The J75 was an axial-flow, twin-spool, turbojet engine developed by Pratt & Whitney from the J57. The J75 powered the F-105 Thunderchief, Boeing 707, F-106 Delta Dart, and the Lockheed U2. It first ran on an aircraft in 1955. The Pratt & Whitney could produce up to 24,500 lbf thrust. In civilian service, it was known as the JT4A and the GG4, which were used in a variety of stationary power generation applications.
After its relatively short lifetime in the aircraft role, the J75 found more enduring use in the naval role, where it was produced in a variety of models between 18,000 and 22,000 hp. Well-known uses include the first all-turbine warships, the Canadian Iroquois class destroyers, as well as the United States Coast Guard's Hamilton class cutters, and it was considered for the US Navy's Asheville class gunboat.