Design of solar high altitude long endurance aircraft for multi payload & operations

Research is being carried out at the Turin Polytechnic University with the aim of designing a HAVE/UAV (High Altitude Very-long Endurance/Unmanned Air Vehicle). The vehicle should be able to climb to an altitude of 17–20 km by taking advantage of direct sun radiation and maintaining a level flight; during the night, a fuel cells energy storage system would be used. A computer program has been developed to carry out a parametric study for the platform design. The solar radiation change over one year, altitude, masses and efficiencies of the solar and fuel cells, as well as the aerodynamic performances have all been taken into account. The parametric studies have shown how the efficiency of the fuel and solar cells and mass have the most influence on the platform dimensions. High modulus CFRP has been used in designing the structure in order to minimize the airframe weight. A Blended Wing Body (BWB) configuration of Solar HALE Aircraft Multi Payload & Operation (SHAMPO) with 8 brushless electric motors has been developed, as a result of the parametric study. The BWB solution, compared with conventional designs, seems to provide the best compromise between performance, availability of surfaces for solar-cells, and volume for multi-payload purposes. Several profiles and wing plans have been analyzed using the CFD software Xfoil and Vsaero. The airfoil coordinates at the root and along the wing span as well as the wing planform were optimised to achieve the best efficiency. A FEM analysis was carried out using the Msc/Patran/Nastran code to predict the static and dynamic behaviour of the UAV structure.     

Synopsis: Horizons in Guidance Computer Component Technology

An extensive survey of semiconductor and memory component manufacturers conducted by the Electronics Research Center of NASA and industry has resulted in estimates of the state of the art of components available to designers of on-board guidance and control computers for long-term, deep-space missions for the 1970-1972 period. The vehicle for the survey was the mission requirements for the synchronous satellite, lunar orbiter, Mars orbiter, and Jupiter fly-by solar probe missions.     

升浮一体飞行器总体参数设计方法

临近空间飞行器近年来得到了广泛的关注和研究。为克服传统飞艇和太阳能飞机尺寸大、抗风能力差的缺点,本文提出了一种升浮一体飞行器概念方案,并对其总体参数设计方法进行研究。以能量平衡分析为核心,建立了太阳能电池系统、燃料电池系统、推进系统等子系统的数学模型,给出了适合于该飞行器的总体参数设计方法,并对总体设计参数进行了研究。结果表明,升浮一体飞行器相对于传统飞艇,体积下降了53%,长度下降了22%,起飞重量下降了4%。相对于固定翼太阳能飞机,翼展下降了52%,机翼面积减小了56%,起飞重量下降了3.5%。该类飞行器总体参数对飞行速度非常敏感,飞行速度从30 m/s提高至40 m/s时,起飞重量增加约1倍,艇体体积增大77%。提高太阳能电池、燃料电池和螺旋桨效率可有效降低起飞重量,且升浮一体飞行器比传统飞艇对上述参数更敏感。     

Design and application of solar sailing: A review on key technologies

Solar sail technology has been proposed and developed for space explorations with advantages of low launch cost, no-propellant consumption, and continuous thrust, which has great potentials in earth polar detection, interstellar explorations and etc. The development of solar sail has made significant progress in structural design, manufacturing, materials, orbit transfer, and stability control in the past few decades, which makes meaningful contributions to astronomy, physics, and aerospace science. Technological breakthroughs of Solar Radiation Pressure (SRP) propulsion and interstellar transfer have been achieved in current solar sail missions. However, there are still many challenges and problems need to be solved. This paper attempts to summarize the research schemes and potential applications of solar sailing in space missions from the viewpoint of key technologies, so as to provide an overall perspective for researchers in this field. Analyses of the key technologies of solar sailing system design are provided. Finally, challenges and prospective development of solar sailing are discussed.     

