Abstract: A helicopter includes a rotor system having a rotor with an adjustable pitch that is controlled at least in part by a pilot using a collective control and which helicopter generates a Low RPM signal that is indicative of a threshold low rotational speed of the rotor. An actuator arrangement configured to move the collective control by exerting a force on the collective control such that the pilot is able to overcome the force but which otherwise moves the collective control from a current operational position toward a minimum pitch position. A control arrangement is configured for receiving the Low RPM signal and for responding to the Low RPM signal by activating the actuator arrangement for at least a predetermined period of time to apply the force to move the collective control from the current operational position to the minimum pitch position.

Abstract: A method for governing the speed of a fluid turbine by establishing a circulating flow and a rotational flow with a rotor, and interrupting the rotational flow with an opposing stator. A related braking apparatus includes a housing, a rotatable shaft, a rotor configured to rotatingly engage the shaft and engage a fluid in the housing with a plurality of radial vanes, and a non-rotating stator comprising a plurality of fluid pockets. The stator is disposed such that the radial vanes of the rotor and the fluid pockets of the stator are oriented in a facing relationship. When the shaft is rotated, the fluid in the housing experiences both a circulating flow and a rotational flow. Thus, the rotational flow is present proximate the radial vanes, but not in the fluid pockets, and the fluid imparts a braking torque on the rotating shaft via the rotor's radial vanes.

Abstract: Rotary jetting tool including a rotor with axially-opposed pressure-balanced mechanical face seals. Vented upper mechanical face seal enables the rotor to be operated with the relativity low starting torque achievable using reaction forces from offset jets energized with a pressurized fluid. When rotor is displaced axially due to set-down conditions, a pressure chamber exerts a pressure imbalance on the rotor, forcing the rotor to return to a normal operating position. Alternate structure to achieve low starting torque includes a volume disposed adjacent to a lower mechanical face seal, the volume being coupled in fluid communication with the pressurized fluid. Mechanical face seal surfaces are fabricated from ultra-hard materials, such as tungsten carbide, silicon carbide, and diamond. A gage ring designed to ensure the jets remove all of the material from the gage of the protective housing before the tool can advance can be incorporated.

Abstract: A rotary jetting tool including a pressure-balanced rotor, which is achieved using a vented volume. Axial movement of the rotor relative to the housing caused by pressure imbalances acting on the rotor selectively uncovers or opens a vent that places the volume in fluid communication with an ambient volume, enabling the rotor to achieve a pressure balanced condition. A plurality of radial clearance seals between the rotor and the housing are used to provide hydrodynamic bearings to reduce friction between the rotor and housing. The diameters of the seals are manipulated to facilitate pressure balancing of the rotor. In one embodiment, the rotor includes a centrifugal brake configured to control a maximum rotational speed of the rotor. Pressurized fluid is introduced into the rotor in an axial direction, enabling a relatively large upstream settling chamber to be incorporated into the rotor, thereby reducing inlet turbulence and improving jet quality.

Abstract: This invention discloses a valve that generates a hydraulic negative pressure pulse and a frequency modulator for the creation of a powerful, broadband swept impulse seismic signal at the drill bit during drilling operations. The signal can be received at monitoring points on the surface or underground locations using geophones. The time required for the seismic signal to travel from the source to the receiver directly and via reflections is used to calculate seismic velocity and other formation properties near the source and between the source and receiver. This information can be used for vertical seismic profiling of formations drilled, to check the location of the bit, or to detect the presence of abnormal pore pressure ahead of the bit. The hydraulic negative pressure pulse can also be used to enhance drilling and production of wells.

Abstract: An apparatus for inspecting an conduit such as a furnace tube comprising at least first and second module shells, each shell having an axially contoured exterior, and a flexible, non-jointed intermodule connector joining the first and second shells. Preferably, each module has a length that is 1.0 to 2.4 times its outer diameter and the connector has a length that is 0.5 to 2.0 times the outer module diameter.

Abstract: Suction pressure pulses are generated within a borehole by closing a valve that interrupts the flow of a drilling fluid (e.g., drilling mud) circulating through one or more high velocity flow courses within the borehole. In one embodiment in which the suction pressure pulses are applied to improve the efficiency of a drilling bit, the valve interrupts the flow of drilling mud directed through the bit and thus through high velocity flow course(s) disposed downstream of the bit. Arresting flow of the drilling mud through the high velocity flow course(s) generates suction pressure pulses of substantial magnitude over a face of the drill bit. The suction pressure pulses provide a sufficient differential pressure that weakens the rock through which the drill bit is advancing and also increase the force with which the drill bit is being advanced toward the rock at the bottom of the borehole.

Abstract: The invention describes a method and apparatus for milling objects by means of high velocity abrasive waterjet. The apparatus includes means for holding and producing relative motion in three dimensions of both the workpiece and the jet. Control means are provided to allow uniform and variable depth milling of complex shapes and automatic variations in relative speed, standoff distance, angle and pressure. The method includes the use of a resistant mask for facilitating milling and production of masks by the same tool used for milling.