The emergence of Low Earth Orbit (LEO) satellite systems has been seen as a potential solution for connecting remote areas where engineering terrestrial infrastructure is prohibitively expensive. Despite the hype, we still lack an open-source modeling framework for assessing the techno-economics of satellite broadband connectivity which is therefore the purpose of this paper. Firstly, a generalizable techno-economic model is presented to assess the engineering-economics of satellite constellations. Secondly, the approach is applied to assess the three main competing LEO constellations which include Starlink, OneWeb and Kuiper. This involves simulating the impact on coverage, capacity and cost, as both the number of satellites and quantity of subscribers increases. Finally, a global assessment is undertaken visualizing the potential capacity and cost per user via different subscriber scenarios. The results demonstrate how limited the capacity will be once resources are spread across users in each satellite coverage area. For example, for 0.1 users per km2 (so 1 user per 10 km2), we estimate a mean per user capacity of 24.94 Mbps, 1.01 Mbps and 10.30 Mbps for Starlink, OneWeb and Kuiper, respectively, in the busiest hour of the day. But if the subscriber density increases to 1 user per km2, then the mean per user capacity drops significantly to 2.49 Mbps, 0.10 Mbps and 1.02 Mbps. LEO broadband will be an essential part of the connectivity toolkit, but the results reveal that these mega-constellations will most likely have to operate below 0.1 users per km2 to provide a service that out-competes other broadband connectivity options.

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A Techno-Economic Framework for Satellite Networks Applied to Low Earth Orbit Constellations: Assessing Starlink, OneWeb and Kuiper

Sustainable aircraft design — A review on optimization methods for electric propulsion with derived optimal number of propulsors

A conceptual multidisciplinary design framework for High Altitude Long Endurance (HALE) aircraft is developed for solar-powered single and multiple-boom aircraft configurations. A defining feature of high-aspect ratio HALE vehicles is the tight coupling among various disciplines in particular aerodynamics and structures. A physics-based framework is required to fully exploit potential couplings that may result in significant mass savings. In order to quickly and accurately explore the design space, first-order physics are employed where possible and reliance on historical empirical data is minimized. Although the framework is useful to rapidly down-select potential configurations, sufficient engineering fidelity is also captured resulting in realistic preliminary designs enabling shorter engineering and development cycles. Low Reynolds number aerodynamics, composite structures, integrated vehicle performance (including solar energy utilization) and their interactions, are captured with an appropriate level of fidelity while maintaining computational efficiency. Several aspects of the framework are validated using higher-fidelity analysis tools. In this paper (Part I), optimization case studies for single and dual-boom configurations are discussed.

HALE Multidisciplinary Design Optimization Part I: Solar-Powered Single and Multiple-Boom Aircraft

Solar-Powered Aircraft Endurance Map

A solar-powered unmanned seaplane is proposed as a new strategy to avoid the challenges faced in a long nonstop solar-powered flight, and is especially designed for sea surveillance mission, like r...

Preliminary design and performance analysis of a solar-powered unmanned seaplane:

Solar Aircraft Design Trade Studies Using Geometric Programming

In this article we introduce a novel solution called SuperCell, which can improve the return on investment (ROI) for rural area network coverage. SuperCell offers two key technical features: it uses tall towers with high-gain antennas for wide coverage and high-order sectorization for high capacity. We show that a solution encompassing a high-elevation platform in excess of 200 meters increases coverage by 5x. Combined with dense frequency reuse by using as many as 36 azimuthal sectors from a single location, our solution can adequately serve the rural coverage and capacity demands. We validate this through propagation analysis, modeling, and experiments. The article gives a design perspective using different classes of antennas: Luneburg lens, active/passive phased array, and spatial multiplexing solutions. For each class, the corresponding analytical model of the resulting signal-to-interference plus noise ratio (SINR) based range and capacity prediction is presented. The spatial multiplexing solution is also validated through field measurements and additional 3D ray-tracing simulation. Finally, in this article we also shed light on two recent SuperCell field trials performed using a Luneburg lens antenna system. The trials took place in rural New Mexico and Mississippi. In the trials, we quantified the coverage and capacity of SuperCell in barren land and in a densely forested location, respectively. In the article, we demonstrate the results obtained in the trials and share the lessons learned regarding green-field and brown-field deployments.

SuperCell: A Wide-Area Coverage Solution Using High-Gain, High-Order Sectorized Antennas on Tall Towers.

A conceptual multidisciplinary framework is developed for the design and analysis of solar-powered, High Altitude Long Endurance (HALE) flight vehicles. Typical design features such as low wing loading and high aspect ratio imply strong inter-disciplinary couplings, in particular, aerodynamics and structures. A MultiDisciplinary Optimization (MDO) framework is therefore required to fully exploit potential couplings that may result in significant weight savings. In order to rapidly and accurately explore the design space, physics-based first principles are emphasized and reliance on historical or empirical data is minimized. In this paper (Part II), we describe how a solar-powered flying-wing configuration may be optimized using a strategy similar to that described in Part I. A key design driver in this case is the suppression of an aeroelastic phenomenon, “Body-FreedomFlutter”, resulting from strong modal interactions due to wing sweep. Consequently, for the present study, it is shown that resulting designs are stiffness-driven as opposed to the strength-driven characteristic of conventional configurations (tail-stabilized). In addition, potential benefits of recent progress in active flutter suppression technologies are investigated.

HALE Multidisciplinary Design Optimization Part II: Solar-Powered Flying-Wing Aircraft

Systems, methods, and non-transitory computer-readable media are disclosed for automatically generating aircraft models by modifying quantitative design variables based on joint analysis of aerodynamic, structural, and/or energy performance. For example, in one or more embodiments, disclosed systems iteratively modify ailerons and a propulsion system based on performance criteria until a balancing metric converges. The disclosed systems then determine performance metrics corresponding to the aircraft model with the modified ailerons and propulsion system, such as stresses and deflections under performance load, a measure of aeroelastic stability, and a battery performance metric. The disclosed systems can then modify design variables based on the determined performance metrics to explore the design space and generate a new aircraft model.

Vishvas S. Suryakumar

Papers

HALE Multidisciplinary Design Optimization Part I: Solar-Powered Single and Multiple-Boom Aircraft

Solar Aircraft Design Trade Studies Using Geometric Programming

SuperCell: A Wide-Area Coverage Solution Using High-Gain, High-Order Sectorized Antennas on Tall Towers.

HALE Multidisciplinary Design Optimization Part II: Solar-Powered Flying-Wing Aircraft

Automatic aircraft design optimization based on joint aerodynamic, structural, and energy performance