Showing papers on "Wing root published in 1990"

Static aeroelastic behavior of an adaptive laminated piezoelectric composite wing

Abstract: The effect of using an adaptive material to modify the static aeroelastic behavior of a uniform wing is examined. The wing structure is idealized as a laminated sandwich structure with piezoelectric layers in the upper and lower skins. A feedback system that senses the wing root loads applies a constant electric field to the piezoelectric actuator. Modification of pure torsional deformaton behavior and pure bending deformation are investigated, as is the case of an anisotropic composite swept wing. The use of piezoelectric actuators to create an adaptive structure is found to alter static aeroelastic behavior in that the proper choice of the feedback gain can increase or decrease the aeroelastic divergence speed. This concept also may be used to actively change the lift effectiveness of a wing. The ability to modify static aeroelastic behavior is limited by physical limitations of the piezoelectric material and the manner in which it is integrated into the parent structure.

Measurements on an oscillating 70-deg delta wing in subsonic flow

Abstract: A series of low-speed wind tunnel tests on a 70-deg sharp leading-edged delta wing at both static and dynamic conditions were performed to investigate the aerodynamic forces and moments. Forces and moments were obtained from a six-component internal strain-gauge balance. Large amplitude dynamic motion was produced by sinusoidally oscillating the model over a range of reduced frequencies. Static results compared well with previous experimental findings. Significant Reynolds number effects were present in the experimental measurements. Reynolds number effects are reduced, but still present when a sharper leading-edge delta wing was tested. Large hysteresis loops and a delay in dynamic stall were seen in the dynamic data. Dynamic forces and moments were a strong function of reduced frequency. Nonzero sideslip created complex rolling moment and lift behavior due to asymmetric vortex bursting.

Wind-turbine wing with a pneumatically actuated spoiler

Abstract: A flexible spoiler is arranged on the suction side of a wing and spoiler is made of a narrow flexible fold tape covering a tunnel which is sealed against the outer airstream and extends inside the wing from the root to the tip thereof. When the fold tape is deployed from a conform position it forms a trip producing stall. Deploying and conforming are achieved by varying the tunnel pressure. The pressure is essentially generated and varied by the tunnel aircolumn under centrifugal acceleration and throttled by an inlet throttle near the wing root and an outlet throttle near the wing tip. Opening the inner throttle increases the tunnel pressure to deploy the fold tape in the case of maximum speed and/or shaft torque of the wind-turbine.

Effects of spoiler surfaces on the aeroelastic behavior of a low-aspect-ratio rectangular wing

Abstract: An experimental research study to determine the effectiveness of spoiler surfaces in suppressing flutter onset for a low-aspect-ratio, rectangular wing was conducted in the Langley Transonic Dynamics Tunnel (TDT). The wing model used in this flutter test consisted of a rigid wing mounted to the wind-tunnel wall by a flexible, rectangular beam. The flexible beam was connected to the wing root and cantilever mounted to the wind-tunnel wall. The wing had a 1.5 aspect ratio based on wing semispan and a NACA 64A010 airfoil shape. The spoiler surfaces consisted of thin, rectangular aluminum plates that were vertically mounted to the wing surface. The spoiler surface geometry and location on the wing surface were varied to determine the effects of these parameters on the classical flutter of the wing model. Subsonically, the experiment showed that spoiler surfaces increased the flutter dynamic pressure with each successive increase in spoiler height or width. This subsonic increase in flutter dynamic pressure was approximately 15 percent for the maximum height spoiler configuration and for the maximum width spoiler configuration. At transonic Mach numbers, the flutter dynamic pressure conditions were increased even more substantially than at subsonic Mach numbers for some of the smaller spoiler surfaces. But greater than a certain spoiler size (in terms of either height or width) the spoilers forced a torsional instability in the transonic regime that was highly Mach number dependent. This detrimental torsional instability was found at dynamic pressures well below the expected flutter conditions. Variations in the spanwise location of the spoiler surfaces on the wing showed little effect on flutter. Flutter analysis was conducted for the basic configuration (clean wing with all spoiler surface mass properties included). The analysis correlated well with the clean wing experimental flutter results.

