scholarly journals The Effects of Icing on Aircraft Longitudinal Aerodynamic Characteristics

Mathematics ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 1171
Author(s):  
Yihua Cao ◽  
Wenyuan Tan ◽  
Yuan Su ◽  
Zhongda Xu ◽  
Guo Zhong
Keyword(s):  
Prediction Method ◽  
Flight Test ◽  
Aerodynamic Characteristics ◽  
Identification System ◽  
Narrow Strip ◽  
Aerodynamic Derivatives ◽  
Strip Theory ◽  
Aerodynamic Parameters ◽  
Flight Dynamics Model ◽  
Derivatives Of

To study the effects of ice accretion on the longitudinal aerodynamic characteristics of an aircraft, a two-part method for predicting longitudinal aerodynamic derivatives of iced aircraft is proposed. For the aircraft with a flight test, a parameter identification system based on maximum likelihood criterion and a longitudinal nonlinear flight dynamics model is established. For the aircraft without a flight test, an engineering prediction method of aerodynamic derivatives based on an individual component CFD calculation and narrow strip theory is established. According to the flight test data of DHC-6 Twin Otter aircraft from NASA, the longitudinal aerodynamic parameters of both clean and artificially iced aircraft are obtained. Additionally, the longitudinal aerodynamic derivatives of the iced aircraft are calculated. Then, the correctness of the prediction method is verified by comparing the calculated results with the identification results. The comparison of these results shows that the prediction method is correct and accurate, and it can be used to calculate the effects of icing on the aircraft longitudinal aerodynamic parameters.

Parameter Identification of Tailplane Iced Aircraft Based on Maximum Likelihood Method

2012 ◽  
Vol 192 ◽  
pp. 57-62 ◽  
Author(s):  
Zhong Da Xu ◽  
Yi Hua Cao ◽  
Ming Zhao
Keyword(s):  
Maximum Likelihood ◽  
Parameter Identification ◽  
Maximum Likelihood Method ◽  
Flight Test ◽  
Likelihood Method ◽  
Identification System ◽  
Flight Performance ◽  
Aerodynamic Parameters ◽  
Flight Dynamics Model ◽  
Ice Shapes

Based on the maximum likelihood method, this paper analyzed the influence of tailplane icing on aerodynamic parameters by parameter identification. A nonlinear longitudinal flight dynamics model for aircraft was built, and an identification system was constructed using maximum likelihood method. According to the flight test data of DHC-6 aircraft, the aerodynamic parameters of clean aircraft and two different cases of iced aircraft with particular ice shapes on the tailplane were identified. Eventually, the results of the identification show that the tailplane icing has several adverse effects on the aircraft flight characteristics, including flight performance, elevator effectiveness, stability and safety.

Identification of Aerodynamic Derivatives of a Flexible Aircraft Using Output Error Method

2011 ◽  
Vol 110-116 ◽  
pp. 5328-5335 ◽  
Author(s):  
M. Majeed ◽  
Indra Narayan Kar
Keyword(s):  
Simulated Data ◽  
Flight Test ◽  
Longitudinal Axis ◽  
Model Structure ◽  
Order Model ◽  
Elastic Mode ◽  
Output Error ◽  
Aerodynamic Derivatives ◽  
Derivatives Of ◽  
Error Method

A full order model of an aeroelastic aircraft has too many parameters to yield satisfactory estimates. In this paper, using simulated data, rigid body and aeroelastic derivatives are estimated in longitudinal axis for single elastic mode. The proposed approach uses an integrated model structure. It emphasizes the use of estimation techniques that have the capability to accurately determine modal characteristics in those flight test situations where the measured data is dominated by elastic effects. Output error method in time domain is applied to the simulated flight data to identify the aircraft derivatives.

scholarly journals Method for designing multi-input system identification signals using a compact time-frequency representation

2021 ◽  
Author(s):  
Mathias Stefan Roeser ◽  
Nicolas Fezans
Keyword(s):  
System Identification ◽  
Design Method ◽  
Flight Test ◽  
Compact Representation ◽  
Time Frequency ◽  
Stability And Control ◽  
Frequency Representation ◽  
Aerodynamic Parameters ◽  
Definition Of ◽  
And Control

