A gas bearing pivot, operational in vacuum, for measuring aerodynamic derivatives of wings in hypersonic flow

1976 ◽  
Vol 9 (2) ◽  
pp. 93-94
Author(s):  
K Ghosh
Keyword(s):  
Hypersonic Flow ◽  
Aerodynamic Derivatives ◽  
Gas Bearing ◽  
Derivatives Of

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.

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.

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.

Stability Derivatives of Sharp Wedges in Viscous Hypersonic Flow

1971 ◽  
Vol 22 (2) ◽  
pp. 127-145 ◽  
Author(s):  
W. H. Hui ◽  
R. A. East
Keyword(s):  
Boundary Layer ◽  
Perturbation Method ◽  
Hypersonic Flow ◽  
Bow Shock ◽  
Vertex Angle ◽  
Reflected Waves ◽  
Displacement Boundary ◽  
Stability Derivatives ◽  
Viscous Hypersonic Flow ◽  
Derivatives Of

SummaryUsing a perturbation method, the formulae for the pitching stability derivatives of sharp wedges at zero incidence in viscous hypersonic flow are obtained in closed form. The results include the effect of unsteady reflected waves from the bow shock and may be applied to any wedge provided that the bow shock is attached. The effect of viscosity of the gas is included in two parts: first, it thickens the wedge, thus introducing the concept of an effective wedge, thicker than the original wedge by a semi-vertex angle equal to the average inclination of the displacement boundary layer; secondly, it makes this effective wedge deformable. Comparison with previous theories is given.

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°.

Aerodynamic pitching derivatives of a wedge in hypersonic flow

AIAA Journal ◽  
1964 ◽  
Vol 2 (11) ◽  
pp. 2034-2036 ◽  
Author(s):  
J. P. APPLETON
Keyword(s):  
Hypersonic Flow ◽  
Derivatives Of
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