The Canberra has broad wings, with a Rolls-Royce Avon turbojet engine halfway along each.

BBC: NEWS | UK | Fact file: Canberra PR9

But once there, a scramjet-powered aircraft should be able to zoom away to speeds unattainable by a turbojet.

ECONOMIST: Jet propulsion

Unlike the more familiar turbojet, which uses a turbine-powered fan to compress the incoming air before it is mixed with fuel, a ramjet compresses air by forcing it down an ever-narrowing funnel.

ECONOMIST: Jet propulsion