Using Precise Solar Limb Shape Measurements to Study the Solar Cycle

Despite 20 years of total solar irradiance measurements from space, the lack of high precision spatially resolved observations limits definitive answers to even simple questions like ``Are the solar irradiance changes caused solely by magnetic fields perturbing the radiative flux at the photosphere?" More subtle questions like how the aspheric structure of the sun changes with the magnetic cycle are only now beginning to be addressed with new tools like p-mode helioseismology. Solar 5-min oscillation studies have yielded precise information on the mean radial interior solar structure and some knowledge about the rotational and thermal solar asphericity. Unfortunately this progress has not been enough to generate a self-consistent theory for why the solar irradiance and luminosity vary with the magnetic cycle. We need sharper tools to describe and understand the sun's global aspheric response to its internal dynamo, and we need to be able to measure the solar cycle manifestation of the magnetic cycle on entropy transport from the interior to the photosphere in much the same way that we study the fundamentally more complex problem of magnetic flux transport from the solar interior. A space experiment called the Solar Physics Explorer for Radius, Irradiance and Shape (SPHERIS) and in particular its Astrometric and Photometric Telescope (APT) component will accomplish these goals.

     

Millimeter wave safety warning system for in-vehicle signing

Georgia Tech Research Institute (GTRI) has developed a millimeter wave safety warning system for in-vehicle signing for use in the nation's Intelligent Transportation System (ITS, formerly IVHS). The Safety Warning System TU (SWS) utilizes a homodyne radar that operates at 24.1 GHz as both a radar and a system to transmit highway safety messages. The warning message is received by a police radar detector or stand-alone safety warning receiver without radar detector capability. When the message is received, it is displayed to the driver via an alphanumeric light emitting diode (LED) display. The message can also be announced by a voice synthesizer internal to the receiver or by a flashing LED labeled “SWS.” The system is designed to inform the driver that he or she is being overtaken by a police car or emergency vehicle in motion. When the police car or emergency vehicle stops, the radar transmitter senses that the platform is no longer moving and the system automatically changes its message to warn approaching drivers of a stationary hazard ahead. A second safety warning transmitter deployment concept is to mount the unit near the highway at a fixed location. The fixed location SWS is designed to be programmable and transmit any one of 64 fixed text messages     

Design and integration of a solar AMTEC power system with anadvanced global positioning satellite

A 1,200-W solar AMTEC (alkali metal thermal-to-electric conversion) power system concept was developed and integrated with an advanced global positioning system (GPS) satellite. The critical integration issues for the SAMTEC with the GPS subsystems included: (1) packaging within the Delta II launch vehicle envelope; (2) deployment and start-up operations for the SAMTEC; (3) SAMTEC operation during all mission phases; (4) satellite field of view restrictions with satellite operations; and (5) effect of the SAMTEC requirements on other satellite subsystems. The SAMTEC power system was compared with a conventional planar solar array/battery power system to assess the differences in system weight, size, and operations, Features of the design include the use of an advanced multitube, vapor anode AMTEC cell design with 24% conversion efficiency, and a direct solar insolation receiver design with integral LiF salt canisters for energy storage to generate power during the maximum solar eclipse cycle, The modular generator design consists of an array of multitube AMTEC cells arranged into a parallel/series electrical network with built-in cell redundancy. Our preliminary assessment indicates that the solar generator design is scaleable over a 500 to 2,500-W range. No battery power is required during the operational phase of the GPS mission. SAMTEC specific power levels greater than 5 We/kg and 160 We/m² are anticipated for a mission duration of 10 to 12 years in orbits with high natural radiation backgrounds     

The development of a series hybrid electric vehicle for near-termapplications

The design of a feasible hybrid electric vehicle for use in near-term applications is presented. The challenge involved cost effectiveness, acceleration, range, safety, and emissions, which were incorporated into the vehicle design. The relationship of the design goals was studied, and compromises were made to provide near-optimal system design. This process resulted in the selection and design of the major vehicle components. The design decisions and the actual vehicle components are reviewed     

GaAs系列太阳电池技术与发展

GaAs系列太阳电池是目前太空应用最广泛的电源,这一系列太阳电池已成为太阳电池领域的研究热点.介绍了GaAs太阳电池的研究历程和最新技术动态.     

