Large-scale design-economics optimization of eVTOL concepts for urban air mobility

Ha, Tae Hyon; Lee, Keunseok; Hwang, John T.

doi:10.2514/6.2019-1218

Cited by 11 publications

(5 citation statements)

References 13 publications

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“…For simplicity, we can treat both computing the objective and constraints, and computing the derivatives as one model evaluation because in efficient implementations, the computation times are similar. State-of-the-art LSDO methods can solve problems [5][6][7][8][9][10][11] with up to tens of thousands of design variables in only hundreds of model evaluations [12] as can be seen in Fig. 2.…”

Section: Optimizer Modelmentioning

confidence: 99%

Unifying Monolithic Architectures for Large-Scale System Design Optimization

Joshy

Hwang

2021

AIAA Journal

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Large-scale system design optimization is a numerical technique used in solving system design problems that involve a large number of design variables. These systems are often multidisciplinary, with many disciplines interacting with each other. The scale of these problems demands a gradient-based approach for efficient solutions, and it is often implemented by coupling an engineering model with an optimizer. A recently developed theory on multidisciplinary derivative computation has made it feasible to solve large-scale system design optimization problems in only hundreds of model evaluations. This has led to an increase in the number of applications for large-scale system design optimization with new applications still emerging. This paper presents a new optimization formulation that can further reduce the required number of model evaluations by unifying two widely used optimization architectures, namely, multidisciplinary feasible, and simultaneous analysis and design. Complex engineering systems that require solutions of large nonlinear systems can potentially benefit from this new formulation, and the optimized solutions can be reached in just tens of equivalent model evaluations. We demonstrate this order of magnitude improvement using a bar design problem. The paper also provides details on the practical implementation of this new formulation in an equality-constrained optimization setting.Nomenclature df dx = total derivative of a variable f with respect to a variable x ∂F ∂x = partial derivative of a function F with respect to a variable x

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Section: Optimizer Modelmentioning

confidence: 99%

Unifying Monolithic Architectures for Large-Scale System Design Optimization

Joshy

Hwang

2021

AIAA Journal

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“…(quoted from the website of a major aero-engines manufacturer, but reported in other studies). There are other examples in the technical literature claiming that eVTOL have the "potential of enabling point-to-point air travel in congested cities" (16) . Yet, this type of services is already available by helicopter, with several safety limitations, among which the rotor downwash is an important example.…”

Section: Fallacy #2: Urban Air Vehicles (Manned or Unmanned) Can Fly mentioning

confidence: 99%

“…Examples shown in the literature refer to the "Los Angeles area", or Dallas or San Francisco, which are not representative of the world at large (16,18) , since these large conurbations do not have a network of public transportation infrastructure that competes with the aircraft. In other reports we read that "consumers" would use a ride-sharing operation "to call VTOL to their desired pickup location and specify drop-off destinations at rooftops throughout a given city".…”

Section: Fallacy #2: Urban Air Vehicles (Manned or Unmanned) Can Fly mentioning

confidence: 99%

Rotorcraft systems for urban air mobility: A reality check

Filippone

Barakos

2020

Aeronaut. j.

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“Urban air vehicles” have been hailed as the next revolution in aviation. Prototypes of various sizes have been flown to demonstrate basic flight (hover and climb), but in most cases there is no demonstration of full flight capability, for example conversion from vertical to level flight (conversion corridor). There are proposals for vehicles in a wide range of scales: from drones specifically designed to deliver goods, to full size vehicles for manned transportation. Most of the concepts proposed include full electric propulsion, multiple (often convertible) rotors (ducted or un-ducted, counter-rotating), and widespread use of composite materials. Start-up companies are seeking funding with high-profile demonstrations in front of the media, but many unresolved technical problems are not been solved. Large aerospace companies have joined the fray. These initiatives are fuelling expectations that achieving the next milestone is within easy reach. This paper aims to fill some gaps in understanding and curb optimism. It takes a holistic view in order to establish a scientific basis for design, manufacturing, operations.

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“…Distributed electric propulsion vertical take‐off and landing (VTOL) aircraft have attracted widespread interest in the aerospace area and is thought to be relevant for the next generation of aircraft in development [1] due to their high overall efficiency and reliability [2]. Some advanced distributed electronic propulsion (DEP) VTOL aircraft have been proposed in recent years, such as the Lilium Jet [3] and DAPPAR Lightning Strike [4] equipped with tiltable ducted fans, Airbus Vahana [5] and NASA GL‐10 [6] with tiltable wings, and Joby S2 [7] with hybrid tiltable and fixed rotors.…”

Section: Introductionmentioning

confidence: 99%

A smooth control allocation method for a distributed electric propulsion VTOL aircraft test platform

Qin¹,

Liu²,

Zhao³

2023

IET Control Theory & Appl

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Distributed electronic propulsion (DEP) aircraft with vertical take-off and landing (VTOL) ability mostly equipped with multiple redundant tiltable propulsors, which are used to provide not only thrusts, but also control torque in all flight mode. The features make the control allocation problem of these aircraft both complex and important. Therefore, this paper proposes: (і) a prototype platform for DEP VTOL aircraft that allows researchers to design and analyse control allocation strategies, and (іі) a uniform hierarchical control allocation method that can be adapted to both MC and FW modes. The platform contains ten fully actuated thrusters, which are distributed in the scaled geometry of a typical DEP-VTOL aircraft. The proposed control allocation strategy uses hierarchical structure to avoid high-dimensional matrix operations for the redundant actuators. The additional constraints on the thrust and tilt angles of the actuators are addressed by adopting cascade generalized inversion (CGI) to force decompensation (FD)-based methods by a coordinate transformation. A novel smooth strategy through Schur Complement is also presented to achieve steady and smooth transition from MC to FW mode. Finally, the proposed method is implemented in the authors' novel platform in both simulations and flight experiments to demonstrate its effectiveness and smoothness.

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Large-scale design-economics optimization of eVTOL concepts for urban air mobility

Cited by 11 publications

References 13 publications

Unifying Monolithic Architectures for Large-Scale System Design Optimization

Unifying Monolithic Architectures for Large-Scale System Design Optimization

Rotorcraft systems for urban air mobility: A reality check

A smooth control allocation method for a distributed electric propulsion VTOL aircraft test platform

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