On the capabilities and limitations of high altitude pseudo-satellites

Gonzalo, Jesús; López, Deibi; Domínguez, Diego; García, Adrián Banos; Escapa, Alberto

doi:10.1016/j.paerosci.2018.03.006

Cited by 103 publications

(41 citation statements)

References 99 publications

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“…The SWaP requirements for these platforms vary with type of platform. For fixed-wing aircraft (for example, the Airbus Zephyr platform), a documented payload weight of up to 5 kg is defined, 5 with a maximum payload power consumption of 250 W and an instrument pod volume of between 15,000 and 24000 cm 3 , depending upon the geometry of the payload. Additional Table 1 Optical specification characteristics for the proposed optical system.…”

Section: Swap Requirementsmentioning

confidence: 99%

“…The maximum payload volume is specified as 24;000;000 mm 3 , with a volume of 150 × 150 × 400 ð¼ 9;000;000Þ mm 3 allocated to the camera system. The current design occupies a volume of 150 × 150 × 438 ð¼ 9;855;000Þ mm 3 . While not conformant with the length specification, this length includes the COTS machine vision camera (57.5 mm).…”

Section: Mechanical Designmentioning

confidence: 99%

“…1,2 Applications such as these require challenging optical performance specifications as well as the engineering requirements specific to HAPS deployment. 3 In addition, most development activity for this technology is focused on the development of high altitude long endurance (HALE) operations. For this mode of operation, a demanding set of SWaP (space, weight, and power) requirements is also established to maximize mission durations.…”

Section: Introductionmentioning

confidence: 99%

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Development of a lightweight camera for high altitude platform systems

Rees

Baker

Thomson³

et al. 2020

Opt. Eng.

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We describe the development of a lightweight, high-resolution surveillance camera for deployment on high altitude platform systems. The instrument is designed to operate at an altitude of ∼20 km and has an expected ground resolution of better than 120 mm with an appropriate sensor. While designed specifically for imaging at visible wavelengths, it is shown that the design is capable of diffraction-limited imaging at NIR and SWIR wavelengths up to 2.5 μm. We have combined a range of materials from aluminum and titanium alloys through to carbon fiberreinforced plastic to produce an instrument with structural components that match the thermal expansion of the optical glasses used. The use of these materials has resulted in an instrument that weighs <2 kg, including a sensor package, and is designed to weigh <3 kg once integrated with an enclosure and actuated gimbal. The successful testing of two prototype systems is described, including several design outcomes from the program intended for implementation in advance of flight trials. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Swap Requirementsmentioning

confidence: 99%

Section: Mechanical Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Development of a lightweight camera for high altitude platform systems

Rees

Baker

Thomson³

et al. 2020

Opt. Eng.

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“…This is true for example for stratospheric solar high-aspect ratio aircraft (NASA Helios, Boeing Oddyseus, Facebook Aquila, Airbus Zephyr, etc.) (Gonzalo et al, 2018). Poor understanding of the low-altitude response of such very flexible aircraft (VFA) has previously led to poorly controlled flight dynamics and even vehicle loss (Noll et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Assessment of low-altitude atmospheric turbulence models for aircraft aeroelasticity

Deskos

Carre

Palacios

2020

Journal of Fluids and Structures

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We investigate the dynamic response of flexible aircraft in low-altitude atmospheric turbulence. To this end, three turbulence models of increasing fidelity, namely, the one-dimensional von Kármán model, the two-dimensional Kaimal model and full three-dimensional wind fields extracted from large-eddy simulations (LES) are used to simulate ambient turbulence near the ground. Load calculations and flight trajectory predictions are conducted for a flexible high-aspect ratio aircraft, using a fully coupled nonlinear flight dynamics/aeroelastic model, when it operates in background atmospheric turbulence generated by the aforementioned models. Comparison of load envelopes and spectral content, on vehicles of varying flexibility, shows strong dependency between the selected turbulence model and aircraft aeroelastic response (e.g. 58% difference in the predicted magnitude of the wing root bending moment between LES and von Kármán models). This is mainly due to the presence of large flow structures at low altitudes that have comparable dimensions to the vehicle, and which despite the relatively small wind speeds within the Earth boundary layer, result in overall high load events. Results show that one-dimensional models that do not capture those effects provide fairly non-conservative load estimates and are unsuitable for very flexible airframe design.

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“…High-altitude long-endurance (HALE) aircrafts, which are being considered for aerial reconnaissance, long-time surveillance, environmental sensing and communication relays, have been the topic of modern flying vehicles [1]. Due to the energy and weight restrictions, HALE aircrafts, especially solar-powered aircrafts, notably feature very low wing-loading and ultra-light wing structure with high aspect-ratio.…”

Section: Introductionmentioning

confidence: 99%

A Comprehensive Framework for Coupled Nonlinear Aeroelasticity and Flight Dynamics of Highly Flexible Aircrafts

et al. 2020

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A framework to model and analyze the coupled nonlinear aeroelasticity and flight dynamics of highly flexible aircrafts is presented. The methodology is based on the dynamics of 3D co-rotational beams. The coupling of axial, bending and torsional effects is added to the stiffness and mass matrices of Euler-Bernoulli beam to capture the most relevant characteristics of a real wing structure. The finite-state aerodynamic model is coupled with the structural model to simulate the unsteady aerodynamics. A scheme of mixed end-point and mid-point time-marching algorithms is proposed and applied into the implicit predictor-corrector integration, where the end-point algorithm is used in the predictor step for efficiency and mid-point algorithm in corrector step for accuracy. The ground, body and airflow axes for flight dynamics are re-defined by the global and elemental ones for structural dynamics, followed by the redefinitions of local Euler angles and airflow angles of each element. The framework can be used for quick analyses of flexible aircrafts in conceptual and preliminary design phases, including linear and nonlinear trim, aerodynamic load estimation, stability assessment, time-domain simulations and flight performance evaluations. The results show the payload mass and its distributions will significantly affect the trim state and longitudinal stability of highly flexible aircrafts.

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On the capabilities and limitations of high altitude pseudo-satellites

Cited by 103 publications

References 99 publications

Development of a lightweight camera for high altitude platform systems

Development of a lightweight camera for high altitude platform systems

Assessment of low-altitude atmospheric turbulence models for aircraft aeroelasticity

A Comprehensive Framework for Coupled Nonlinear Aeroelasticity and Flight Dynamics of Highly Flexible Aircrafts

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