For 27 years, the Concorde provided its passengers with a rare luxury: time saved. For a pricey fare, the sleek supersonic jet ferried its ticketholders from New York to Paris in a mere three-and-a-half hours — just enough time for a nap and an aperitif. Over the years, expensive tickets, high fuel costs, limited seating and noise disruption from the jet’s sonic boom slowed interest and ticket sales. On Nov. 26, 2003, the Concorde — and commercial supersonic travel — retired from service.
Since then, a number of groups have been working on designs for the next generation of supersonic jets. Now an MIT researcher has come up with a concept that may solve many of the problems that grounded the Concorde. Qiqi Wang, an assistant professor of aeronautics and astronautics, says the solution, in principle, is simple: Instead of flying with one wing to a side, why not 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, have shown through a computer model that a modified biplane can, in fact, produce significantly less drag than a conventional single-wing aircraft at supersonic cruise speeds. The group will publish their results in the Journal of Aircraft.
This decreased drag, according to Wang, means the plane would require 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,” Wang says. “It’s like hearing gunfire. It’s so annoying that supersonic jets were not allowed to fly over land.”
Double the wings, double the fun
With Wang’s design, a jet with two wings — one positioned above the other — would cancel out the shock waves produced from either wing alone. Wang credits German engineer Adolf Busemann for the original concept. In the 1950s, Busemann came up with a biplane design that essentially eliminates shock waves at supersonic speeds.
Normally, as a conventional jet nears the speed of sound, air starts to compress at the front and back of the jet. As the plane reaches and surpasses the speed of sound, or Mach 1, the sudden increase in air pressure creates two huge shock waves that radiate out at both ends of the plane, producing a sonic boom.
Through calculations, Busemann found that a biplane design could essentially do away with shock waves. Each wing of the design, when seen from the side, is shaped like a flattened triangle, with the top and bottom wings pointing toward each other. The configuration, according to his calculations, cancels out shock waves produced by each wing alone.
However, the design lacks lift: The two wings create a very narrow channel through which only a limited amount of air can flow. When transitioning to supersonic speeds, the channel, Wang says, could essentially “choke,” creating incredible drag. While the design could work beautifully at supersonic speeds, it can’t overcome the drag to reach those speeds.
Giving lift to a grounded theory
To address the drag issue, Wang, Hu and Jameson designed a computer model to simulate the performance of Busemann’s biplane at various speeds. At a given speed, the model determined the optimal wing shape to minimize 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 three-dimensional model to account for other factors affecting flight. While the MIT researchers are looking for a single optimal design for supersonic flight, Wang points out that a group in Japan has made progress in designing a Busemann-like biplane with moving parts: The wings would essentially change shape in mid-flight to attain supersonic speeds.
“Now people are having more ideas on how to improve [Busemann’s] design,” Wang says. “This may lead to a dramatic improvement, and there may be a boom in the field in the coming years.”
Written by: Jennifer Chu, MIT News Office
Kimberly Allen | EurekAlert!
Study sets new distance record for medical drone transport
13.09.2017 | Johns Hopkins Medicine
Researchers 'count cars' -- literally -- to find a better way to control heavy traffic
10.08.2017 | Florida Atlantic University
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
25.09.2017 | Power and Electrical Engineering
25.09.2017 | Health and Medicine
25.09.2017 | Physics and Astronomy