Abstract: An optical viewing tube having an eyepiece at one end and a viewing prism at an optical tip at the other end is provided with an optical system therebetween which will provide a focus for an object being viewed. A distance indicating disk or device on said tube is movable by a focusing mechanism to indicate the distance from the optical tip of the viewing tube to a viewed object. A camera is provided to be attached to the viewing tube to take a picture of the viewed object, and an eyepiece with a properly marked reticle is placed on the photograph taken, to indicate proper distances between spaced points on the object as seen in the photographs. The viewing tube is calibrated along its length so that tube penetration can be accurately known and a retention adapter is used with the tube to rigidly fix it in place. The retention adapter includes a compass rose which indicates the position of the viewing prism.

Abstract: A rotor blade system which is adapted for long term reliable operation in a gas turbine engine is disclosed. Techniques for altering the natural frequency of the blade system to reduce the detrimental combined effects of external excitation and self-excitation are developed. One structure shown utilizes a shroud for the control of self-excitation in combination with a pin root to lower the fundamental first natural bending frequency of the blade system below the level of the 2E frequency at idle.

Abstract: A turbine stator assembly which is adapted for long term, reliable operation in the high temperature environment of a gas turbine engine is disclosed. Various construction details and material selections are discussed. The system cooperatively employs varied increments of component thermal expansion to hold ceramic vanes in compression throughout the operating cycle of the engine.

Abstract: A connector assembly which is adapted for use with fiber optic cable is disclosed. Techniques for aligning the corresponding light ways of a multiway cable and for minimizing the loss of light energy across the connector are developed. The connector illustrated includes a spacer disposed between the opposing ends of the corresponding light ways within the connector. The ends of the light ways are accessible for optical cleaning after repeated use to restore efficient light transmissive capabilities to the connector.

Abstract: An airfoil cooling system for use in a gas turbine engine having high turbine inlet temperatures is disclosed. Various construction details designed to prevent thermal deterioration are developed. The system is built around impingement, film, and convective cooling techniques which are combined to limit the temperature of the airfoil material and to reduce thermal gradients within the component.

Abstract: Apparatus for reducing the leakage of working medium gases between the rotor and stator assemblies of a gas turbine engine is disclosed. Concepts for maintaining concentric correspondence between a stator outer air seal of a gas turbine engine and the arc circumscribed by blades of the rotor assembly are discussed. Techniques for uniformly distributing the cooling air about the inner circumference of the case to control thermal distortions of the case and techniques for sealing the working medium flow are employed in one embodiment.

Abstract: Apparatus for controlling the direction of flow of the working medium gases in the compression section of a gas turbine engine is disclosed. Vanes are disposed across the flow path for the medium gases to direct the flow to a preferred downstream angle. In one embodiment vanes are disposed across the compressor exit passage. The camber of the vanes at the compressor exit is variable in response to engine operating conditions to conform the flow to a fixed optimum angle of entry into the combustion section.

Abstract: A coolable nozzle guide vane in the turbine section of a gas turbine engine is disclosed. The vane has a platform section and an airfoil section which are adapted to receive and distribute cooling air about the walls of the sections which are in contact with the hot working medium gases flowing through the turbine during operation of the engine. Impingement cooling and transpiration cooling techniques are combined to maximize the cooling effectiveness of the air supplied.

Abstract: Apparatus for varying the nozzle area in the turbine section of a gas turbine engine is disclosed. Nozzle guide vanes extend across the flow path for the working medium gases and are rotatable to alter the area of the nozzle. In one embodiment the rotatable vanes are cantilevered from the outer engine case and are opposed at their radially inner ends by a shroud which is affixed to the inner engine case.

Abstract: A stator vane capable of use in the high temperature environment of a gas turbine engine is disclosed. Various construction details implement vane cooling concepts which are designed to prolong the service life of the vane. An effective leading edge cooling system is built around the uniform flow of film cooling air over the exterior surface of the leading edge from a cavity within the airfoil section of the vane.

Abstract: Apparatus for reducing the pressure loss imposed upon the working medium gases flowing through an exhaust case of a turbine machine is disclosed. Various construction details which reduce the cross flow of secondary air from the pressure side of one case strut to the opposing side of the adjacent strut are developed. The loss reduction system is built around vortex generators which energize the flow boundary layer at the inner wall of the flow path for the working medium gases.

