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The purpose of this paper is to investigate the effect of spanwise shape of the leading edge on unsteady aerodynamic characteristics of wings during forward flapping and gliding flight.

A computational fluid dynamics approach was conducted to analyze the flow around airfoils with sinusoidal‐like protuberances at a Reynolds number of 10⁴. Three‐dimensional time‐dependent incompressible Navier‐Stokes equations are numerically solved by using finite volume method. A multigrid mesh method, which was applied to the situation of fluid across the heaving models is used to simulate this type of flow. The simulations are performed for the wavelength between neighbouring peaks of 0.25c and 0.5c. For each wavelength, two heights of the tubercles which are 5 per cent and 10 per cent of the chordwise length of wing, are employed on the leading edge of wings. The aerodynamic forces and flow structure around airfoils are presented and compared in detail. Special attention is paid to investigate the effect of leading‐edge shape on the fluid dynamic forces.

Present results reveal that the wings with leading‐edge tubercles have an aerodynamic advantage during gliding flight and also have the potential advantages during flapping forward flight.

On the basis of computational study, an improved scenario for flapping wing microaviation vehicle has been originally proposed.

Whilst all published information on the arrow wing concept for future Supersonic Transport designs has, in general, placed considerable importance on the benefits of this particular layout, we should now be investigating ways and means in which the theorising and experimenting may be supplanted by active in‐flight research.

DURING the first forty years or so of the history of manned flight, the application of aerodynamics was confined largely to subsonic speeds and to one basic aircraft shape. Since the end of the Second World War the aerodynamic domain has expanded in spectacular fashion in terms of speed and shape until at the present time ‘conventional’ manned aircraft are penetrating into the realms of hypersonic velocities and the satellite vehicle has brought with it aerodynamic problems at what must surely be the near‐ultimate speed range for the technology. Nor are these advances confined to high‐speed aerodynamics: they include radically new approaches to low‐speed problems, particularly those arising from take‐off and landing manoeuvres.

BACKGROUND IN the early stages of World War II the U.S. Navy used the Lockheed PV‐1 (Ventura) in considerable quantities as a land‐based patrol plane for anti‐submarine and anti‐surface vessel patrol and attack. Inasmuch as the PV‐1 was the first high speed land based patrol aeroplane used by the U.S. Navy, and realizing that its aero‐dynamic configuration grew out of the commercial Lockheed Lodestar, it can be understood that its tactical utility was a compromise.

Flow separation on wings, blades and vehicles can be delayed or even suppressed by the use of vortex generators (VG). Numerous studies, documented in the literature, extensively describe the performance of triangular and rectangular VG winglets. This paper aims to focus on the use of non-conventional VG shapes, more specifically an array of trapezoildal-perforated VG tabs.

In this study, computational fluid dynamic simulations are performed on an inline array of trapezoidal VG with various dimensions and inclination angles, in addition to considering perforations in the VG centers. The methodology of the present numerical study is validated with experimental data from the literature.

The performance and the associated flow structures of these tested non-conventional VG are compared to classical triangular winglets. For the proposed non-conventional trapezoidal VG, at the onset of stall, a 21% increase of lift over drag on the airfoil is observed. The trapezoidal VG enhancement is also witnessed during stall where the lift over drag ratio is increased by 120% for the airfoil and by 10% with respect to the triangular winglets documented in the literature.

The originality of this paper is the use of non-conventional vortex generator shape to enhance lift over drag coefficient using three-dimensional numerical simulations.

This study aims to clarify the mechanism of film hole location at the span-wise direction of an internal cooling channel with crescent ribs on the adiabatic film cooling performance, three configurations are designed to observe the effects of the distance between the center of the ellipse and the side wall(Case 1, l = w/2, Case 2, l = w/3 and for Case 3, l = w/4).

Numerical simulations are conducted under two blowing ratios (i.e. 0.5 and 1) and a fixed cross-flow Reynolds number (Re_c = 100,000) with a verified turbulence model.

