Supersonic jets are making a comeback – but despite the hype, don’t expect to book yet

Chris James, The University of QueenslandLate last week, American company Boom Supersonic flew faster than the speed of sound with its XB-1 supersonic demonstrator aircraft. It’s now the first piloted non-military aircraft to break the sound barrier since the Concorde was retired from service in 2003. It’s the first step in Boom’s ambitious goal to have supersonic airliners carry passengers by 2029. But what exactly is supersonic travel? There are good reasons why it’s not more common, despite the hype. What is supersonic flight? The Mach number is defined as a plane’s speed divided by the speed that sound waves move through the air. To “break the sound barrier” means to fly faster than the speed of sound, with Mach numbers greater than 1. The Mach number is an important ratio: as a plane flies, it disturbs the air in front of it. These disturbances move at the speed of sound. In supersonic flight these disturbances combine to form shock waves around the vehicle. When people say you can see a fighter jet before you hear it, they’re referring to supersonic flight: fighter jets can travel at around Mach 2. The sound from the fighter jet is trapped inside its shock wave; until the shock wave moves to your position on the ground, you won’t hear the plane. The allure of supersonic travel For efficiency reasons, most passenger...

Read More........→February 03, 2025

High-Speed Videos May Unlock The Secrets To Bird Flight

Photo: L.A. Cicero Stanford mechanical engineering professor David Lentink and his students capture slow-motion video from the fastest wings in the bird world, with an eye toward building flying robots that take design cues from Mother Nature. BY BJORN CAREY Kurt Hickman Students use a special high-speed camera to discover new, never-before-seen intricacies of flight and slow motion video to analyze flight parameters for future  More related videos applications. "The best way to prevent a small drone from spying on you in your office is to turn on the air-conditioning," said David Lentink, an assistant professor of mechanical engineering at Stanford. That little blast of air, he explained, creates enough turbulence to knock a hand-size UAV off balance, and possibly send it crashing to the floor. A pigeon, on the other hand, can swoop down busy city streets, navigate around pedestrians, sign posts and other birds, keep its path in all sorts of windy conditions, and deftly land on the tiniest of hard-to-reach perches. Graduate student Eirik Ravnan works with a parrotlet that he is training to fly from perch to perch in order to be filmed by a high-speed camera. "Wouldn't it be remarkable if a robot could do that?" Lentink wondered. If robots are to become a bigger presence in urban environments, they will need...

Read More........→July 02, 2013