AbstractA flight test campaign for system identification is a costly and time-consuming task. Models derived from wind tunnel experiments and CFD calculations must be validated and/or updated with flight data to match the real aircraft stability and control characteristics. Classical maneuvers for system identification are mostly one-surface-at-a-time inputs and need to be performed several times at each flight condition. Various methods for defining very rich multi-axis maneuvers, for instance based on multisine/sum of sines signals, already exist. A new design method based on the wavelet transform allowing the definition of multi-axis inputs in the time-frequency domain has been developed. The compact representation chosen allows the user to define fairly complex maneuvers with very few parameters. This method is demonstrated using simulated flight test data from a high-quality Airbus A320 dynamic model. System identification is then performed with this data, and the results show that aerodynamic parameters can still be accurately estimated from these fairly simple multi-axis maneuvers.

Three-Dimensional Aerodynamic Characteristics of Oscillating Supersonic and Transonic Annular Cascades

1982 ◽  
Author(s):  
M. Namba ◽  
A. Ishikawa
Keyword(s):  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Forces ◽  
Numerical Work ◽  
Dimensional Effects ◽  
Mathematical Expressions ◽  
Strip Theory ◽  
Clear Insight ◽  
Theory Approximation ◽  
Insight Into

A lifting surface theory is developed for unsteady three-dimensional flow in rotating subsonic, transonic and supersonic annular cascades with fluctuating blade loadings. Application of a finite radial eigenfunction series approximation not only affords a clear insight into the three-dimensional structures of acoustic fields but also provides mathematical expressions advantageous to numerical work. The theory is applied to oscillating blades. Numerical examples are presented to demonstrate three-dimensional effects on aerodynamic characteristics. Three-dimensional effects in supersonic cascades are generally small and strip theory predicts local aerodynamic forces as well as total aerodynamic forces with good accuracy. In transonic flow, however, the strip theory approximation breaks down near the sonic span station and three-dimensional effects are of primary importance.

scholarly journals Identification of Fixed-Wing Micro Aerial Vehicle Aerodynamic Derivatives from Dynamic Water Tunnel Tests

Aerospace ◽  
2020 ◽  
Vol 7 (8) ◽  
pp. 116
Author(s):  
Krzysztof Sibilski ◽  
Mirosław Nowakowski ◽  
Dariusz Rykaczewski ◽  
Paweł Szczepaniak ◽  
Andrzej Żyluk ◽  
...  
Keyword(s):  
Unsteady Aerodynamics ◽  
Linear Functions ◽  
Water Tunnel ◽  
Micro Aerial Vehicle ◽  
Indicial Function ◽  
Reduced Frequency ◽  
Aerodynamic Derivatives ◽  
Aerial Vehicle ◽  
Institute Of Technology ◽  
Derivatives Of

A micro air vehicle (MAV) is a class of miniature unmanned aerial vehicles that has a size restriction and may be autonomous. Fixed-wing MAVs are very attractive for outdoor surveillance missions since they generally offer better payload and endurance capabilities than rotorcraft or flapping-wing vehicles of equal size. This research paper describes the methodology applying indicial function theory and artificial neural networks for identification of aerodynamic derivatives for fixed-wing MAV. The formulation herein proposed extends well- known aerodynamic theories, which are limited to thin aerofoils in incompressible flow, to strake wing planforms. Using results from dynamic water tunnel tests and indicial functions approach allowed to identify MAV aerodynamic derivatives. The experiments were conducted in a water tunnel in the course of dynamic tests of periodic oscillatory motion. The tests program range was set at high angles of attack and a wide scope of reduced frequencies of angular movements. Due to a built-in propeller, the model’s structure test program was repeated for a turned-on propelled drive system. As a result of these studies, unsteady aerodynamics characteristics and aerodynamic derivatives of the micro-aircraft were identified as functions of state parameters. At the Warsaw University of Technology and the Air Force Institute of Technology, a “Bee” fixed wings micro aerial vehicle with an innovative strake-wing outline and a propeller placed in the wing gap was worked. This article is devoted to the problems of identification of aerodynamic derivatives of this micro-aircraft. The result of this research was the identification of the aerodynamic derivatives of the fixed wing MAV “Bee” as non-linear functions of the angle of attack, and reduced frequency. The identification was carried out using the indicial function approach.

