It is behind a paywall, so many thanks for posting.Ron5 wrote:The Japanese defense ministry’s studies point to a need for a very big fighter with an empty weight well above 20 metric tons (40,000 lb.), larger than the Lockheed Martin F-22 Raptor. Superior endurance and internal weapon capacity are the key factors behind this choice.
No western European country has operated a fighter more than about two-thirds as big, but Storr said a large configuration for the Tempest cannot be ruled out. The mockup exhibited at the 2018 Farnborough International Airshow was bigger than the F-22.
Still, the UK and other European partners might want a much smaller fighter; concept designs that have not been shown are not as big as the mockup. But the concept for cooperation would allow for Japan to devise its own airframe while, for example, using the same engine and some weapons, software and avionics as other partners. The architecture of the software is intended to be open, accepting different programs easily.
I actually hope we go with a larger aircraft. I know the 'steel is cheap and air is free' mantra from shipbuilding doesn't apply to aircraft. But there is a lot to be said for space, particularly in regard to payload bays, range and the inevitable additional systems that are added in an aircrafts lifetime. With an LO design there just isn't the option of sticking some new protuberances on the outside like we've done for time immemorial, there needs to be some spare space left for upgrades. It might be there is a slight fuel penalty to be paid (same as with the ships) but the cost of upgrading pays for itself in the end. Pretty sure the F-22 and F-35 designers would go back and design in bigger bays if they could as well.
Also the Japanese as an island nation have a huge area to patrol and protect. Their strategic position is obviously different with the proximity of both Russia, China and North Korea (let alone their differences with South Korea) but we both have large ADIZ's to patrol and protect with enemies who have long range bombers and missiles.