Exclusive Interview

Rolls Royce – Pushing the Engineering Boundaries

Rolls Royce – Pushing the Engineering Boundaries
Exclusive Interview with Dr Holger Klinger, Sub-System Executive Power Gearbox, Rolls-Royce.

In an Exclusive Interview with Dr Holger Klinger, Sub-System Executive Power Gearbox, Rolls-Royce, he speaks about the milestone achieved and the challenges faced, Swati K. finds more…

Q – First of all, I would like to congratulate you on achieving a remarkable feat of Rolls Royce’s UltraFan power gearbox which has set a new world record. Can you tell us more about this important milestone?

A – Many thanks,indeed, it is a fantastic achievement of the team working very hard over the last 5 years. This successful demonstrationresulted from a list of improvements incorporated into the Power Gearbox based on previous testing but also on improved modelling capability.

We started testing a prototype gearbox in 2016 on an Attitude Rig with the ability to change pitch and role conditions between +/- 45° whilst the gearbox is in operation at low load. Since 2017 tests have also taken place on a Power Rig up to nominal MTO conditions and since 2019 we are testing gearboxes with engine representative hardware even at overload conditions. These vehicles are heavily instrumented, sometimes with two telemetries, and up to 700 measurement parameters.

For special test purposes weperformed experiments on dedicated component rig facilities at sub and full scale.Strip evidence of the tested unitshave thenbeen fed into the process of design optimisation.

The outcome of all the effort is the successful overload test of a compact gearbox perfectly designed for the aviation industry.

Q – What were the challenges faced by the team while achieving this magnificent feat?

A – Just to give you an impression on the power density we are working with:two gear teeth transmit the same power as the entire starting grid of a Formula 1 race.

The UltraFan®Power Gearbox is based on a planetary conceptwith five planets driven by a sun gear in the middle and a static ring gear on the outside. At high power the planets operate within a field of very high g-loads so that every part of the component needs to be carefully designed and supported.

In order to operate in this environment, the intention is to isolate thegearbox from engine vibration, shaft misalignment and bending moments as much as possible.

Another challenge is to keep load dependent as well as load independent power losses in the system extremely low to avoid the need for additional cooling devices.

Essential element is also the development of world-leading manufacturing methods to ensure adequate quality of the highly loaded components.

Q – What was the inspiration behind you and your team to achieve this milestone?

A – We wanted to explore the boundaries for the power transmission capability of our gearbox to identify any potential for further optimisation. We are convinced we could have gone to even higher running conditions as all the critical measurement parameters were still below limits. With the vehicle now in disassembly and first inspection results being available we found the hardware in almost brand-new condition.

Q – The entire aviation industry is geared towards achieving sustainable aviation and net-zero emissions by 2050 as per the UN’s mandate. Are the steps taken collectively by the aerospace fraternity enough to achieve this objective?

A – For decades the aviation industry has continuously invested in R&D and improved its environmental performance. For example, flying today uses 80% less fuel per Revenue Passenger Kilometre (RPK) than it did fifty years ago and aviation accounts for 2.5% of all man-made CO2 emissions, while generating 4% of global GDP and supporting 88 million jobs.

At Rolls-Royce, we have a long, proud history as pioneers of the power that enables the modern world to function. We have joined the UN Race to Zero campaign with a bold ambition to play a leading role in pioneering a resilient, inclusive, net zero carbon future.This will see Rolls-Royce become net zero carbon in its operations by 2030 and, more fundamentally, set an ambition to play a leading role in enabling the sectors in which we operate to reach net zero carbon by 2050 through the development of new products and technologies.  Rolls-Royce has affirmed that position in joining the Business Ambition for 1.5oC campaign.

But we all have to work together as an industry and that’s why just recently the Chief Technology Officers (CTOs) of seven of the world’s leading aerospace manufacturers have reaffirmed their commitment to achieving more sustainable aviation and to reaching industry-wide Air Transport Action Group targets in a joint statement. This statement is supporting the aviation sector’s ambition to achieve net-zero carbon emissions by 2050.

The CTOs, whose firms have spent over $75B in R&D combined over the past five years,have committed to working together to focus on three core areas of aviation technology:

  • Advancing the state-of-the-art in aircraft and engine design and technology
  • Supporting increased availability and adoption of Sustainable Aviation Fuel (SAF) and investigating hydrogen as a fuel of the future
  • Continuing to develop novel technologies that will eventually enable net-zero carbon aviation while maintaining the safety and quality standards of the industry.

Q – If not, what according to you is lacking in aviation sector and where is the scope for further improvement to achieve green aviation?

A – I don’t think there is anything lacking in the aviation sector. Achieving net zero will require the transformation of core systems that support our global economy. Power generation, transport and the built environment will be key. These are the very sectors in which reducing emissions is hardest. Together they represent 73% of annual global CO2 emissions in 2020.

The CTOs of Airbus, Boeing, Dassault Aviation, GE Aviation, Pratt & Whitney, Rolls-Royce, and Safran will also issue a call to action to policymakers, research institutions, suppliers, fuel producers and airport operators to build on the progress made in recent years and deliver on the aviation sector’s sustainability agenda.

No individual company, sector or technology has all the answers. That’s why we are forging partnerships across borders, industries and technologies to seek out – and scale – solutions that can get us to net zero.

We are also stepping up our advocacy for policies that can accelerate action to drive down emissions. Pioneering sustainable, net zero power now sits at the very heart of our strategy, innovation plans and growth agenda.

Q – How efficient is SAF for achieving sustainable aviation?

A – If SAF production can be scaled up – and aviation needs 500 million tonnes a year by 2050 – we can make a huge contribution for our planet.

The net CO2 lifecycle emissions of unblended SAF are at least 75 per cent less than conventional jet fuel, and as methods of production advance there is the possibility of further reductions in years to come

We know that is a huge undertaking and will require teamwork right across a number of stakeholders, including aviation, the fuel industry and government bodies.

Our contribution to that is demonstrating that our current engines can operate with 100% SAF as a full “drop-in” option, laying the groundwork for moving such fuels towards certification.

That is why we have recently carried out a series of ground and flight tests on Rolls-Royce engines using 100% SAF for the first time.

The aim of the tests is to confirm that unblended SAF makes a significant contribution to improving the environmental performance of gas turbine engines. At present SAF is only certified for blends of up to 50% – so a change to allow 100% SAF would be ground-breaking in terms of sustainability.

We have just announced that within two years we will have proven that net zero carbon operation is possible with over 40% of the world’s long-haul aircraft engines. That’s all our Trent engines assembled in Derby, UK.
And by the way, our whole Pearl engine family, which powers the latest generation of business jets from Bombardier, Dassault and Gulfstream, will be compatible with 100% SAF as well by 2023.

Q – When are you planning the first test run of the engine?

A – The first UltraFan® demonstrator engine is currently in build and testing is due to take place next year. The Power Gearbox for this engine has already been assembled and is now going through a pass off test procedure to make sure everything is fine for the engine test.

And to come back to your previous questions, the very first test run of the engine will be on 100% SAF and the engine will be 100% SAF compatible from entry into service.

Q – After the power gear box technology, what is the next milestone in making?

A –
Our sustainability strategy consists of three pillars. While we are further improving gas turbine technology with our new Pearl engine family and the first UltraFan demonstrator engine and making sure all our in-production engines are compatible with 100% SAF we are also working on the electrification of flight. With Tecnam/Wideroe and Vertical Aerospace we are working on customer projects for an all-electric commuter airplane and an eVTOL. Both are planned to enter service by mid of this decade already.