Supersonic jet aircraft

Abstract

A supersonic jet aircraft and a method of operating the same. The supersonic jet aircraft having at least three turbofan engines and an engine management computer. A first engine of the at least three turbofan engines is configured to be de-activatable during flight to move from an operational state in which it provides thrust to an operational state in which it stops providing thrust. Other engines of the at least three turbofan engines are configured to provide sufficient thrust to the supersonic jet aircraft when the first engine is de-activated such that the aircraft can perform a supersonic climb operation and/or a supersonic cruise operation.

Claims

1. A supersonic jet aircraft comprising: at least three turbofan engines that each have identical turbofan engine cores, the at least three turbofan engines being configured to provide thrust to the supersonic jet aircraft to perform subsonic flight operations and two of the at least three turbofan engines being configured to provide supersonic flight operations, the at least three turbofan engines including: a first engine configured to be de-activatable during flight to move from a first operational state in which the first engine provides thrust to a second operational state in which the first engine stops providing thrust, the first engine having a non-supersonic inlet, and the other engines of the at least three turbofan engines configured to provide thrust to the supersonic jet aircraft when the first engine is de-activated such that the supersonic jet aircraft performs a supersonic climb operation or a supersonic cruise operation; and an engine management computer configured to: command thrust from the first engine during the subsonic flight operations of the supersonic jet aircraft; and automatically de-activate the first engine when the subsonic flight operations are complete.

2. The supersonic jet aircraft of claim 1, wherein the first engine is further configured to be re-activatable during flight to move back to the first operational state in which the first engine provides thrust.

3. The supersonic jet aircraft of claim 1, wherein the at least three turbofan engines are provided in a tri-jet configuration.

4. The supersonic jet aircraft of claim 1, wherein the first engine is mounted within a fuselage of the supersonic jet aircraft.

5. The supersonic jet aircraft of claim 1, wherein only three turbofan engines are included.

6. The supersonic jet aircraft of claim 1, further comprising one or more doors configured to: in a first position, allow air flow into an inlet of the first engine, and in a second position, block air flow into the inlet of the first engine.

7. The supersonic jet aircraft of claim 1, wherein an air inlet for the first engine is an S-duct air inlet, a bifurcated air inlet, or a pitot air intake.

8. The supersonic jet aircraft of claim 1, wherein each of the at least three turbofan engines has a bypass ratio of no more than 3.

9. A method of operating the supersonic jet aircraft of claim 1, the method including the steps of: completing a subsonic flight operation of the supersonic jet aircraft, in which each of the at least three turbofan engines is operated to obtain thrust therefrom; de-activating the first engine of the at least three turbofan engines such that the first engine stops providing thrust; and after the first engine is de-activated, performing a supersonic climb operation or a supersonic cruise operation using the thrust obtained from only the remaining operating turbofan engines.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the disclosure will now be described by way of example with reference to the accompanying drawings in which:

(2) FIG. 1 shows a top-down schematic view of a supersonic jet aircraft;

(3) FIG. 2A shows a front-on schematic view of the supersonic jet aircraft of FIG. 1;

(4) FIG. 2B shows a front-on schematic view of a variant to the supersonic jet aircraft shown in FIG. 1;

(5) FIG. 3A shows a side-on schematic view of the tail section of the supersonic jet aircraft of FIG. 1;

(6) FIG. 3B shows a side-on schematic view of the tail section of the variant supersonic jet aircraft shown in FIG. 2B;

(7) FIG. 4 shows a top-down schematic view of a variant of the supersonic jet aircraft of FIG. 1; and

(8) FIG. 5 shows a flow diagram for operating a supersonic jet aircraft.

DETAILED DESCRIPTION OF THE DISCLOSURE

(9) Aspects and embodiments of the present disclosure will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art.

(10) FIG. 1 shows a top-down schematic view of a supersonic jet aircraft 100. The aircraft includes a fuselage 101, wings 102, and engines 103-105. A first engine 103 is mounted to the fuselage 101 behind engines 104 and 105, which are mounted underneath respective wings.

(11) The aircraft includes an engine management computer (108) that is configured to: command thrust from the first engine during a subsonic operation of the supersonic jet aircraft; and automatically de-activate the first engine when the subsonic operation is complete. The engine management computer can be located at any suitable location of the aircraft.

