Biplanes Could Get Supersonic Jets Back In Action; Double Wings Mean Double Fun!

The life of supersonic jets came to an end after Concorde. Even though passengers could get from one point to another in minimum time, with very highly priced tickets owing to the high fuel consumption, limited seating and disruption from the jet’s supersonic boom, ticket sales got down. Ever since, the researchers are working on a cheaper, quieter and fuel-efficient alternative to the supersonic jets. And we might have found some really good solution.

Qiqi Wang, an assistant professor of aeronautics and astronautics, MIT has worked out an idea. The concept is really simple - Why use one wing to a side, when you can use two? Wang and his colleagues Rui Hu, a postdoc in the Department of Aeronautics and Astronautics, and Antony Jameson, a professor of engineering at Stanford University, represented their idea with a computer model of a modified biplane. They figured it out that such a model at a supersonic speed will produce significantly less drag than a conventional single-wing aircraft. And in turn, less drag equals less noise and less fuel consumption


Conceptual drawing of a supersonic biplane. Image: Christine Daniloff/MIT News based on original drawing courtesy of Tohoku University

Well, Wang is not the first one to come up with the concept of biplanes for supersonic flight. Way back in the 1950s, this idea was proposed by Adolf Busemann, a German engineer. He saw that when a conventional aircraft approaches the speed of sound, air  gets compressed at the front and back of the jet. And when it surpasses that speed, there is a sudden increase in air pressure to produce a sonic boom. So, he calculated that use of biplanes configuration could remove these shock waves completely.

As you can see from the image above, each wing of the design is shaped like a flattened triangle, with the top and bottom wings pointing toward each other. But, there was a flaw. Due to these two wings, a very narrow channel gets created limiting the amount of air through. So, the Busemann's design would work fine at supersonic speeds, but could not overcome the drag to reach those speeds.

Now, when the computer model designed by Wang, Hu and Jameson simulated the performance of Busemann’s biplane at various speeds, such that at a given speed, an optimal wing shape was determined to minimize drag, they finally came up with a useful solution. If the inner surface of each wing was smoothened, more air could pass through the channel in between the wings. Moreover, if the the top edge of the higher wing, and the bottom edge of the lower wing was bumped out the drag is reduced by one half.

Moving forward with the implementation, the team plans to design a 3D model to solve other problems. Something on the lines of wings changing the shape in mid-flight to attain supersonic speeds is possible. So, stay tuned!

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