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501.
    
This article sheds light on the key player needed for any space tourism adventure: the pilot who flies the spacecraft. The paper addresses the potential benefits of including a pilot at the controls when designing a space tourism spacecraft. It examines the basic qualifications and advanced skills required of space tourism pilots and discusses key training requirements for selected pilots and space pilots' pay and benefits. In addition, the research concludes that, just as the pioneers of passenger transport in aviation entertained and captured the interest of their passengers, the space pilot should have the skills of a tour guide.  相似文献   
502.
利用前缘旋转控制边条翼外翼分离   总被引:1,自引:0,他引:1       下载免费PDF全文
边条翼在边条较小时中等迎角以上外翼就会出现分离,现提出用转动前缘表面来控制边条翼外翼分离。通过测力、油流和烟丝实验研究了转动前缘对机翼气动特性的影响。结果表明,在这种机翼上转动前缘对控制分离是有效的,升力增量最大可达30%。可以预期,转动前缘与边条的综合作用,机翼的分离特性将有较大的改善  相似文献   
503.
俯仰三角翼的流态及结构   总被引:1,自引:0,他引:1       下载免费PDF全文
本文对俯仰三角翼的流动特性进行了实验研究,给出了俯仰三角翼的截面流态特点,对三角翼俯仰运动的流动机理进行了分析.  相似文献   
504.
One of the Skylab experiments dealt with motion sickness, comparing susceptibility in the workshop aloft with susceptibility preflight and postflight. Tests were conducted on and after mission-day 8 (MD 8) by which time the astronauts were adapted to working conditions. Stressful accelerations were generated by requiring the astronauts, with eyes covered, to execute standardized head movements (front, back, left, and right) while in a chair that could be rotated at angular velocities up to 30 rpm. The selected endpoint was either 150 discrete head movements or a very mild level of motion sickness. In all rotation experiments aloft, the five astronauts tested (astronaut 1 did not participate) were virtually symptom free, thus demonstrating lower susceptibility aloft than in preflight and postflight tests on the ground when symptoms were always elicited. Inasmuch as the eyes were covered and the canalicular stimuli were the same aloft as on the ground, it would appear that lifting the stimulus to the otolith organs due to gravity was an important factor in reducing susceptibility to motion sickness even though the transient stimuli generated under the test conditions were substantial and abnormal in pattern. Some of the astronauts experienced motion sickness under operational conditions aloft or after splashdown, but attention is centered chiefly on symptoms manifested in zero gravity. None of the Skylab-II crew (astronauts 1 to 3) was motion sick aloft. Astronaut 6 of the Skylab-III crew (astronauts 4 to 6) experienced motion sickness within an hour after transition into orbit; this constitutes the earliest such diagnosis on record under orbital flight conditions. The eliciting stimuli were associated with head and body movements, and astronaut 6 obtained relief by avoiding such movements and by one dose of the drug combination 1-scopolamine 0.35 mg + d-amphetamine 5.0 mg. All three astronauts of Skylab-III experienced motion sickness in the workshop where astronaut 6 was most susceptible and astronaut 4, least susceptible. The higher susceptibility of SL-III crewmen in the workshop, as compared with SL-II crewmen, may be attributable to the fact that they were based in the command module less than one-third as long as SL-II crewmen. The unnatural movements, often resembling acrobatics, permitted in the open spaces of the workshop revealed the great potentialities in weightlessness for generating complex interactions of abnormal or unusual vestibular and visual stimuli. Symptoms were controlled by body restraint and by drugs, but high susceptibility to motion sickness persisted for 3 days and probably much longer; restoration was complete on MD 7. From the foregoing statements it is clear that on and after MD 8 the susceptibility of SL-II and SL-III crewmen to motion sickness under experimental conditions was indistinguishable. The role played by the acquisition of adaptation effects prior to MD 8 is less clear and is a subject to be discussed.  相似文献   
505.
    
