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Title:
LIFTING APPARATUS AND METHOD
Document Type and Number:
WIPO Patent Application WO/2006/099686
Kind Code:
A1
Abstract:
A lifting apparatus (1) for supplementing the load lifting capability of a vertical take-off and landing aircraft, the apparatus being locatable between the aircraft and the load to be lifted, and comprising: (a) a thrust device (1A) for providing vertical lift to the load in a load lifting phase; (b) sensing means (4A, 4B) to sense a load parameter; and (c) control means 13 in communication with the thrust device (1) and the sensing means (4A, 4B), for adjusting the magnitude of the vertical lift provided by the thrust device (1A) in response to signals from the sensing means (4A, 4B).

Inventors:
ROBERTSON MARK (AU)
HALL GEOFF (AU)
Application Number:
PCT/AU2006/000404
Publication Date:
September 28, 2006
Filing Date:
March 24, 2006
Export Citation:
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Assignee:
ROBERTSON MARK (AU)
HALL GEOFF (AU)
International Classes:
B64C15/00; B64C29/00; B64D1/22; B64D9/00
Domestic Patent References:
WO2003059737A12003-07-24
Foreign References:
US3946971A1976-03-30
US3888435A1975-06-10
Attorney, Agent or Firm:
ALLENS ARTHUR ROBINSON PATENT & TRADE MARKS ATTORNEYS (530 Collins Street Melbourne, VIC 3000, AU)
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Claims:
Claims
1. A lifting apparatus for supplementing the load lifting capability of a vertical takeoff and landing aircraft, the apparatus being locatable between the aircraft and the load to be lifted, and comprising: (a) a thrust device for providing vertical lift to the load in a load lifting phase; (b) sensing means to sense a load parameter; and (c) control means in communication with the thrust device and the sensing means, for adjusting the magnitude of the vertical lift provided by the thrust device in response to signals from the sensing means.
2. A lifting apparatus according to claim 1, wherein the load parameter is the weight of the load.
3. A lifting apparatus according to claim 2, wherein the sensing means includes means for periodically sensing the weight of the load as it is lifted from the ground, wherein the control means may, in response, periodically adjust the magnitude of the vertical lift so that sufficient vertical lift is provided to lift the load without exceeding the lifting capacity of the aircraft.
4. A lifting apparatus according to claim 3, wherein the sensing means includes means for sensing the weight of the load around 256 times per second.
5. A lifting apparatus according to any one of claims 1 to 4, wherein the sensing means is a fluid that is compressible by at least a part of the weight of the load so that the weight of the load may be sensed by measuring the pressure of the fluid.
6. An apparatus according to claim 5, wherein the fluid is a hydraulic fluid contained within a hydraulic cylinder.
7. An apparatus according to claim 6, and further including: (a) an apparatus support cable extending from the apparatus for connecting the apparatus to the aircraft; (b) a load support cable extending from the apparatus attachable to the load to be lifted to the apparatus; and (c) a hydraulic cylinder containing hydraulic fluid, interposed between the apparatus support cable and the load support cable.
8. A lifting apparatus according to any one of claims 1 to 7, wherein the thrust device . includes a rotor for providing vertical lift to the load, the rotor pitch being adjustable by operation of the control means to thereby adjust the magnitude of the vertical lift provided by the thrust device.
9. A lifting apparatus according to any one of claims 1 to 7, wherein the thrust device is a jet engine and the control means incudes means for controlling the volume of fuel delivered to the engine to thereby adjust the magnitude of the vertical lift provided by the thrust device.
10. A lifting apparatus according to any one of claims 1 to 9, and further including torque control means for controlling the torque of the apparatus when suspended from the aircraft.
11. An apparatus according to claim 10, wherein the torquecontrol means include at least one curved member, rotatably attached to the base of the apparatus, the curvature of the member directing the flow of exhaust and/or air from the thrust device as the exhaust/air exits the base of the frame.
12. A method for increasing the lifting capacity of an aircraft, the method including the steps of: (a) attaching an apparatus according to claim 1 between the aircraft and a load to be lifted; (b) causing the aircraft to lift the apparatus; (c) causing the apparatus to at least partially lift the load; and (d) periodically sensing the weight of the load as it is lifted from the ground and, in response, periodically adjusting the magnitude of the vertical lift provided the thrust device, wherein the apparatus effectively reduces the weight of the load and thereby increases the lifting capacity of the aircraft.
Description:
lifting Apparatus and Method