(12) The first engine 103, has an air inlet 106 also mounted to the fuselage 101. The air inlet in this example is a bifurcated air inlet in that it has two inlet apertures feeding the engine 103. This is seen more clearly in FIG. 2A, which is a front-on schematic view of the aircraft of FIG. 1. As can more clearly be seen, the air inlet 106 has a first inlet aperture 106a and a second inlet aperture 106b, each located on an opposing side of the fuselage 101.

(13) As shown in FIG. 1, the first engine may be positioned rearward from the other engines with a separation angle 107 indicated that minimises any engine to engine debris.

(14) In some examples, the first engine 103 has an air inlet 201 which is an S-duct inlet. This is shown in FIG. 2B. The S-duct inlet 201 has an inlet aperture located above the first engine 103, and mounted in the fuselage 101.

(15) For sharp edged supersonic installations, both an S-duct inlet and a bifurcated inlet are likely to generate more fan face distortion (both pressure induced and generated via swirl). It is advantageous then to decrease the effect these inlets will have. As discussed below, this can be achieved in the present disclosure by de-activating the first engine 103 during flight so that it only has to operate under subsonic conditions, whereby its inlet can be a subsonic inlet.

(16) FIG. 3A shows the tail section of the aircraft of FIG. 2A from a side-on perspective. Here, one of the inlet apertures 106b can be seen, providing air to the first engine 103 whilst being substantially in-line with it. In contrast, as shown in FIG. 3B, an S-duct inlet 201 has an inlet aperture located above the first engine 103 relative to the fuselage. The air flows in an S-shaped path, to be provided to the first engine 103. In a different configuration, not shown, the inlet aperture is located below the first engine 103 relative to the fuselage.

(17) During a subsonic operation, the aircraft operates using all three engines. That is to say, all three engines are maintained in an operational state and thereby provide thrust to the aircraft. Conveniently all three engines have a substantially identical configuration. For example, all three engines have a commonly sized engine core and a common fan diameter. When the aircraft finishes the subsonic operation, e.g. has taken-off and/or has completed an initial climb, the first engine 103 is de-activated. The aircraft then performs one or more supersonic operations, for example a supersonic climb operation or a supersonic cruise operation.

(18) The engines are configured such that engines 104 and 105 can, by themselves, allow the aircraft to perform these supersonic operations. Thus the engines are over-sized for take-off requirements from a core temperature and flow perspective such that only two engines are required for the supersonic climb or cruise operations.

(19) In one example, each engine has a main engine fan diameter of 1534 mm (60.4″), and a bypass ratio of 2.82, which gives a supersonic effective engine face area of 3.697 m.sup.2 (5731 in.sup.2) across the two active engines when the first engine is de-activated. The subsonic effective engine face area across all three engines, by contrast, can be around 5.546 m.sup.2 (8596 in.sup.2).

(20) In a comparative configuration providing similar levels of performance but in which all three engines operate both in sub- and supersonic operations the engine fan diameter could be about 1584 mm (62.4″), the bypass ratio could be 3.52, and the non-dimensional high-pressure compressor size could be 66% of that of the aforementioned engine. Such a configuration would have a supersonic effective cross-sectional area of 5.919 m.sup.2 (9175 in.sup.2), and a subsonic effective cross-sectional area of the same.

(21) Therefore, it can be seen that a configuration according to the present disclosure can offer a reduction in supersonic effective cross-sectional area of approximately 38%.

(22) Similarly, a configuration according to the present disclosure offers a reduction in subsonic effective cross-sectional area of approximately 6.3%. The non-dimensional high-pressure compressor size=(W26*SQRT(T30))/P30, where W26 is the inlet flow rate of air in lbm/s to the compressor, T30 is the exit temperature of the high-pressure compressor in Kelvin, and P30 is the exit pressure of the high-pressure compressor in lbs/sq.in.

(23) These engines sizes are intended to meet expected noise requirements. Such engines must generally be conditioned to meet a subsonic Mach number of the order of 0.4 to 0.6 for typical fan inlet Mach numbers. Comparing the example configuration according to the present disclosure to the comparative configuration in which all three engines operate, it can be observed that the bypass ratio has reduced from 3.52 to 2.82, and the non-dimensional high-pressure compressor size has increased significantly by a factor of about 1.5 multiple to account for the increased supersonic power requirement when the de-activatable engine is de-activated.

