GB2630134A

GB2630134A - Fuel tank and suction pipe

Info

Publication number: GB2630134A
Application number: GB2307512.0A
Authority: GB
Inventors: Sharpe Nick
Original assignee: Modini Ltd
Current assignee: Modini Ltd
Priority date: 2023-05-19
Filing date: 2023-05-19
Publication date: 2024-11-20
Also published as: WO2024241024A1; GB202307512D0

Abstract

A fuel tank for an unmanned aerial vehicle (UAV). The fuel tank includes a bladder 603 configured to be housed inside the fuselage of the unmanned aerial vehicle, e.g. connected at coupling points 650. The bladder includes a series of baffles 605 for reducing slosh of fuel in the bladder when the unmanned aerial vehicle changes direction, and may be configured to expand or contract based on the volume of fuel. The baffles may be concentric (figure 7) or located parallel to a longitudinal axis of the fuel tank, and may include apertures to control the degree of fluid flow. Also claimed is a fuel tank suction pipe including a submersible fuel hose coupled to a weighted nozzle 375 configured to settle at the bottom of the tank.

Description

Fuel tank and suction pipe

Field of the invention

The present disclosure relates to a fuel tank such as a fuel tank for an unmanned aerial 5 vehicle, and a fuel tank suction pipe for drawing fuel from the fuel tank.

Background

Unmanned aerial vehicles may be powered by gas turbine engines fed by fuel from a fuel tank. For effective control of the unmanned aerial vehicle, it is important that there is a continuous and regular supply of fuel to the gas turbine engine. The flow of fuel to the gas turbine engine may be interrupted or may vary depending on movement of the unmanned aerial vehicle -for example, a high acceleration or deceleration, or sudden ascent or descent, may affect the flow of fuel out of the fuel tank.

Furthermore, movement of the unmanned aerial vehicle may result in movement or slosh of fuel in the tank, particularly when the tank is not completely full. This may impact on the manoeuvrability of the unmanned aerial vehicle in flight.

Summary of the invention

Aspects of the invention are as set out in the independent claims and optional features are set out in the dependent claims. Aspects of the invention may be provided in conjunction with each other and features of one aspect may be applied to other aspects.

In a first aspect of the disclosure there is provided a fuel tank for an unmanned aerial vehicle. The fuel tank comprises a primary bladder configured to be housed inside the fuselage of the unmanned aerial vehicle. The primary bladder comprises a series of baffles for reducing slosh of fuel in the bladder when the unmanned aerial vehicle changes direction.

Advantageously using a bladder to store fuel in an unmanned aerial vehicle reduces the likelihood of air being drawn into the engine of the unmanned aerial vehicle. Providing a series of baffles inside the bladder furthermore reduces slosh of fuel inside the bladder. For example, the baffles may reduce slosh in both the forward/rearward direction (for example when accelerating/decelerating but also when climbing descending), but additionally or alternatively when the unmanned aerial vehicle is rolling to bank and turn -2 -in one direction or the other. This may improve the stability of the unmanned aerial vehicle.

The primary bladder may be in the general shape of a cylinder. The primary bladder 5 may have an elongate dimension for fitting inside the fuselage. The primary bladder may have a longitudinal axis corresponding to the elongate dimension.

In some examples, the series of baffles are arranged transverse to the longitudinal axis. This may prevent fuel from sloshing forwards/rearwards, for example when the unmanned aerial vehicle is climbing and descending or accelerating or decelerating. In other examples, the series of baffles are arranged parallel to the longitudinal axis. This may prevent fuel from sloshing from side to side when the unmanned aerial vehicle is rolling to bank and turn in one direction or the other.

In some examples the series of baffles are provided by a series of concentric subservient bladders arranged inside the primary bladder.

Each baffle of the series of baffles may comprise a corresponding aperture for allowing a controlled degree of fuel to flow therebetween. This may advantageously allow fuel to be drawn to a suction hose but prevent bulk/large flows when there are sudden movements to the unmanned aerial vehicle. The apertures of one baffle may be offset relative to the corresponding apertures of an adjacent baffle.