Field of the Invention

The present invention relates to an apparatus and a method for lifting a load. In particular, the present invention relates to an apparatus and a method for lifting a load that is suspended from an aircraft.

Background, of the Invention

In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date: (i) part of common general knowledge; or

(ii) known to be relevant to an attempt to solve any problem with which this specification is concerned.

Aircraft, whether they be fixed-wing or rotor-driven, are often used to carry persons and cargo to locations that can not be conveniently reached by other methods of transportation. For example, it may be necessary to transport cargo or persons into inhospitable terrain, such as mountainous regions or dense rainforest. Additionally, other obstacles such as bushfires or floods may prevent transportation into an otherwise accessible location. In such circumstances it is often preferable to utilise an aircraft that allows for a vertical take-off and landing such as a helicopter. Aircraft have a maximum lifting capacity, also sometimes known as total lift performance, being the weight that can be safely carried either within or suspended below the aircraft. This maximum capacity is affected by factors such as the size of the aircraft and/or the size of its engines with respect to the load to be carried. Although a larger aircraft and/or engine may allow for a greater lifting capacity, it may also reduce the overall manoeuvrability of the aircraft, possibly making it unsuitable for some applications such as transportation to inhospitable locations.

Accordingly the problem of providing an aircraft with sufficient lifting capacity when that aircraft is used for transportation to inhospitable locations is not solved simply by increasing the size of the aircraft and/or the engine. Thus, the problem remains of providing an aircraft with sufficient lifting capacity whilst preserving the aircraft's overall manoeuvrability.

So-called "hybrid" aircraft have been proposed for lifting heavy loads.

One such aerial load lifting system is described in US Patent No 4,601,444 to Lindenbaum. The system proposed in that patent comprises a lighter than air unit, such as a blimp, below which is suspended a powered heavier than air unit, such as a helicopter. The weight of the load is shared between the heavier than air unit and the lighter than air unit with both units providing an upward lifting force to lift the load. Control of the system is solely maintained by the lower, heavier than air unit, which provides an upward lifting force for lifting the load which can be tilted to provide for translational motion of both units in any direction.

The load lifting system proposed in Lindenbaum would not be well suited to applications such as transportation to inhospitable locations, primarily because of its reliance on a bulky lighter than air unit which is also slow-moving, difficult to manoeuvre in uneven terrain, and a soft target in a combat zone.

Accordingly, it is an object of the present invention to provide an apparatus for lifting a load that is suspended from an aircraft that is an improvement or a useful alternative to the system proposed in Lindenbaum and other similar hybrid systems.

Summary of the Invention

According to a first aspect of the present invention there is provided a lifting apparatus for supplementing the load lifting capability of a vertical take-off and landing aircraft, the apparatus being locatable between the aircraft and the load to be lifted, and comprising: (a) a thrust device for providing vertical lift to the load in a load lifting phase;

(b) sensing means to sense a load parameter; and

(c) control means in communication with the thrust device and the sensing means, for adjusting the magnitude of the vertical lift provided by the thrust device in response to signals from the sensing means. In this specification the term "vertical take-off and landing aircraft" will generally refer to a helicopter. It will be appreciated that such an aircraft is also capable of forward, reverse and sideways propulsion, or any combination of these.