Measured forces and moments on a delta wing during pitch-up

Abstract: A series of low-speed wind tunnel tests on a 70-deg, sharp, leading-edge delta wing undergoing ramp pitching motion of high amplitude were performed to investigate the aerodynamic forces and moments. Forces and moments were obtained from a six-component interanl balance. Large amplitude oscillatory motion was produced by sinusoidally oscillating the model over a range of reduced frequencies. Ramp motion was produced by pitching the model through a half cycle of sinusoidal motion at a root chord Reynolds number of 1.54 million. The effect of ramp and oscillatory motions on the forces and moments are almost identical at matched pitch rates. Pitch rate had strong effect on the magnitude of the aerodynamic forces and moments. Upon completion of the model motion, some time is required for the forces and moments to decay to their static values. This convergence of the dynamic values to the static ones was a function of the pitch rate.

Toy glider with variable dihedral wings

Abstract: A toy glider has an elongated fuselage including a nose section and a tail empennage section, an elongated, recessed wing mounting channel on each side of the flight axis including a female, V-shaped bottom for receiving a pair of wings. Each wing has a wing root in the form of an elongated polygon having male corners matching the V-bottom channel of the fuselage. A tension means, such as an elastic band, urges each wing root into a mating engagement with the wing root channel of the fuselage, whereby the tension means may be manually overcome to disengage wing root and permit movement of either wing in a vertical direction from the horizontal plane. In a preferred embodiment one male corner of the wing root as an upstanding rib matching an elongated groove in the V-bottom of the fuselage channel, providing a positive position for the wing in a flight configuration. A preferred embodiment provides separate, manually movable inboard and outboard wing sections which permit the wings to be configured as planar wings, gull wings, inverted gull wings or substantially folded gull wings.

System to lower the stresses applied to a wing, especially at the mast-base connection of the wings from a flying aircraft

Abstract: The present invention relates to a system for lowering the forces applied to the wing structure and especially the wing root (1) of the wings (2) of an aircraft (3) in flight, comprising means (4) for detection and for measurement of the vertical acceleration gamma of the aircraft, and means (5) for supplying control signals to aerodynamic surfaces (6) linked to the wings (2) of the aircraft, said means of control (5) driving the deflection angle of the said aerodynamic surfaces (6) as a function of the acceleration signals which they receive. According to the invention, the said means of control (5) are activated only when the said vertical acceleration gamma exceeds a predetermined threshold gamma s.

Reconfigurable toy glider

Abstract: A toy glider has an elongated fuselage having a longitudinal axis in the normal horizontal flight attitude, a nose section and a tail section having airfoil portions in horizontal and vertical planes. The fuselage includes a trapezoidal portion with non-parallel sides forming wing root fairings at an angle to the longitudinal axis for mounting a pair of wings having wing roots at an angle to a wing span axis, and pivotal on the wing root fairings. The wings may be extended into normal flight position and may also be pivoted into a retracted position parallel to the longitudinal axis. In a preferred embodiment the nose section simulates a head, and the vertical tail portions simulate feet, providing the appearance of an animal figure. The glider has the aft edges of the tail section in a vertical, transverse plane, whereby the glider can stand on its tail in an erect, standing posture, and the aft edges of the vertical tail portions also include wheels so the erect glider may also be rolled on the wheels. The tail is depending with wheels below the fuselage in the horizontal orientation. The nose pivots downward and also includes a wheel, so the glider may land on wheels or roll with wings retracted as a toy automobile. With the nose section and wheel elevated, the glider also simulates a toy boat.

