Eurofighter Typhoon ISPA5

ISPA5 is the fifth of the Eurofighter Typhoon programme's Instrumented Series Production Aircraft (ISPA), the class of production airframes that industry borrows from the customer air forces to evaluate avionics modifications without tying up the dedicated test aircraft. It is the British member of the group and, unlike the first three ISPAs, which were Tranche 1 airframes, it belongs to the programme's second production batch: it was built in March 2011 as a Tranche 2 aircraft and was earmarked to take over from ISPA1, the British two-seater that had opened the category in 2004.

The ISPAs differ from the Instrumented Production Aircraft (IPA) in both origin and level of instrumentation. Both are diverted from the assembly line, but the ISPAs carry less telemetry than the IPAs and are designed to be returned to production standard once their task is over. In these airframes the space occupied by the internal cannon is used to house the test avionics, which are connected to the aircraft's fibre-optic bus. Legally the ISPAs remain the property of the user nations and are only lent to industry, which is why their life cycle always ends with a handover, or rather a return, to the relevant air force. Whereas the IPAs were used to develop the aircraft from one tranche to the next, the ISPA fleet, five aircraft in its original form, was devoted to evaluating avionics changes on aircraft representative of the production line.

ISPA5's direct predecessor was ISPA1, a Tranche 1 two-seater built by BAE Systems at Warton that first flew on 11 May 2004. In February 2005 it crossed the Atlantic, staging through Lajes, Bangor, Little Rock and Cannon, to the Naval Air Weapons Station at China Lake, accompanied by Harrier GR7s and Tornado GR4s from RAF Coningsby, to take part in exercise High Rider 10. On its return it continued as a testbed for the DASS defensive aids system, the Striker helmet and the integration of laser designator pods, until in June 2009 it was restored to production standard and delivered to the Royal Air Force. That return left the United Kingdom without an instrumented series aircraft, and ISPA5 was brought in to fill the gap on an airframe from the following tranche.

Its arrival was part of a joint renewal of the ISPA fleet on Tranche 2 airframes, carried out almost simultaneously in the three countries that had contributed aircraft of this kind. In May 2011 Italy fielded ISPA4, used to test the PIRATE infrared sensor and the inertial navigation system; in June 2011 Spain received ISPA3, on which the Litening designator pod was trialled among other equipment; and in March 2011 the British ISPA5 was built. All three airframes went back to their air forces within a few weeks of one another: ISPA4 in January 2014, ISPA3 in February 2014 and ISPA5, after its test flights, in January 2014, when it passed to the Royal Air Force.

The fact that ISPA5 was a Tranche 2 aircraft matters because of what that batch meant for the programme. Tranche 2 Typhoons began to be delivered in October 2008 and cleared the obsolescence issues of the first batch while extending the basic air-to-air and air-to-surface capabilities: Block 8 introduced a new STANAG 4626-compliant hardware standard for all the computers, and the later blocks brought IFF Mode 5, the MIDS/Link 16 data link, new weapons such as the digital IRIS-T and Paveway IV, the display of ground targets in the HMSS helmet and the ability to cue the laser pod through the helmet visor. Having an instrumented series aircraft with that architecture allowed avionics modifications to be tested on the same standard that was reaching the squadrons, rather than on Tranche 1 airframes such as ISPA1.

The sources consulted do not give ISPA5's serial number, whether the airframe was a single- or two-seater, or the detail of the test programmes assigned to it during its almost three years in industry hands, beyond its role as ISPA1's successor in evaluating avionics modifications. Its known history therefore comes down to three milestones: manufacture as a Tranche 2 aircraft in March 2011, a period of test flying, and handover to the Royal Air Force in January 2014.