The first QEC- carrier - Queen Elizabeth - will become HMS Queen Elizabeth on 4 July. (Aircraft Carrier Alliance). 

This month on 4 July the first of the UK's new Queen Elizabeth-class (QEC) carriers is set to be launched by Her Majesty the Queen — an important milestone in restoring Britain's naval air power. TIM ROBINSON talks to some of the engineers responsible for putting the 'air' in aircraft carrier. 

“The thing to bear in mind with the QEC,” says David Atkinson, F-35 Integration Lead, BAE Systems, “is the sheer scale of the flight deck. It is just huge — three times bigger than the Invincible-class deck.” Atkinson is part of the industry team that is working on this giant flagship project. This BAE team, distinct from the company’s prime role in the Aircraft Carrier Alliance (ACA), is the interface between the aircraft (F-35) and naval teams working on this project — to ensure that the UK's new stealth fighter and its new carriers mesh as smoothly as possible. The team, reporting up to the F-35 Joint Programme Office via Lockheed Martin, is the first ‘port of call’ for ACA and the MoD for questions about F-35 integration. Says Atkinson: “Our role is to help the MoD and ACA ensure the F-35B is integrated as efficiently and effectively as possible with the QE Class aircraft carrier.” This has involved extensive engineering, simulation and modelling — going back a number of years.

However, as defence observers will know, the CVF future carrier project hasn't always been smooth sailing. The UK Government's switch from STOVL F-35B to CV (cats and traps) variant and back again in 2012, not only looked like dithering and cost valuable resources, but also set project engineers racing to make up lost time. “That interruption has had an effect on the programme, however our simulator models have helped to ease the transitions between aircraft variants” notes Atkinson.

Leveraging simulation

The F-35 motion simulator at BAE Systems in Warton has be crucial in developing QEC CONOPS.(BAE Systems)

Integration of the F-35 with the QEC, in particular, has harnessed the growing power of simulation and synthetic modelling to de-risk the process. Inside a F-35 motion simulator at BAE Warton's facility, test pilots can assess the aircraft in the landing pattern, develop CONOPS (CONcepts of OPerationS) and take-off and land on a ‘virtual’ HMS Queen Elizabeth. The simulation is not bound to the F-35B and QEC either — it can also emulate F-35C and CVN characteristics. Additionally, to enhance realism and develop procedures for take-off and recovery, other multiple ‘virtual’ F-35s can be inserted into the simulations — to allow the pilot to assess how a formation of aircraft would recover to the ship. Says Atkinson: “There is a unique capability here in the UK at BAE Systems at Warton, which is to simulate operation of the F-35 with our, or anybody else’s, aircraft carrier who provides their model to us.” He observes: “It is the result of many years of [flight simulation] experience in the facilties at Warton which has resulted in the leading edge that we have and can bring to bear on these two hugely important programmes.”

Though the F-35B’s advanced fly-by-wire flight control system has taken much of the hard work out of vertical landings — the simulation has already proved its worth in helping test the Shipborne Rolling Vertical Landing (SRVL) manoeuvre, which is a UK-specific landing technique that allows higher ‘bring-back’ (several thousand pounds additional weight) of weapons and fuel — especially in hot climates. SRVL sees the pilot land in hover mode but with forward speed — enabling the wings to generate useful lift. Unlike a traditional carrier approach at 130kts, where the pilot is prepared to ram the throttle open in case of a 'bolter' — the SRVL ends with the aircraft automatically moving the propulsion system to idle and the pilot applies the brakes. Input from test pilots in the simulator has also added SRVL-specific symbology — a ship-referenced velocity vector to the pilots HMDS (Helmet Mounted Display System), to better judge the approach path using this recovery technique.

Lights, camera, action

 

Lighting has been optimised for F-35 operations. (Aircraft Carrier Alliance).

