The McDonnell Douglas (now Boeing) F-15 Eagle is one of the world's most outstanding combat aircraft. Conceived in the 1960s, taking into account lessons learned during the Vietnam War, the Eagle was procured by the US Air Force as its new air superiority fighter, and first flew in prototype form in July 1972. Service entry of the F-15A model occurred in early 1976. Soon it and the two-seat F-15B conversion trainer were superseded in production by the corresponding F-15C and F-15D models, with an upgraded radar and greater fuel capacity for improved range. The Eagle has many times proved its worth in combat, notching up more than 100 reported air-to-air kills in use with the USAF, Israel and Saudi Arabia. The basic fighter design also spawned the multi-role F-15E Strike Eagle and derivatives. Today the F-15C, much updated, remains very much at the tip of the USAF's air combat spear. The sole examples stationed in Europe are on the strength of the 493rd Fighter Squadron 'Grim Reapers', part of the RAF Lakenheath-based 48th Fighter Wing.