A commonly accepted view is that life began in a marine environment, which would imply the presence of inorganic ions such as Na+, Cl-, Mg2+, Ca2+, and Fe2+. We have investigated two processes relevant to the origin of life--membrane self-assembly and RNA polymerization--and established that both are adversely affected by ionic solute concentrations much lower than those of contemporary oceans. In particular, monocarboxylic acid vesicles, which are plausible models of primitive membrane systems, are completely disrupted by low concentrations of divalent cations, such as magnesium and calcium, and by high sodium chloride concentrations as well. Similarly, a nonenzymatic, nontemplated polymerization of activated RNA monomers in ice/eutectic phases (in a solution of low initial ionic strength) yields oligomers with > 80% of the original monomers incorporated, but polymerization in initially higher ionic strength aqueous solutions is markedly inhibited. These observations suggest that cellular life may not have begun in a marine environment because the abundance of ionic inorganic solutes would have significantly inhibited the chemical and physical processes that lead to self-assembly of more complex molecular systems.  相似文献   
506.
    
Adaptation to the weightless state and readaptation after space flight to the 1-G environment on the ground are accompanied by various transitory symptoms of vestibular instability, kinetosis, and illusory sensations. Aside from the problem of how to treat and if possible prevent such symptoms, they offer a clue to a better understanding of normal vestibular functions. Weightlessness is a powerful new \"tool\" of vestibular research. Graybiel reported as early as 1952 that human subjects observed the illusion that a real target and the visual afterimage seemed to raise in the visual field during centrifugation when the subjects were looking toward the axis of rotation (oculogravic illusion). In aircraft parabolic-flight weightlessness, human subjects observed that fixed real targets appeared to have moved downward while visual afterimages appeared to have moved upward (oculoagravic illusion). It can be shown by electronystagmography as well as by a method employing double afterimages that part of this illusion is caused by eye movements that are triggered by the changing input from the otolith system. Another part of the illusion is based on a change of the subjective horizontal and must be caused by convergence of vestibular and visual impulses \"behind\" the eyes. This part was measured independently of the first one by using a new method. Eye movements could be prevented during these experiments by optical fixation with the right eye on a target at the end of a 24-in. long tube which was rigidly attached parallel to the longitudinal axis of an aircraft. At the same time the subject tried to line up a shorter tube, which was pivoting around his left eye, with the subjective horizon.  相似文献   
507.
The nonstationary process of the accumulation of ions of meteoric origin, which is caused by propagation of planetary waves at altitudes of the lower ionosphere, is considered. Based on horizontal and vertical ion drift in planetary waves, a possibility of plasma density increases by a factor of 10–20 in comparison with the background concentration is demonstrated. This process takes place in areas of cyclonic motion with a scale of the order of 1500 km. The connection of this process with subsequent formation of midlatitude sporadic layers and irregularities producing radio reflections is considered. It is shown that the action of planetary waves on ions of meteoric origin is a necessary element in the scheme of the occurrence of midlatitude sporadic layers.  相似文献   
508.
论述了具有小推力飞行段的长征运载火箭在飞行过程中二级游机提前或推迟关机的机理,明确给出了游机可能提前或推迟关机的时间范围,为以后的火箭飞行参数判定提供理论依据。  相似文献   
509.
510.
航空发动机试验舱的气动特性影响发动机性能评估准确性。为提高某型航空发动机试验舱的流场均匀性,文章针对试验舱前舱的扩压段和稳压段,设计了4套不同的整流系统组合方案,包括折流板、锥形多孔板、平面多孔板、蜂窝器和阻尼网等元素。应用计算流体动力学(CFD)方法对各个方案的前舱、来流管道及来流阀门的流场进行计算。结果表明,来流管道中的阀门对来流流场造成了一定影响,导致进入前舱的气流不均匀;折流板和锥形多孔板减小了气流的掺混作用,对不均匀来流试验舱的整流效果有限;而多层平面多孔板在不均匀来流试验舱的整流方面表现更为优异。以上研究结果可为试验舱整流系统的设计提供参考。  相似文献   
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