Previous Flight Test Research Articles

Magnetic Navigation on an F-16 Aircraft Using Online Calibration

Magnetic anomaly navigation is gaining popularity as an alternative-navigation system that addresses the challenges of GPS denial. Magnetic anomaly navigation has recently been flight test proven on an F-16 aircraft. The corrupting magnetic environment on this operational platform is 2–3 orders of magnitude larger than previous flight-tests on geo-survey aircraft, while also displaying stochastic drift. The difficult magnetic environment of the platform necessitated a combination of batch and online calibration to obtain accurate navigation solutions. Superiority of the new method is shown in comparison to prior published methods. Real navigation results on the F-16 are shown to obtain accuracies 50% better than these competing methods, with low-altitude results obtaining 59-m distance root-mean-squared errors on 1.5 h flights versus 111 m using batch-only calibrations.

Development of Mobile Ground Control System and GPS Base Auto Tracking Antenna

Flight test of both rocket and high speed Unmanned Aerial Vehicle (UAV), which is currently developed by LAPAN, can not be separated from the need for a monitoring system of all the attitude of the vehicles. Utilizing and combining some of the available equipment components into a ground control system (GCS) equipped with GPS based auto tracking antenna, makes it easy in previous flight test activities that only do tracking antenna manually. This ground control system is equipped with automatic tracking antenna that always leads to the vehicle, so that the data attitude of flying the vehicle will be maximally monitored and analyzed directly with ease. This system has been tested on a laboratory scale related to testing using hardware in the loop simulation system

航空機にリブレットを適用した際の簡便な抵抗低減率推算手法

This paper proposes a simple estimation technique for drag-reducing performance of riblet applied to the whole body of an aircraft. The point of this technique is how to estimate the wall shear stress on the aircraft body covered with riblets. First, RANS analysis of flow around an aircraft which is not covered with riblets is conducted to obtain the whole-body distributions of wall shear stress. The distributions of wall shear stress of an aircraft covered with riblet are obtained from the combination of the RANS results and drag reduction rate graphs obtained from wind-tunnel test. Finally, drag reduction rates are estimated from surface integration of the wall shear stress on both the riblet surface and smooth surface. As a result, the estimated drag reduction rates are close to that obtained by the previous flight tests, which indicates that this technique is reasonable. As a future plan, the effects of pressure gradient, angle between riblet and local flow will be considered.

Water Tank Study of the Decay of Trailing Vortices

Underwater towing experiments were carried out with a rectangular airfoil of aspect ratio 5.3 at 4° and 8° angles of attack and at chord-based Reynolds numbers between 2.2 x 10 5 and 7.5 x 10 5. Tangential velocity measurements in the downstream region between 100 and 1000 chord lengths indicate rates of vortex decay proportional to r 7/8 at 8°, whereas previous flight tests show that the decay rate approaches £~ 1/2 far downstream. The observed behavior is explained in terms of an analytical solution that includes time dependence of the turbulent eddy viscosity, VT ~ tm. It shows that, for m > 0, an isolated turbulent vortex decays faster than t~1/2. In this case, the decay is accompanied by increasing vr, or levels of turbulence, which corresponds to turbulent nonequilibrium flow. The special case of vortex decay with equilibrium flow (m = 0) leads to the well-known decay rate 2. Since, in towing tank experiments at low Reynolds number, turbulent vortex decay may occur predominantly in nonequilibrium, it is doubtful that such tests correctly predict the late stage of decay of aircraft trailing vortices, when turbulence is the only dissipating mechanism.