<p>Airbus designed a hypothetical supersonic plane that some are calling the Concorde 2. The aircraft would be a long-haul commercial transport flying at altitudes of 100,000 feet. The study calls for advanced smart materials able to withstand the extreme temperature changes associated with such high altitudes and a planned maximum speed of Mach 4.</p><p>The concept is anything but simple, with a radical three-tier propulsion system. The power required for takeoff would be created by a typical turbo jet engine that would accelerate the craft near the speed of sound. Rocket boosters would then take over, propelling the aircraft in excess of Mach 2, after which supersonic ramjets would continue the acceleration to Mach 4.</p><p>If that sounds crazy, just imagine a proposed fuel source made from a combination of seaweed and hydrogen/oxygen resulting in the emission of zero pollutants. Airbus recently filed patents confirming plans to develop such an aircraft, but don't expect to see anything like this rolling up to your gate at the airport anytime soon. The first takeoff isn't scheduled until something like 2050.</p>
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