Aerodynamic effects of a folding wingtip to increase take-off, landing and cruise performance.

The main purpose of a folding wing tip is to allow aerodynamically efficient high aspect ratio wing. To allow a wing tip to move in flight is to alleviate the loads and achieve lower wing weight or enable wing span to maximize. Thus reduces the induced drag and improve fuel efficiency. The folding wing tip may include spring devices in order to provide an additional gust loads alleviation ability in flight. A wing without a winglet produces wingtip vortices which increases drag as the air from the bottom surface of the wing (high pressure) tries to move to the upper surface (low pressure). To avoid this and have less vortices a winglet is used, around which the flow is same on both surfaces. A folding wingtip can be set at an angle of 0° to have maximum cruise performance and aspect ratio. If the wingtip is set in the range of 15°-50° it can increase lift during take-off. This folding wingtip can access any airport in the world because if it is folded at an angle of 90°, it can meet the gate requirements and restrictions of any airport. To study the performance of this mechanism, the wing tip was designed by using CATIA V5 software. The analysis of the wingtip at different angle of attacks was done using ANSYS and XFLR 5 softwares.

Effect of Vertical Canard Location on Skin Friction Drag

This study investigates the viscous skin friction drag generation due to the three different vertical canard locations on the mid winger un-swept aircraft scaled-down model by using boundary layer measurements in the wind tunnel. The N22 airfoil was selected for the canard and the modified S1223 airfoil was selected for the wing. The laser cutting technique was employed for the fabrication of the wing, and canard airfoils, which gave sufficient dimensional accuracy to the model. The canard, wing, and fuselage were fabricated by balsa wood and strengthened by Aluminum stripes. The assembled model is tested in an open subsonic wind tunnel a fixed chord Reynolds number 3.8*106. The boundary layers were measured at 70% of the chord and at three different wingspan locations i.e. 30%, 60%, and 90% with 00 incidence angle. The canards were positioned at three vertical positions one at fuselage reference line (FRL) and the remaining two locations at ± 0.16 c from the FRL. The results were compared with wing-body alone and with three canard locations and found that the high canard configuration outperformed the other two configurations and also wing-body alone configuration as it provides half of the total drag. However, the high canard produces 15% more drag than the wing-body alone at the wing tip (90%).The aerodynamic performance of the high canard configuration was found to be significantly promising for the future use in drones and other small aircrafts.

AN ALTERNATIVE APPROACH TO INDUCED DRAG REDUCTION

Induced drag constitutes approximately 40% of the total drag of subsonic civil transport aircraft at cruise conditions. Various types of winglets and several non-planar concepts, such as the C-wing, the joined wings, and the box plane, have been proposed for its reduction. Here, a new approach to induced drag reduction in the form of a combination of an elliptical and an astroid hypocycloid lift distribution is put forward. Lift is mainly generated from high circulation in the center part of the wing and fades away along the semi-span towards the wing tip. Using lifting line theory, the analysis shows that for fixed lift and wingspan the combined lift distribution results in an induced drag reduction of 50% with respect to the elliptical distribution. Due to its wing planform the combined lift distribution leads to a 51.5% higher aspect ratio. If structural constraints are placed, then the higher aspect ratio may affect wing weight. Although any substantial increase of wing weight is not envisaged, further study of the matter is required. Zero-lift drag and lift-dependent drag due to skin friction and viscosity-related pressure remain unaffected. The proposed lift distribution is particularly useful in a blended wing-body design.

Towards higher aerodynamic efficiency of propeller-driven aircraft with distributed propulsion

The scope of the present paper is to assess the potential of distributed propulsion for a regional aircraft regarding aero-propulsive efficiency. Several sensitivities such as the effect of wingtip propellers, thrust distribution, and shape modifications are investigated based on a configuration with 12 propulsors. Furthermore, an initial assessment of the high-lift performance is undertaken in order to estimate potential wing sizing effects. The performance of the main wing and the propellers are thereby equally considered with the required power being the overall performance indicator. The results indicate that distributed propulsion is not necessarily beneficial regarding the aero-propulsive efficiency in cruise flight. However, the use of wing tip propellers, optimization of the thrust distribution, and wing resizing effects lead to a reduction in required propulsive power by $$-2.9$$ - 2.9 to $$-3.3\,\%$$ - 3.3 % compared to a configuration with two propulsors. Adapting the leading edge to the local flow conditions did not show any substantial improvement in cruise configuration to date.

Effect of Chaotic Nature on IPHICLUS and NEARCTIC Flapping MAV Wings in Lift Generation using Welch Power Spectral

The application of bio-mimetic in Micro Aerial Vehicles (MAV) is a developing field and has enormous applications in the aviation industry. In this work, experimental investigation of the insect like MAV having flapping wing is discussed. The iphiclus-egensis-aile flexible wing and the nearctic-ceratopogonidae flexible wing were chosen for this study. Values of the coefficient of lift for the unsteady aerodynamics were converted to normalized frequency domain using Welch power spectral density method at various flapping frequencies and Reynolds number. The wing tip vortices were captured using laser visualization technique and further the images were processed using MATLAB. Experimental investigations were carried out in wind tunnel for various velocities and Angle of Attack (AoA) and the results were obtained using digital six component balancing system. Detailed study of both the results shows that the nearctic-ceratopogonidae flexible wing has better lifting properties than the iphiclus-egensis-aile flexible wing at low flapping frequencies and low AoA. For higher flapping frequencies and high AoA, the latter shows better lifting properties than the former.

Simultaneous PIV and DIC Measurements in a Towing Tank Environment with a Flexible Hydrofoil

Due to their good mechanical properties composite materials are increasingly applied for the construction of lifting surfaces in the maritime industry. However, besides improving the strength to weight ratio of a structure, the anisotropic material properties can also exhibit bend-twist coupling, when exposed to higher loads. In order to experimentally measure the fluid structure interaction, the object of investigation needs to exposed to the same fluid loadings, as it would experience during operation. To investigate the possibility to obtain simultaneous deformation and flow field measurements in a large hydrodynamic testing facility simultaneous PIV and DIC measurements are performed to obtain the deformation of a flexible NACA 0008 hydrofoil and to measure the flow field in the wing tip region. For the assessment of the performance of the methods two scenarios are presented including tests in stationary conditions with constant angles of attack and forced plunging oscillations. The calibration of both measurement systems is done independently and the wing tip, visible in the PIV images, is used for triangulation to find the position of the wing within the PIV coordinate system. The combination of both measurement techniques allows for an accurate determination of tip vortex center positions with respect to the deformed wing and their evolution downstream of the wing. During forced plunging motions, the phase lag of the wing tip and the influence on the wing tip vortex is observed.