Abstract: An aircraft engine is mounted on an aircraft wing such that the wing wake sheds along a zone at a predetermined position on the engine disk thereby minimizing dynamic loads or resonance. For a prechosen or design set of engine conditions the strength of the dynamic load is a function of the radial location of the zone on the disk having at least one relative minima between the centerline and the perimeter of the disk. The zone is positioned on the disk such that the value of the function is essentially a relative minima.

Abstract: High by-pass fan jet engine includes counterrotating turbine blade sets for receiving hot combustion gases from a core engine portion and driving the fan blades through a planetary gear-type reduction gear assembly. Lightweight, highspeed, concentric, counterrotating shafts transmit power from both turbine blade sets to the fan via the reduction gear assembly. A pair of planetary gear assemblies with fixed fing gears and a rotatable common planetary gear carrier is used to drive a single set of fan blades via the carrier, and a pair of planetary gear assemblies with a fixed common planetary gear carrier and rotatable ring gears is used to drive two or more counterrotating fan blade sets via the ring gears. A low pressure "booster" compressor feeding the core engine portion can be directly driven from one of the two high speed shafts.

Abstract: A high bypass ratio turbofan engine having a fan section, a booster compressor disposed aft of the fan section relative to the flow of combustion gases through the engine, and a core section disposed aft of the booster compressor. A low pressure counterrotating turbine, disposed aft of the core section, is used for driving the fan section and the booster compressor. The counterrotating turbine includes at least one set of rotating turbine blades and at least one set of oppositely rotating counterrotating turbine blades. A twin spool shaft is provided for coupling the turbine blades to the booster compressor and for coupling the counterrotating turbine blades to the fan section. A reduction gear is disposed in the drive shaft for coupling the turbine blades to the fan section and for reducing the rotational speed of the turbine output power to match the rotational speed of the fan section thereby splitting the usable work of the turbine blades between the fan section and the booster.

Abstract: The invention concerns a system for reducing the resisting torque which must be overcome in changing pitch of aircraft propeller blades. The resisting torque includes gas twisting moment and centrifugal twisting moment. The invention includes a bearing system which derives a torque from radial motion of the blade, the radial motion being induced by centrifugal force. The derived torque opposes the resisting torque. The derived torque can also be used to not only oppose, but also overcome, the resisting torques. Such overcoming can be desirable because the resisting torques can drive the propeller blades into a flat pitch position if the pitch change mechanism fails.

Abstract: A power takeoff for an unducted fan gas turbine engine having first and second counterrotating coaxial rotors coupled respectively to first and second propellers. The rotors and propellers are oriented for rotation about a longitudinal axis of the engine. A gear is coupled to each of the rotors for rotation therewith and arranged to provide rotational motion about an axis transverse to the engine axis. A shaft is coupled to the gear for rotation about the transverse axis. Each of the propellers includes a plurality of propeller blades, each of the blades is rotatable about a corresponding blade axis, and a control is coupled to the blades for varying the pitch thereof whereby power is selectively distributed between the propellers and the power takeoff. The power takeoff may include a propeller coupled to the shaft for developing thrust substantially transverse to the engine axis and/or a pump, compressor, or generator to supply fluids or electric power to other apparatus.

Abstract: The present invention provides a high bypass turbofan engine configuration wherein a fan drive turbine is divided into first and second turbine sections mounted for independent rotation within the engine frame. The first, higher pressure, higher speed turbine section is coupled to the fan section drive shaft via a gear box which reduces the rotational speed of the power delivered by the higher pressure first turbine section to match the design rotational speed of the fan section. The second turbine section, having a larger diameter and lower rotational speed as compared to the first turbine section, is directly connected to the fan section and drives the fan section at the same rotational speed as that of the second turbine section. In this manner, the fan drive shaft horsepower is provided while reducing the weight and size of the necessary gearing between the fan drive turbine and the fan. The weight and size of the fan drive turbine and the booster compressor are also reduced.

Abstract: A pitch feathering system for a gas turbine driven aircraft propeller having multiple variable pitch blades utilizes a counter-weight linked to the blades. The weight is constrained to move, when effecting a pitch change, only in a radial plane and about an axis which rotates about the propeller axis. The system includes a linkage allowing the weight to move through a larger angle than the associated pitch change of the blade.

Abstract: In one form of the invention, a counterrotating pair of aircraft propellers produces noise in the form of a frequency-modulated carrier wave. The frequency modulation allows a designer to manipulate the energy spectrum of the noise in order to, for example, place much of the acoustic energy into inaudible frequency ranges.

Abstract: A turbofan engine having a power generating portion of the engine supporting a fan and surrounded by a cowl. The cowl is split with the two sections being arcuate and hinged so that they can pivotally open for access and removability of the power generating portion of the engine. The split cowl is supported directly from a support pylon whereby there is no fan frame required.

