摘要 :
The loiter radius with the highest chargerate for a solar-powered aircraft flying circuits over a fixed point on the ground is determined. The aircraft is assumed to be flying in horizontal atmospheric winds. Chargerate is calcula...
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The loiter radius with the highest chargerate for a solar-powered aircraft flying circuits over a fixed point on the ground is determined. The aircraft is assumed to be flying in horizontal atmospheric winds. Chargerate is calculated as the difference between the average solar-power input and power required to fly the circular loiter for each wind scenario. Model validation was performed using flight test data from the CREATeV solar-powered aircraft, with comparisons found to be within a 10% difference. A parametric sweep was performed to determine the optimum loiter at different sun elevations for various wind conditions. It was found that, for the solar-powered aircraft under consideration, in most scenarios, the chargerate is maximized by flying a large loiter radius. The exceptions to this case are when: (1) The sun elevation is higher than 20°, and there is a high windspeed with a large component of the wind vector perpendicular to the sun vector, and (2) The sun elevation is lower than 20°, and the wind vector is not aligned with the sun vector. Overall, flying with a changing loiter radius based on wind conditions and sun position can lead to a power gain of up to 11 W. Although these results are specific to the CREATeV solar-powered aircraft, the model discussed in this paper can be modified to apply to any solar-powered aircraft.
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摘要 :
Several existing flight-testing methodologies for determining the in-flight power requirements for uninhabited aerial vehicles less than 25kg were assessed. Three common methods were selected and tested using a representative airc...
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Several existing flight-testing methodologies for determining the in-flight power requirements for uninhabited aerial vehicles less than 25kg were assessed. Three common methods were selected and tested using a representative aircraft. Several factors inhibited precise measurement of power required, including changing atmospheric conditions and perturbations introduced by the flight controller. Cruising methods were found to be the least hampered by altitude restrictions imposed on aircraft of this class, but require considerable time to perform the necessary flight mission profiles.
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摘要 :
As part of an aircraft fatigue assessment program, the rotor loads of a tandem-rotor helicopter are deduced via flight test measurements. During in-flight maneuvers, accelerations and angular displacements of the rotor blades were...
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As part of an aircraft fatigue assessment program, the rotor loads of a tandem-rotor helicopter are deduced via flight test measurements. During in-flight maneuvers, accelerations and angular displacements of the rotor blades were measured. After correcting the measurements for installation errors, the experimental data and the blade mass properties were used in the rotor blade equations of motion, in order to derive the hub loads. Aside from describing the experimental setup and data reduction, the development of the equations of motion of a fully articulated rotor blade and a solution approach is outlined in this paper. The resulting hub loads deduced from the blade equations of motion are compared to several sources.
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