F3/F6
There are few more facts about the F3/F6 variants that may interest followers of this thread. The 2 F3 variants on the last 2 squadrons to operate the Lightning were important as they were not constrained by airfame fatigue conservation limits. These fatigue constraints were so severe on the F6 that we could do 1 v 1 combat training for only a few days each year. The in-service life of the F6 had to be preserved until the Tornado F3 was ready to enter service. A side benefit of having an F3 available was that we could continue to satisfy the public demand for Lightning aerobatic shows. In war, these F3 would be replaced by F6 from the huge reserve held at Binbrook. That was important because the range limitations of the F3(and T5)made it incompatible with many of the Air Patrol and intercept procedures - even with AAR.
The F6 was the only variant to enter Service with the Over Wing Tank capability. This unusual configuration gave rise to significant problems if jettison was needed. Upward ejection was by cartridge but the tanks had to be empty or the downward reaction in the jettison gun would damage the wing. Rapid emptying was achieved by another explosive device that blew off the back of the tank! With full OWT, the all up weight was close to the maximum and would be exceeded with 2x Red top, full ammo and the refuelling probe. Tyre wear at that weight even at 300+ psi was another concern and x-wind take off and landing limits were severe. Maximum IAS and 'G' were also limited. The odd configuration was dictated by the long undercarriage retracting outwards into the wing thus precluding the usual underwing attachments. The OWT were designed for long range ferry and they did their job allowing safe ferry to Singapore and the USA for example. What a great machine!