The Solar Isotope Spectrometer for the Advanced Composition Explorer

The Solar Isotope Spectrometer (SIS), one of nine instruments on the Advanced Composition Explorer (ACE), is designed to provide high- resolution measurements of the isotopic composition of energetic nuclei from He to Zn (Z=2 to 30) over the energy range from ∼10 to ∼100 MeV nucl−1. During large solar events SIS will measure the isotopic abundances of solar energetic particles to determine directly the composition of the solar corona and to study particle acceleration processes. During solar quiet times SIS will measure the isotopes of low-energy cosmic rays from the Galaxy and isotopes of the anomalous cosmic-ray component, which originates in the nearby interstellar medium. SIS has two telescopes composed of silicon solid-state detectors that provide measurements of the nuclear charge, mass, and kinetic energy of incident nuclei. Within each telescope, particle trajectories are measured with a pair of two-dimensional silicon-strip detectors instrumented with custom, very large-scale integrated (VLSI) electronics to provide both position and energy-loss measurements. SIS was especially designed to achieve excellent mass resolution under the extreme, high flux conditions encountered in large solar particle events. It provides a geometry factor of ∼40 cm2 sr, significantly greater than earlier solar particle isotope spectrometers. A microprocessor controls the instrument operation, sorts events into prioritized buffers on the basis of their charge, range, angle of incidence, and quality of trajectory determination, and formats data for readout by the spacecraft. This paper describes the design and operation of SIS and the scientific objectives that the instrument will address. This revised version was published online in June 2006 with corrections to the Cover Date.     

临近空间飞行器信息系统一体化载荷平台

介绍了临近空间日趋受到各国的关注和研究、临近空间的概念以及临近空间飞行器的概况。从高超声速临近空间飞行器设计层面分析了临近空间飞行器信息系统多任务需求和现有设计的矛盾,指出研究临近空间飞行器一体化综合电子系统信号交链和多任务一体化协同技术是解决此矛盾的有效途径。通过对临近空间飞行器信息系统一体化载荷平台的研究,构建了采用冗余备份技术的包括信号处理模块、控制模块的统一开放的柔性系统平台架构。     

Elemental Abundances in the Solar Upper Atmosphere Derived by Spectroscopic Means

The composition of the solar photosphere is believed to be uniform. Indeed a quantity that does not vary with solar surface location or with a particular solar feature, i.e., no observational evidence is available to indicate that the photospheric composition near the solar equator is different from the photospheric composition near the solar poles or that the photospheric composition in quiet regions is different from the composition in active regions. In contrast, the composition of the solar upper atmosphere is not well defined. Solar composition work in recent decades has brought the recognition that there are systematic differences between the composition of the corona and the photosphere and revealed evidence for spatial and time variability in the composition of various coronal features. We review the spectroscopic techniques used and the progress that was made in recent years in deriving the plasma compositions of various solar upper atmosphere structures. This revised version was published online in August 2006 with corrections to the Cover Date.     

The SOHO concept and its realisation

The Solar and Heliospheric Observatory (SOHO) — a space observatory to be placed, in 1995, 1.5 Gm sunward from the Earth in a halo orbit around the L1 Lagrange point — will investigate:

the solar corona, its heating and expansion into the solar wind, by both studying the radiation emerging from the outer solar atmosphere and in-situ solar wind measurements near 1 AU, and

the structure and dynamics of the solar interior by the method of helioseismology.

The science policy evolution leading to this comprehensive observatory concept is described. SOHO's link to the space-plasma-physics mission CLUSTER — devoted to the three-dimensional study of small structures in the magnetosphere — within the Solar Terrestrial Science Programme (STSP) and the embedding of STSP in the much larger International Solar Terrestrial Physics (ISTP) Programme are cited as well. The scientific subjects to be addressed by SOHO are introduced, and their current status assessed. Subsequently, the measurements required to advance these subjects are stated quantitatively and the payload, which will actually perform these measurements, is presented. The mission design, comprising spacecraft, orbit, operations and the data and ground systems are described. The special efforts made to obtain a reliable radiometric calibration of the instruments observing the Sun in the extreme-ultraviolet and to achieve a stable sensitivity through extreme cleanliness of spacecraft and instruments are emphasized and substantiated.     

