What will a sixth-generation fighter jet look like? And what technology will be used on an aircraft not due to begin service for another 15 years?
The Tempest project is working on creating Britain’s next generation of fighter.
Some of the concepts being explored include mind-reading flight systems and highly advanced artificial intelligence.
The F-35B, Britain's most advanced fighter ever, is now in use with the military, but the push to stay ahead of the game never ceases.
Since 2003, the Eurofighter Typhoon has been at the forefront of Royal Air Force operations, but it is to be replaced by Tempest by 2035.
In March, the Defence Command Paper reiterated a £2 billion investment into the project over the next four years.
How could the sixth-generation aircraft look?
That is something that Richard Dewar, head of Next Generation Technologies at BAE Systems, said in 2020 it was "undefined yet".
He said the Tempest is a series of concepts, rather than a specific design or aircraft.
It is understood the pilots may fly a central aircraft, flanked by smaller, less costly, less capable planes known at this stage as Lightweight Affordable Novel Combat Aircraft (LANCA), which could act as decoys.
The LANCA concept could also allow the unmanned aircraft to feed information and tactical options to mission commanders and operational pilots.
"We will always want a pilot in the centre of that, and we will always want to make sure that he's in control," Mr Dewar said - despite the RAF website referencing potential for an "uncrewed combat air 'fleet' in the future".
"However, we're looking at autonomous systems which can switch on and switch off different activities for the pilot," he added, reducing the potential for information or resource overload for those flying the aircraft.
"If you think about this aircraft flying for five, six, seven decades, the pilots that pilot this haven't probably even been born yet," he said.
Project Manager of the Tempest Programme at BAE Systems, Christian Ainsley, said it is crucial to ensure they are fully aware of the pace of change.
"The environment's changing, and the threat's changing, and therefore we are looking at laser-directed energy weapons," he said.
"They're around and about on ships; there are other countries investing in them as well.
"This would be the first fast jet with a laser-directed energy weapon on it," he said.
Mr Ainsley said it would be more accurate than a missile, and it could also act as a highly effective defensive mechanism on a future air platform.
Watch: Inside the fighter jet of the future.
New cockpit, or no cockpit?
The Tempest designs are examining the use of a software reconfigurable wearable cockpit, employing the use of a hi-tech 'Striker II' helmet - without a single physical dial or screen in the cockpit.
The headgear allows the pilot to see the outside world, and displays information in a virtual 3D landscape overlay of the outside seen through the visor, as well as physical objects which appear in reality.
It would operate in a very different fashion to cockpits of the past, which were dependent on physical instruments and windows.
There has been some scepticism over what would happen if it were to fail, and questions over whether there would need to be 'real' buttons.
"What we're trying to do is stop the cockpit getting too cluttered, trying to keep it as clean and as easy to upgrade as possible. As soon as you start to put buttons in, people will start to want to use them," Suzy Broadbent, Human Factors Lead of Research and Technology at BAE Systems told us last year.
"At the moment, we're very much taking the angle of 'prove to me it needs to be in there for a safety reason, or something like that' - otherwise the idea is it would all be virtual," she added.
Watch: How could artificial intelligence influence future cockpit design?
The technology aims to enable pilots to operate controls more efficiently.
With eye tracking software there would be one set of controls, operating multiple displays with it, instead of multiple interfaces per display.
"It's one hundred times more challenging because we've got so many more capabilities we can develop for it," Systems Engineer at BAE Systems Chris Hepburn said.
"But at the same time, so many more opportunities for the pilot to make things so much better for them."
A new definition of 'fighter pilot'?
The Tempest concept designs are closely examining how the aircraft and system can be more responsive to pilots' actions or needs, garnered directly from brain signals.
BAE is learning to see what pilots are thinking when they fly, effectively reading minds.
The pilots of the future would become operators, providing human input into a largely automated system, Ms Broadbent said.
As part of the company's research behind the scenes, electroencephalogram (EEG) caps are being used to track brain wave patterns of test subjects to detect such cerebral signals, fitted under the helmet.
"Live, during the flight [tasks during research] we can start to see when they're getting overloaded, if they're getting stressed," Ms Broadbent said.
"At the moment it's very much subjective opinion - it's up to the pilot what they think is going on and data is captured in a debrief session afterwards," she added.
She said the objective data captured would enable pilots to devote their attention to the most crucial of tasks, but also help in a crisis if, for example, a pilot were to miss an alarm or alert.
"The machine could either take over, or present the information to you in a different way, or hand control back to somebody on the ground."
Critical safety considerations are also involved in BAE's designs and planning, such as the detection of hypoxia (a pilot losing consciousness due to lack of oxygen to the brain), but also "everything has to go through the ethics committee", according to Ms Broadbent.
"Essentially, pilots are quite keen to understand anything they can to get that performance edge," she said.
The technology can also be of benefit in training, where focus can be on more specific and personal elements for each individual pilot.
This story was originally published in 2020.
Watch our documentary looking at what we know about the Tempest project here.