Speed has never gone out of style, but efforts to prioritize it when it comes to flight sure has. But all that is changing on both commercial and military fronts. Maybe the biggest indication of this aeronautical revolution of sorts is NASA's March 3rd, 2018 announcement that it is diving back into the manned x-plane game in a major way in the form of the Quiet Supersonic Transport, or QueSST, aircraft, which is part of the agency's ambitious low-boom flight demonstration initiative.
This piloted flying spike of an airplane will be built by Lockheed's legendary Skunk Works for a cool $247.5M and is scheduled to be delivered to Armstrong Flight Research Center by the end of 2021.
This announcement is truly a glorious one for aerospace aficionados that have felt disillusioned by a promised supersonic air travel future that never really materialized. The one aircraft that did spend decades ferrying travelers at supersonic speeds, the Concorde, has been out of service for 15 years now, and exist as a page in aerospace history books and as museum pieces scattered around the western world.
NASA's goal with this x-plane is to prove that supersonic flight doesn't have to result in a thunderous booms heard on the ground—a key factor that doomed Concorde's own business case. Currently supersonic flight over land is banned except for the military, and they can only fly supersonically under emergency circumstances or in designated and remote airspace. So any supersonic transport aircraft would have to throttle back to subsonic speeds during transits over the ground, that is unless they integrate new design technologies that the Low-Boom Demonstration is hopefully going to prove.
The jet, which will be powered by a single General Electric F414 turbofan—the same engine used on the Navy's Super Hornet—won't just be used for collecting data over desolate test ranges. Instead NASA wants to fly it over populated areas so that its scientists can gain real-world data that can be used to evaluate the feasibility of constant operational supersonic travel over such locales. People's perceptions of the audible signature of the jet as it flies over will be one data set that NASA is going to build during the QueSST's trials.
The aircraft's shape is supposed to keep shock waves from converging, and thus significantly lowering the audible signature of the aircraft as it travels at supersonic speed. In a press release, NASA stated:
"The answer to how the X-plane's design makes a quiet sonic boom is in the way its uniquely-shaped hull generates supersonic shockwaves. Shockwaves from a conventional aircraft design coalesce as they expand away from the airplane’s nose and tail, resulting in two distinct and thunderous sonic booms.But the design’s shape sends those shockwaves away from the aircraft in a way that prevents them from coming together in two loud booms. Instead, the much weaker shockwaves reach the ground still separated, which will be heard as a quick series of soft thumps – again, if anyone standing outside notices them at all.It’s an idea first theorized during the 1960s and tested by NASA and others during the years since, including flying from 2003-2004 an F-5E Tiger fighter jet modified with a uniquely-shaped nose, which proved the boom-reducing theory was sound.NASA’s confidence in the Low-Boom Flight Demonstration design is buoyed by its more recent research using results from the latest in wind-tunnel testing, and advanced computer simulation tools, and actual flight testing."
As for the aircraft itself, it was largely designed as the result of a contract awarded to Lockheed in 2016 and will be 94 feet long while having a wingspan of just 29.5 feet. Its gross takeoff weight is set at 32,500lbs, which is akin to the unloaded and unfueled weight of an F-15E Strike Eagle.
Once built, the craft is supposed to cruise at 55,000 feet and mach 1.42 or 940mph. This is about the same performance as an F-22 while executing a supercruise dash. It will top out at mach 1.5 and its cockpit configuration will be based on the rear cockpit of a T-38 Talon trainer. As you can see in the concept art, the pilot will have no forward view and will likely have to rely on instruments and a closed circuit video stream or a periscope-like arrangement for navigation.
thedrive