The bladder may be configured to be coupled to the inside of the fuselage by a coupling point. The coupling point may advantageously prevent the bladder from shifting inside the fuselage when the unmanned aerial vehicle is moving. This may be particularly relevant when the bladder has been partly emptied of fuel, as there will then be a space between the inside of the fuselage and the bladder.

In some examples the bladder is configured to be coupled to the inside of the fuselage by a pair of opposing coupling points on opposing sides of the bladder. For example, the bladder may be coupled at the top and bottom (for example, on opposing sides transverse to the longitudinal axis), or at either end along the longitudinal axis (for example, in a plane parallel to the longitudinal axis). -3 -

In another aspect there is provided a fuel tank suction pipe. The fuel tank suction pipe comprises a submersible fuel hose configured to extract fuel from the fuel tank coupled to a weighted nozzle. The weighted nozzle is configured to settle at the bottom of the fuel tank in use. The bottom of the fuel tank may be opposite to an inlet port for filling the fuel tank with fuel.

Advantageously, this means that whatever orientation the unmanned aerial vehicle is heading in (whether ascending, descending, or banking left or right, for example), the fuel tank suction pipe will still settle at the bottom of the tank to ensure fuel is drawn into 10 the engine and reduce the likelihood of air being drawn into the engine.

The weighted nozzle may comprise a frustoconical shaped tip, but it will be understood that other geometries may be used -for example the tip may be generally conical or semispherical. The frustoconical shaped tip may comprise rounded edges. More rounded geometries (i.e., geometries without sharp point or edges) are generally preferred to reduce the chance of damage occurring by interaction between the tip and the fuel tank itself, particularly in examples where a bladder is used.

The weighted nozzle may comprise a plurality of apertures for sucking fuel therethrough.

The weighted nozzle may also comprise a filter for filtering fuel sucked through the nozzle.

The fuel tank suction pipe may further comprise a rigid pipe portion coupling the weighted nozzle to the submersible fuel hose. The rigid pipe portion may be proximate to the weighted nozzle. This may advantageously prevent kinks from occurring in the fuel tank suction pipe in the region adjacent to the nozzle, which may otherwise block or restrict the flow rate of fuel to the engine.

The fuel tank suction pipe may be used with the fuel tank described above. For example, the fuel tank suction pipe may be used with fuel tanks comprising a bladder.

In another aspect there is provided an unmanned aerial vehicle comprising the fuel tank described above. The fuel tank may comprise the fuel tank suction pipe described 35 above. -4 -

Drawings Embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 shows a perspective view of the fuselage of an example unmanned aerial vehicle; Fig. 2A shows a cross-section through a fuel tank of an example unmanned aerial vehicle; Fig. 2B shows a perspective view of the cross-section of Fig. 2A; Fig. 3 shows a cross-section of an example fuel tank suction pipe; Fig. 4 shows a cross-section through an example fuel tank for an unmanned aerial vehicle; Fig. 5 shows the fuel tank of Fig. 4 when some of the fuel in the tank has been used up; Fig. 6 shows a cross-section of another example fuel tank for an unmanned aerial 15 vehicle; and Fig. 7 shows a cross-section of another example fuel tank for an unmanned aerial vehicle.

It will be understood that similar reference numerals denote the same or similar features 20 with a similar functionality.

Specific description

Fig. 1 shows a perspective view of the fuselage 101 of an example unmanned aerial vehicle 101. The fuselage 101 in this example is elongate and has a main body portion having a cylindrical nature that connects the front cone and rear tail section. The fuselage 101 has a longitudinal axis that corresponds to the longitudinal axis of the main body portion of the fuselage and extends from the front cone to the rear tail section.

The fuselage 101 shown in Fig. 1 has a cavity 130 for receiving fuel for powering an 30 engine, such as a gas turbine engine. In some examples, fuel may be fed into the cavity 130 directly such that the fuselage may be considered a "wet cavity". In other examples, the fuselage 101 may be lined or have some other means for providing a fuel tank.

