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A Pitot‐static tube structure comprising, in combination, a shell having a hollow protuberance thereon, said shell having a dynamic pressure opening at the front end and a static opening at the side thereof; a partition in said shell separating an interior portion of said protuberance from the remainder of the space in said shell; a dynamic pressure duct within said shell connecting said dynamic opening with the hollow of said protuberance above said partition; a continuation duct leading from a point near the top interior of said protuberance downwardly and out of said shell; a second duct leading outward from the interior of said shell; a heating element positioned internally near the forward end of said shell adjacent said dynamic pressure duct; a second heating element positioned nearer to said protuberance; and a heat conveying member arranged to conduct heat from said second heating element to an outer wall of said protuberance.

The purpose of this paper is to develop the analytical model of the rotary hook geometric parameters’ interconnections, which allows determining the characteristic modes of interaction of its elements. In this study, the interaction mechanism of the bobbin case, the rotary hook and the support finger was defined, which allows to reduce the unit vibro-impact activity.

As practice shows, the bobbin case sometimes turns against the rotary hook movement. This phenomenon can be used for the free passage of the needle thread. The change in the geometric parameters of the rotary assemble will allow to decrease its vibro-impact activity.

The interrelations of rotary assemble geometric parameters are established, and it is possible to determine the characteristic modes of its elements interaction and to establish a mechanism for controlling them. This allows reducing the vibro-impact activity of joint, improving friction modes and sewing technology. Criteria and values of a gap formation between the right contacting face of bobbin case and support finger protuberance are found.

In the future, it is necessary to conduct research on the behavior of the rotary assemble elements in the frequency operating modes of the sewing machine. It is necessary to show the influence of the resonance modes of operation of the rotary hook drive on the interaction of elements.

The practical use of the results of the work makes it possible to reduce the vibratory impact of the shuttle, and also to create conditions for the smooth operation of the rotary hook and the bobbin case, and ensure the formation of a gap between the contacting face of bobbin case and support finger protuberance for the free passage of the needle thread. The results of the work can be used in the design of a rotary assemble with specified characteristic parameters and modes of elements interaction.

An analytical model of interrelations of geometric parameters of a rotating hook is developed. The characteristic modes of interaction of the rotary assemble elements were studied. The reasons for the vibro-impact activity of the rotary hook are studied. Also, the conditions under which the bobbin case will move against the direction of rotary hook rotation are determined.

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.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics, and publications of other similar research bodies as issued

The purpose of this paper is to explore the flow and heat transfer characteristics of the jet impingement onto a conical heat sink and evaluate the ability of heat transfer enhancement.

A numerical study of the flow and heat transfer of liquid impingement on cone heat sinks was conducted, and transition SST turbulence model was validated and adopted. The flow and thermal performances were investigated with the Reynolds number that ranges from 5,000 to 23,000 and cone angle that ranges from 0° to 70° in four regions.

Local Nusselt numbers are large, and pressure coefficients drop rapidly near the stagnation point. In the conical bottom edge, a secondary inclined jet was observed, thereby introducing a horseshoe vortex that causes drastic fluctuations in the curves of the flow and heat transfer. The average Nusselt numbers are higher in a conical protuberance than in flat plates in most cases, thus indicating that the heat transfer performance of jet impingement can be improved by a cone heat sink. The maximum increase is 13.6 per cent when the cone angle is 60°, and the Reynolds number is 23,000.

The flow and heat transfer behavior at the bottom edge of the cone heat sink is supplemented. The average heat transfer capacity of different heat transfer radii was evaluated, which provided a basis for the study of cone arrays.

This study aims to systematically investigate the tribological behaviors of metal and polyethylene using lubricants composed of four synovial fluid (SF) components. In addition, the changes in protein conformation during wear were analyzed to establish the correlation between protein conformation and tribological properties.

A pin-on-disk tester with multidirectional sliding motion was used for tribological properties observation between metal and polyethylene pairs. Simulated SFs with four main constituents were used as the testing lubricants. Differential scanning calorimetry and Raman were used to characterize the changes in protein conformation during wear.

The coupling of lipids and hyaluronic acid further suppressed protein denaturation. The protein structures of the adsorption film and the ensnared protein chains in the friction zone were maintained to a certain extent, thus improving the friction and wear of polyethylene.

These findings established the correlation between protein conformation and friction and wear, promoting the understanding of the lubrication mechanism of artificial joints.

An aircraft undercarriage comprises a retractable nose wheel unit N, which supports approximately 10 per cent of total aircraft weight and a main unit comprising a retractable leg C positioned in the mid‐part of the fuselage on its fore‐and‐aft centre line and two lateral legs O1,O2 each arranged for retraction into an engine nacelle at the tip of each wing. The legs of the main unit may be in transverse alignment or leg C may be forward of the transverse plane containing legs 01 and 02. Leg C is arranged to carry approximately 40 to 70 per cent of total aircraft weight whilst the remaining 20 to 50 per cent is divided between undercarriages 01 and 02.

Today's high speed aircraft must have external surfaces as smooth as possible, and in order to reduce drag to a minimum it is usual to employ flush riveting for all external skin sheeting. Whilst this method of construction provides a basis for a smooth surface it is not in itself fully satisfactory, especially on a curved surface where there is no certainty that all the rivet heads lie flush with the surrounding skin sheeting. It is possible to attain a finish nearer to that desired by using an end milling tool on the rivet heads, but there is still a danger when using normal tools of this type that the surface of the sheeting will be damaged. Thus it has become necessary to provide a tool with which the likelihood of such damage is greatly reduced. The Short Rivet Milling Tool has been designed by Short Brothers and Harland Limited to overcome this problem. It can be used in conjunction with a portable power driven unit, e.g. a compressed air operated hand drill, and comprises a circumferential milling cutter, a cutter spindle, a housing containing bearings for supporting the spindle at right angles to the driving axis and an attachment to the power unit. Two guide rollers, one each side of the cutter, project very slightly and thus prevent the cutter from touching sheeting surrounding the rivet under treatment. Although these guides extend only 0.0005 in. this is sufficient to ensure that the cutter operates only on the rivet head. Varying widths of milling cutters may be fitted to the tool by withdrawing the cutter spindle and inserting spacing bushes of appropriate width. In operation the tool can be used for ‘rubbing down’ protuberances, in the same manner as a smoothing plane, with the drill shaft axis at an angle of about 60 deg. to the surface being worked upon. Exhaust air from the tool is collected internally and used for the dispersal of swarf.

In combination with an aircraft fuselage, an annular support member inwardly spaced from the fuselage surface and intermediate the fuselage length, said surface having an opening concentric with and of larger diameter than the support member, a ring concentric with and carried by said support member for rotation relative thereto, an upwardly and outwardly flaring element terminating substantially at the edge of said fuselage opening, and a flat conical transparent turret carried by said member having its cone base substantially in the plane of the fuselage surface, said turret affording a substantially streamlined protuberance above the fuselage surface.

DURING the past year the increase in performance shown by certain American and Continental aircraft has merited the attention of all aircraft technicians. The performance is, of course, partly due to increase in horse‐power, but this is a small factor compared with the advance shown in the reduction of drag. Now that it has been shown that it is possible to build aeroplanes of low form‐drag and with little interference, the drag due to skin friction is becoming of great importance, and it will probably be of advantage to outline the methods of estimating skin friction, and discuss what information is now available on the effect of surface finish and protuberances.