scholarly journals Research on high attack angle stall and spin characteristics with flight test of a general electric aircraft

2021 ◽  
Vol 39 (3) ◽  
pp. 650-659
Author(s):  
Yadong Li ◽  
Junyao Zhang ◽  
Fengtian Yang ◽  
Yongliang Chen
Keyword(s):  
Numerical Simulation ◽  
Aspect Ratio ◽  
Aerodynamic Force ◽  
Angle Of Attack ◽  
Wind Tunnel Test ◽  
Flight Test ◽  
High Angle ◽  
High Angle Of Attack ◽  
Linear Change ◽  
Electric Aircraft

When the aircraft is flying at high angle of attack, the local separation of the air flow on the surface of the aircraft, the linear change of aerodynamic force is destroyed, and the maneuverability and stability are reduced to varying degrees, resulting in the aircraft stalling or entering the spin. The stall characteristics and spin characteristics directly affect the safety of the aircraft. In order to analyze the stall and spin characteristics, a full-scale 6-DOF nonlinear high angle of attack dynamic model is established for a two-seater electric high aspect ratio aircraft based on the wind tunnel test data. The stall characteristics of an electric aircraft at high angle of attack are obtained by numerical simulation and analysis. According to the stall characteristics of simulation calculation, flight test is carried out to verify the reliability of numerical simulation, which provides reference for the later analysis of stall/spin test of large aspect ratio series electric aircraft at nonlinear high angle of attack.

scholarly journals Power reduction and the radial limit of stall delay in revolving wings of different aspect ratio

2015 ◽  
Vol 12 (105) ◽  
pp. 20150051 ◽  
Author(s):  
Jan W. Kruyt ◽  
GertJan F. van Heijst ◽  
Douglas L. Altshuler ◽  
David Lentink
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Angle Of Attack ◽  
Radial Distance ◽  
Leading Edge ◽  
High Angle ◽  
High Angle Of Attack ◽  
Low Aspect Ratio ◽  
Aspect Ratios ◽  
Low Aspect Ratio Wings

Airplanes and helicopters use high aspect ratio wings to reduce the power required to fly, but must operate at low angle of attack to prevent flow separation and stall. Animals capable of slow sustained flight, such as hummingbirds, have low aspect ratio wings and flap their wings at high angle of attack without stalling. Instead, they generate an attached vortex along the leading edge of the wing that elevates lift. Previous studies have demonstrated that this vortex and high lift can be reproduced by revolving the animal wing at the same angle of attack. How do flapping and revolving animal wings delay stall and reduce power? It has been hypothesized that stall delay derives from having a short radial distance between the shoulder joint and wing tip, measured in chord lengths. This non-dimensional measure of wing length represents the relative magnitude of inertial forces versus rotational accelerations operating in the boundary layer of revolving and flapping wings. Here we show for a suite of aspect ratios, which represent both animal and aircraft wings, that the attachment of the leading edge vortex on a revolving wing is determined by wing aspect ratio, defined with respect to the centre of revolution. At high angle of attack, the vortex remains attached when the local radius is shorter than four chord lengths and separates outboard on higher aspect ratio wings. This radial stall limit explains why revolving high aspect ratio wings (of helicopters) require less power compared with low aspect ratio wings (of hummingbirds) at low angle of attack and vice versa at high angle of attack.

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