Aerodynamic Characteristics and Longitudinal Stability of Tube Launched Tandem-Scheme UAV

Experimental Investigation of the Ground Effect of WIG Craft—NEW1 Model

Proceedings ◽

10.3390/proceedings2019039017 ◽

2020 ◽

Vol 39 (1) ◽

pp. 17

Author(s):

Sakornsin ◽

Thipyopas ◽

Atipan

Keyword(s):

Lift Coefficient ◽

Ground Surface ◽

Ground Effect ◽

Aerodynamic Characteristics ◽

Scale Model ◽

Negative Slope ◽

Stream Velocity ◽

Longitudinal Stability ◽

Moment Coefficient ◽

The Moment

Navy Experimental Wing-in-Ground-Effect (WIG) craft namely as NEW1, is the first version of 2-seated WIG craft which has been designed and developed by Royal Thai Navy since 2017. This experimental research is a part of the NEW1 project which aims to investigate the aerodynamic characteristics and aspects of the flow passing through the WIG craft model when in ground effect. In the experiment, the WIG craft—NEW1 of 1:15 scale model is tested in a close circuit wind tunnel of 1 m × 1 m test section at Kasetsart University. The tests are conducted at the free stream velocity of 40 m/s or Reynolds number of 280,000, at angles of attack ranging from −9° to 21°, and at the wing to ground distances ranging from 5.0 C to 0.3 C. The measurement of 6-DoF of forces and moments and pressure distributions on the ground surface underneath the WIG craft model are made during the tests. The results show that the ground has significant effects on the aerodynamic characteristics of the WIG craft model when the wing to ground distance is less than its mean chord. It was found that when the model move from 5.0 C (out of ground effect) to 0.3 C, the lift coefficient increases up to 15.7%, the drag coefficient decreases up to 5.6%, and the lift to drag ratio increases 33.4%. The proximity of the model to the ground also affects the longitudinal stability of the model. The moment coefficient curves against angle of attack has negative slope for both in and out of ground effect indicating favorable longitudinal stability. However, it was found that the aerodynamic center move further aft toward the trailing edge when the model move closer to the ground.

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Parametric study of different fins for a rocket at supersonic flow

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406215590642 ◽

2015 ◽

Vol 229 (18) ◽

pp. 3392-3404

Author(s):

GQ Zhang ◽

LC Ji ◽

Y Xu ◽

J Schlüter

Keyword(s):

Supersonic Flow ◽

Parametric Study ◽

Static Pressure ◽

Aerodynamic Characteristics ◽

The Self ◽

Curvature Radius ◽

Longitudinal Stability ◽

Flight Condition ◽

Pressure Distributions ◽

Symmetric Effect

Various parameters including the fins with variable span to chord ratio, curvature radius, and setting angle have been investigated between the flat fin and wrap around fin (WAF) rocket configurations at supersonic flow. The results show that under the same flight condition, the flat fins can provide a higher lift and pitching moments than the WAFs. Due to the symmetric effect, any extra side forces, moments as well as the self-induced rolling characteristics will be not generated as compared to the WAF configurations. The WAFs can greatly improve the longitudinal stability and enhance the longitudinal aerodynamic characteristics for the whole rocket. The static pressure distributions at different chordwise positions together with the force variations around the fins have been obtained computationally and analyzed in detail.

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INVESTIGATION OF AERODYNAMICS AND LONGITUDINAL STABILITY OF UNMANNED AERIAL VEHICLE WITH ELEVATOR DEFLECTION

Vietnam Journal of Mechanics ◽

10.15625/0866-7136/13018 ◽

2019 ◽

Author(s):

Hoang Thi Bich Ngoc

Keyword(s):

Unmanned Aerial Vehicles ◽

Aerodynamic Force ◽

Steady Motion ◽

Viscous Flows ◽

Aerodynamic Characteristics ◽

Pitching Moment ◽

Longitudinal Stability ◽

Flying Qualities ◽

Aerial Vehicle ◽

A Minor

The elevators are usually hinged to the horizontal tail, which acts as a balance and controls the altitude, establishes a steady motion for the aircraft at all lift coefficients. During elevator rotating, the aircraft needs to be stable to establish a new altitude. Longitudinal flying qualities depend on the aerodynamic force of components (wing, tail, fuselage) and configuration of the aircraft. The horizontal tail has a major role in the value of the airplane's pitching moment (due to the long arm from the aerodynamic center of the tail to the center of gravity) for equilibrium and stability of the aircraft. The horizontal tail should be considered an aerodynamic component behind the main wing, influenced by the wing downwash wing rather than just a minor wing. Therefore, method of solving the differential equations for viscous flows through unmanned aerial vehicles (UAV) was used. Small disturbance theory was used to calculate the longitudinal stability of the UAV when controlling the elevator. Flying qualities were assessed so that changes in the aerodynamic characteristics of the wing, tail, fuselage and configuration of the aircraft may be required.

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The Effect of Nose Bluntness and Forebody Strakes on Aerodynamic Characteristics of Air-Launched Rocket Model

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.391.143 ◽

2013 ◽

Vol 391 ◽

pp. 143-149

Author(s):

Yan Hua Zhang ◽

Hua Xing Li ◽

Deng Cheng Zhang ◽

Liang Qu

Keyword(s):

Wind Tunnel ◽

Aerodynamic Characteristics ◽

Angle Of Incidence ◽

Pitching Moment ◽

Longitudinal Stability ◽

Side Force ◽

Low Speed Wind Tunnel ◽

Yaw Moment ◽

Improve Stability ◽

Blunt Nose

In this paper, the aerodynamic characteristics of the rocket model that might be used in a cabin air-launched system have been studied through experiments in low speed wind tunnel. The angle of incidence range is 0-80°, and the speed is 17m/s or 25m/s, including typical flight conditions prior to engine ignition. Forces and moments were measured through six-component balance. It is found that vortex asymmetry appears under certain condition with zero side slip. Asymmetrical phenomenon leads to larger side force and yaw moment, which can affect the trajectory of the rocket and put the carrier aircraft at risk. In addition, changes in regulation of the pitching moment with angle of attack are important to longitudinal stability, so the model with convergent-expanded afterbody was designed to improve stability. The effects of nose bluntness and forebody strakes on side force and yaw moment were presented, and the differences of aerodynamic characteristics with pointed and blunt nose, with and without forebody strakes were described. Results show that nose bluntness delays the appearance of asymmetric vortex, and the maximum side force is reduced by at least 50%. The forebody strakes reduce side force and yaw moment by weakening the asymmetric vortical interactions. The results can provide some references for designing the cabin air-launched rocket.

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