English Electric Lightning F.7
The early development of the Lightning will be familiar to most, culminating in the capable F.6 model. However the introduction of the radar guided Sparrow missile into RAF service produced the definitive versions of this fine aircraft. Due to the workload involved in operating the early Sparrows and their attendant radar system, a two seat aircraft was deemed necessary to avoid overloading the pilot, hence the F.7 Lightning was based on the T.5 two seat trainer airframe ( many were actually rebuilt F.6 airframes, and retained their original serial number ), with both fuselage and overwing pylons wired and stressed to carry the new missiles. The F.7 was also capable of mounting the underwing pylons previously only seen on export versions, though the planned wingtip rails were not included at this stage due to high drag predicted by wind tunnel testing.
As radar and missile technology improved operation from a single seat aircraft became viable, resulting in the F.8, though in RAF service these were operated in addition to the existing F.7 equipped squadrons.