Wind Tunnel Flutter Testing of a Highly Swept All-Movable Wing with a Control Surface

2016 ◽  
Author(s):  
Dale M. Pitt ◽  
Bradley Sexton ◽  
KwanHwa Byun
Keyword(s):  
Wind Tunnel ◽  
Control Surface ◽  
Flutter Testing

scholarly journals Airfoil Selection Procedure, Wind Tunnel Experimentation and Implementation of 6DOF Modeling on a Flying Wing Micro Aerial Vehicle

Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 553 ◽  
Author(s):  
Taimur Ali Shams ◽  
Syed Irtiza Ali Shah ◽  
Ali Javed ◽  
Syed Hossein Raza Hamdani
Keyword(s):  
Wind Tunnel ◽  
Equations Of Motion ◽  
Selection Procedure ◽  
Leading Edge ◽  
Control Surface ◽  
Flight Tests ◽  
Micro Aerial Vehicle ◽  
Aerial Vehicle ◽  
P Factor ◽  
Control Surfaces

Airfoil selection procedure, wind tunnel testing and an implementation of 6-DOF model on flying wing micro aerial vehicle (FWMAV) has been proposed in this research. The selection procedure of airfoil has been developed by considering parameters related to aerodynamic efficiency and flight stability. Airfoil aerodynamic parameters have been calculated using a potential flow solver for ten candidate airfoils. Eppler-387 proved to be the most efficient reflexed airfoil and therefore was selected for fabrication and further flight testing of vehicle. Elevon control surfaces have been designed and evaluated for longitudinal and lateral control. The vehicle was fabricated using hot wire machine with EPP styrofoam of density 50 Kg/ m 3 . Static aerodynamic coefficients were evaluated using wind tunnel tests conducted at cruise velocity of 20 m/s for varying angles of attack. Rate derivatives and elevon control derivatives have also been calculated. Equations of motion for FWMAV have been written in a body axis system yielding a 6-DOF model. It was found during flight tests that vehicle conducted coordinated turns with no appreciable adverse yaw. Since FWMAV was not designed with a vertical stabilizer and rudder control surface, directional stability was therefore augmented through winglets and high wing leading edge sweep. Major problems encountered during flight tests were related to left rolling tendency. The left roll tendency was found inherent to clockwise rotating propeller as ‘P’ factor, gyroscopic precession, torque effect and spiraling slipstream. To achieve successful flights, many actions were required including removal of excessive play from elevon control rods, active actuation of control surfaces, enhanced launch speed during take off, and increased throttle control during initial phase of flight. FWMAV flew many successful stable flights in which intended mission profile was accomplished, thereby validating the proposed airfoil selection procedure, modeling technique and proposed design.

Supersonic Unstalled Flutter In Fan Rotors; Analytical and Experimental Results

1974 ◽  
Vol 96 (4) ◽  
pp. 379-386 ◽  
Author(s):  
L. E. Snyder ◽  
G. L. Commerford
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Reduced Frequency ◽  
Cascade Analysis ◽  
Blade Shape ◽  
Supersonic Flutter ◽  
Transonic Fan ◽  
Flutter Testing ◽  
Stagger Angle ◽  
Interblade Phase Angle

Supersonic unstalled flutter is predicted using an unsteady supersonic cascade analysis, a cascade wind tunnel and a high speed fan rotor. Since the unsteady analysis assumes thin flat plate airfoils, the effect of thickness and blade shape was examined experimentally by flutter testing two sets of supersonic blading in a cascade wind tunnel. The effects of changes in Mach number, reduced frequency, stagger angle and interblade phase angle were examined from the analysis and tests. Results show that the trends are in agreement, but that blade shape has an effect on the level of reduced velocity at the incipient flutter point. The unsteady aerodynamic analysis is applied to two transonic fan stages. The first rotor was designed as a supersonic flutter test vehicle while the second was designed to be flutter free. Results of the fan tests show that the analysis correctly predicts the susceptibility to flutter of each rotor.

scholarly journals The Challenge of Controlling a Small Mars Plane

2020 ◽  
Author(s):  
Seiki Chiba ◽  
Mikio Waki
Keyword(s):  
Wind Tunnel ◽  
Power Control ◽  
High Power ◽  
Structural Model ◽  
High Efficiency ◽  
Wind Tunnel Test ◽  
Martian Atmosphere ◽  
Planetary Exploration ◽  
Control Surface ◽  
Dielectric Elastomers

Dielectric elastomers (DEs) are lightweight and high-power, making them ideal for power control in a planetary exploration spacecraft. In this chapter, we will discuss the control of an exploration airplane exploring the surface of Mars using DEs. This airplane requires lightweight and powerful actuators to fly in the rare Martian atmosphere. DEs are a possible candidate for use as actuator controlling the airplane since they have high power, and high efficiency. A structural model of a wing having a control surface, a DE, and a linkage was built and a wind tunnel test of a control surface actuation using a DE actuator was carried out.

