In the 1950s, the British developed mixed-power jet designs employing both rocket and jet engines to cover the performance gap that existed in turbojet designs. The rocket was the main engine for delivering the speed and height required for high-speed interception of high-level bombers and the turbojet gave increased fuel economy in other parts of flight, most notably to ensure the aircraft was able to make a powered landing rather than risking an unpredictable gliding return.
in the 1950s the british developed mixed-power jet designs employing both rocket and jet engines to cover the performance gap that existed in turbojet designs the rocket was the main engine for delivering the speed and height required for high-speed interception of high-level bombers and the turbojet gave increased fuel economy in other parts of flight most notably to ensure the aircraft was able to make a powered landing rather than risking an unpredictable gliding return