An example fuel tank 200 is shown in Figs. 2A and 2B. The fuel tank 200 has a liner 203 35 which in this example is relatively rigid and may be metal from a metal such as -5 -aluminium. The fuel tank 200 shown in Figs. 2A and 2B is generally cylindrical and elongate in nature so as to fit within the cavity 130 and main body portion of the fuselage and has a longitudinal axis that extends in the elongate dimension. In the example shown the fuel tank 200 has a pair of coupling points 240 on opposing sides of the fuel tank -on either side of the fuel tank 200 along the longitudinal axis. In the example shown both coupling points 240 are provided on the base of the fuel tank 200, but it will be understood that in other examples the coupling points 240 may be provided on other parts of the fuel tank 200 -such as on the top of the fuel tank 200.

As can be seen, in the example shown in Figs. 2A and 2B, the fuel tank has a series or plurality of repeating baffles 205 (specifically the tank has three baffles 205). The baffles 205 are a series of repeating screens that extend across at least a portion of the internal cross-section of the fuel tank 200 when viewed along the longitudinal axis -that is, the baffles 205 extend in a direction transverse to (in this example, orthogonal to) the longitudinal axis of the fuel tank 200. In the example shown, the baffles 205 do not extend across the entire internal cross-section of the fuel tank 200 but instead leave a gap or cut-out portion at the bottom. This may advantageously allow a fuel tank suction pipe 300 to extend along the fuel tank 200 along the longitudinal axis to draw fuel from a position closer to the centre of the fuel tank 200.

Each of the baffles 205 comprises at least one aperture, and in the examples shown, a plurality of apertures 207. The plurality of apertures 207 advantageously allow the flow of fuel past the baffles, but at a controlled rate. In this way, when there are any changes in orientation or direction of the fuel tank (for example, when the unmanned aerial vehicle is ascending or descending, accelerating or decelerating) there is not a sudden slosh of fuel from front to back or back to front. This may improve the stability of the unmanned aerial vehicle particularly when performing manoeuvres.

In the example shown, each of the apertures 207 are circular and of the same size and dimension, however, it will be understood that the shape of the apertures 207 may vary (e.g., they may have a square or diamond shape) and the relative sizing of the apertures 207 may differ -for example, apertures 207 nearer the bottom of the tank 200 may be larger than apertures 207 near the top of the tank 200.

In the example shown, each of the apertures 207 of one baffle 205 align with each of the -6 -apertures 207 of another baffle 205, however it will be understood that in other examples the apertures 207 of one baffle 205 may not align with the apertures 207 of another baffle 205 -instead, for example, the apertures 207 of adjacent baffles 205 may be offset to slow the flow of fuel therebetween.

As noted above, a fuel tank suction pipe 300 extends into the tank 200 via an inlet 290. An example fuel tank suction pipe 300 is shown in Fig. 3. In the example shown in Fig. 3, the fuel tank suction pipe 300 is configured to extract fuel from a fuel tank (such as fuel tank 200 described above) and has a weighted nozzle 375 configured to settle at the bottom of the tank 200 in use. Advantageously, this reduces the likelihood of air bubbles entering the fuel pipe and being fed to the engine.

In more detail, the fuel tank suction pipe 300 comprises a submersible fuel hose 350 which is flexible and can bend to accommodate movement of the weighted nozzle 375 within the tank 200. Coupling the fuel hose 350 to the weighted nozzle 375 is a rigid pipe portion 355. The rigid pipe portion 355 may be of the same material as the fuel hose 350 but with a different Youngs modulus or may be made of a different more rigid material. In any event, the rigid pipe portion 355 is configured to be more rigid than the fuel hose 350. Advantageously this may reduce the chance of it becoming kinked or narrowing the cross-sectional area of fuel flow inside the pipe, which could lead to problems in performance from the engine.

In the example shown, the weighted nozzle 375 comprises a generally frustoconical shaped tip 377 but with rounded edges, so as not to provide any sharp edges that may damage or pierce the fuel tank 200 when in use and when the weighted nozzle 375 is likely to move around inside the tank 200. This may be particularly relevant in examples where a bladder is used, as will be described in more detail below with reference to Figs. 4 to 7.

