In the South Korean competition, as elsewhere, rivals have offered a range of options for local production, officials say. It is always cheaper to fully import fighters, taking them from factories that are well experienced in building them, but if the customer wants to pay for a lot of local production, it can do so. One question will be how much work there will be in making detailed parts and building assemblies, as distinct from simply mating parts sent from the U.S. or Europe.
The newer F-35 and Typhoon offer higher manufacturing technology than the F-15 can. The F-35, in particular, would bring the technology for building to the tight tolerances required for a stealthy aircraft.
Eurofighter cites its freedom from U.S. regulations as a strength for technology transfer. The Typhoon could serve as the basis for a proposed indigenous fighter, the KF-X, that is sought in the future, or Eurofighter could supply technology for an all-new aircraft. Lockheed Martin and Boeing are also offering to support development of the KF-X. They are handicapped by the U.S. government's restrictions, but Eurofighter's governments will surely not give it a completely free hand.
The Silent Eagle, based on the F-15E, is stealthier, thanks to limited internal weapons carriage and tail fins counted outward by 15 deg. When stealth is unneeded, after enemy air defenses have been suppressed, it can be adapted to carry larger loads. Boeing signed an agreement in late 2010 with KAI to design and build the conformal weapons bays for the aircraft.
An F-35 selection, by contrast, would bring with it the cachet of South Korea's participation in the largest fighter procurement in history. The per-unit price of the F-35 would likely be higher. But, interoperability with allied forces would be simplified by operating identical platforms. Also, the F-35 would offer a higher-end stealth solution for South Korea to complement its purchase of F-15Ks already on order.
The drawbacks for an F-35 sale, however, could include the following: limited payload versus the F-15 Silent Eagle's capacity and the uncertainty associated with maintenance and sustainment cost. Also, the Pentagon is hopeful that development will wrap up by October 2017, but this could be subject to change if a major problem crops up in flight testing. So, there could be risk associated in the delivery.
Risk, however, is not minimal for the Silent Eagle, which has yet to conduct a full suite of testing.