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Abstract Attention has been devoted to distributed position and orientation system (DPOS) which can provide high precision spatial and temporal information for all remote sensing loads for airborne multi-task synthetical earth observation system in recent years. Since there are restrictions of space, weight and cost of the DPOS, it is unrealistic to install an IMU of DPOS at the location of each load, and the optimized layout of DPOS has become an urgent problem should be solved. However, there is no report on the optimized layout method for airborne DPOS yet. In this paper, the optimized layout of DPOS is classified as the optimization problem, and two classical optimization algorithms, the genetic algorithm (GA) and particle swarm optimization (PSO), and two novel optimization algorithms, the particle swarm optimization with mutation (PSOM) and hybrid of PSO and GA (HPSOGA), are used and compared for the first time to determine the optimal layout of DPOS. The mathematical simulation shows that the novel method named HPSOGA is superior to the other three methods. In order to accelerate the convergence rate of this layout method, further mathematical simulation and semi-physical simulation based on flight experiment is carried out and the results show that the calculation amount of this method can be reduced by adjusting the individual number calculated by PSO. The work of this paper can provide new ideas and make a good start for the optimized layout study of DPOS. [ABSTRACT FROM AUTHOR]

Abstract: The handling qualities of an aircraft will be improved if the Direct Lift Control (DLC) system is applied. In this paper, an attempt has been made to evaluate the influence of DLC-type system parameters on the aircraft''s maneuverability and to determine the desired values of these parameters for the purpose of obtaining required values of the handling maneuverability criteria. Published papers which deal with direct lift control do not list requirements for evaluating handling qualities and maneuverability of aircraft equipped with DLC system. In this paper, three new criteria permitting the evaluation of results of employing DLC have been defined. Analysis of influence of DLC system parameters on selected known handling qualities criteria (for example CAP, ), as well as new DLC efficiency coefficients, have been illustrated with a numeric example of A4D “Skyhawk” fighter aircraft and PZL M-18 “Dromader” agricultural airplane control system modification. [Copyright &y& Elsevier]

Abstract: In this paper, a novel strapdown stellar-inertial guidance scheme is developed to correct the velocity and position navigation errors for responsive launch vehicle. Three types of error sources consisting of initial localization and misorientation errors, inertial sensor errors and gravity computation errors due to position navigation errors are discussed. The digital platform error model arising from initial localization and misorientation errors and gyro measurement error is derived. The detailed analysis for the velocity and position navigation errors caused by initial position errors, digital platform errors, accelerometer measurement error and gravity computation errors is performed. For the gravity computation errors due to the position navigation errors, an effective first-order approximation compensation scheme is addressed. A dual star correction strategy scheme is presented to estimate the error parameters and correct the cumulative velocity and position navigation errors. Compared with traditional stellar-inertial guidance algorithm based on nominal trajectory data and priori subsystem error statistics, the proposed algorithm uses the real-time trajectory data to calculate the function matrices used in the navigation error propagation equations. Thus, the corrections for velocity and position navigation errors are provided by the stringent navigation error model rather than the statistics of the subsystem errors caused by individual error source. Numerical examples are given to analyze the effects of the individual error factor with respect to the accuracy of strapdown INS and compare the navigation performances for all-inertial, stellar-inertial, and stellar-inertial plus gravity compensation guidance schemes. [Copyright &y& Elsevier]

Abstract: LISA (Laser Interferometer Space Antenna) is a joint mission of ESA and NASA which aims to be the first space-borne gravitational wave observatory. Due to the high complexity and technological challenges that LISA will face, ESA decided to launch a technological demonstrator, LISA Pathfinder. The payload of LISA Pathfinder is the so-called LISA Technology Package, and will be the highest sensitivity geodesic explorer flown to date. The LISA Technology Package is designed to measure relative accelerations between two test masses in nominal free fall (geodesic motion). The magnetic, thermal and radiation disturbances affecting the payload are monitored and dealt by the diagnostics subsystem. The diagnostics subsystem consists of several modules, and one of these is the magnetic diagnostics unit. Its main function is the assessment of differential acceleration noise between test masses due to the magnetic effects. To do so, it has to determine the magnetic characteristics of the test masses, namely their magnetic remanences and susceptibilities. In this paper we show how this can be achieved to the desired accuracy. [Copyright &y& Elsevier]

