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Article
Publication date: 27 September 2018

Miodrag Milenković-Babić

This paper aims to present the new information about propeller thrust force contribution to airplane longitudinal stability analysis.

Abstract

Purpose

This paper aims to present the new information about propeller thrust force contribution to airplane longitudinal stability analysis.

Design/methodology/approach

The method presented in this paper is empirical, shows how propeller thrust force derivative can be obtained and gives some additional information about misinterpretation of the propeller thrust effects that are present in the current literature.

Findings

New information about propeller thrust force contribution to airplane longitudinal stability analysis has been presented. This information should enable more precise insight in aircraft stability analysis and better understanding of the physical process that occurs during maneuver flight.

Practical implications

The information presented in this paper is new and specific to the propeller aircraft configuration. The methods used here are standard procedure to evaluating propeller thrust force derivative.

Originality/value

The information in this paper presents theoretical results. The method for calculating thrust force contribution to the airplane longitudinal stability is given depending on the propeller type and should enable good engineering results.

Details

Aircraft Engineering and Aerospace Technology, vol. 90 no. 9
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 11 May 2015

Waqas Khan and Meyer Nahon

The purpose of this paper is to develop a physics-based model for UAV propellers that is capable of predicting all aerodynamic forces and moments in any general forward flight…

1066

Abstract

Purpose

The purpose of this paper is to develop a physics-based model for UAV propellers that is capable of predicting all aerodynamic forces and moments in any general forward flight condition such as no flow, pure axial flow and pure side flow etc.

Design/methodology/approach

The methodology adopted in this paper is the widely used Blade Element Momentum Theory (BEMT) for propeller model development. The difficulty arising from the variation of induced flow with blade’s angular position is overcome by supplementing the BEMT with the inflow model developed by Pitt and Peters. More so, high angle of attack aerodynamics is embedded in the simulation as it is likely for the blades to stall in general forward flight, for example during extreme aerobatics/maneuvers.

Findings

The validity of the model is demonstrated via comparison with experiments as well as with other existing models. It is found that one of the secondary forces is negligible while the other is one order of magnitude less than the primary static thrust, and as such may be neglected depending on the level of accuracy required. On the other hand, both secondary moments must be considered as they are of similar order of magnitude as the primary static torque.

Research limitations/implications

The paper does not consider the swirl component of the induced flow under the assumption that it is negligible compared to the axial component.

Originality/value

This paper fulfills the identified need of a propeller model for general forward flight conditions, and aims to fill this void in the existing literature pertaining to UAVs.

Details

International Journal of Intelligent Unmanned Systems, vol. 3 no. 2/3
Type: Research Article
ISSN: 2049-6427

Keywords

Article
Publication date: 15 July 2021

Yang Liu, Qingwei Gong, Yongning Bian and Qinghui Suo

Hydrodynamic forces and efficiency of bare propeller and ducted propellers with a wide range of advance ratio (J) and attack angle (θ) are examined. The thrust and torque…

Abstract

Purpose

Hydrodynamic forces and efficiency of bare propeller and ducted propellers with a wide range of advance ratio (J) and attack angle (θ) are examined. The thrust and torque coefficients and the efficiency are presented and discussed in detail. The present results give a reliable guidance to the improvement of the hydrodynamic characteristics of ducted propellers.

Design/methodology/approach

The effect of a duct on the hydrodynamic performance of the KP458 propeller is numerically investigated in this study. Finite volume method (FVM)-based simulations are performed for a wide range of advance ratio J (0 ≤ J ≤ 0.75) and attack angle θ of the duct (15° ≤ θ ≤ 45°). A cubic computational domain is employed in this study, and the moving reference frame (MRF) approach is adopted to handle the rotation of the propeller. Turbulence is accounted for with the RNG k-ε model. The present numerical results are first compared against available experimental data and a good agreement is achieved.

Findings

The simulation results demonstrate that the hydrodynamic forces and efficiency increases and decreases with J, respectively, at the same attack angle. In addition, it is demonstrated that the hydrodynamic forces and efficiency are both improved due to the presence of the duct, which eventually leads a better hydrodynamic performance at high advance ratios. It is further revealed that as the attack angle increases, the pressure difference between the suction- and pressure-surfaces of the propeller is also augmented, which results in a larger thrust. The wake field is more uniform at θ = 30°, suggesting that a higher efficiency can be obtained.

