Investigation of the effect of variable tail dihedral on airplane stability and control

Kidd, James A.

doi:10.2514/6.1988-4335

Cited by 4 publications

(2 citation statements)

References 2 publications

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“…It has been observed that the three-dimensional panel technique can be used to regulate the aerodynamic loads for some airfoils at different angles of attack. During the analyses of the designed aircraft model with or without the body, using any of the three methods, i.e., LLT, 3D panels, or VLM methods, it has been established that all three methods can correctly predict the lift coefficient at zero moment value and the moment coefficient at zero lift with some exceptions [56,57]. Moreover, a tolerable trend of Cmα can also be obtained by using LLT or VLM methods.…”

Section: Xflr Analysis Techniquementioning

confidence: 99%

Estimation of Stability Parameters for Wide Body Aircraft Using Computational Techniques

et al. 2021

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In this paper, we present the procedure of estimating the aerodynamic coefficients for a commercial aviation aircraft from geometric parameters at low-cruise-flight conditions using US DATCOM (United States Data Compendium) and XFLR software. The purpose of this research was to compare the stability parameters from both pieces of software to determine the efficacy of software solution for a wide-body aircraft at the stated flight conditions. During the initial phase of this project, the geometric parameters were acquired from established literature. In the next phase, stability and control coefficients of the aircraft were estimated using both pieces of software in parallel. Results obtained from both pieces of software were compared for any differences and the both pieces of software were validated with analytical correlations as presented in literature. The plots of various parameters with variations of the angle of attack or control surface deflection have also been obtained and presented. The differences between the software solutions and the analytical results can be associated with approximations of techniques used in software (the vortex lattice method is the background theory used in both DATCOM and XFLR). Additionally, from the results, it can be concluded that XFLR is more reliable than DATCOM for longitudinal, directional, and lateral stability/control coefficients. Analyses of a Boeing 747-200 (a wide-body commercial airliner) in DATCOM and XFLR for complete stability/control analysis including all modes in the longitudinal and lateral directions have been presented. DATCOM already has a sample analysis of a previous version of the Boeing 737; however, the Boeing 747-200 is much larger than the former, and complete analysis was, therefore, felt necessary to study its aerodynamics characteristics. Furthermore, in this research, it was concluded that XFLR is more reliable for various categories of aircraft alike in terms of general stability and control coefficients, and hence many aircraft can be dependably modeled and analyzed in this software.

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Section: Xflr Analysis Techniquementioning

confidence: 99%

Estimation of Stability Parameters for Wide Body Aircraft Using Computational Techniques

et al. 2021

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“…By increasing tail dihedral aircraft directional static stability increases due to an addition in vertical projection area of the tail. On the other hand, increasing tail dihedral reduces longitudinal static stability due to reduction in horizontal projection area of the tail [3] Dihedral angle of the horizontal tail can be selected in such a way to provide adequate static longitudinal stability and directional stability. A horizontal tail with dihedral angle provides better stability and control characteristics if it is mounted above the vertical tail.…”

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confidence: 99%

Mathematical Modeling of Aircraft Flying Qualities with Varying Tail Dihedral

Khan¹

2019

IJMMM

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V-tail is a tail geometry setup that provides stability and controllability about longitudinal and directional axes simultaneously. In addition, the setup has less wetted area and interference, thus producing less drag as compared to conventional tails. The dihedral angle of a V-tail determines its contribution to both longitudinal and directional dynamics. However, there is no well-defined empirical method to compute the most suitable dihedral angle for a V-tail in order to meet the required flying qualities. This work presents a method to select the most appropriate dihedral angle of a V-tail to fulfill the requirements of aircraft flying qualities. Numerical calculations were used to generate a complete flight dynamics model with different tail dihedral angles. Subsequently, damping ratios for longitudinal and lateral-directional modes were extracted from these models. Using a curve fitting technique a polynomial was generated for longitudinal and lateral-directional damping ratios against tail dihedral angle. It was observed that by increasing the tail dihedral the longitudinal damping ratio was reduced. In addition, the lateral-directional damping ratio increased with the increase in tail dihedral angle. The lower bound of the tail dihedral angle was obtained using the lateral-directional damping limit in accordance to the flying qualities. Similarly, the upper bound of the tail dihedral angle was obtained using the longitudinal damping limit. The tail dihedral angle in between these bounds was found to be optimal for adequate longitudinal and lateraldirectional flying qualities. In addition, it was observed that the mathematical model was not valid for a different flight dynamics model. This is due to the change in aerodynamic behavior of the aircraft.

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Investigation of the Tail Dihedral Effects on the Aerodynamic Characteristics for the Low Speed Aircraft

Zhang

Chien

et al. 2013

Advances in Mechanical Engineering

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The aerodynamic characteristics for the vee-tail aircraft configuration have been investigated numerically at low Reynolds number (Re < 106). Three types of vee-tails have been adopted to be compared with the conventional tail type (with horizontal and vertical tails). The results show that the effect created by the vee-tail can greatly affect the aerodynamic characteristics of the whole aircraft. If the dihedral angle of the vee-tail is too large, it can directly affect the flight stability. The main reason for the longitudinal moment curve “moving up” at high dihedral angle can be attributed to the serious asymmetric downwash effect. Based on these, the force variation and the corresponding aerodynamic characteristics for three different sizes of aileron with different deflection angles have also been obtained computationally and analyzed in detail.

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Investigation of the effect of variable tail dihedral on airplane stability and control

Cited by 4 publications

References 2 publications

Estimation of Stability Parameters for Wide Body Aircraft Using Computational Techniques

Estimation of Stability Parameters for Wide Body Aircraft Using Computational Techniques

Mathematical Modeling of Aircraft Flying Qualities with Varying Tail Dihedral

Investigation of the Tail Dihedral Effects on the Aerodynamic Characteristics for the Low Speed Aircraft

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