Showing papers on "Leading edge published in 1971"

Predictions of vortex-lift characteristics based on a leading-edge suction analogy.

Abstract: Leading edge suction analogy for predicting low speed lift and drag-due-to-lift characteristics of sharp edge delta and related wing planforms

Laminar wave train structure of collisionless magnetic slow shocks

Abstract: The laminar wave-train structure of collisionless magnetic slow shocks is investigated using two-fluid hydromagnetics with ion-cyclotron-radius dispersion. For shock strengths less than the maximally strong switch-off shock, in the shock-leading edge, dispersive steepening forms a magnetic-field gradient, while in the downstream flow dispersive propagation forms a trailing wave train; dispersion scale lengths are the ion inerrial length if β > 1 and the ion cyclotron radius if β > 1. In the switch-off slow-shock leading edge, dispersion only produces rotations of the magnetic-field direction; the gradient of the magnetic-field magnitude, and hence the shock-steepening length, is determined solely by resistive diffusion. The switch-off shock structure consists of a long trailing train of magnetic rotations which are gradually damped by resistivity. The low-6 parallel fast switch-on shock has a similar wave-train structure with the magnitude of the field rotations gradually increasing toward the downstream flow.

High lift leading edge device

Abstract: The retractable leading edge wing flap has a skin surface with tapered thickness in order that it can more easily assume the desired nonuniform degree of curvature when the flap is in its extended position. Through the inherent resilency of the flap skin surface material in combination with an actuating mechanism having a minimum of operating elements, the surface of the flap is provided with a variable contour thereby producing a variable camber to the flap panel and likewise to the wing airfoil section that is in combination therewith. More specifically, the flap extension and retraction mechanism operates in a chordwise plane and requires a maximum of five links to produce the desired result. Further, the actuating mechanism operates to position the flap panel relative to the fixed wing leading edge so as to vary the wing airfoil section aerodynamic flow characteristics by changing the total overall amount of effective wing camber. For the landing condition, the arrangement of the linkage mechanism produces an angular relationship of the flap chord plane relative to the wing chord plane such that the overall aerodynamic affect is a greater airfoil section camber at said landing condition than at the take off condition. Also, the arrangement of the linkage mechanism for the landing condition is such that the leading edge wing flap is extended further forward from the relatively fixed leading edge of the main wing section in addition to being spaced away from the wing leading edge, to form an aerodynamic slot; whereas, at the take off position the movable flap section and wing leading edge are in abutment relation thereby forming a substantially continuous upper surface without the slot.

Suppression of flutter

Abstract: An active aerodynamic control system to control flutter over a large range of oscillatory frequencies unaffected by mass, stiffness, elastic axis, or center-of-gravity location of the system, mode of vibration or subsonic Mach number consisting of one or more pairs of leading edge and trailing edge hinged or deformable control surfaces, each pair operated in concert by a stability augmentation system. Torsion and bending motions or deflections of the fluttering member are sensed and converted by the stability augmentation system into leading and trailing edge control surface deflections which produce lift forces and pitching moments to suppress flutter.

A feasibility study of heat-pipe-cooled leading edges for hypersonic cruise aircraft

Abstract: A theoretical study of the use of heat pipe structures for cooling the leading edges of hypersonic cruise aircraft was carried out over a Mach number range of 6 to 12. Preliminary design studies showed that a heat pipe cooling structure with a 33-in. chordwise length could maintain the maximum temperature of a 65 deg sweepback wing with a 0.5-in. leading edge radius below 1600 F during cruise at Mach 8. A few relatively minor changes in the steady-state design of the structure were found necessary to insure satisfactory cooling during the climb to cruise speed and altitude. It was concluded that heat pipe cooling is an attractive, feasible technique for limiting leading edge temperatures of hypersonic cruise aircraft.

Semi-rigid airfoil for airborne vehicles

Abstract: The present invention relates to a semi-rigid airfoil for use with airborne vehicles and capable of being folded and/or warped. The airfoil includes a rigid spar defining a leading edge and a cable defining the trailing edge with the root end thereof secured to the fuselage of the vehicle and the other end to a tip truss structure, with a flexible material forming top and bottom airfoil surfaces. Means are also provided for twisting portions of the airfoil about an axis extending through the root end, and means for pivoting the spar to fold against the fuselage.