Abstract: A coolable shroud surrounding the tips of the turbine blades of a gas turbine engine is disclosed. The shroud comprises a plurality of arcuate segments which are supported by the turbine case concentrically about the axis of the engine in end to end relationship. Each segment is adapted to receive and distribute cooling air about the walls of the shroud which are exposed to the hot working medium gases flowing through the turbine during operation of the engine. A combination of impingement cooling and transpiration cooling techniques maximize the cooling effectiveness of the air supplied.

Abstract: A fan structure which is particularly well suited for use in a high tip speed turbofan, gas turbine engine is disclosed. Various construction details accommodate both subsonic and supersonic flow across the fan blades. The system is built around compression shock wave phenomenon which are utilized to stably convert a portion of the dynamic energy of a supersonic stream to pressure energy within a subsonic stream.

Abstract: Methods and apparatus for flowing cooling air from the compressor section to the turbine section of a gas turbine engine are disclosed. Cooling air from the compressor is flowed radially inward through the compressor drum cavity and thence axially rearward along the rotor shaft to the turbine. Vortex pressure losses in the drum cavity are diminished to enable effective utilization of a lower pressure, lower temperature cooling air source. The use of air from the lower pressure, lower temperature source improves the overall engine operating efficiency while maintaining turbine cooling rates which are consonant with durable operation of the engine.

Abstract: Methods and apparatus for controlling the radial clearance between the rotor and stator elements in the turbine section of a gas turbine engine is disclosed. A cooling air valve is operatively disposed at the upstream end of the turbine section to control the admission of cooling air to the turbine in response to engine operating temperatures. In one specific embodiment the thermal growth of the case and the stator elements supported thereby is controlled by the valve. At low power conditions the case and the supported elements grow radially with the rotor in response to increasing gas path temperatures. At elevated conditions cooling air is flowable to the case to retard the thermal growth of the case and allow the rotor to grow radially toward the stator elements.

Abstract: A disk having a closed channel construction and which is especially suited for supporting the rotating blades of a gas turbine engine is disclosed. In one embodiment, the disk supports the fan blades of a turbofan engine which extend radially therefrom. The disk structurally includes an upsteam web, a downstream web and a plurality of arcuate plugs disposed in end to end relationship between the webs to form a toroidal type structure having a substantially rectangular cross section. The disk is contoured to provide a level of torsional and bending stiffness which limits the most critical stage vibratory frequencies to values above the engine operating range while limiting the maximum value of the disk hoop stress during operation to a level below the durability limits of the disk material utilized. A method for making the disk is further disclosed.

Abstract: Methods and apparatus for measuring wear on the contact faces of a mid-span shroud of the type extending between the adjacent blades of a gas turbine engine are disclosed. A segment of the shroud extends circumferentially from each blade into abutting relationship with a corresponding segment extending from the adjacent blade. Each segment has a contact face which is susceptible to wear at the abutting location with the adjacent segment. In one engine embodiment, the contact faces are coated with a wear resistance material to prolong the effective life of the shroud. The initial depth of the wear resistant coating or the extent of the abrasion after use are measurable in accordance within the concepts taught herein.

Abstract: Means for preventing the wasteful leakage of cooling air within the turbine section of a gas turbine engine is disclosed. A segmented shroud radially separates the flow path for the working medium gases from cooling air supply chambers which are disposed radially outward of the flow path. Rotatable vanes penetrate the shroud and extend into the medium flow path to control the flow of medium gases through the turbine. A ring, which is split, is urged against the vane and the adjacent shroud segments in operative response to a spring member to prevent the excess leakage of cooling air therebetween.

Abstract: A rotor blade capable of use in the high temperature environment of the turbine section of a gas turbine engine is disclosed. Various construction details which tend to equalize the metal temperature of the blade during operation also improve the cooling effectiveness of the cooling medium utilized. The system is built around convective, impingement, and film cooling techniques which are employed singly or in combination to improve the service life of the blade.

Abstract: A preconsolidated tape of continuous, high strength filaments in a metal matrix is coated with a layer of adhesive polymer and cut into shaped plies. The coated plies are stacked in a mold and resin bonded together by the application of heat and pressure. Many of the desirable physical properties of a diffusion bonded metal matrix article are also found in the resin bonded metal matrix article of the subject invention. Also, the use of preconsolidated adhesive coated plies eliminates the need for high diffusion bonding pressures and temperatures, thereby cutting the time involved for the bonding and molding operation by a factor of 8 in some instances.