Ultracapacitors + DC-DC converters in regenerative braking system

An ultracapacitor system for an electric vehicle has been implemented. The device allows higher accelerations and decelerations of the vehicle with minimal loss of energy and minimal degradation of the main battery pack. The system uses a DC-DC power converter, which is connected between the ultracapacitor and the main battery pack. The design has been optimized in weight and size, by using water-cooled heat sinks for the power converter, and an aluminum coil with air core for the smoothing inductance. The ratings of the ultracapacitor are: nominal voltage: 300 Vdc; nominal current: 200 Adc; capacitance: 20 Farads. The amount of energy stored allows us to have 40 kW of power during 20 seconds, which is enough to accelerate the vehicle without the help of the traction batteries. The vehicle uses a brushless DC motor with a nominal power of 32 kW and a peak power of 53 kW. A control system based on a Digital Signal Processor (DSP) manipulates all the aforementioned variables and controls the Pulse Width Modulation (PWM) switching pattern of the converter transistors. The car used for the implementation of this system is a Chevrolet LUV truck.     

车载里程仪参数的实时标定方法

针对里程仪输出的速度(或位置增量),其参数标定误差残差是影响定位定向系统性能的关键因素,传统里程仪参数标定方法需在行车过程中设置精确标志点,且有行驶路线受限的缺点,因此提出一种基于速度量测的定位定向系统误差实时估计和补偿方法.该方法将里程仪刻度系数误差、安装误差残差纳入状态变量进行实时估计并补偿,将惯性导航系统输出的速度与里程仪输出的速度进行对比,构建量测方程.设计跑车试验对该方法进行验证,结果表明该车载里程仪参数的实时标定方法,仅需要在里程仪安装在车辆上后,导航系统做一次正常罗经对准并转惯性/里程仪组合导航模式,在车辆正常行驶过程中,即可自动标定出里程仪参数误差,具有自主、灵活简便、精度高的特点,同时提高了惯性/里程仪组合导航系统定位精度.     

Solar flux and its variations

We present data on the solar irradiance as derived from a number of sources. An attempt was made to bring these data onto a uniform scale. The results are presented in Table IV and Figure 6. Summation of fluxes at all wavelengths yields a figure of 1357.826 W m^-2 for the solar constant. Estimates are made of the solar flux variations due to flares, active regions (slowly varying component), solar rotation and the 11-year cycle.Solar activity does not produce a significant variation in the value of the solar constant. Nevertheless, variations in the X-ray and extreme ultraviolet portions of the solar flux may be several orders of magnitude during solar activity, especially at times of major flares. It is well established that these short wavelength flux enhancements cause significant changes in the terrestrial ionosphere.     

Characteristics of shocks in the solar corona,as inferred from radio,optical, and theoretical investigations

Solar radio bursts of spectral type II provide one of the chief diagnostics for the propagation of shocks through the solar corona. Radio data on the shocks are compared with computer models for propagation of fast-mode MHD shocks through the solar corona. Data on coronal shocks and high-velocity ejecta from solar flares are then discussed in terms of a general model consisting of three main velocity regimes.An invited paper presented at STIP Workshop on Shock Waves in the Solar Corona and Interplanetary Space, 15–19 June, 1980, Smolenice, Czechoslovakia.     

小型太阳能无人机超大展弦比轻质主梁设计

太阳能无人机表面需要铺设太阳能电池,这就要求太阳能无人机的结构要同时满足不影响太阳能电池效率的光学特性和要达到足够强度、刚度的力学特性。文章针对小型太阳能飞机超大展弦比机翼进行轻质化结构设计,过程中充分考虑超大展弦比机翼的柔性变形,对比不同的设计方案并提出合理设计方案。