Fans

Claim 2

A fan assembly for a gas turbine engine of the ducted-fan bypass type including a non-rotative by-pass duct and a singlestage fan mounted for rotation by the engine within the by-pass duct, said fan having flow-varying blading Capable of movement from positive pitch into negative pitch whereby the direction of flow of air in the duct is reversed, and said duct having means located downstream with respect to the fan blading when in positive pitch and operative when the fan blading is in negative pitch to increase the amount of air introduced to the duct.

Claim 3

A fan assembly as claimed in claim 1, wherein said means comprises flap valves pivotally mounted in the wall of the duct and openable automatically, when the fan blading is adjusted to negative pitch, by consequent suction created in the duct.

Claim 4

A fan assembly as claimed in claim 2, wherein ports are provided in the wall of the duct with which the flap valves are co-operable, said ports being arranged in alignment peripherally of the duct.

Claim 5

A fan assembly as claimed in claim 3, wherein the axes about which the flap valves are pivotable are parallel to the rotational axis of the fan.

Claim 6

A fan assembly as claimed in claim 3, wherein the axes about which the flap valves are pivotable are arranged transversely with respect to the rotational axis of the fan.

Claim 7

A fan assembly as claimed in claim 1, wherein said means comprises a rearward portion of the duct which is axially displaceable rearwardly with respect to a main portion thereof by operating means to produce an annular auxiliary intake in the wall of the duct.

Claim 8

A fan assembly as claimed in claim 6, wherein said operating means comprises fluid-pressure-operable jacks carried within the structure of the main portion of the duct, with their axes parallel to the rotational axis of the fan, and directly connected between said main portion and said rearward portion of the duct.

Claim 9

A fan assembly as claimed in claim 1, wherein said means comprises two intermediary annular portions of the duct which are ported and which are relatively rotatable about the rotational axis of the fan by operating means, the ports when in registry, those of one of said portions with respect to those of the other of said portions, producing a series of peripherally spaced intake openings through the wall of the duct.

Claim 10

A fan assembly as claimed in claim 8, wherein said operating means comprises fluid-pressure-operable jacks carried within the structure of the duct, with their axes parallel to the rotational axis of the fan.

Claim 11

A fan assembly as claimed in claim 9, wherein said jacks are connected between said structure and helical drive means in one of said two intermediary annular portions, said helical drive means converting linear movement of the jacks into rotary movement of said one portion with respect to the other portion.

Claim 12

A fan assembly as claimed in claim 1, wherein said means comprises a series of peripherally arranged gill-like members pivotally mounted upon the rearward end portion of said duct and capable, as or when the fan blading is moved into negative pitch, of being moved outwardly about their pivots so as collectively to provide a flared entry for the rearward end portion of the duct.

Claim 13

A fan assembly as claimed in claim 11, wherein said gill-like members are operated by fluid-pressure-operable jacks housed within the duct structure.

Claim 14

A fan assembly, for attachment to the front of a main gas turbine engine assembly to provide an engine of the ducted-fan by-pass type, and constructed as a unitary assembly which can be fitted and removed as such and comprises a non-rotative portion, which includes a by-pass duct, and a rotative sub-assembly comprising a single-stage fan supported in bearings by the non-rotative portion, said fan having flow-varying blading surrounded by said by-pass duct and capable of movement from positive pitch into negative pitch whereby the direction of flow of air in the duct is reversed, and said duct having means located downstream with respect to the fan blading when in positive pitch and operative when the fan blading is in negative pitch to increase the amount of air introduced to the duct.

Claim 15

A fan assembly, for attachment to the front of a main gas turbine engine assembly to provide an engine of the ducted-fan by-pass type, and constructed as a unitary assembly which can be fitted and removed as such and comprises a non-rotative portion, which includes a by-pass duct, and a rotative sub-assembly comprising a single-stage fan supported in bearings by the non-rotative portion, said fan having flow-varying blading surrounded by said by-pass duct and capable of movement from positive pitch into negative pitch whereby the direction of flow of air in the duct is reversed, and said duct having means located downstream with respect to the fan blading when in positive pitch and operative when the fan blading is in negative pitch to increase the amount of air introduced to the duct.

Claim 16

A gas turbine engine of the ducted-faN by-pass type having a front-mounted fan assembly which includes a single-stage fan and a non-rotative duct within which the fan is rotatable, said fan having flow-varying blading capable of movement from positive pitch into negative pitch whereby the direction of flow of air in the duct is reversed, and said duct having means located downstream with respect to the fan blading when in positive pitch and operative when the fan blading is in negative pitch to increase the amount of air introduced to the duct.

Claim 17

A gas turbine engine of the ducted-faN by-pass type having a front-mounted fan assembly which includes a single-stage fan and a non-rotative duct within which the fan is rotatable, said fan having flow-varying blading capable of movement from positive pitch into negative pitch whereby the direction of flow of air in the duct is reversed, and said duct having means located downstream with respect to the fan blading when in positive pitch and operative when the fan blading is in negative pitch to increase the amount of air introduced to the duct.

Claim 18

A gas turbine engine of the ducted-fan by-pass type having a front-mounted fan assembly which is detachable from the remainder of the engine as a complete assembly and which comprises a rotative sub-assembly, in the form of a single-stage fan including a hub and flow-varying blading, and a non-rotative portion by which the complete assembly is mounted and which includes a stationary duct which surrounds said flow-varying blading, said flow-varying blading being capable of movement from positive pitch into negative pitch whereby the direction of flow of air in the duct is reversed, and said duct having means located downstream with respect to the fan blading when in positive pitch and operative when the fan blading is in negative pitch to increase the amount of air introduced to the duct.

Claim 19

A gas turbine engine of the ducted-fan by-pass type having a front-mounted fan assembly which is detachable from the remainder of the engine as a complete assembly and which comprises a rotative sub-assembly, in the form of a single-stage fan including a hub and flow-varying blading, and a non-rotative portion by which the complete assembly is mounted and which includes a stationary duct which surrounds said flow-varying blading, said flow-varying blading being capable of movement from positive pitch into negative pitch whereby the direction of flow of air in the duct is reversed, and said duct having means located downstream with respect to the fan blading when in positive pitch and operative when the fan blading is in negative pitch to increase the amount of air introduced to the duct.