Multi-mission tandem propulsion system

Claim 2

A tandem variable cycle propulsion system comprising: a forward turbofan engine having a fan, gas generator, and fan turbine arranged in axially spaced serial flow relation; a coaxially displaced downstream turbojet engine having a compressor, combustor and turbine arranged in axially spaced serial flow relation; outer exhaust duct means for directing the exhaust stream from the turbofan engine rearward around the turbojet engine; and variable cross-over valve means which may assume a first subsonic mode whereby the flow exiting from the fan and bypassed around the gas generator is directed to the outer exhaust duct means while an inlet ambient airflow is directed to the inlet of the turbojet and a seocnd transonic and supersonic mode whereby the flow exiting from the fan and bypassed around the gas generator is directed to the turbojet inlet.

Claim 3

The propulsion system of claim 1 wherein: the gas generator includes an outer casing; the fan includes an outer casing spaced apart from the gas generator casing so as to define an inner bypass duct therebetween; the turbojet engine includes an outer casing open at one end to form an inlet; the propulsion system includes an outer casing spaced apart from both the fan casing and turbojet casing so as to respectively define a forward annular outer bypass duct and the outer exhaust duct means, and variable blocker door means provided within the forward annular outer bypass duct to regulate the inlet flow of ambient air therethrough.

Claim 4

The propulsion system of claim 2 wherein the cross-over valve is disposed between the fan casing and turbojet casing such that the first mode provides direct flow connection between the inner bypass duct and outer exhaust duct means together with direct flow connection between the outer bypass duct and the inlet to the turbojet with the second mode providing direct flow connection between the inner bypass duct and the inlet to the turbojet, and wherein the exhaust gases exiting from the gas generator are ducted across the inlet airflow to the turbojet into the outer exhaust duct means.

Claim 5

The propulsion system of claim 3, including: a mixer chute disposed within the outer exhaust duct means to accommodate the comminglinG of bypass fan air exiting through the inner bypass duct and exhaust gases exiting from the gas generator; a first variable exhaust nozzle disposed at the downstream end of the turbojet engine; a second variable convergent-convergent/divergent exhaust nozzle disposed at the downstream end of the outer exhaust duct means, and a thrust reversing means disposed within the outer exhaust duct means upstream of the second nozzle.

Claim 6

The propulsion system of claim 2 wherein: the cross-over valve includes a plurality of axially extending and circumferentially spaced apart ducts each of which is rotatably hinged to the downstream end of the fan casing such that all the ducts may be simultaneously rotated to provide either direct flow communication between the inner bypass duct and outer exhaust duct means whereupon direct flow communication is also established between the outer bypass duct and the inlet to the turbojet through the spaces intermediate the ducts or direct flow communication between the inner bypass duct and the inlet to the turbojet, and the exhaust gases exiting from the gas generator are directed through a plurality of circumferentially spaced apart, outwardly flared, exhaust ducts which cross over the inlet airflow to the turbojet and empty into the outer exhaust duct means through a mixer chute.

Claim 7

The propulsion system of claim 5 including: a first variable exhaust nozzle disposed at the downstream end of the turbojet engine and having an axially translatable plug which may be translated to entirely close off the first nozzle, a second variable convergent-convergent/divergent exhaust nozzle disposed at the downstream end of the outer exhaust duct means, and a thrust reverser having an opening through the propulsion system outer casing with a cascade of arcuate fins disposed therein for reversing the direction of fluid flow therethrough together with a plurality of blocker flaps which may be swung into the outer exhaust duct means to direct the flow of fluid through the cascade.

Claim 8

The propulsion system of claim 2 wherein: the cross-over valve includes a plurality of axially extending and circumferentially spaced apart ducts each of which is rotatably hinged to the upstream end of the turbojet casing such that all the ducts may be simultaneously rotated to provide either direct flow communication between the outer bypass duct and the inlet to the turbojet whereupon direct flow communication is also established between the inner bypass duct and outer exhaust duct means through the spaces intermediate the ducts, or direct flow communication between the inner bypass duct and the inlet to the turbojet, and the exhaust gases exiting from the gas generator are directed through a plurality of circumferentially spaced apart, outwardly flared, exhaust ducts which cross over the inlet airflow to the turbojet and empty into the outer exhaust duct means through a mixer chute.

