Supersonic silent biplane COMING SOON ...ish
Researchers from MIT and Stanford have shown via computer modelling that a modified biplane can produce significantly less drag than a single-wing craft, improving the fuel efficiency and quietening that sonic boom. However Qiqi Wang, his MIT colleague Rui Hu and Antony Jameson of Stanford University admit that it's not the first time someone has suggested biplanes could sort out the sonic problems.
Back in the 1950s, German engineer Adolf Busemann was the first to come up with a biplane design that thwarts shockwaves at supersonic speeds. The problem with a regular single-wing aeroplane is that as the jet nears the speed of sound, air compresses in front of and behind it, and when the plane goes past Mach 1, the sudden increase in air pressure sends two shockwaves radiating out.
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Busemann showed that with a biplane, the configuration of the top and bottom wings would cancel out the shockwaves of each other. But because the wings create a small space for air to go through, when the biplane is still going below the speed of sound but getting faster, the wings could "choke", creating huge drag.
Wang, Hu and Jameson came up with a computer model to simulate the biplane's performance at every speed along the way, so that they could compile the results into a shape for each wing that would allow the supersonic biplane to fly at all speeds.
http://www.theregister.co.uk/2012/03/16/supersonic_biplane/
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