Nonlinear Dynamics of Aeroelastic Systems

2000 ◽  
Author(s):  
Earl H. Dowell
Keyword(s):  
Wind Tunnel ◽  
Delta Wing ◽  
Free Play ◽  
Physical Models ◽  
Forced Oscillations ◽  
Control Surface ◽  
Dynamical Response ◽  
Wind Tunnel Experiments ◽  
Nonlinear Dynamical ◽  
Flight Regimes

Abstract Aeroelastic systems are those that involve the coupled interaction between a convecting fluid and a flexible elastic structure. The nonlinear dynamical response of such systems is of great current interest. Existing aircraft are known to encounter limit cycle oscillations (LCO) in certain flight regimes, and relatively simple experimental wind tunnel models have been designed to exhibit LCO as well. In the present paper, the results of these wind tunnel experiments are discussed and compared to comparable results from mathematical models. The physical models include (1) an airfoil and a control surface attached with an elastic spring including free-play and (2) a delta wing with elastic geometrical nonlinearities due to bending and torsional deformations. Both self-excited oscillations such as flutter and LCO, as well as forced oscillations due to an aerodynamic gust, are discussed. The advantages of representing the unsteady aerodynamic flow field in terms of global modes for such studies are emphasized and illustrated.

Wind Tunnel Testing of Composite Wing Flutter Speed due to Control Surface Excitation

2013 ◽  
Vol 315 ◽  
pp. 359-363 ◽  
Author(s):  
Mahzan Muhammad Iyas ◽  
Muhamad Sallehuddin ◽  
Mat Ali Mohamed Sukri ◽  
Mansor Mohd Shuhaimi
Keyword(s):  
Wind Tunnel ◽  
Dynamic Instability ◽  
Wind Tunnel Test ◽  
Control Surface ◽  
Wind Tunnel Testing ◽  
Structural Stiffness ◽  
Wing Flutter ◽  
Flutter Speed ◽  
Surface Excitation ◽  
Composite Wing

Flutter is a dynamic instability problem represents the interaction among aerodynamic forces and structural stiffness during flight. The study was conducted to investigate whether deflecting the control surface will affect the flutter speed and the flutter frequency. A wind tunnel test was performed using a flat plate wing made of composite material. It was found that by deflecting the control surface at 45°, the wing entered flutter state at wind speed of 28.1 m/s instead of 33.4 m/s. In addition, the flutter frequency also reduced from 224.52 Hz to 198.96 Hz. It was concluded that by deflecting the control surface, the wing experienced flutter at lower speed and frequency.

Composite Wing Flutter Speed and Frequency due to Variable Control Surface Deflection in Low Speed Wind Tunnel

2013 ◽  
Vol 390 ◽  
pp. 3-7
Author(s):  
Muhammad Iyas Mahzan ◽  
Sallehuddin Muhamad ◽  
Sa’ardin Abdul Aziz ◽  
Mohamed Sukri Mat Ali
Keyword(s):  
Wind Tunnel ◽  
Dynamic Instability ◽  
Wind Tunnel Test ◽  
Control Surface ◽  
Wing Flutter ◽  
Flutter Speed ◽  
Surface Deflection ◽  
Relationship Of ◽  
Low Speed Wind Tunnel ◽  
The Relationship

Flutter is a dynamic instability problem represents the interaction among structural, aerodynamic, elastic and inertial forces and occurred when the energy is continuously transformed by the surrounding fluids to a flying structure in the form of kinetic energy. The study was conducted to investigate the relationship of the control surface deflection angle to the flutter speed and the flutter frequency. A wind tunnel test was performed using a flat plate wing made of composite material. It was found that by deflecting the control surface up to 45°, the flutter speed reduced almost linearly from 35.6 m/s to 22.7 m/s. The flutter frequency greatly reduced from 48 Hz without the control surface deflected to 34 Hz with the control surface deflected at 15°. After 15° deflection up to 45°, the flutter frequency reduced almost linearly.

Optimal Excitation for Aircraft Flutter Testing

1995 ◽  
Vol 209 (4) ◽  
pp. 313-325 ◽  
Author(s):  
A P Burrows ◽  
J R Wright ◽  
J A Coote
Keyword(s):  
Wind Tunnel ◽  
Signal Amplitude ◽  
Frequency Range ◽  
Wind Tunnel Model ◽  
Variable Amplitude ◽  
Excitation Signal ◽  
Tunnel Model ◽  
Optimal Excitation ◽  
Variable Power ◽  
Flutter Testing

The choice of excitation signal for flutter testing of a full-scale aircraft or wind tunnel model is crucial if the flutter test clearance is to be performed quickly and with confidence. The use of chirps (that is, sinusoidal signals with varying frequency) is commonplace but has limitations. In this paper the idea of a simple chirp is extended to the development of a multi-sectional variable amplitude/variable power chirp in which the relative signal amplitude and power between sections may be specified over the frequency range of interest. An optimal chirp for a particular application may thus be designed. Sample results from a wind tunnel model flutter test are presented. In addition, the practice of sweeping up and then down in frequency is shown to be inadvisable under certain circumstances.

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