Abstract: The cooling air flowpath for a turbomachine includes a plurality of valves placed in mutually parallel relationship to collectively provide for the modulation of the cooling airflow. Minimum flow requirements are assured while economizing on air to increase efficiency. Any single valve passes only a small portion of the total air so that a valve failure does not appreciably reduce the overall cooling function.

Abstract: A gas turbine engine comprising a fan, a compressor and a turbine, wherein the torque requirements of the fan or compressor can be modulated, is provided with differential gearing to transmit all of the fan and compressor power requirements from the turbine. The differential gearing maintains an adjustable speed relationship between the fan and compressor with respect to the turbine depending upon the torque requirements thereof and the gear ratios within the differential gearing.

Abstract: A variable cycle turboshaft engine includes a remote fan system and respective high and low pressure systems for selectively driving the fan system in such a manner as to provide VTOL takeoff capability and minimum specific fuel consumption (SFC) at cruise and loiter conditions. For takeoff the fan system is primarily driven by the relatively large low pressure system whose combustor receives the motive fluid from a core bypass duct and, for cruise and loiter conditions, the fan system is driven by both a relativelysmall high pressure core and the low pressure system with its combustor inoperative. A mixer is disposed downstream of the high pressure system for mixing the relatively cold air from the bypass duct and the relatively hot air from the core prior to its flow to the low pressure turbine.

Abstract: A core engine with a single shaft driving both a forward and a rear fan, with the fans discharging into separate nozzles which are variable to direct exhaust gases in either the downward or rearward direction or in any direction therebetween. Separate flow modulating means are provided with the fans to selectively vary the respective thrusts produced. By selective modulation of the nozzles and the flow-varying means, both engine angle control and position control may be obtained in all three planes. A third variable position nozzle is provided to direct the discharge flow of the core turbine between the downward and rear directions to thereby augment the thrust and control functions.

Abstract: A device is provided for containing blades of rotating turbomachinery comprising a high-strength ring supported in radial spacial relationship over the blade tips by means of a stationary support structure. The ring is supported in such a manner that it is capable of spinning with respect to the support structure when acted upon by a predetermined blade force.

Abstract: A nacelle for use with a gas turbine engine is provided with an integral webbed structure resembling a spoked wheel for rigidly interconnecting the nacelle and engine. The nacelle is entirely supported in its spacial relationship with the engine by means of the webbed structure. The inner surface of the nacelle defines the outer limits of the engine motive fluid flow annulus while the outer surface of the nacelle defines a streamlined envelope for the engine.

Abstract: A method of reducing carbon monoxide and unburned hydrocarbon emissions in a gas turbine engine by bleeding hot air from the engine cycle and introducing it back into the engine upstream of the bleed location and upstream of the combustor inlet. As this hot inlet air is recycled, the combustor inlet temperature rises rapidly at a constant engine thrust level. In most combustors, this will reduce carbon monoxide and unburned hydrocarbon emissions significantly. The preferred locations for hot air extraction are at the compressor discharge or from within the turbine, whereas the preferred re-entry location is at the compressor inlet.

Abstract: An improved method of operating a gas turbine engine is presented wherein engine-generated noise is maintained at a reduced level during reduced thrust operation. Fan speed is maintained at a constant level while fan nozzle area is increased. This maintains high inlet Mach numbers for reduced forward noise propagation and also permits reduced nozzle exhaust velocity for reduced shear noise. In another embodiment, airflow is increased by means of a fan blade pitch change or speed increase while the fan nozzle area is increased, yielding both a net reduction in engine thrust and noise.

Abstract: Drive means for connecting a gas turbine engine to its accessories are so constructed as to allow the accessories to be selectively positioned to any one of several predetermined circumferential positions about the perimeter of the engine. This feature permits convenient mounting of the same engine upon vehicles demanding radically different engine mounting arrangements.

Abstract: A nacelle for use with a gas turbine engine is provided with an integral webbed structure resembling a spoked wheel for rigidly interconnecting the nacelle and engine. The nacelle is entirely supported in its spacial relationship with the engine by means of the webbed structure. The inner surface of the nacelle defines the outer limits of the engine motive fluid flow annulus while the outer surface of the nacelle defines a steamlined envelope for the engine.

Abstract: An article such as a blade fabricated from a plurality of high-strength, reinforcing filaments embedded in a matrix material and characterized by a portion of the filaments oriented transverse to the blade longitudinal axis in a direction through the blade to enhance transverse shear strength. In one embodiment, a plurality of columnar filament cores are each wrapped with a filament sheet and bonded together laterally to form the blade primary structure. The orientation of the filaments within the sheet forms an angle with the core longitudinal axes such that at least a portion of the sheet filaments runs transverse to the blade from one aerodynamic surface to the other. In an alternative embodiment, a blade is formed of a plurality of bonded filament laminates accordian folded with the fold lines angled with respect to the longitudinal axes of the filaments, the distance between fold lines being equal to or greater than the blade thickness.