Indeed the SRVL concept has also made another change in the F-35/QE integration — that of a new stabilised lighting system or ‘Bedford Array'. Independent of the two glide path indicators (for both helicopters and fixed-wing aircraft) in the port catwalk, this proprietary system, developed by QinetiQ and manufactured by AGI Ltd uses LED lights in the deck tramlines to provide a gyro-stabilised glidepath alignment cue and a forward and aft limit line to F-35B pilots carrying out SRVL approaches. The ‘Bedford Array’ approach lighting was trialed with QinetiQ's VAAC Harrier testbed in 2008. Indeed, work on the QEC visual landing aids goes back even further, to the very start of the CVF programme and these aids have been progressively developed using the Warton flight simulator.

The lighting on the QEC is innovative in other ways. Giant TV-style ‘departure boards' on the side of the islands allow information (and even video) to be viewed by flight deck personnel or aircrew sitting in readiness. It can also, if needed, project white light, acting as floodlights for maintenance or other operations at night.

Not your father's ski-jump

 

The QE-class's ski-jump, too, has been carefully designed and engineered from the beginning — drawing on BAE's Harrier heritage. Says Atkinson: “We had to go back into the archives and talk to people who had actually been involved with trials with the Sea Harrier and Harrier to make sure we understood the history of ski-jump ramp development. The aircraft carrier ski-jump is a UK innovation and something the UK is very proud of”. The QEC's ski-jump is longer (200ft) than the Invincible-class (150ft) and designed so that the aircraft has all three (including the nose) wheels in contact right up until the point where the aircraft leaves the deck — giving positive nosewheel authority throughout. Additionally, the F-35Bs smart flight control system ‘knows’ when it is going up a ramp and will pre-position the control surfaces and effectors to launch at the optimum angle to avoid pitch-up or down.

Thermal challenges

The F-35's aero-thermal environment was the biggest integration challenge for engineers. (Lockheed Martin).

However, the biggest engineering challenge in F-35 integration, says Atkinson, is the aero-thermal environment surrounding the hot-exhaust gas of the F-35B and its 40,000lb thrust F135 engine. This challenge is not novel to the F-35 but has been known about since the 1960s and the Hawker Siddeley P.1154, when it was realised that any supersonic P.1127/Harrier follow-on would need extra effort to tackle this problem. Indeed, a scale F-35 hot-gas test rig has been used at Warton for some years to explore the aircraft's external thermal environment.

For the QE-class this has been dealt with in the development of a thermal metal spray to protect the flight deck against high-exhaust temperatures. This says Atkinson, was a unique challenge — while thermal metal spray existed, for use on an aircraft carrier it had to combine heat-resistant properties with those needed by a flight deck — for example the friction characteristics needed to grip aircraft tyres in wet conditions. Thermal proofing measures such as higher temperature resistant paints and shields also extends to the catwalk and liferafts. Says Atkinson: “The historic STOVL knowledge and experience that was developed throughout the 60s to 80s has allowed UK understanding of ground erosion and hot gas to be brought to bear on this aircraft's ship interface.”
 

Conclusion

Power projection - the largest UK warship ever - HMS Queen Elizabeth will be a valuable piece of floating real estate. (Aircraft  Carrier Alliance).

After the launch, the next milestone will see HMS Queen Elizabeth head for sea trials in 2016. This will most likely see the first aircraft landings on the carrier, albeit with helicopters to support this activity. First rotary-wing ship operating limit tests are planned for 2017. First of class fixed-wing deck trials with F-35Bs from the US are planned to begin by the end of 2018 and to be completed in 2019, leading to an Initial Operating Capability in 2020.

Thus, in 2020, the UK will possess a state-of-the-art warship and valuable floating piece of real estate — able to embark up to 36 stealth F-35s and/or helicopters (including Chinooks) to project power, presence or offer assistance anywhere in the world. This potent carrier strike force represents a massive jump in capability over the Invincible/Harrier era — and perhaps, in one way, sees the UK's CVA-01/P.1154 ambitions of the 1960s come full circle.
 

Tim Robinson
30 June 2014