The J35 engine is a family of turbojet engines developed by Pratt & Whitney in the 1950s. It was primarily used in military aircraft, including the McDonnell Douglas F-4 Phantom II and the Lockheed A-12. The engine is known for its reliability and performance, making it a popular choice for various applications. The J35 features a single-spool design and is capable of producing significant thrust, which enhances the speed and maneuverability of the aircraft it powers. Its design has influenced subsequent engine developments, contributing to advancements in jet propulsion technology.