• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.30 no.4
• /
• pp.57-64
• /
• 2022

A study on propllers for unmaned aerial vehicles is conducted using the open softwares. Since the shape of the propeller is closely related to the thurst characteristics of the propulsion system, adopting an appropriate propeller will significantly reflect stable aerodynamic performances. In this study, propellers for unmanned aerial vehicles were modeled by using OpenVSP and Propel for comparison, the thrust characteristics according to the number of blades and the diameter of the propeller were analyzed. In addition, the tendency of thrust characteristics according to various propeller pitch angles was confirmed. Based on the analysis results of this study, the applicability of the propeller shape to the design of the unmanned aerial vehicle was confirmed. It is shownthat the analysis results of this study can be utilized when modeling the propeller shape in research such as a conceptual design of unmanned aerial vehicle. In this case, it should be noted that OpenVSP does not involve the viscous effect of air.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.26 no.2
• /
• pp.149-158
• /
• 2023

To predict the aerodynamic characteristics of the grid fins from subsonic to supersonic speeds, low fidelity SW as well as CFD SW were applied. VLM(Vortex Lattice Method) and SE(Shock-Expansion) method were used at subsonic and supersonic speed domain respectively for the rapid prediction of low fidelity SW. For 2 configurations of the grid fins, the CFD computations and tests using the trisonic wind tunnel were also performed to compare the results of the grid fins. The results of low fidelity SW, CFD SW and the wind tunnel tests data were agreed well each other. Through further research on the grid fins, the effective parameters of the grid fin configurations according to the speed regime will be investigated.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.2
• /
• pp.156-162
• /
• 2008

The static aeroelastic analysis of composite hingeless rotor blades in hover was performed using free-wake method. Large deflection beam theory was applied to analyze blade motions as a one-dimension beam. Anisotropic beam theory was applied to perform a cross-sectional analysis for composite rotor blades. Aerodynamic loads were calculated through a three-dimensional aerodynamic model which is based on the unsteady vortex lattice method. The wake geometry in hover was described using a time-marching free-wake method. Numerical results of the steady-state deflections for the composite hingeless rotor blades were presented and compared with those results based on two-dimensional quasi-steady strip theory and prescribed wake method. It was shown that wakes affect the steady-state deflections.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.8
• /
• pp.695-702
• /
• 2012

In this study, Multi-fidelity analysis is performed to improve the accuracy of analysis result during conceptual design stage. Multidisciplinary Design Optimization(MDO) method is also considered to satisfy the total system requirements. Low-fidelity analysis codes which are based on empirical equations are developed and validated for analyzing the Unmanned Aerial Vehicle(UAV) which have unconventional configurations. Analysis codes consist of initial sizing, aerodynamics, propulsion, mission, weight, performance, and stability modules. Design synthesis program which is composed of those modules is developed. To improve the accuracy of the design method for UAV, Vortex Lattice Method is used for the strategy of MFA. Multi-Disciplinary Feasible(MDF) method is used for MDO technique. To demonstrate the validity of presented method, the optimization results of both methods are compared. According to those results, the presented method is demonstrated to be applicable to improve the accuracy of the analyses during conceptual design stage.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.44 no.6
• /
• pp.520-529
• /
• 2016

The main purpose of this study was to analyze the performance of a medium-altitude long endurance unmanned aerial vehicle through reverse-engineering method. The external configuration data of the RQ-1 Predator was reverse-engineered from related photos and specification data available on public domains, which also were used to generate the CATIA modeling and weigh distribution data of the UAV. The aerodynamic characteristics of RQ-1 Predator were mainly predicted the vortex lattice method and an empirical method, which the propeller performance was analyzed by the empirical method proposed by Howe. The rate of climb, service ceiling, range, and the loiter endurance of the UAV was analyzed, which showed good agreement with the reference data.

• Journal of the Society of Naval Architects of Korea
• /
• v.49 no.6
• /
• pp.528-533
• /
• 2012

Flexible composite propellers are subject to large deformation under heavy loading, and hence the hydrodynamic performance of deformed propeller might deviate from that of the metallic propeller under negligible deformation. To design the flexible propeller, it is therefore necessary to be able to evaluate the structural response of the blades to the hydrodynamic loadings, and then the influence of the blade deformation upon the hydrodynamic loadings. We use the lifting-surface-theory-based propeller analysis and design codes in solving the hydrodynamic problem, and the finite-element-method program formulated with 20-node iso-parametric solid elements for the analysis of the structural response. The two different hydrodynamic and structural programs are arranged to communicate through the carefully-designed interface scheme which leads to the derivation of the geometric parameters such as the pitch, the rake and the skew distributions common to both programs. The design of flexible propellers, suitable for manufacturing, is shown to perform the required thrust performance when deformed in operation. Sample design shows the fast iteration scheme and the robustness of the design procedure of the flexible propellers.

• Journal of the Society of Naval Architects of Korea
• /
• v.38 no.4
• /
• pp.11-22
• /
• 2001

The interaction between forward mounted propeller and wing in ground effect, and its aerodynamic performance are analyzed by potential flow approximation. A Vortex Lattice Method(VLM) for the propeller analysis and a potential based panel method for the WIG are used together with an image method by assuming the free surface as a rigid wall. The interaction of propeller and wing in the proximity of the ground is taken into account by an iterative procedure where the boundary conditions are satisfied with the given convergence criteria. The program developed is first checked by comparing its numerical results with the experimental data and other numerical results for the propeller MP101-rudder MR21 system. Then, the propeller-WIG interaction and its performance versus ground clearance are investigated by changing parameters such as propeller position, diameter and speed of revolution. It is shown that the forward mounted propeller increases the lift forces of the wing and also enhances the height stability, depending on the design parameter. Therefore, the appropriate selection of the design parameter such as propeller diameter, revolution, the longitudinal and vertical position of propeller is necessary.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.7
• /
• pp.479-487
• /
• 2022

This paper presents the control and guidance algorithm of a KAU-SPUAV(Korea Aerospace University - Solar Powered Unmanned Aerial Vehicle) which is designed and developed in Korea Aerospace University. Aerodynamic coefficients are calculated using the vortex-lattice method and applied to the aircraft's six degrees of freedom equation. In addition, the thrust and torque coefficients of the propeller are calculated using the blade element theory. An altitude controller using thrust was used for longitudinal control of KAU-SPUAV to glide efficiently when it comes across the upwind. Also describes wind estimation technic for considering wind effect during flight. Finally, introduce some guidance laws for endurance, mission and coping with strong headwinds and autonomous landing.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.47 no.7
• /
• pp.469-478
• /
• 2019

Multirotor configurations such as VTOL and urban air mobility have been focused on today due to the high maneuverability. Aerodynamic and aeroacoustic characteristics of multirotor have much difference to those of a single rotor. In this study, a numerical analysis based on the free wake vortex lattice method is used for identifying the wake interaction effect. In order to compare the various configurations and operating conditions, the effects of the spacing between the rotors in hovering flight and the effects of the advancing ratio and the formation in forward flight are discussed. In the hovering flight, the unsteady loading of multirotor changes periodically and loading fluctuation increases as decreasing the spacing. It causes the variation in unsteady loading noise and the noise directivity pattern. In the forward flight, the difference in loading fluctuation and noise characteristics are observed according to the diamond and square formation of rotors. By comparing with results of single rotor analysis, multirotor configurations have different directivity pattern and amplitude of loading noise according to the location of each rotor. As a result, wake interaction effect becomes a highly important factor for aerodynamic and aeroacoustic analysis according to multirotor configurations and operating conditions.