Abstract: A rotor assembly for a gas turbine engine includes a rotatable hub that has a main body and an array of annular flanges that extend about an outer periphery of the main body to define an array of annular channels. An array of airfoils are circumferentially distributed about the outer periphery. Each one of the airfoils includes an airfoil section extending from a root section received in the annular channels. Retention pins extend through the root section of a respective one of the airfoils and through the array of annular flanges to mechanically attach each root section to the hub.

Abstract: A rotor assembly for a gas turbine engine includes a rotatable hub that has a main body and an array of annular flanges that extend about an outer periphery of the main body to define an array of annular channels. An array of airfoils are circumferentially distributed about the outer periphery. Each one of the airfoils includes an airfoil section extending from a root section received in the annular channels. Retention pins extend through the root section of a respective one of the airfoils and through the array of annular flanges to mechanically attach each root section to the hub.

Abstract: A turbofan engine includes a propulsor section that has a propulsor shaft in driving engagement with a propulsor. An epicyclic gear system has a gear mesh lateral stiffness and a gear mesh transverse stiffness. A gear system input defines a gear system input lateral stiffness and a gear system input transverse stiffness. The gear system input lateral stiffness is less than 5% of the gear mesh lateral stiffness. A first turbine section rotates at a first speed, and a second turbine rotates at a second speed that is faster than the first speed. A first performance quantity is defined as the product of the first speed squared and the first area of the first turbine, a second performance quantity is defined as the product of the second speed squared and the second area of the second turbine, and a performance quantity ratio is between 0.5 and 1.5.

Abstract: A gas turbine engine according to an example of the present disclosure includes, among other things, a fan shaft configured to drive a fan, a support configured to support at least a portion of the fan shaft, the support defining a support transverse stiffness and a support lateral stiffness, a gear system coupled to the fan shaft, and a flexible support configured to at least partially support the gear system. The flexible support defines a flexible support transverse stiffness with respect to the support transverse stiffness and a flexible support lateral stiffness with respect to the support lateral stiffness. The input defines an input transverse stiffness with respect to the support transverse stiffness and an input lateral stiffness with respect to the support lateral stiffness.

Abstract: A turbofan engine includes a fan section that drives air along a bypass flow path in a bypass duct. An epicyclic gear system in driving engagement with the fan shaft and has a gear mesh lateral stiffness and a gear mesh transverse stiffness. A gear system input to the gear system defines a gear system input lateral stiffness and a gear system input transverse stiffness. The gear system input lateral stiffness is less than 5% of the gear mesh lateral stiffness. A first performance quantity is defined as the product of a first speed squared and a first area and a second performance quantity is defined as the product of a second speed squared and a second area. A performance quantity ratio of a first performance quantity to a second performance quantity is between 0.5 and 1.5.

Abstract: A method for forming a blade for a gas turbine engine may include forming a suction side sheath and a pressure side sheath, a first cavity and a second cavity established on opposed sides of a rib, forming a structural core configured for positioning in an interior section of the blade between the suction side sheath and the pressure side sheath, the structural core including a first core member, a second core member and a root interconnecting the first and second core members, assembling the suction side sheath and the pressure side sheath with the structural core such that the first core member is positioned in the first cavity and such that the second core member is positioned in the second cavity, and securing the suction side sheath to the pressure side sheath to form the blade.

Abstract: A turbofan engine includes a fan section. A turbine section is in driving engagement with the fan section through a geared architecture. A flexible support supports the geared architecture relative to an engine static structure. A deflection limiter includes at least one of an axially extending branch or a radially extending branch. A flexible output shaft is in driving engagement with the fan section and driven by the geared architecture. A speed change mechanism for a gas turbine engine is also disclosed.

Abstract: An airfoil for a gas turbine engine according to an example of the present disclosure includes, among other things, an airfoil section extending from a root section. The airfoil section includes a sheath that receives a core. The core includes first and second ligaments received in respective internal channels defined by the sheath, and each one of the first and second ligaments includes at least one interface portion in the root section dimensioned to receive a retention pin.

Abstract: A platform for a gas turbine engine according to an example of the present disclosure includes, among other things, a platform body that extends in a circumferential direction between first and second sidewalls to define a gas path surface, and opposed rows of flexible retention tabs that extend from the platform body and are dimensioned to wedge the platform between adjacent airfoils.

Abstract: An airfoil for a gas turbine engine according to an example of the present disclosure includes, among other things, an airfoil section that extends from a root section. The airfoil section extends between a leading edge and a trailing edge in a chordwise direction and extends between a tip portion and the root section in a radial direction, and the airfoil section defines a pressure side and a suction side separated in a thickness direction. The airfoil section includes a metallic sheath that receives a composite core, and the core includes first and second ligaments received in respective internal channels defined by the sheath such that the first and second ligaments are spaced apart along the root section with respect to the chordwise direction. The first and second ligaments define respective sets of bores, and the respective sets of bores are aligned to receive a common set of retention pins.

