sentences:  These were for the two Canadair CL-41 prototype trainers with a rating of 12.9 kN (2,900 lb st).The modified JT12A-3 turbojets with a basic rating of 14.69 kN (3,300 lb st) were tested in the two Lockheed XV-4A Hummingbird VTOL research aircraft.The next version, JT12A-21, had an afterburner which delivered a maximum thrust of 17.91 kN (4,025 lb st).