Originality/value

The present study aims to investigate the effect of a duct on the KP458 propeller subjected to uniform inbound flow. The relationship between the uniform incoming flow and the attack angle of the duct is mainly focused, and the design of the ducted propellers for any ship hull can be improved according to this relationship.

Details

Engineering Computations, vol. 39 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 December 1951

M.L Wisniewski

This study aims at presenting one of the most important problems of aeroplane design, Static Longitudinal Stability, in a possibly complete but easy way.

Abstract

This study aims at presenting one of the most important problems of aeroplane design, Static Longitudinal Stability, in a possibly complete but easy way.

Details

Aircraft Engineering and Aerospace Technology, vol. 23 no. 12
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 17 May 2011

Matthew J. Traum

High autogyro accident rates prompted experimental investigation of this type of aircraft's low‐speed pitch characteristics. Pitch control is typically derived from main rotor…

Abstract

Purpose

High autogyro accident rates prompted experimental investigation of this type of aircraft's low‐speed pitch characteristics. Pitch control is typically derived from main rotor tip‐path‐plane adjustment. Thus, autogyro designers often omit horizontal tails and pitch control surfaces. The purpose of this paper is to enable autogyro low‐speed pitch control by intentionally placing elevators in the propeller wake.

Design/methodology/approach

Wind tunnel tests were conducted on a 1:10 scale teetering rotor autogyro model. The model included a horizontal tail with elevators placed in the propeller wake. Straight‐and‐level flight conditions were estimated via a scaling scheme based on the main rotor diameter. At minimum flight speed, the pitching moment induced by 30° elevator deflection was measured. This process was repeated for a range of elevator positions behind the centre of the pitching rotation.

Findings

When placed in an autogyro propeller wake, deflected elevators induce significant pitching moments. If the elevator is shadowed from free stream flow by the autogyro cowling, the pitching moment remains unchanged regardless of the distance between elevators and centre of pitch rotation. However, if the elevator is immersed in the freestream, the pitching moment increases via deflection of both propeller wake and freestream flow.

Research limitations/implications

Kinematic similarity ensures ratios between propeller wake, wind speed, and main rotor flows are representative of full scale. Without flow visualization, main‐rotor‐diameter‐based scaling does not ensure kinematic similarity. Results are therefore qualitative.

Practical implications

Elevators mounted in autogyro propeller wake are worthy of inclusion on all autogyros for pitch control at low speed.

Originality/value

Improved low‐speed pitch control arising from elevators mounted in autogyro propeller wake could potentially reduce accidents.

Details

Aircraft Engineering and Aerospace Technology, vol. 83 no. 3
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 2 January 2018

Yu Hu, Hailang Zhang and Gengqi Wang

This paper aims to investigate the mechanisms lying behind the cycloidal rotor under hovering status.

Abstract

Purpose

This paper aims to investigate the mechanisms lying behind the cycloidal rotor under hovering status.

Design/methodology/approach

Experiments were conducted to validate the numerical simulation results. The simulations were based on unsteady Reynolds-averaged Navier–Stokes (URANS) equations solver and the sliding mesh technique was used to model the blade motion. 2D and 2.5D simulations were made to investigate the 3D effects of turbulence. The effects of pressure and viscosity were compared to study the significance of the blade motion on force generation.

Findings

The 2.5D numerical simulation cannot produce more accurate results than the 2D counterpart. The pitching motion of the blade results in dynamic stall. The dynamic stall vortices induce parallel blade vortex interaction (BVI) upon downstream blades. The interactions between the blades delay the stall of the blade which is beneficial to the thrust generation. The blade pitching motion is the dominant contributor to the force generation and the turbulence is the secondary. Strong downwash in the rotor cage varied the inflow velocity as well as the effective angle of attack (AOA) of the blade.

Practical implications

Cycloidal rotor is a propulsion device that can provide omni-directional vectored thrust with high efficiency and low noise. To understand the mechanisms lying behind the cycloidal rotor helps the authors to design efficient cycloidal rotors for aircraft.

Originality/value

The authors discovered that the blade pitching motion plays primary role in force generation. The effects of the dynamic stall and BVI were studied. The reason why cycloidal rotor can be more efficient was discussed.

