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1 – 10 of 352
Article
Publication date: 9 February 2015

Hoang Vu Phan, Quang-Tri Truong and Hoon-Cheol Park

The purpose of this paper is to demonstrate the uncontrolled vertical takeoff of an insect-mimicking flapping-wing micro air vehicle (FW-MAV) of 12.5 cm wing span with a body…

Abstract

Purpose

The purpose of this paper is to demonstrate the uncontrolled vertical takeoff of an insect-mimicking flapping-wing micro air vehicle (FW-MAV) of 12.5 cm wing span with a body weight of 7.36 g after installing batteries and power control.

Design/methodology/approach

The forces were measured using a load cell and estimated by the unsteady blade element theory (UBET), which is based on full three-dimensional wing kinematics. In addition, the mean aerodynamic force center (AC) was determined based on the UBET calculations using the measured wing kinematics.

Findings

The wing flapping frequency can reach to 43 Hz at the flapping angle of 150°. By flapping wings at a frequency of 34 Hz, the FW-MAV can produce enough thrust to over its own weight. For this condition, the difference between the estimated and average measured vertical forces was about 7.3 percent with respect to the estimated force. All parts for the FW-MAV were integrated such that the distance between the mean AC and the center of gravity is close to zero. In this manner, pitching moment generation was prevented to facilitate stable vertical takeoff. An uncontrolled takeoff test successfully demonstrated that the FW-MAV possesses initial pitching stability for takeoff.

Originality/value

This work has successfully demonstrated an insect-mimicking flapping-wing MAV that can stably takeoff with initial stability.

Details

International Journal of Intelligent Unmanned Systems, vol. 3 no. 1
Type: Research Article
ISSN: 2049-6427

Keywords

Article
Publication date: 11 April 2023

JingHui Deng, Jinhe Chen and ZhengZhong Wang

The paper aims to establish a comprehensive optimization analysis model for a helicopter roll on the ground and take off based on optimal control method. The trajectory and…

Abstract

Purpose

The paper aims to establish a comprehensive optimization analysis model for a helicopter roll on the ground and take off based on optimal control method. The trajectory and control of the entire process are studied, and the key factors affecting the helicopter takeoff distance are analyzed.

Design/methodology/approach

First, based on the equivalent stiffness and damping, the landing gear model is established, and a six-degree-of-freedom helicopter model is formed. Then, the simulation of the roll-on takeoff is transformed into a nonlinear optimal control problem (NOCP). Meanwhile, a hybrid single-multiple shooting method-based transcription process is used for discretizing the problem, leading to a finite nonlinear programming model, which is solved by sequential quadratic programming. Finally, the process was calculated and compared with flight test data, which verified the feasibility of the NOCP. The influence of takeoff weight, takeoff power and liftoff airspeed on the takeoff distance of the helicopter was analyzed.

Findings

The results show that the takeoff weight can be increased by 17% under the maximum takeoff power, which is roll-on takeoff at an altitude of 0 m. When the helicopter takes off with the maximum weight at an altitude of 5000 m, the liftoff airspeed should be over 49.2 km/h.

Originality/value

The novelty of this paper lies in the comprehensive consideration of helicopter taxiing and taking-off phases, and the application of optimal control theory to establish a comprehensive analysis model, which can quickly analyze the maximum takeoff weight, takeoff distance, optimal liftoff speed and so on. Meanwhile, the method is verified based on the flight data.

Details

Aircraft Engineering and Aerospace Technology, vol. 95 no. 6
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 26 July 2021

Liang Zhang, Liang Jing, Liheng Ye and Xing Gao

This paper aims to investigate the problem of attitude control for a horizontal takeoff and horizontal landing reusable launch vehicle.

Abstract

Purpose

This paper aims to investigate the problem of attitude control for a horizontal takeoff and horizontal landing reusable launch vehicle.

Design/methodology/approach

In this paper, a predefined-time attitude tracking controller is presented for a horizontal takeoff and horizontal landing reusable launch vehicle (HTHLRLV). Firstly, the attitude tracking error dynamics model of the HTHLRLV is developed. Subsequently, a novel sliding mode surface is designed with predefined-time stability. Furthermore, by using the proposed sliding mode surface, a predefined-time controller is derived. To compensate the external disturbances or model uncertainties, a fixed-time disturbance observer is developed, and its convergence time can be defined as a prior control parameter. Finally, the stability of the proposed sliding mode surface and the controller can be proved by the Lyapunov theory.

Findings

In contrast to other fixed-time methods, this controller only requires three control parameters, and the convergence time can be predefined instead of being estimated. The simulation results also demonstrate the effectiveness of the proposed controller.

Originality/value

A novel predefined-time attitude tracking controller is developed based on the predefined-time sliding mode surface (SMS) and fixed-time disturbance observer (FxTDO). The convergence time of the system can be selected as a prior control parameter for SMS and FxTDO.