It is shown that at low blowing ratio, reducing the distance increases the film cooling effectiveness but keeps the trend of the effectiveness unchanged, while at high blowing ratio, the characteristic is a little bit different in the range of 0 = x/D = 10.

These features could be explained by the fact that shrinking the distance between the hole and side wall induces a much smaller reserved region and vortex downstream the ribs and a lower resistance for cooling air entering the film hole. Furthermore, the spiral flow inside the hole is impaired.

As a result, the kidney-shaped vortices originating from the jet flow are weakened, and the target surface can be well covered, resulting in an enhancement of the adiabatic film cooling performance.

Some historical notes of the early stages in the development of a slender wing supersonic transport aircraft. This article recounts some of the early steps in the development of the concept of a slender wing supersonic transport aircraft during the 1960s, which ultimately led to the design of Concorde. It attempts to indicate how an advanced design problem was met successfully by a completely new approach to aerodynamic design. Since a complete history of the work would fill a large book, the approach is necessarily selective in a way intended to illustrate the development of the main aerodynamic issues.

To delay the full opening of a parachute after initial deployment, the skirt is provided with one or more reefing lines 20 formed with looped ends 22 which engage over a rod 16 forming part of a spring loaded time delay mechanism 13 carried on the parachute canopy 10 by a mounting plate 14. The outer end of the rod is guided by a plate 17, spaced from the mechanism 13 to accommodate the loops 13 and the rod is drilled at 18 for a locking pin 19 secured by a lan‐yard 23 to one of the rigging lines 11. When the parachute is launched tensioning by the load of the rigging lines withdraws pin 19, permitting mechanism 13 to retract rod 16 and free lines 20, thus permitting full deployment of the parachute. Two mechanisms 13 may be arranged diametrically opposite on the skirt.

Blended wing body (BWB) is a very advantageous design in terms of low fuel consumption, low emission and low noise levels. Because of these advantages, the BWB is a candidate to become the commercial passenger aircraft of the future by providing a paradigm shift in conventional designs. This paper aims to propose a key design parameter for wing sizing of subsonic BWB and a performance parameter for calculating the lift/drag ratio values of BWBs.

The parameter proposed in the study is based on the square/cube law, that is, the idea that the wetted area is proportional to the power of 2/3 of the weight. Data on the weight, wing area, wingspan, lift-to-drag (L/D) ratio for 19 BWB used in the analyzes were compiled from the published literature and a theoretical methodology was developed to estimate the maximum lift to drag ratio of BWBs. The accuracy of the proposed key design parameter was questioned by comparing the estimated L/Dmax values with the actual values.

In the current study, it is claimed that the wingspan/(take-off gross weight)^(1/3) parameter provides an L/D efficiency coefficient regardless of aircraft size. The proposed key design parameter is useful both for small-scale BWB, that is unmanned aerial vehicles BWB and for large-scale BWB designs. Therefore, the b/Wg^(1/3) parameter offers a dimensionless L/D efficiency coefficient for BWB designs of different scales. The wetted aspect ratio explains how low aspect ratio (AR)-BWB designs can compete with high AR-tube-and-wing designs. The key parameter is also useful for getting an idea of good or bad BWB with design and performance data published in the literature. As a result, reducing the blending area and designing a smaller central body are typical features of aerodynamically efficient BWB.

As the role of the square/cube law in the conceptual aircraft design stage has not been sufficiently studied in the literature, the application of this law to BWBs, a new generation of designs, makes the study original. Estimation of the wetted area ratio using only wingspan and gross weight data is an alternative and practical method for assessing the aerodynamic performance of the BWB. According to the model proposed in the current study, reducing the take-off gross weight of the BWBs using lighter building materials and designing with a larger wingspan (b) are the main recommendations for an aerodynamically efficient BWB.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United States National Advisory Committee for Aeronautics and publications of other similar Research Bodies as issued.