D-SEND project / Silent supersonic transport technology
Currently, airplanes fly at about Mach 0.8, which is markedly slower than the speed of sound. From Japan, which is distant from Europe and the United States, it takes more than 12 hours to fly the distance. If we were able to fly faster than the speed of sound, for example at twice the speed, then the time for flying would be halved and the flight duration from Japan to Europe or the United States would be about 6 hours. If the travelling time were shortened, then economic activities would be bolstered by increased opportunities for business and tourism. Moreover, measures against natural disasters could be taken quickly, thereby ushering in a safer and more affluent society. If the flight duration were less than 6 hours, then the increasing frequency of hazards, nuisances, and ailments such as economy-class syndrome could be prevented. Perhaps most importantly, everyone would be able to enjoy travel more comfortably than ever. These airplanes that enable high-speed transportation, which fly at a speed faster than the speed of sound, are called supersonic civil transport.
Although the realization of supersonic civil transport is highly anticipated, successors to the Concorde, which was retired in 2003, have not been forthcoming. Shortcomings of the Concorde included poor fuel consumption and extremely high operational costs. In addition, because sonic booms are created, supersonic flight over land was not permitted. Its routes were severely restricted, which is another reason that business success eluded the Concorde. During flight experiments in 2002–2005 using NEXST-1, a small supersonic experimental plane, JAXA demonstrated a technology to reduce air resistance and to improve fuel consumption efficiency. The D-SEND project first phase test was conducted in 2011. The second phase test was conducted in 2013, in an attempt to verify the concept of an airframe design technology for sonic boom abatement. As described, key technologies will be acquired to meet the requirements of supersonic passenger aircraft and to present JAXA's original low sonic boom design concept model, "Quieter supersonic civil transport".
Concept image of small supersonic passenger aircraft
The "Drop test for Simplified Evaluation of Non-symmetrically Distributed sonic boom (D-SEND)" is a project for the demonstration and evaluation of the design concept of airframe configuration for reduction of "sonic booms", which is one critical agenda item for the realization of future supersonic civil transport. We intend to use flight experiments to demonstrate the possibility of a "low-sonic boom design concept", and to acquire measurement methods for aerial sonic booms, which might contribute to the ongoing deliberation of international standards for sonic booms of next-generation supersonic aircraft.
NEXST-1 (small supersonic experimental plane) with a supersonic aircraft airframe configuration to improve fuel consumption efficiency was tested at Woomera experimental yard, Australia, in 2002 and 2005, where reduction of air resistance by as much as about 13% was achieved beyond that of the Concorde.
Airframe concepts of small supersonic civil transport (Mach 1.6, 36–50 passengers, takeoff weight 70 ton class) designed using aircraft design technology demonstrated by NEXST1 and D-SEND project will be presented.