Avro 720

The Avro 720 was an in-development British single-seat interceptor of the 1950s, designed by Avro in competition with the Saunders-Roe SR.53. It was a small tailless delta-winged aircraft of metal honeycomb sandwich construction, intended to use mixed propulsion: an 8,000 lbf Armstrong Siddeley Screamer rocket burning kerosene with liquid oxygen for rapid climb and high speed, plus a single 1,750 lbf Armstrong Siddeley Viper turbojet for cruising. A pair of prototypes was ordered, but the Screamer was cancelled in late 1956, partly over the practicality of liquid oxygen in service, and the project ended before any aircraft was completed, leaving one partly finished structural test airframe at a cost of about 1 million pounds.