In the 1930s engineer Adolf Busemann conceived of a supersonic biplane that produced no sonic boom—the shock waves would bounce off the plane's two wings at opposing angles, nullifying each other. But the design created so much drag that the plane wouldn't have been able to fly. Now two groups are trying to improve the concept with computer simulations. Engineers at Japan's Tohoku University devised wings with shifting flaps that adjust for drag at different speeds.
When supersonic travel inevitably returns to the skies, the airplanes are going to look a lot different. At least one design harks back to the early days of aviation with a biplane design, rather than a sleek delta-winged jet like the Concorde. This shape can apparently produce much less drag and therefore much less noise at supersonic speeds, MIT engineers say.