Details

Aircraft Engineering and Aerospace Technology, vol. 93 no. 6
Type: Research Article
ISSN: 1748-8842

Keywords

Content available
Article
Publication date: 1 December 1998

99

Abstract

Details

Aircraft Engineering and Aerospace Technology, vol. 70 no. 6
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 1 September 1973

JOHN L. BEILMAN

MANY AIRCRAFT built in the last six decades have been deficient (or even failures) in accomplishing their primary missions because of unsuitable stability and/or control…

Abstract

MANY AIRCRAFT built in the last six decades have been deficient (or even failures) in accomplishing their primary missions because of unsuitable stability and/or control characteristics.

Details

Aircraft Engineering and Aerospace Technology, vol. 45 no. 9
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 3 August 2012

Mohammad Hasan Shojaeefard and Salar Askari

The purpose of this paper is to study flap application in the airfoil comprising a cross flow fan by experiment and numerical simulation.

Abstract

Purpose

The purpose of this paper is to study flap application in the airfoil comprising a cross flow fan by experiment and numerical simulation.

Design/methodology/approach

An airfoil was made and tested in a blowing wind tunnel. Because of complicated shape of the airfoil, distributed quantities in the flow field cannot be measured. They were computed by establishing a CFD code validated by the experimental data. The k‐ε model was used for the Reynolds stress modeling. Flow was considered incompressible, two dimensional and steady‐state. The pressure‐velocity coupling was performed by the SIMPLEC algorithm and convection terms were discretized by using the second‐order upwind discretization scheme.

Findings

Computed aerodynamic coefficients were in good agreement with the experimental results. Flap augmented lift and pitching moment coefficients of the airfoil considerably. It was perceived that the airfoil aerodynamic coefficients decrease with the Reynolds number, its lift and pitching moment coefficients increase and its drag coefficient decreases with the fan speed. Static pressure difference between the airfoil surfaces increased with the flap angle and consequently at higher flap angles it must have larger aerodynamic coefficients as proved by the experiments. This pressure difference increases with the Reynolds number that is equivalent to higher aerodynamic forces. It was shown by the numerical solution that surface pressure on the airfoil upper wall decreases with the fan speed while it is not sensitive to the fan speed on the airfoil bottom wall.

Originality/value

This is the first instance in which flap application in the airfoil with forced airflow provided by an integrated cross flow fan is studied.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 22 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 18 October 2011

Ngoc Anh Vu, Young‐Jae Lee, Jae‐Woo Lee, Sangho Kim and In Jae Chung

The purpose of this paper is to study the conceptual design and optimisation of a compound gyroplane. A study of a compound gyroplane configuration and its characteristics was…

Abstract

Purpose

The purpose of this paper is to study the conceptual design and optimisation of a compound gyroplane. A study of a compound gyroplane configuration and its characteristics was performed to develop a sizing program.

Design/methodology/approach

The vertical takeoff and landing capabilities of a helicopter are particularly important. The need for efficient hover and the effectiveness of forward flight in the helicopter can cause conflicts within the design process. The designers usually wish to increase the helicopter's maximum forward speed. Recently, the compound aircraft is one of the concepts considered for the purpose of expanding the flight envelope of rotorcraft. The study of the compound gyroplane showed its advance capabilities for this purpose. Understanding its characteristics, a number of calculations are conducted to implement a sizing program for compound gyroplanes based on the conventional helicopter sizing process.

Findings

The results of the sizing program were validated using existing aircraft data such as the Challis Heliplane, Carter Copter, FB‐1 Gyrodyne, and Jet Gyrodyne. The program is appropriate to size a compound gyroplane at the conceptual design phase. An optimisation study was also performed to enhance sizing results. The compromise between the rotor lift sharing factor and the ratio of the wing span (Bw) to rotor diameter (D) was solved by choosing the total gross weight (TOGW) as the objective function, while the design variables are compromising factors. The optimum results showed that the TOGW of all four kinds of compound gyroplanes was considerably reduced.

Originality/value

A conceptual sizing program for unconventional compound aircraft was developed. The study showed that an optimum design process is necessary to enhance the sizing results.

Details

Aircraft Engineering and Aerospace Technology, vol. 83 no. 6
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 6 January 2021

Navya Thirumaleshwar Hegde, V. I. George, C. Gurudas Nayak and Aldrin Claytus Vaz

This paper aims to provide a mathematical modeling and design of H-infinity controller for an autonomous vertical take-off and landing (VTOL) Quad Tiltrotor hybrid unmanned aerial…

Abstract

Purpose

This paper aims to provide a mathematical modeling and design of H-infinity controller for an autonomous vertical take-off and landing (VTOL) Quad Tiltrotor hybrid unmanned aerial vehicles (UAVs). The variation in the aerodynamics and model dynamics of these aerial vehicles due to its tilting rotors are the key issues and challenges, which attracts the attention of many researchers. They carry parametric uncertainties (such as non-linear friction force, backlash, etc.), which drives the designed controller based on the nominal model to instability or performance degradation. The controller needs to take these factors into consideration and still give good stability and performance. Hence, a robust H-infinity controller is proposed that can handle these uncertainties.