Design and evaluation of active cooling systems for Mach 6 cruise vehicle wings

Abstract: Active cooling systems, which included transpiration, film, and convective cooling concepts, are examined. Coolants included hydrogen, helium, air, and water. Heat shields, radiation barriers, and thermal insulation are considered to reduce heat flow to the cooling systems. Wing sweep angles are varied from 0 deg to 75 deg and wing leading edge radii of 0.05 inch and 2.0 inches are examined. Structural temperatures are varied to allow comparison of aluminum alloy, titanium alloy, and superalloy structural materials. Cooled wing concepts are compared among themselves, and with the uncooled concept on the basis of structural weight, cooling system weight, and coolant weight.

Anti-cavitation means for marine propulsion device

Abstract: Cavitation eminating from the leading edge near the hub of a propeller of a marine propulsion device is prevented by introducing exhaust gas air adjacent the junction of the leading edge of each blade of the propeller and the propeller hub from the interior of the hub through which the exhaust gas or air flows.

Sheet laying apparatus

Abstract: After a cutter cutting sheets out of a travelling web has been arranged a pair of drive rollers rotated at a linear velocity at least equal to that of the web. The sheets are thrown by the pair of drive rollers and received and further delivered to a laying station by conveying means operated at a velocity lower than that of the drive rollers so as to cause the sheets to assume a partially overlapping relationship. After the drive rollers there is preferably arranged guide means for forcing the trailing edge of the sheet downward to enable the leading edge of the next sheet freely to pass over said trailing end.

Alleviation of vortex-induced heating to the lee side of slender wings in hypersonic flow

Abstract: Vortex-induced heating alleviation to lee side of slender wings in hypersonic flow by contouring leading edge planform

Streamline Curvature Analysis of Compressible and High Mach Number Cascade Flows

Abstract: A blade to blade design tool for analysing the subsonic, transonic and supersonic flows in axial turbine blades is presented using the streamline curvature method. The work includes a numerical convergence analysis which produced convergence of the digital computer programme for all cases attempted. Computed results are compared with experiment and other theory. Comparisons for turbine type cascades up to Mach 10 show a satisfactory agreement and techniques introduced give improved leading edge results and allow the Kutta–Joukowski condition to be applied at the trailing edge for the accurate determination of the velocity distribution and the cascade deviation. Predictions for convergent-divergent supersonic wind tunnel type nozzles agree closely with experiment and with other theories. Numerical difficulties are found to be more acute for subsonic/supersonic turbine cascades and experimental agreement, while acceptable, is inferior to that obtained for subsonic cascades.

The compressible turbulent boundary layer on a blunt swept slab with and without leading- edge blowing

Abstract: Finite difference method for solving equations for compressible turbulent boundary layers on swept infinite cylinders

Wear resistant outsert for a paper machine foil

Abstract: A paper machine foil having a wear resistant outset releasable yet securely positioned thereon to form the supporting surface and leading edge of the foil. The leading edge of the outset is formed by a small radius of curve and a wear resistant coating is applied to the supporting surface, the leading edge and a portion of the doctoring surface of the outset.

Asynchronous pulse width filter

Abstract: An asynchronous pulse width filter having four two-state logic circuits, the first having a retriggerable circuit capable of delaying the leading edge of an input pulse by a presettable time Delta t, coupled to a second logic circuit capable of detecting the trailing edge of the input pulse after the delayed leading edge, coupled to a third logic circuit of non-retriggerable capabilities but capable of delaying the trailing edge from the prior logic circuit a fixed amount of time Delta t and coupled to a fourth logic circuit capable of triggering a leading edge at the trailing edge of the output pulse of the second logic circuit and of triggering a trailing edge at the trailing edge of the delayed output Delta t of the third logic circuit to provide discrimination of pulse width to reproduce valid pulses precisely in pulse width and in relative position.

Centrifugal compressor diffuser

Abstract: The diffuser of a centrifugal compressor having an unshrouded rotor has boundary layer fences on the walls bounding the diffuser in advance of the diffuser vanes. These vanes are directed across the direction of flow of boundary layer air on the diffuser wall and curve into the direction of the diffuser vanes as they merge with the leading edge of the vanes.