The tip 377 of the weighted nozzle 375 may comprise one or more apertures 379 for sucking fuel therethrough, preferably a plurality of apertures 379. The apertures 379 may be of a circular cross-section and may all be of the same size, although it will be understood that other cross-section shapes may be used and that the size of the apertures 379 may vary based, for example, on distance from the absolute tip of the weighted nozzle 375. -7 -

Fig. 4 shows a cross-section through an example fuel tank 400 for an unmanned aerial vehicle such as that shown in Fig. 1. The fuel tank 400 comprises a primary bladder 403 bounded by the cylindrical fuselage 401 of the unmanned aerial vehicle.

The primary bladder 403 therefore has an elongate dimension for fitting inside the fuselage 401 and has a longitudinal axis corresponding to the elongate dimension (and corresponding to the longitudinal axis of the fuselage 401).

The primary bladder 403 is configured to expand or contract based on the volume of fuel it contains -as the fuel inside the primary bladder 403 is used up, the primary bladder 403 contracts. This helps to minimise any air inside the tank 400 and therefore reduce the change of any air entering the engine.

The primary bladder 403 comprises a series of baffles 405 for reducing slosh of fuel in the bladder. The baffles 405 may be similar to the baffles 205 described above with reference to Figs. 2A and 2B. In the example shown in Fig. 4, the baffles 405 extend across the primary bladder 403 in a direction transverse to the longitudinal axis of the fuel tank 403 and extend across the entire cross-section of the primary bladder 403.

However, as with the example baffles 205 shown in Figs. 2A and 2B, in some examples the baffles 405 may extend only across a portion of the cross-sectional area of the primary bladder 403 -for example, the baffles 405 may not cover the lower portion of the primary bladder 403 in use. This may advantageously allow a fuel tank suction pipe 300, such as the one described above with reference to Fig. 3, to extend along the longitudinal axis of the primary bladder 403.

Each of the baffles 405 comprises at least one aperture 407, and as with the example of Figs. 2A and 2B in some examples the baffles 405 may comprise a plurality of apertures 407. The plurality of baffles 407 may each be of the same size or may be of differing size, for example the apertures 407 may increase in size towards the bottom of the primary bladder 403 in use.

As can be seen in Fig. 4, the fuel tank 400 also comprises the fuel tank suction pipe 300 described above with reference to Fig. 3, and as such the primary bladder 403 comprises 35 an inlet port 490 for allowing the fuel tank suction pipe 300 to pass therethrough. The -8 -inlet port 590 is preferably towards the top of the fuel tank 400 in use so that the fuel tank 400 can be topped up with fuel. The inlet port 490 may also be used for filling the primary bladder 403 with fuel. However, additionally, or alternatively the primary bladder 403 may comprise a separate port (not shown) for filling the primary bladder 403 with fuel.

Fig. 5 shows the fuel tank of Fig. 4 when some of the fuel in the tank has been used up. As can be seen, the primary bladder 403 has contracted as the fuel has been used up.

Fig. 6 shows a cross-section of another example fuel tank 600 for an unmanned aerial vehicle. The fuel tank 600 of Fig. 6 is in many respects the same as the fuel tank 400 described above with reference to Figs. 4 and 5, however in this example the primary bladder 403 is configured to be coupled to the inside of the fuselage 401 by a pair of opposing coupling points 650 on opposing sides of the bladder 603.

It will be understood that in some examples, rather than be arranged transverse or orthogonal to the longitudinal axis, in some examples the series of baffles may be arranged parallel to the longitudinal axis. This may advantageously reduce fuel slosh when the unmanned aerial vehicle is turning or banking. In some examples, a combination of baffles parallel to the longitudinal axis and transverse or orthogonal to the longitudinal axis may be used, for example to create "pockets" or subservient bladders inside the primary bladder 403.

