The J85 engine is a small turbojet engine developed by General Electric in the 1950s. It is known for its compact size and high thrust-to-weight ratio, making it suitable for various military aircraft, including the Northrop F-5 and the McDonnell Douglas A-4 Skyhawk. With a thrust output of approximately 3,000 to 4,000 pounds, the J85 engine has been widely used in both training and combat aircraft. Its reliability and performance have made it a popular choice for military applications, and it has been produced in various configurations to meet different operational needs.