Details

Aircraft Engineering and Aerospace Technology, vol. 90 no. 1
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 8 February 2022

Mohamed Awad and Eike Stumpf

This research aims to present an aero-propulsive interaction model applied to conceptual aircraft design with distributed electric propulsion (DeP). The developed model includes a…

Abstract

Purpose

This research aims to present an aero-propulsive interaction model applied to conceptual aircraft design with distributed electric propulsion (DeP). The developed model includes a series of electric ducted fans integrated into the wing upper trailing edge, taking into account the effect of boundary layer ingestion (BLI). The developed model aims to estimate the aerodynamic performance of the wing with DeP using an accurate low-order computational model, which can be easily used in the overall aircraft design's optimization process.

Design/methodology/approach

First, the ducted fan aerodynamic performance is investigated using a low-order computational model over a range of angle of attack required for conventional flight based on ducted fan design code program and analytical models. Subsequently, the aero-propulsive coupling with the wing is introduced. The DeP location chordwise is placed at the wing's trailing edge to have the full benefits of the BLI. After that, the propulsion integration process is introduced. The nacelle design's primary function is to minimize the losses due to distortion. Finally, the aerodynamic forces of the overall configuration are estimated based on Athena Vortex Lattice program and the developed ducted fan model.

Findings

The ducted fan model is validated with experimental measurements from the literature. Subsequently, the overall model, the wing with DeP, is validated with experimental measurements and computational fluid dynamics, both from the literature. The results reveal that the currently developed model successfully estimates the aerodynamic performance of DeP located at the wing trailing edge.

Originality/value

The developed model's value is to capture the aero-propulsive coupling accurately and fast enough to execute multiple times in the overall aircraft design's optimization loop without increasing runtime substantially.

Details

Aircraft Engineering and Aerospace Technology, vol. 94 no. 6
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 10 June 2021

Witold Artur Klimczyk

This paper aims to present a methodology of designing a custom propeller for specified needs. The example of propeller design for large unmanned air vehicle (UAV) is considered.

Abstract

Purpose

This paper aims to present a methodology of designing a custom propeller for specified needs. The example of propeller design for large unmanned air vehicle (UAV) is considered.

Design/methodology/approach

Starting from low fidelity Blade Element (BE) methods, the design is obtained using evolutionary algorithm-driven process. Realistic constraints are used, including minimum thickness required for stiffness, as well as manufacturing ones – including leading and trailing edge limits. Hence, the interactions between propellers in hex-rotor configuration, and their influence on structural integrity of the UAV are investigated. Unsteady Reynolds-Averaged Navier–Stokes (URANS) are used to obtain loading on the propeller blades in hover. Optimization of the propeller by designing a problem-specific airfoil using surrogate modeling-driven optimization process is performed.

Findings

The methodology described in the current paper proved to deliver an efficient blade. The optimization approach allowed to further improve the blade efficiency, with power consumption at hover reduced by around 7%.

Practical implications

The methodology can be generalized to any blade design problem. Depending on the requirements and constraints the result will be different.

Originality/value

Current work deals with the relatively new class of design problems, where very specific requirements are put on the propellers. Depending on these requirements, the optimum blade geometry may vary significantly.

Details

Aircraft Engineering and Aerospace Technology, vol. 94 no. 1
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 1 October 1959

Milton A. Schwartzberg

There has been some speculation anions STOL aircraft designers (hat a net increase in lift might be realized from a combination of blown flap and slip‐stream deflexion. A recent…

Abstract

There has been some speculation anions STOL aircraft designers (hat a net increase in lift might be realized from a combination of blown flap and slip‐stream deflexion. A recent wind tunnel investigation confirms the speculation for large flap deflexions. At small flap deflexions, however, the lift gained by the combination is less than the sum of the separate contributions. The effect at medium flap deflexion is dependent on the strength of the slipstream. These results should be applicable to most configurations with a blown plain flap in the slipstream behind the propellers.

Details

Aircraft Engineering and Aerospace Technology, vol. 31 no. 10
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 August 1959

J.F. Harriman

THE engine and propeller when installed in an airframe transmit various loads to the aircraft structure through the engine mounting. These can be grouped as follows:

Abstract

THE engine and propeller when installed in an airframe transmit various loads to the aircraft structure through the engine mounting. These can be grouped as follows:

Details

Aircraft Engineering and Aerospace Technology, vol. 31 no. 8
Type: Research Article
ISSN: 0002-2667

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