Claim 9

The propulsion system of claim 7 including: a first variable exhaust nozzle disposed at the downstream end of the turbojet engine and having an axially translatable plug which may be translated to entirely close off the first nozzle; a second variable convergent-convergent/divergent exhaust nozzle disposed at the downstream end of the outer exhaust duct means, and a thrust reverser having an opening through the propulsion system outer casing with a cascade of arcuate fins disposed therein for reversing the direction of fluid flow therethrough together with a plurality of blocker doors which may be swung into the outer exhaust duct means to direct the flow of fluid through the cascade.

Claim 10

A tandem variable cycle propulsion system comprising: a forward turbofan engine ahving a fan operable within a bypass duct, a gas generator, and a fan turbine arranged in axially spaced serial flow relation; a coaxially displaced downstream independent turbojet engine having variable inlet guide vanes, a compressor, a combustor, and a turbine arranged in axially spaced serial flow relation; outer exhaust duct means in flow communication with the bypass duct for directing the exhaust stream from the turbofan engine rearward around the turbojet engine whereupon the exhaust stream is commingled with a portion of the airflow exiting from the fan; and inlet passageway means whereby the remaining portion of the airflow exiting from the fan crosses the exhaust duct means and enters the inlet of the turbojet such that the proportions of total thrust of the propulsion system attiributable to the turbojet and turbofan may be varied to provide either low noise levels and relative efficiency commonly associated with subsonic gas turbine operation or a high rate of airflow commonly associated with supersonic gas turbine operation.

Claim 11

A tandem variable cycle propulsion system comprising: a forward turbofan engine ahving a fan operable within a bypass duct, a gas generator, and a fan turbine arranged in axially spaced serial flow relation; a coaxially displaced downstream independent turbojet engine having variable inlet guide vanes, a compressor, a combustor, and a turbine arranged in axially spaced serial flow relation; outer exhaust duct means in flow communication with the bypass duct for directing the exhaust stream from the turbofan engine rearward around the turbojet engine whereupon the exhaust stream is commingled with a portion of the airflow exiting from the fan; and inlet passageway means whereby the remaining portion of the airflow exiting from the fan crosses the exhaust duct means and enters the inlet of the turbojet such that the proportions of total thrust of the propulsion system attiributable to the turbojet and turbofan may be varied to provide either low noise levels and relative efficiency commonly associated with subsonic gas turbine operation or a high rate of airflow commonly associated with supersonic gas turbine operation.

Claim 12

The propulsion system of claim 9 wherein: the gas generator includes an outer casing; the turbojet engine includes an outer casing open at one end to form an inlet; and the propulsion system includes an outer casing spaced apart from both the gas generator and the turbojet casing so as to respectively define a bypass duct therebetween and the outer exhaust duct means which is in serial flow communication with the bypass duct.

Claim 13

The propulsion system of claim 10, including: a mixer chute disposed within the outer exhaust duct means to accommodate the commingling of bypass fan air exiting through the bypass duct and exhaust gases exiting from the gas generator; a first variable exhaust nozzle disposed at the downstream end of the turbojet engine; a second variable convergent-convergent/divergent exhaust nozzle disposed at the downstream end of the outer exhaust duct means, and a thrust reversing means disposed within the outer exhaust duct means upstream of the second nozzle.

Claim 14

The propulsion system of claim 10, including: a mixer chute disposed within the outer exhaust duct means to accommodate the commingling of bypass fan air exiting through the bypass duct and exhaust gases exiting from the gas generator; a first variable exhaust nozzle disposed at the downstream end of the turbojet engine and having an axially translatable plug which may be translated to entirely close off the first nozzle; a second variable convergent-convergent/divergent exhaust nozzle disposed at the downstream end of the outer exhaust duct means, and a thrust reverser having an opening through the propulsion system outer casing with a cascade of arcuate fins disposed therein for reversing the direction of fluid flow therethrough together with a plurality of blocker doors which may be swung into the outer exhaust duct means to direct the flow of fluid through the cascade.