Disclosed herein is an article comprising a first group of plies having a number of plies N.sub.1 each having unidirectional tows oriented in a first direction β.sub.1 and a second group of plies having a number of plies N.sub.2 each having unidirectional tows oriented in a second direction β.sub.2; where β.sub.1 is not equal to β.sub.2; wherein N.sub.1 and N.sub.2 are both integer numbers. At least one of the first group of plies or the second group of plies has at least one tow of different thickness from another tow, has a different tow spacing from another tow spacing, or a combination thereof.

A hollow airfoil body includes a baffle that is arranged in the airfoil body that extends in a radial direction and provides a fluid flow direction. The baffle has multiple holes that include first and second holes that are configured to conduct the cooling airflow in a chordwise direction toward the trailing edge of the airfoil body. The airfoil has a first standoff that extends from the airfoil body to support the baffle. The first axial standoff has a first length that defines an axial passage including the multiple holes. The airfoil includes a second standoff that has a second length less than the first length. The second standoff is arranged radially between the first and second holes. The first hole is smaller than the second hole. The second hole is downstream from the first hole relative to the fluid flow direction.

An integrated bladed rotor of a gas turbine engine is provided. The integrated bladed rotor includes a hub having a rotation axis and a radially outer platform relative to the rotation axis, and a plurality of blades extending radially outwardly from the outer platform of the hub. The blades are integrally formed with the hub to define a monolithic component with the hub. Two or more of the blades each include: an airfoil including a groove formed in an outer surface of the airfoil to mitigate crack propagation, and a root fillet providing a transition between the outer platform of the hub and the airfoil.

A gas turbine engine includes a fan section, a compressor section, and a turbine section. The fan section has a plurality of vane assemblies spaced circumferentially about an engine axis. The vane assemblies each include an airfoil extending between a leading edge and a trailing edge, a control rod extending through the airfoil, and a mechanism driven by the control rod to change the shape of the airfoil. A vane system for a gas turbine engine is also disclosed.

A gas turbine engine includes a compressor section that provides first and second compressor stages that are configured to respectively provide first and second cooling fluids. The first compressor stage has a higher pressure than the second compressor stage. The gas turbine engine further includes a component that has platform with an internal cooling passage fed by first and second inlets that respectively receive fluid from the first and second cooling sources. The second inlet is downstream from the first inlet.

An airfoil for a gas turbine engine according to an example of the present disclosure includes a platform section and an airfoil section extending in a spanwise direction from the platform section to a tip portion establishing a tip. The airfoil section has an external wall defining pressure and suction sides extending in a chordwise direction between a leading edge and a trailing edge, and the pressure and suction sides are spaced apart in a thickness direction between the leading edge and the trailing edge. The tip portion includes a tip pocket and a tip shelf extending inwardly from the tip. The tip pocket and tip shelf are on opposite sides of a shelf wall.

Examples described herein provide a computer-implemented method that includes providing the hybrid electric engine, the hybrid electric engine having a gas generating core and an electric machine powered by electric energy. The method further includes determining, by a processing device, whether a use of the electric energy will increase time on wing of the hybrid electric engine of the aircraft a threshold amount. The method further includes, responsive to determining that the use of energy will increase time on wing the threshold amount, apportioning the electric energy from a battery system of the aircraft to increase the time on wing.

A gas turbine engine is provided including a turbomachine having a compressor section, a combustion section, and a turbine section arranged in serial flow order; a rotor assembly driven by the turbomachine, the rotor assembly, the turbomachine, or both comprising a substantially annular duct relative to the centerline of the gas turbine engine, the annular duct defining a flowpath; a heat exchanger positioned within the annular duct and extending substantially continuously along the circumferential direction, the heat exchanger comprising a first material defining a heat exchange surface exposed to the flowpath, wherein the first material defines a heat exchange coefficient and wherein the heat exchange surface defines a surface area (A), and wherein the heat exchanger has an effective transmission loss (ETL) of between 5 decibels and 1 decibel for an operating condition.

A hybrid electric propulsion system includes a gas turbine engine having a low speed spool and a high speed spool. The low speed spool includes a low pressure compressor and a low pressure turbine, and the high speed spool includes a high pressure compressor and a high pressure turbine. The hybrid electric propulsion system also includes an energy storage system, an electric motor configured to augment rotational power of the high speed spool, and a controller. The controller is operable to detect a start condition of the gas turbine engine, control power delivery from the energy storage system to the electric motor based on detecting the start condition, and provide a compressor stall margin using a power-assist provided by the electric motor to the high speed spool over a targeted speed range during starting of the gas turbine engine.

One embodiment is an electric drive system for an aircraft including a motor, a gear box associated with the motor, and a cooling fan for drawing air into the unit across an electronic component to cool the electronic component and for expelling air into an oil cooler for cooling oil contained therein. The electric drive system further includes an oil distribution system for distributing oil cooled by the oil cooler to at least one motor and at least one gearbox, the distributed oil being used to cool the motor and the gearbox, a reservoir for collecting the distributed oil after it has been used to cool the motor and the gearbox, and at least one structural element for retaining the motor, gearbox, the cooling fan, the oil distribution system, and the reservoir together as a unit.