Abstract: A gas turbine engine according to an example of the present disclosure includes, among other things, a fan shaft configured to drive a fan, a support configured to support at least a portion of the fan shaft, the support defining a support transverse stiffness and a support lateral stiffness, a gear system coupled to the fan shaft, and a flexible support configured to at least partially support the gear system. The flexible support defines a flexible support transverse stiffness with respect to the support transverse stiffness and a flexible support lateral stiffness with respect to the support lateral stiffness. The input defines an input transverse stiffness with respect to the support transverse stiffness and an input lateral stiffness with respect to the support lateral stiffness.

Abstract: A gas turbine engine including a drive shaft that drives a propulsor. A frame which supports the drive shaft is a K-frame bearing support. A gear system is connected to the drive shaft. The gear system includes a gear mesh that defines a gear mesh lateral stiffness and a gear mesh transverse. A flexible support supports the gear system that defines a flexible support transverse stiffness and a flexible support lateral stiffness. The flexible support lateral stiffness is less than 8% of the gear mesh lateral stiffness.

Abstract: A turbofan engine includes a fan section. A turbine section is in driving engagement with the fan section through a planetary gear system. The planetary gear system includes a plurality of planet gears surrounding a sun gear. A carrier supports the plurality of planet gears and includes a first carrier bearing flange. A ring gear surrounds the plurality of planet gears and includes a ring gear bearing flange. At least one ring gear carrier bearing engages the carrier bearing flange and the ring gear bearing flange. A speed change mechanism for a gas turbine is also disclosed.

Abstract: A gas turbine engine includes a fan section that has fan blades that drive air along a bypass flow path in a bypass duct. A fan shaft is drivingly connected to the fan. A turbine section includes a turbine drive shaft. A gear system is connected to the turbine draft shaft through an input and connected to the fan shaft through an output. At least one of the input and the output include a flexible coupling. A gear system flex mount arrangement accommodates misalignment of the fan shaft and the turbine drive shaft during operation. The gear system flex mount arrangement includes a gear mesh that defines a gear mesh lateral stiffness and a ring gear that defines a ring gear lateral stiffness that is less than 12% of the gear mesh lateral stiffness.

Abstract: A gas turbine engine includes a fan shaft that drives a fan that has fan blades. The fan delivers airflow to a bypass duct. A gear system is connected to the fan shaft and is driven through an input defining an input lateral stiffness and an input transverse stiffness. A gear system flex mount arrangement accommodates misalignment of the fan shaft and the input during operation. A frame for supporting the fan shaft defines a frame lateral stiffness and a frame transverse stiffness. The input lateral stiffness is less than 11% of the frame lateral stiffness and the input transverse stiffness is less that 11% of the frame transverse stiffness.

Abstract: A rotor assembly for a gas turbine engine includes a rotatable hub that has a main body and an array of annular flanges that extend about an outer periphery of the main body to define an array of annular channels. An array of airfoils are circumferentially distributed about the outer periphery. Each one of the airfoils includes an airfoil section extending from a root section received in the annular channels. Retention pins extend through the root section of a respective one of the airfoils and through the array of annular flanges to mechanically attach each root section to the hub.

Abstract: An airfoil for a gas turbine engine according to an example of the present disclosure includes, among other things, an airfoil section that extends from a root section. The airfoil section extends between a leading edge and a trailing edge in a chordwise direction and extends between a tip portion and the root section in a radial direction. The airfoil section defines a pressure side and a suction side separated in a thickness direction, and the airfoil section includes a metallic sheath that defines an internal cavity receiving a composite core. The root section defines at least one bore dimensioned to receive a retention pin. At least one damping element is received in the internal cavity and that selectively causes the airfoil section to stiffen.

Abstract: A turbofan engine includes a fan section that drives air along a bypass flow path in a bypass duct. An epicyclic gear system in driving engagement with the fan shaft and has a gear mesh lateral stiffness and a gear mesh transverse stiffness. A gear system input to the gear system defines a gear system input lateral stiffness and a gear system input transverse stiffness. The gear system input lateral stiffness is less than 5% of the gear mesh lateral stiffness. A first performance quantity is defined as the product of a first speed squared and a first area and a second performance quantity is defined as the product of a second speed squared and a second area. A performance quantity ratio of a first performance quantity to a second performance quantity is between 0.5 and 1.5.

Abstract: A gas turbine engine includes a fan shaft that drives a fan that has fan blades. An outer housing surrounds the fan. A bypass flow path is within the outer housing. A fan shaft support that supports the fan shaft defines a fan shaft support transverse stiffness. A gear system is connected to the fan shaft. The gear system includes a gear mesh that defines a gear mesh transverse stiffness. A flexible support which supports the gear system relative to a static structure defines a flexible support transverse stiffness. The flexible support transverse stiffness is less than 11% of the fan shaft support transverse stiffness. The flexible support transverse stiffness is less than 8% of the gear mesh transverse stiffness.

Abstract: A rotor assembly for a gas turbine engine includes, among other things, a rotatable hub that has a metallic main body that extends along a longitudinal axis, and that has an array of annular flanges that extend about an outer periphery of the main body to define an array of annular channels along the longitudinal axis. Each of the annular channels receives a composite reinforcement member that extends about the outer periphery of the hub.