps this is an initial concept to prove the integrated starter/generator and variable bypass will be incorporated later.