Aerodynamic brake for wind turbine blade

Abstract: Wing (1) with aerodynamic brake for wind turbines, with a flexible pleated band extending radially along the wing suction side as a disturbing body (6), which is tightly clamped on its long sides and has narrow gaps on the transverse sides to the end plates. If the pressure is increased in a channel (5) covered by the fold band serving as a disturbing body (6), the fold band bends out and generates a disturbance threshold which causes a flow stall. The air column inside the duct (5), which is under centrifugal acceleration and into which supply air is fed from the wing root, serves as a pressure source. The pressure in the channel is increased, for example, by increasing the passage cross section of an inner throttle (4) arranged at the channel inlet compared to that of an outer throttle (7) via which the channel (5) is connected to a vacuum source. The internal throttle (4) is opened when the permissible speed or the permissible torque is exceeded.

Experimental study of the turbulent boundary layer on a transport wing in subsonic flow

Abstract: The upper-surface boundary layer on a transport wing model was extensively surveyed with miniature yaw probes at a subsonic cruise condition. Significant variation in flow direction with distance from the surface was observed near the trailing edge, everywhere except at the wing root and tip. Values of streamwise displacement thickness, normalized by the local chord, were maximum at the highly loaded midsemispan stations. The data are intended to provide a test case for computational fluid dynamics code validation.

An experimental study of the turbulent boundary layer on a transport wing in subsonic and transonic flow

Abstract: The upper surface boundary layer on a transport wing model was extensively surveyed with miniature yaw probes at a subsonic and a transonic cruise condition. Additional data were obtained at a second transonic test condition, for which a separated region was present at mid-semispan, aft of mid-chord. Significant variation in flow direction with distance from the surface was observed near the trailing edge except at the wing root and tip. The data collected at the transonic cruise condition show boundary layer growth associated with shock wave/boundary layer interaction, followed by recovery of the boundary layer downstream of the shock. Measurements of fluctuating surface pressure and wingtip acceleration were also obtained. The influence of flow field unsteadiness on the boundary layer data is discussed. Comparisons among the data and predictions from a variety of computational methods are presented. The computed predictions are in reasonable agreement with the experimental data in the outboard regions where 3-D effects are moderate and adverse pressure gradients are mild. In the more highly loaded mid-span region near the trailing edge, displacement thickness growth was significantly underpredicted, except when unrealistically severe adverse pressure gradients associated with inviscid calculations were used to perform boundary layer calculations.

Water tunnel flow visualization studies of a Canard-Configured X-31A- like fighter aircraft model

Abstract: : A water tunnel flow visualization investigation was performed to study the vortex bursting phenomena on a 2.3% scale model of a X-31A-like fighter aircraft. The main focus of this study was two-fold: (1) to determine the optimum canard location that produces favorable aerodynamic interference on the main wing and (2) to determine the effect of pitch rate on the optimum- configured model during simple pitch-up and simple pitch-down maneuvers. It was found that a close-coupled canard configuration resulted in a more favorable interference between the vortex systems of the canard and the wing. The dynamic tests indicated that the location of the wing root vortex burst point relative to the static case moved downstream with increasing pitch rate.

Generation of an aerodynamic force by lateral blowing of air at the underwing of aircraft wings from the wing extremities towards the wing root at the aircraft fuselage

Abstract: The lateral blowing of air modifies the aerodynamic field about the wings and, according to the importance of the blown air flow rate, it improves the aerodynamic efficiency of the wings or even provides for the propulsion of the aircraft or for its lift or yet to pilot the aircraft according to its roll and pitch axes. This lateral air blowing may be carried out in part or completely by taking air from the turbomachine compressors, by using pressure air evacuated from the fuselage or by any other gas mixture evacuated to the outside. Aerodynamics and more particularly aircraft engineering are the fields concerned by said lateral air blowing.

A hub for adjustable or variable pitch axial and propeller fans

Abstract: The hub, formed from sheet material, has recesses 2, 5 in back plate 1 and clamp plate 4 to receive fan wing roots 3 A sleeve, needle, ball or roller bearing may be interposed between roots 3 and plates 1, 4 to enable pitch adjustment during operation A flange 8 on each root engages slots 7, 10 in the plates The hub may be made in any desired size and with any desired number of wing root recesses, enabling the production of a fan with optimum performance and characteristics The size of the recesses may be altered to suit different wing roots, and the hub may be made in any desired shape