This paper presents the instrument flight certification procedure for, and major flight test results of, a newly developed military helicopter. Instrument flight certification is achieved by combining the evaluation of aircraft system suitability, flight characteristics, and pilot workload assessments during flight tests. The suitability of the aircraft system is determined by whether or not the instruments and equipment required for instrument flight are mounted on the aircraft and if they are installed properly and protected. The performance of the equipment installed is verified through both ground and flight tests. In addition, it should be verified that the aircraft has sufficient static and dynamic stability with respect to longitudinal, lateral, and directional axes. The static stability is determined by the tendency to recover after disturbance. The dynamic stability is also evaluated. As another important study, a series of simulated IMC flight tests were conducted and the pilot workloads assessed using the Bedford rating scale. The pilot workloads are evaluated not only for normal aircraft flight conditions, but also for malfunction of the stability augmentation system or essential flight instruments. After completion of the simulated IMC flight tests, actual instrument flights were performed under real air traffic control.

The Japan Aerospace Exploration Agency (JAXA) and The Korea Aerospace Research Institute (KARI) jointly started activities related to the research and development of “Active Tab,” a helicopter noise reduction technique. KARI constructed the analytical methodology consisting of the aerodynamic, structural dynamic and acoustic codes for defining the requirements to be used in evaluating the performance of Active Tab when installed in a Mach scaled assumed blade. Based on the requirements defined, JAXA carried out a conceptual design study, developed the Active Tab drive mechanism and evaluated its performance. The analytical results show Active Tab satisfying the requirements has sufficient noise reduction capability. Evaluation for the Active Tab drive mechanism demonstrated the dynamic performance and durability required practical use installed in helicopter blades.

This paper describes our work building and testing a concept to share information among operators of manned aircraft and small unmanned aerial systems (sUASs) using the same low-altitude airspace to reduce collision risk, which is an urgent issue due to the rapid growth of sUASs use in many countries. Our concept is to share the positions of manned aircraft and sUASs on a web-based UAS Traffic Management (UTM) platform and provide alerts that give the operators of sUAS sufficient time to land the sUASs before a manned aircraft reaches the designated minimum airspace distance necessary for separation from the sUASs. The purpose of this paper and the flight demonstrations is to investigate the feasibility and problems in building such a platform. This paper also reports on the latest sUAS situations, including regulatory discussions, operations, the experimental environment, and the required regulatory arrangements.

The spectroscopic measurement of low-pressure microwave-discharged nitrogen plasma was conducted in the wavelength region of 550 to 1070 nm. Radiation from the N₂ first positive band of the Δv=0 to Δv=+4 band series and nitrogen atomic lines were observed. The experimental spectrum was compared with the theoretical spectrum, showing the effect of the predissociation of N₂ B ³Π_g state through N₂ A′⁵Σ_g⁺ state and triplet splitting for the transition of ³Π to the ³Σ state. They agreed very well with each other for the Δv=0 to Δv=+2 band series, which consisted of the lower vibrational levels of Δv′=0 to 7, but did not agree well for the higher vibrational levels of Δv′=8 to 12 in the Δv=+3 and +4 band series. By comparing the band head intensity of the experimental and theoretical spectra, the experimental vibrational population on each vibrational level for the B ³Π_g state was estimated to be a non-Boltzmann distribution at the higher vibrational levels. In addition, the theoretical vibrational population distribution in the B ³Π_g state was calculated using a master equation, and then agreement between the experimental spectrum and the theoretical spectrum with the non-Boltzmann distribution obtained from the master equation was improved.

A simple cellwise implicit time integration scheme for high-order discontinuous Galerkin (DG) methods is presented for solving unsteady turbulent flows. One motivation of this study is to utilize the advantages of the cellwise feature of DG methods in implicit time integration to accurately predict the time evolution of unsteady turbulent flows. Our approach is to extend a block Jacobi (BJ) scheme to high-order implicit DG schemes. With the BJ scheme, the cellwise feature is ensured because sweeps referring to up-to-date solutions in nearby cells are not required, and accurate time evolution can be simulated by iteratively solving a linear system formulated in implicit time integration. Although the computational cost required for iterative solutions is of some concern, we found that few sub-iterations are needed to simulate unsteady turbulent flows accurately when the flowfield is well-resolved by high-order DG methods. These advantages are demonstrated through problems such as canonical vortex advection and the inviscid Taylor–Green vortex. The developed BJ-based implicit DG methods were applied to a large eddy simulation of turbulent channel flow, and the results show that, in addition to being a cellwise scheme, the proposed scheme outperforms explicit time integration in terms of the computation time.