(24) It was also found that the sizing of the engines in configurations according to the present disclosure can improve the supersonic climb and supersonic cruise specific fuel consumptions. This is due to improved component matching during supersonic operations when the bypass ratio is decreased/specific thrust is increased. This results in improved positioning of the cruise condition on the component characteristics relative to the other flight conditions, and can be observed by a higher low-pressure spool speed required for a cycle for a given fan diameter at common altitude and airframe thrust demand conditions. This allows for improved fan efficiency relative to the configuration with no de-activatable engines.

(25) It was further found that the core mass increase across all three engines, to account for only two being used for supersonic operations, could be offset by the simplification of the subsonic-only installation for the de-activatable engine on the aircraft. Only a basic installation for the de-activatable engine is required as it is only used during subsonic flight operations. Moreover, as a result, some elements of supersonic installations can be avoided. In particular, as already mentioned above, the de-activatable engine can have a simplified (nonsupersonic) inlet. There is also likely to be no requirement for a variable exhaust nozzle (used during supersonic operations) in the de-activatable engine. Indeed, for take-off roll climb-out and subsonic climb it is likely that the engine can be operated with fixed final nozzle areas.

(26) The reduction in contribution of these items to supersonic drag also significantly reduces the wetted area and wave drag contributions from the turbofan engines in supersonic cruise.

(27) Additionally, significant weight can be saved on the aircraft structure as a result of the removal or simplification of mounting and load path arrangements generally needed for supersonic installations. Subsonic capable inlets are much more readily integrated into the fuselage lofted shape for supersonic jet aircraft, and therefore flow direction passage devices such as bifurcations and S-ducts can either be removed entirely or significantly simplified.

(28) Thus whilst there is a weight penalty due to the core compressor, combustor, and turbine(s) being over-sized to meet a higher supersonic climb and cruise thrust requirement, this can be more than balanced by the advantages discussed above.

(29) A further significant advantage of the configuration of the present disclosure is the ability to have only one type of turbomachinery for all three of the engines. Advantageously, this can allow the first engine to be swapped with relative ease with any of the other engines. As the first engine is generally used sparingly, this can further increase the reliability of the supersonic jet aircraft.

(30) Removal of the supersonic installation for the de-activatable engine, leaving only a single style for the non-de-activatable engines, can also reduce the variety of distortion conditions which the engine type may need to be adapted for. This can allow for improved fan efficiency or the adaptation of a fan with a lower baseline surge margin.

(31) FIG. 4 shows a top-down schematic of a further variant of the supersonic jet aircraft including a pair of doors 401 and 402, which are moveable between a first position, in which air flows into an air inlet of the first engine 103, and a second position in which air is blocked from flowing into the inlet of the first engine 103. The dotted lines indicate the open position of the doors 401, 402 whereby air cannot flow into pitot intakes 403 and 404 respectively. The doors close by moving in the direction indicated by arrows 405 and 406 respectively, so that the doors form an inlet for their respective pitot intakes. In the closed position, the doors generally align with an exterior of the fuselage when in plan view.

(32) A hinge is connected to each door at a point distal to the respective pitot intake, and a seal is provided at a point proximal to each respective pitot intake.

(33) The doors, when open, provide a continuous aerodynamic surface on an exterior of the fuselage, and so decrease deleterious effects due to drag. This can be particularly beneficial to wave drag which is a function of discontinuities in the lofted cross sectional area of the aircraft.

(34) FIG. 5 shows a flow diagram for operating the supersonic jet aircraft. In a first a step, 501, the first engine (mounted to the fuselage) and the remaining engines (mounted to the wings) are activated. Subsequently, in step 502, the supersonic jet aircraft performs one or more subsonic operations. For example, the aircraft may take-off, climb, and achieve a subsonic cruise. A check is performed, in step 503, to ascertain whether the subsonic operation has completed.

(35) When the subsonic operation has completed the first engine is de-activated, as shown in step 504. The supersonic jet aircraft then performs one or more supersonic operations in step 505. For example the supersonic jet aircraft may perform a supersonic climb, a transonic operation, or a supersonic cruise.

(36) It will be understood that the disclosure is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.