Design/methodology/approach

A unique VTOL Quad Tiltrotor hybrid UAV, which operates in three flight modes, is mathematically modeled using Newton–Euler equations of motion. The contribution of the model is its ability to combine high-speed level flight, VTOL and transition between these two phases. The transition involves the tilting of the proprotors from 90° to 0° and vice-versa in 15° intervals. A robust H-infinity control strategy is proposed, evaluated and analyzed through simulation to control the flight dynamics for different modes of operation.

Findings

The main contribution of this research is the mathematical modeling of three flight modes (vertical takeoff–forward, transition–cruise-back, transition-vertical landing) of operation by controlling the revolutions per minute and tilt angles, which are independent of each other. An autonomous flight control system using a robust H-infinity controller to stabilize the mode of transition is designed for the Quad Tiltrotor UAV in the presence of uncertainties, noise and disturbances using MATLAB/SIMULINK. This paper focused on improving the disturbance rejection properties of the proposed UAV by designing a robust H-infinity controller for position and orientation trajectory regulation in the presence of uncertainty. The simulation results show that the Tiltrotor achieves transition successfully with disturbances, noise and uncertainties being present.

Originality/value

A novel VTOL Quad Tiltrotor UAV mathematical model is developed with a special tilting rotor mechanism, which combines both aircraft and helicopter flight modes with the transition taking place in between phases using robust H-infinity controller for attitude, altitude and trajectory regulation in the presence of uncertainty.

Details

International Journal of Intelligent Unmanned Systems, vol. 9 no. 3
Type: Research Article
ISSN: 2049-6427

Keywords

Article
Publication date: 17 March 2023

Lutz Taubert, Garrett Kay, Israel Wygnanski and Michael Ol

This paper aims to address shortcomings of current tiltrotor designs, such as the small aspect ratio of the wings, large download and the close proximity of the rotor tips. It…

Abstract

Purpose

This paper aims to address shortcomings of current tiltrotor designs, such as the small aspect ratio of the wings, large download and the close proximity of the rotor tips. It also aims to avoid the complex transition of tiltrotors to normal airplane mode.

Design/methodology/approach

This design combines tiltrotor and tiltwing aircraft designs into a hybrid that is augmented by active flow control, using a gimbaled channel wing for attitude control in hover.

Findings

The proposed hybrid design is based on experimental results of components that were tested individually for potential use in hover and steep ascend from a stationary position.

Originality/value

This research was inspired by the extremely short take-off of the V-22, when its rotors were tilted forward. It combines several design approaches in a unique way to achieve extremely short take-off capabilities combined with high-speed and reduced maintenance costs.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 33 no. 4
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 6 May 2020

Federico Barra, Matteo Scanavino and Giorgio Guglieri

The primary purpose of this study is to analyse the performance of multirotor unmanned aircraft system platforms for passenger transport and compare them with an ordinary…

Abstract

Purpose

The primary purpose of this study is to analyse the performance of multirotor unmanned aircraft system platforms for passenger transport and compare them with an ordinary helicopter solution. This study aims to define a standard procedure for power budget analysis of unconventional vehicles recently proposed in the aerospace industry, providing guidelines on rotor sizing in terms of required power and the total number of rotors. The ultimate purpose of the proposed work is to describe a methodology for power estimation with regard to emerging electric vertical takeoff and landing (EVTOL) vehicles.

Design/methodology/approach

In the context of urban mobility, short-range passenger transport between critical hubs in cities is taken into account and innovative aircraft and traditional helicopters are compared according to a common mission profile. The power budget equations used in the helicopter literature are revisited to consider different multirotor configurations (up to 20 rotors) and evaluate the feasibility of innovative aerospace vehicle design.

Findings

The paper includes insights into the maximum number of rotors that ensure a significative, relative power reduction compared to helicopter platforms (the power-to-cruise over power-to-hover ratio appears to be improved). Based on this preliminary analysis, the results suggest the benefit of reducing the installed rotors to avoid excessive power loss in forward flight.

Practical implications

The proposed study provides guidelines for further design considerations and the future development of EVTOL multirotor aircraft.

Originality/value

This paper fulfils the identified need for a systematic approach on performance analysis for innovative vehicles involved in commercial applications.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 6
Type: Research Article
ISSN: 1748-8842

Keywords

1 – 10 of 352