Cheaper, more fuel efficient biplane could be key to supersonic travel

The novel design is a jet with two wings - one positioned above the other - which in simulation tests produced significantly less drag than conventional single wing aircrafts. According to its developer Qiqi Wang, an assistant professor of aeronautics and astronautics, the decreased drag means the plane would require significantly less fuel to fly. It also means the plane would produce less of a sonic boom. "The sonic boom is really the shock waves created by the supersonic airplanes, propagated to the ground," explained Wang. "It's like hearing gunfire. It's so annoying that supersonic jets were not allowed to fly over land." By positioning the jet's wings on top of each other, Wang found that the design cancelled out the shock waves produced from either wing alone. To address the issue of drag, he and his team designed a computer model to simulate the performance of a biplane at various speeds. To do this he used a concept from the 1950's created by German engineer Adolf Busemann. At a given speed, the model determined the optimal wing shape to minimise drag. The researchers then aggregated the results from a dozen different speeds and 700 wing configurations to come up with an optimal shape for each wing. They found that smoothing out the inner surface of each wing slightly created a wider channel through which air could flow. The researchers also found that by bumping out the top edge of the higher wing, and the bottom edge of the lower wing, the conceptual plane was able to fly at supersonic speeds, with half the drag of conventional supersonic jets such as the Concorde. Wang says this kind of performance could potentially cut the amount of fuel required to fly the plane by more than half. "If you think about it, when you take off, not only do you have to carry the passengers, but also the fuel, and if you can reduce the fuel burn, you can reduce how much fuel you need to carry, which in turn reduces the size of the structure you need to carry the fuel," Wang says. "It's kind of a chain reaction." The team's next step is to design a 3D model to account for other factors affecting flight. Wang believes supersonic travel could be on the horizon in the next few years.