Airfoil for aircraft

Abstract: An airfoil for fixed and rotary wing aircraft comprising a continuous upper surface that joins with a generally planar portion of the under surface at the leading edge to form the apex of a wedge-like airfoil section that extends toward and terminates abruptly in advance of the trailing edge.

Earth working rotor with improved tines

Abstract: Tines of an earth working rotor, detachably fixed to axially spaced disc-like tine carriers, are L-shaped, with flat shank and hoe portions. A sharp leading edge on the hoe is provided by a bevel on its surface remote from the shank, and on the shank by a bevel on its surface facing the hoe. A clamping plate, secured by bolts threaded into the carrier, clamps the shank flatwise thereagainst. Work reaction force is taken by a pair of abutments on the carrier, one engaging the leading edge of the shank and the other, axially farther out, engaging its trailing edge.

Shuttle ascent and shock impingement aerodynamic heating studies

Abstract: The collection and analysis of aerodynamic heating data obtained from shock impingement experimental investigation were completed. The data were categorized into four interference areas; fin leading edge, wing/fuselage fin/plate corners, and space shuttle configurations. The effects of shock impingement were found to increase the heating rates 10 to 40 times the undisturbed values. A test program was completed at NASA/Langley Research Center to investigate the magnitudes and surface patterns of the mated shock interference flowfield. A 0.0065 scale thin-skin model of the MDAC 256-20 space shuttle booster mated with a Stycast model of the MDAC Internal tank orbiter was tested in the 20-inch M=6 tunnel, the 31-inch M=10 tunnel, and the 48-inch Unitary Plan Tunnel. The gap region of the ascent configuration was the principal area of interest where both thermocouple and phase-change paint data were obtained. Pressure and heat transfer distributions data on the leeward surface of a 75-degree sweep slab delta wing are presented. The effects of surface roughness on boundary layer transition and aerodynamic heating were investigated.

Combustion chamber assembly for a gas turbine engine

Abstract: A combustion chamber liner is comprised of two telescoping sections, the leading edge of the downstream section overlapping the trailing edge of the upstream section. The end of the upstream section is provided with a plurality of peripherally spaced bosses. The outer peripheral surface of each of the bosses is grooved to accept the complementary depressed ring in the end of the larger downstream section. When cool, the dimensions of the upstream and downstream sections are such that there is a loose connection between the sections. However, the upstream section is heated more than the downstream section and causes its expansion to provide a tight fit.

A modeling study of several aspects of canopy flow

Abstract: Several aspects of canopy flow are investigated. The problem of steady flow in a horizontally infinite canopy under neutral thermal stratification is treated theoretically. The resulting analytical model is then used as a boundary condition for a nonlinear numerical model designed to study transition regions near the leading and trailing edges of a canopy. This model shows a wave effect downstream from a leading edge observed in the field and laboratory. A tendency for a splitting of the flow near a windward canopy edge is also brought out.

The role of heat conduction in leading edge heating

Abstract: The effect of heat conduction of material on the temperature distribution in the vicinity of a wing leading edge in hypersonic flight is investigated. The theory is based on a conducting plate subjected to aerodynamic heating. It is found that the role played by the conductivity of the material and the leading edge thickness in moderating the nose temperature is very significant. Numerical solutions for various shapes of leading edge are given. An experimental technique has been developed by which a number of models representing a wing leading edge can be tested and the results thus obtained are compared with those predicted by the theory.

Banding machine and method

Abstract: This specification discloses a wire banding machine which comprises a base member, a circular guideway and wire feeding and tensioning means Wire is fed across the base and past an article to be bound and then around the guideway until the leading edge thereof strikes a stop At this time, clamping means on a first member on the base clamps and holds the leading end of the wire Then the feeding means is reversed to tension the wire about the article At the end of the tensioning step a second member on the base clamps the wire and moves across a severing means into alignment with the leading edge As alignment with the leading edge is approached the second member slightly retracts to allow such alignment to take place and then is moved inwardly to bring the ends into contact as a welding current is passed across the aligned ends to effect a weld therebetween

In-line fluid mixer

Abstract: An in-line spiral mixer characterized by successive left and right hand spaced spiral vanes disposed within a cylindrical tube. Each of the vanes comprises at least two separate parts with a central opening therebetween. The leading edge of each part is tapered from the outer to inner ends in the direction of fluid flow to minimize accumulation of material on the edge and cause self cleaning.

