Collaborative Payload Lifting using Tethered Unmanned Fixed-Wing Aircraft

直升机对现代社会至关重要，因为它们是空中运输大量有效载荷的唯一解决方案，而不需要复杂的长达数英里的跑道基础设施。然而，直升机本质上效率低，并且在时间和距离上都限于短期任务。目前的替代方法，如飞艇，造成存储复杂性和有限的机动性，而新的概念，试图增加转子盘面积，以尽量减少电力需求，降低了能力，以翻译。 一个颠覆性的垂直升降概念使用系留固定翼飞机来提升有效载荷，其中每架飞机都模仿一个单独的叶片，并具有自己的轨迹控制。虽然与现代直升机有着根本的不同，但早在1942年就提出了使用多架固定翼飞机进行载荷提升。 载人系留飞机的系留长度为千米，多架重型飞机之间的协调也具有挑战性，限制了飞行路径的灵活性。因此，承载能力有限，并与传统的跑道的要求，在这个概念的兴趣已经消退。 新颖的想法是用具有远程能源的电动固定翼飞机取代系留有人驾驶飞机（具有机载能源，燃料），这与一些机载风能概念相似。通过将能量源（电池和/或发电机）保持在“有效载荷”部分并通过系绳传输能量，轻型飞机具有增加的敏捷性和推重比，从而允许真正的垂直起飞。在敏捷飞行器上使用电动机沿着现代感测和控制是系绳飞行器在有效载荷上方执行复杂飞行路径的使能器，所述复杂飞行路径被定义为具有空速、飞行器姿态和系绳张力的连续变化的非圆形。执行复杂飞行轨迹的能力被确定为在非悬停条件下使用系留固定翼进行有效载荷提升的主要推动力。初步的数值研究还表明，与同等有效载荷能力的直升机相比，功率降低了5倍，并且对单架系留飞机进行的初步飞行试验支持了这些预测。 该研究计划的短期目标是开发第一个具有复杂飞行路径能力的三电动绳系飞机概念的小规模演示器。这项工作将在三个方面推动科学发展：（1）通过发展空气动力学、动力学和控制方面的基础知识，使系留飞行系统成为可能;（2）通过开发设计、建造和测试这种新飞行系统的工程技术;（3）通过提供一套完整的实验数据，这些数据是证实理论理解和推断能力所必需的的方法。拟议的项目将有助于在先进的飞机设计领域培养2名博士生和3名硕士生。

Helicopters have been essential to modern society as they have been the only solution for air-transporting substantial payloads with no need for complex mile-long runway infrastructures. However, helicopters intrinsically have a low efficiency and are limited to short missions, both in time and distance. Current alternative approaches, such as airships pose storage complexity and limited maneuverability, while novel concepts attempting to increase the rotor disk area to minimize power requirements have reduced capability to translate. A disruptive concept to vertical lift uses tethered fixed-wing aircraft to lift a payload, where each aircraft mimics an individual blade with its own trajectory control. Although radically different from modern helicopters, load lifting using multiple fixed-wing aircraft was proposed as early as 1942. Manned tethered airplanes imposed km-long tethers and challenging coordination between multiple heavy aircraft limited flight path flexibility. As a result, the load capacity was limited and with the requirement for a conventional runway, the interest in the concept has faded. The novel idea is to replace tethered manned aircraft (with onboard energy, fuel) with electric-powered fixed-wing aircraft with remote energy source, which shows similarity with some airborne wind energy concepts. By keeping the energy source (battery and/or generator) in the “payload” section and transmitting the energy through the tethers, the lightweight airplanes have an increased agility and thrust-to-weight ratio allowing for a true vertical takeoff. The use of electric motors on agile aircraft along with modern sensing and control is an enabler for the tethered aircraft to perform complex flight path above the payload, defined as non-circular with continuous variation in airspeed, aircraft attitude, and tether tension. The ability to perform complex flight paths was identified as the main enabler for efficient load lifting with tethered fixed wing in a non-hover condition. Initial numerical studies also demonstrated a 5 times power reduction compared to an equivalent helicopter for similar payload capacity, and preliminary flight tests on a single tethered aircraft support those predictions. The short term objective of this research program is to develop the first small-scale demonstrator of a three electric-powered tethered aircraft concept with complex flight path capability. The work will advance science in three ways, (1) by developing the fundamental knowledge in aerodynamics, dynamics, and controls needed to enable tethered flight systems; (2), by developing the engineering knowhow to design, build, and test such new flight systems, and (3), by providing a complete set of experimental data that is necessary to corroborate the theoretical understanding and to extrapolate on the capabilities of the approach. The proposed project will contribute in training 2 PhD and 3 MSc students in the domain of advanced aircraft design.