Abstract: This paper presents the development of solar arrays for Argentine satellite missions performed within the frame of cooperation agreements between the Argentine National Atomic Energy Commission (CNEA) and the Argentine National Commission for Space Activities (CONAE). Relevant issues such as simulation and design, solar cells characterisation, set up of soldering and bonding processes, radiation damage and development of testing techniques, are reviewed. A chamber for testing solar cells and other devices in a simulated space environment, and the integration and tests of two engineering models for qualification of space technology processes are described. The requirements and solar array design for 3 missions, Aquarius/SAC-D and SAOCOM 1A and 1B, are presented. Finally, the flight model for the SAC-D mission, which was launched on 10 June 2011, is outlined, and telemetry data analysis from the first stages of the mission is presented. [Copyright &y& Elsevier]

Abstract: In this paper, we consider the attitude stabilization problem for a rigid spacecraft with external disturbances. To obtain a better disturbance rejection property, we employ finite-time control techniques. In the absence of disturbances, by employing continuous finite-time control method, a continuous finite-time controller is designed such that the attitude of the rigid spacecraft will converge to the origin in finite time. In the presence of disturbances, by employing terminal sliding mode method, a discontinuous finite-time control law is proposed such that the states will eventually converge to a small region of the origin, which can be rendered as small as desired. Numerical simulation results show the effectiveness of the method. [Copyright &y& Elsevier]

Abstract: This paper discusses the application of an integrated multidisciplinary design process to an unconventional Low Noise Aircraft (LNA) configuration, with a focus on the topic of structural sizing. Through the use of higher fidelity numerical methods, structural sizing can be performed and analysed at a much higher level than in classic conceptual design processes. The effects governing structural sizing for this specific configuration are illustrated and discussed. It is shown that considerable differences exist between the LNA and a conventional reference configuration. This analysis provides a basic understanding of how an unconventional geometry can impact the global parameters of an aircraft design. [Copyright &y& Elsevier]

Advanced CFD tools are nowadays used routinely for analysis and design of rotorcraft with the research community shifting towards simulations of rotorcraft during maneuvering flight. One of the impediments of this effort is the lack of data for validation, evaluation and thorough assessment of CFD methods when it comes to rotors with time-varying control inputs. This paper presents a first effort to validate CFD tools for step-inputs in rotor control angles against previously un-published experimental data. The experimental study was carried out at the Nanjing University of Aeronautics and Astronautics in China and consists of time varying control inputs for a hovering rotor. The agreement between the simulation and experimental study is good and quantify the overshoot in loads for this dynamic case. The results examine the lag in loads response to and the dynamic response of the wake with recommendations on spatial and temporal resolution to capture these effects. [ABSTRACT FROM AUTHOR]

A stall inception prediction model considering radial inlet distortions is established in this paper in order to quickly and accurately predict the stall limit of a compressor at radially distorted inlet flow conditions. Furthermore, the quantitative effect of the radial inlet distortion on compressor stability is investigated on a low-speed single-stage axial-flow compressor which is named TA36 and located in Beijing University of Aeronautics and Astronautics. Two kinds of distortion intensities are achieved by two radial inlet distortion generators in experiments. By utilizing the developed stability model, the predicted stall limits of TA36 at clean, 10% and 20% radially distorted inlet flow conditions all agree well with the experimental data only with relative errors of −0.74%, 1.28%, and 0.53% respectively. These relative errors less than 1.50% validate the ability of the developed stability model to predict the stall onset of a compressor with clean inlet or radial inlet distortions. Moreover, the predicted results confirm that radial inlet distortions deteriorate the compressor stability, and the adverse effect becomes more severe with the increase of distortion intensity, which can also be concluded from the experimental data. After comparing the load distribution on the rotor blade at the three inlet conditions, the increase of the maximum load at the tip region at distorted inlet conditions is considered to be a critical factor contributing to the negative effect of radial inlet distortions on compressor stability. [ABSTRACT FROM AUTHOR]