Fig. 7 shows a cross-section of another example fuel tank 700 for an unmanned aerial vehicle, such as the unmanned aerial vehicle of Fig. 1. As with the examples of Figs. 4 to 6, the fuel tank 700 comprises a flexible primary bladder 703. However, in this example, the primary bladder 703 comprises a series of baffles 705 provided by a series of concentric subservient bladders arranged inside the primary bladder 703. Each of the baffles 705 may comprise one or more apertures 707, in this example each baffle 705 comprises a plurality of equally spaced apertures 707. In the example shown there are apertures 707 in the baffles 705 or subservient bladders at roughly 90-degree intervals, however, it will be understood that apertures 707 may be spaced at a greater or lesser pitch.

In the example shown, the apertures 707 of one baffle 705 align with the apertures 707 -9 -of another baffle 705, however, it will be understood that in other examples the apertures 707 of one baffle 705 may not align with the apertures 707 of another baffle 705, for example so that the apertures 707 of one baffle 705 may be offset relative to the apertures 707 of an adjacent baffle 705. Not aligning the apertures 707 of different baffles 705 may advantageously slow the flow of fuel past the baffles 705.

It is also noted that in this example the fuel tank suction pipe 300 sits between two baffles 705 (in particular between the primary bladder 703 internal wall and the outermost bladder 705). Advantageously this means that baffles 705 can cover more of the internal area of the tank 700 rather than needing a cut out portion, as for example is the case with the example of Figs. 2A and 2B.

It will be appreciated from the discussion above that the embodiments shown in the Figures are merely exemplary, and include features which may be generalised, removed or replaced as described herein and as set out in the claims. In the context of the present disclosure other examples and variations of the apparatus and methods described herein will be apparent to a person of skill in the art.

Claims

-10 -CLAIMS: 1. A fuel tank for an unmanned aerial vehicle, wherein the fuel tank comprises a primary bladder configured to be housed inside the fuselage of the unmanned aerial 5 vehicle, wherein the primary bladder comprises a series of baffles for reducing slosh of fuel in the bladder when the unmanned aerial vehicle changes direction.
2. The fuel tank of claim 1 wherein the primary bladder has an elongate dimension for fitting inside the fuselage and has a longitudinal axis corresponding to the elongate 10 dimension, and wherein the series of baffles are arranged transverse to the longitudinal axis.
3. The fuel tank of claim 1 wherein the primary bladder has an elongate dimension for fitting inside the fuselage and has a longitudinal axis corresponding to the elongate 15 dimension, and wherein the series of baffles are arranged parallel to the longitudinal axis.
4. The fuel tank of claim 1 wherein the series of baffles are provided by a series of concentric subservient bladders arranged inside the primary bladder.
5. The fuel tank of any of the previous claims wherein the series of baffles each comprise a corresponding aperture for allowing a controlled degree of fuel to flow therebetween.
6. The fuel tank of claim 5 wherein the apertures of one baffle are offset relative to the corresponding apertures of an adjacent baffle.
7. The fuel tank of any of the previous claims wherein the bladder is configured to be coupled to the inside of the fuselage by a coupling point.
8. The fuel tank of claim 7 wherein the bladder is configured to be coupled to the inside of the fuselage by a pair of opposing coupling points on opposing sides of the primary bladder.
9. A fuel tank suction pipe, the fuel tank suction pipe comprising a submersible fuel -11 -hose configured to extract fuel from the fuel tank coupled to a weighted nozzle, the weighted nozzle configured to settle at the bottom of the fuel tank.
10. The fuel tank suction pipe of claim 9 wherein the weighted nozzle comprises a 5 frustoconical shaped tip.
11. The fuel tank suction pipe of claim 10 wherein the frustoconical shaped tip comprises rounded edges.
12. The fuel tank suction pipe of any of claims 9 to 11 wherein the weighted nozzle comprises a plurality of apertures for sucking fuel therethrough.
13. The fuel tank suction pipe of any of claims 9 to 12 wherein the weighted nozzle comprises a filter for filtering fuel sucked through the nozzle.
14. The fuel tank suction pipe of any of claims 9 to 13 further comprising a rigid pipe portion coupling the weighted nozzle to the submersible fuel hose.
15. The fuel tank of any of claims 1 to 8 comprising the fuel tank suction pipe of any of claims 9 to 14.
16. An unmanned aerial vehicle comprising the fuel tank of any of claims 1 to 8 and 15.