Supersonic passenger planes could again race through the skies with Airbus having filed a patent for a successor to Concorde. The new jet would fly from London to New York in an hour, opening up the possibility of a transatlantic return journey in a day.Concorde 2 would fly at more than four times the speed of sound, or more than 4000km/h, according to documents filed at the US Patent Office.The filings refer to an "ultra-rapid air vehicle" that would cruise at an altitude of more than 30km and carry up to 20 passengers or two or three tons of cargo. It would have a range of about 8800km.A rocket motor would be used in combination with conventional jets to power a "near vertical" ascent . When the aircraft broke through the sound barrier, the jet and rocket engines would be retracted into the fuselage and ramjets would take over.The aircraft would then cruise at the edge of space, high above conventional aircraft, before entering normal air traffic lanes close to its destination.Airbus suggested that the market for the new aircraft would be "principally that of business travel and VIP passengers, who require transcontinental return journeys within one day".It also imagines the military using the new aircraft for strategic reconnaissance and "ultra-rapid transport of high-value goods or commandos".The height the aircraft would fly at gives it "almost total invulnerability to conventional anti-aircraft systems" the designers say, adding that it could be used for "precision strikes and to take out preferred high-added-value targets".The filing acknowledges the problem of supersonic aircraft making sonic booms as they break the sound barrier.This boom was one of the main reasons for Concorde not being a commercial success. Noise complaints led to it being banned from operating at high speed over land by many countries, negating the main attraction of travelling on the fastest passenger jet in the world.The Airbus patent filing says: "The air vehicle proposed substantially reduces the noise emitted when the sound barrier is broken."But there is little indication as to how this is achieved. ..