The unique Boeing 757 that will be employed in support of the UK’s Future Combat Air System (FCAS) activity has completed a first series of post-modification sorties, as industry officials also eye a future supporting role during the three-nation Global Combat Air Programme (GCAP).
Named Excalibur, the heavily adapted flight-test aircraft (FTA) now features the first three external “lumps and bumps” that will accommodate a range of in-development sensors required for a “sixth-generation” fighter named Tempest by the UK.
On 6 December, a package of so-called Flight Test 1 Alpha stability proving flights – conducted from the UK Ministry of Defence’s (MoD’s) Qinetiq-operated Boscombe Down site in Wiltshire – was completed, two weeks ahead of schedule.
Registered G-FTAI, the ex-airline 757-200 had performed its first post-modification flight on 4 November, when it was ferried to the test site from 2Excel Aviation’s facility at Lasham airfield in Hampshire. Its external structures were then installed prior to stability testing, which commenced on 26 November.
The assessment activity totalled five flights, including the move from Lasham, with some 14h 45min accumulated.
Described by Leonardo as a “flying laboratory for combat air technology”, the aircraft has so far been fitted with one large fairing to either side of its forward fuselage, plus a belly-mounted pod. Each offers a wide field of regard without obstructions, to support future testing of Leonardo UK-developed Integrated Sensing and Non-Kinetic Effects and Integrated Communications Systems (ISANKE & ICS) equipment.
The aircraft also will be operated with other sensors and effectors, via a series of technology demonstrator programmes for the UK MoD and also involving Leonardo’s Team Tempest partners BAE Systems, MBDA and Rolls-Royce.
Steve Riley, 2Excel’s director of capability development, notes that the current configuration represents the “most unstable” modification for the aircraft. Despite the significant updates, 2Excel director Chris Norton says pilots reported that “It flies like a 757 – you can’t really tell.”
A Beechcraft King Air chase plane accompanied the ex-airliner, to support visual assessment of airflow-indicating strings added to the new airframe features.
Disrupted airflow affecting the 757’s static ports – which are fitted just below the side pods – resulted in an expected discrepancy to their delivery of flight data regarding the aircraft’s altitude and speed.
2Excel had designed and installed an additional sensor probe, mounted atop the aircraft’s tail fin, to ensure the provision of accurate air data post-modification.
By using information collected during the stability tests, Riley notes: “We now have a correction curve that will remove that error.” Similar stability assessment work will be conducted following future airframe additions.
Riley says six of an eventual 11 modification milestones have now been completed on the Excalibur programme.
During the course of 2025, the FTA also will receive a new nose section. Designed to accommodate “advanced radar-based sensor demonstrators”, this will increase the aircraft’s length by around 3m (9ft 8in). A large pod also will be installed beneath its rear fuselage, which will be roughly twice the size of the one currently fitted further forward. And its existing belly pod will undergo modification, to add “fish-eye” sensor apertures, ahead of future payload tests.
Two heat exchangers also will be mounted on the lower-rear fuselage. Riley describes these as “looking like mini jet engines”, of approximately 0.6m (2ft) in length and with a diameter of around 0.45m.
Additional work will include installing a liquid cooling system, to support the use of advanced sensors.
“Next year we will restore that [wider] aerodynamic stability,” Riley says of the future external modifications. “We know we’re only going to get more stable.”
The 757 has already been equipped with five different flight-test instrumentation systems, plus 280 strain gauges and sensors throughout the aircraft. Significant reinforcement work also was required before the current sensor pods could be mounted.
As an example, Norton notes that the large side-fuselage structures alone “generate 10t of ‘suck’ on each the side of the aeroplane”.
Inside the aircraft, the forward cabin will accommodate 10 ‘task operator stations’ with individual work consoles. Its mid-section will house 16 mission equipment racks, and the rear area will have seating for 16 people, to enable demonstration viewing.
“Excalibur is expected to fly with ISANKE & ICS technology on-board within the next years, when on-board scientists and engineers will be able to test and refine the systems whilst in flight,” Leonardo says.
Speaking at the Farnborough air show in July, programme officials indicated that flight-test activities to be conducted in support of the FCAS effort would begin “in the next couple of years”.
“Excalibur will allow us to test the technologies and systems which we plan to put into the GCAP aircraft, set to take to the skies from 2035,” says Air Commodore Martin Lowe, the MoD’s FCAS programme director. The GCAP effort is being advanced by the UK along with joint partners Italy and Japan.
“We are de-risking what we’re going to do in GCAP… and demonstrating this [development and test] cycle that we will use to left-shift delivering capability to the warfighter much quicker,” says Leonardo vice-president, capability, Jonathan Smith. He notes that the platform also could be used beyond the in-service date of a new fighter, to support spiral upgrades.
“This approach is fully bought into by our GCAP partners, so we believe this will become a valuable GCAP test asset… working alongside other national assets,” Smith says.
“We have been briefing our partners about this for probably the last 18 months, to a varying degree of detail,” says Andrew Howard, Leonardo UK’s senior responsible owner, Tempest and GCAP. “If they choose to work with us in the next phase, after the Team Tempest activity concludes, it would logically transition to GCAP. We are progressively looking at international partnerships from 2027 or 2028.”
HOW SENSOR INTEGRATION WILL TRANSFORM FUTURE FIGHTER
The Excalibur platform’s new airframe additions will be used to support testing of Leonardo’s ISANKE & ICS equipment.
“Up to now they have been federated, standalone systems, with a radar, communications, and electronic warfare [EW] and self-defence systems,” Dave Morris, Leonardo UK’s head of campaigns, future combat air, says of equipment aboard current-generation fighters. “Everything now is working in a completely integrated fashion – all of the sensors work together to deliver a solution to the operator,” he explains.
Technology to be employed within the ISANKE & ICS framework will include a multifunction RF (radio frequency) system – “We are no longer talking about just a radar; this system exploits all of that RF capability, doing a number of different roles,” Morris says.
Once combined with electro-optical/infrared sensors, communications and EW systems, the capability will “exploit the entirety of the EM [electromagnetic] spectrum to our advantage”, he says.
Some technology has already been flown aboard Excalibur, 2Excel’s Riley reveals. “We managed to fly some kit last year,” he says, without providing further details. “The aircraft is ready to accept it, and we have some flexibility to go [flying] earlier.”