Plate clamping device for intaglio printing presses

Abstract: A clamping system is provided for tightening printing plates on a form cylinder of an intaglio printing press to avoid plate ruptures. Adjacent the sides of the grooves in the cylinder in which the leading and trailing ends of the plates are clamped, the cylinder is formed with a convex transition curve over which the ends of the plate are led and this transition curve has a curvature which curves the plate such that it does not exceed the elastic limit of the plate and the plate fits snugly around the cylinder surface, thus the tension force that is applied to the plate end does not act on this transition portion of the plate such that it deforms it. Clamping bars for the leading and trailing ends of the plates are slidably mounted in the grooves. There is a clamping strip having screws mounting it on the clamping bar and under which the end of the plate is clamped to the bar. Each clamping bar has a convexly curved surface portion in its upper portion joining at its upper end with a flat surface portion thereon lying in a plane extending tangentially to the radius of curvature of the convexly curved portion and adjacent the convex curved portion on the cylinder so as to receive and direct the end of the printing plate into the cylinder groove and a portion to lie in the plane as a straight line portion as it leaves the transition portion of the cylinder. The clamping bars for the trailing edge are divided into segments and each has a pressure adjusting screw acting on a spring pressing against a wall of the groove. A compression spring is positioned between the clamping bar for the leading edge and each clamping bar segment for the trailing edge of the plate and moves the clamping bars into their initial position. An adjusting screw is mounted in the clamping bar for the leading edge, and it acts against an adjacent wall of the grooves. The clamping bars are slidably secured in the grooves by securing bars.

Experimental Study of Shock Impingement on a Blunt Leading Edge with Application to Hypersonic Inlet Design.

Abstract: : An experimental study was made of the interaction of an oblique shock with the bow shock of blunt leading edge. The interactions were classified according to the interference patterns described by Edney. Peak heating rates 5.5 times those of the blunt leading edge alone were studied. All interactions appeared to be unsteady except when the slipstream of the interaction passed above the blunt leading edge. (Author)

Log debarking apparatus

Abstract: A curving arm member and mounting assembly for use with a ring type log debarker. The mounting assembly comprises a shaft and cantilevered mounting plate to which the arm member is attached in a plane perpendicular to the axis of the shaft. The arm member has front and rear faces reducing in width from base to tip and leading and trailing edges at opposite sides thereof. A bark cutting edge is provided at the tip. The front face and leading edge converge in a spiral-like log engaging climbing edge from the base to the top. The cutting edge and a substantial portion of the climbing edge are carried on a removable insert member.

Aircraft propulsion system

Abstract: The invention relates to a propulsion system particularly adapted to VTOL and STOL type of aircraft and in which a main wing has an auxiliary wing arranged either above or below in spaced biplane relation with the space between the wings, in combination with suitable end plates, forming a rectangular propulsion duct extending spanwise on each side of a central fuselage. A gas turbine driving an air compressor has the compressed air therefrom delivered through a conduit formed in one of the wings from whence it passes to a series of injection nozzles which inject air into the duct inlet to entrain and mix with atmospheric air drawn into the inlet and which expands in a diffuser portion of the duct to generate an augmented propulsive thrust. The nozzles are housed in streamlined struts or housings extending vertically between the wings and transverse to the duct. One of the wings is provided with an adjustable trailing edge flap for varying the discharge area of the propulsive duct diffuser and the other wing is provided with a flap provided with nozzles at its leading edge and adapted to discharge over the suction surface of the flap and when the flap is depressed downward to cause additional downward deflection of the propulsive duct discharge by "Coanda" effect.

Engine exhaust recirculation

Abstract: Automobile exhaust gases are recycled through the engine via a bypass duct connecting a cool portion of the exhaust system with the fuel-air inlet induction conduit A servo valve is controlled by the pressure at a vacuum sensing port opening into the inlet induction conduit at the leading edge of a blade type throttle valve when the latter is at its idle position, so as to operate in response to throttle position and in turn control a recycling valve in the bypass duct to effect controlled exhaust recycling in increasing amounts as the throttle valve opens from its idle to part load positions, and to reduce the exhaust recycling at both idle and wide open throttle positions