Response in Yaw

1946 ◽  
Vol 50 (424) ◽  
pp. 275-286 ◽  
Author(s):  
E. J. N. Archbold ◽  
Kieran T. McKenzie
Keyword(s):  
Equations Of Motion ◽  
General Curve ◽  
Aerodynamic Derivatives ◽  
Derivatives Of

SummaryIf the motion of an aircraft is restricted, near the ground, to zero bank, comparatively simple solutions to the resulting equations of motion can be obtained, enabling the response to an applied yawing moment to be calculated rapidly. In this paper the analysis is made for three simple forms of applied yawing moment. From the results obtained in a particular case it is possible to judge the suitability of the fin and rudder design chosen on the basis of maximum sideslip reached. A general curve of overswing, in terms of the aerodynamic derivatives of the aircraft, enables the maximum sideslip to be calculated rapidly in a particular case.Because of typogiaphical difficulties the symbols ^ have been replaced by ° with v, r and t throughout the paper.

Rapid computation of rotary derivatives for subsonic and low transonic flows

2019 ◽  
Vol 36 (9) ◽  
pp. 3108-3121
Author(s):  
Jian-Ming Fu ◽  
Hai-Min Tang ◽  
Hong-Quan Chen
Keyword(s):  
Mach Number ◽  
Normal Velocity ◽  
New Approach ◽  
Content Type ◽  
Strip Theory ◽  
Model Aircraft ◽  
Computational Fluid Dynamics Cfd ◽  
Steady Solutions ◽  
State Pressure ◽  
Derivatives Of

Purpose The purpose of this paper is to develop a new approach for rapid computation of subsonic and low-transonic rotary derivatives with the available steady solutions obtained by Euler computational fluid dynamics (CFD) codes. Design/methodology/approach The approach is achieved by the perturbation on the steady-state pressure of Euler CFD codes. The resulting perturbation relation is established at a reference Mach number between rotary derivatives and normal velocity on surface due to angular velocity. The solution of the reference Mach number is generated technically by Prandtl–Glauert compressibility correction based on any Mach number of interest under the assumption of simple strip theory. Rotary derivatives of any Mach number of interest are then inversely predicted by the Prandtl–Glauert rule based on the reference Mach number aforementioned. Findings The resulting method has been verified for three typical different cases of the Basic Finner Reference Projectile, the Standard Dynamics Model Aircraft and the Orion Crew Module. In comparison with the original perturbation method, the performance at subsonic and low-transonic Mach numbers has significantly improved with satisfactory accuracy for most design efforts. Originality/value The approach presented is verified to be an efficient way for computation of subsonic and low-transonic rotary derivatives, which are performed almost at the same time as an accounting solution of steady Euler equations.

Identification of aerodynamic derivatives of bridge decks at high testing wind speed

2018 ◽  
Vol 45 (11) ◽  
pp. 1004-1014
Author(s):  
Quanshun Ding ◽  
Shuanghu Dong ◽  
Zhiyong Zhou
Keyword(s):  
Wind Speed ◽  
Wind Tunnel Test ◽  
Participation Rate ◽  
Single Mode ◽  
High Wind ◽  
Wind Speeds ◽  
Aerodynamic Derivatives ◽  
Vibration Responses ◽  
Mode Extraction ◽  
Derivatives Of

An identification of eight aerodynamic derivatives based on dual-mode and single-mode extraction of system is presented to improve the applicability and accuracy of identification at high testing wind speed. The participation rate to measure the contribution of modes on free-vibration responses is defined and the single-mode extraction is presented to extract the modal parameters of the system at high wind speed. To verify the reliability and applicability of the presented method, the aerodynamic derivatives of a dummy section with known self-excited forces are identified. It is noted that there is a very good agreement between the identified results and the target ones in the range of the low and high wind speeds and the presented method works well after the critical state of flutter. The sectional wind tunnel test of the Tanggu-haihe bridge is performed to identify the aerodynamic derivatives of the deck at the attack angles of −3°, 0°, and 3°.

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