The Japan Aerospace Exploration Agency (JAXA) today announced that the first drop test conducted as part of its second phase of the "Drop test for Simplified Evaluation of Non-symmetrically Distributed sonic boom" (D-SEND#2) at the Esrange Space Center, Sweden, on August 16th, 2013 (Sweden Standard Time), was unsuccessful.
After its separation from a balloon, the supersonic airplane model deviated from the expected flight path about 12 kilometers short of the targeted boom measurement area, and reached the ground about 8 kilometers short of the target area. Although JAXA's sonic boom measurement system worked properly and captured the sonic boom, it was confirmed that the pressure waveform measured was not from the expected nominal flight.
As of today, the cause of the flight deviation remains under investigation by a team led by the director of the Program Management and Integration Department of the Institute of Aeronautical Technology. Therefore, JAXA decided to postpone its second drop test of D-SEND#2 by taking the remaining test window until August 24 into account.
JAXA will make a further decision as to whether to continue carrying out the second test of the D-SEND#2 or not upon completion of a full analysis and investigation into the cause.
Because of its high speed and high mobility, air transportation has become an indispensable means for long-range transport as well as search and rescue. However, the air transportation system in the future is expected to meet the requirements of being not only "more environmentally friendly" and "safer", but also "faster" and "usable by anyone at anytime and anywhere", like a car.
With its Sky Frontier program, JAXA aims to meet these various requirements with technical innovation by challenging new frontiers of air transportation based on long-term vision. Specifically, in the areas of quest for higher speeds (supersonic/hypersonic aircraft), the expanded use of airspace (short/vertical takeoff and landing), and new energies (shift from fossil fuel/electric propulsion), JAXA creates innovative aircraft concepts and key technologies through research and development that focuses on system design, and contribute to the advancement of our society.
The Drop test for Simplified Evaluation of Non-symmetrically Distributed sonic boom (D-SEND) project aims at verifying and evaluating the design concept and method of an aircraft configuration to reduce "sonic boom", one of the most important challenges for realizing future supersonic passenger aircraft. The goal is to demonstrate, through flight tests, the feasibility of the "low sonic boom design concept", where JAXA has the technical advantage in environmentally compatible technology over the rest of the world, and to obtain an aerial boom measurement method that would be able to contribute to an international standard assessment of sonic booms for the next-generation supersonic transport that is currently being examined.
JAXA performed the first phase D-SEND project (D-SEND#1) at Esrange test range in Sweden in May 2011 (Press release dated May 19, 2011.) At the D-SEND#1, two kinds of axisymmetric bodies (the "LBM" (low-boom model), which generates normal sonic boom waves, and the "NWM" (N-wave model), whose shape is designed to reduce sonic boom) were ascended by a balloon and dropped in turn from 20 to 30 km above the ground. Then sonic booms generated in the course of acceleration to supersonic speed by free fall were measured by the Airborne Blimp Boom Acquisition (ABBA) system developed by JAXA and also by a ground measurement system. As a result of the two drop tests, we have established the measuring method of sonic booms at a drop test using a balloon, which will be also used for D-SEND#2. Also, data of sonic booms generated by the simple axisymmetric configuration is quite rare and valuable as verification data for sonic boom estimation methods, thus they are expected to contribute to future sonic boom studies.
For the D-SEND#2 scheduled in the summer of 2013, an innovative experimental supersonic airplane (S3CM: S-cube Concept Model) will be used. The S3CM is designed using JAXA's original low-boom design technology with sonic boom abatement at the fore and aft of the airplane. We plan to conduct the test at Esrange test range in Sweden to ascend the airplane by a balloon and drop it from an altitude of 30km. The airplane will reach supersonic speed by the falling speed, then will glide at Mach 1.3 and at a flight-path angle of 50 degrees so that we will measure generated sonic boom shape directly underneath the airplane.
Electric aviation technology
An electric airplane is an innovative technological breakthrough that can drastically reduce fuel consumption and maintenance costs. It is one of the most important technologies that will significantly influence upon future aviation technology competitiveness. In order for Japan to be internationally advantageous in this field in the future, JAXA will begin the "Flight demonstration of Aircraft Technology for Harmonized Ecological Revolution (FEATHER)" project aiming at promoting the development of electric aviation technology by making a precedent of a manned flight of an electric aircraft in Japan.