A load parameter according to the invention may be any detectable parameter of the load which permits the sensing means to transmit input data regarding the load to the rotor pitch control means to enable an adjustment to die pitch of the rotor in response to the received input data. The load parameter will typically be predicated on either the mass or weight of the load. Other load parameters are envisaged within the scope of the invention. One example includes the degree of tension in cables, ropes or slings

supporting the load. In a typical embodiment, when the pitch of the rotor of the thrust device changes in response to signals from the sensing means regarding a load parameter, then so does the action on the load mass.

Apparatus according to the invention is intended to assist a vertical take-off and landing aircraft in lifting loads which would normally exceed the aircraft's total lift performance or capability. The assistance the apparatus can provide to die aircraft's lift performance or capability may be expressed such that the apparatus acts on the load mass so that downward force is of a lower magnitude than the weight of the load. Expressed another way, the apparatus is intended to provide upwards thrust to the load in order to supplement the normal lift capacity of the aircraft.

For failsafe operation of the aircraft using the apparatus according to the invention, the weight the aircraft lifts must be less than the total lift performance of the aircraft by a tolerable margin.

That weight may accordingly be calculated in one way on the basis that it must be less by a tolerable margin the actual weight the aircraft lifts, that is, less than the weight of the load as it appears to the aircraft after supplementation by apparatus according to the invention plus the weight of the apparatus itself and any other accumulated weight effects as a consequence of forces such as drag forces on die apparatus and load when being carried by the aircraft. The apparatus will typically be supported by a frame. The frame will typically be suspended from the vertical take-off and landing aircraft by one or more supports such as a cable, rope or sling. The load to be lifted will in turn typically be suspended from the frame by one or more supports such as a cable, rope or sling.

Preferably, the thrust device includes a propeller having blades that are rotatably driven by an engine. The propeller blades may be rotatable at a fixed speed and have an adjustable pitch. The engine may be of any suitable type including a turbo engine or a reciprocating engine.

In a typical preferred embodiment the sensing means is capable of continuously sensing the weight of die load, a control unit in that embodiment being provided for continuously adjusting the magnitude of the lifting force.

Typically, the sensor means is a hydraulic cylinder that is connected to the frame of the apparatus so diat die pressure of hydraulic fluid in the hydraulic sensor is analogous to the weight of die load. Preferably, die hydraulic cylinder is connected to supports for the frame and for the suspended load in the form of cables, with die tension in die load

support cable compressing the fluid in the hydraulic cylinder proportionally to the weight of the load.

The sensing means may also be capable of sensing the tension in the frame support cable to determine the weight of the load carried by the aircraft. The control unit may adjust the magnitude of the lifting force to set the tension in the frame support cable to a predetermined level.

Typically, the control unit adjusts the magnitude of the lifting force by adjusting the pitch of the propeller blades.

The apparatus may further include means for controlling the torque of the frame. Preferably, the torque control means includes at least one curved member, rotatably attached to the base of the frame, the curvature of the member directing the flow of air from the propeller blades as the air exits the base of the frame.

According to a second aspect of the present invention there is provided a lifting apparatus for supplementing the load lifting capability of a vertical take-off and landing aircraft, the apparatus being locatable between the aircraft and the load to be lifted, and comprising:

(a) a thrust device having a rotor for providing vertical lift to the load in a load lifting phase;

(b) sensing means to sense a load parameter; and

(c) rotor pitch control means in communication with the thrust device and the sensing means, for adjusting the pitch of the rotor in response to signals from the sensing means and so as to provide lift to the load.

According to a third aspect the present invention there is provided a lifting apparatus for supplementing the load lifting capability of a vertical take-off and landing aircraft, the apparatus being locatable between the aircraft and the load to be lifted, and comprising: (a) a thrust device capable of providing vertical lift to the load in a load lifting phase;

(b) sensing means to sense a load parameter;

(c) control means in communication with the thrust device and the sensing means, for adjusting the thrust device in response to signals from the sensing means and so as to provide lift to the load.

The thrust device of this aspect of the invention need not utilise a rotor to provide vertical lift to the load. For example the thrust device could be a jet engine that utilises engine

exhaust to provide vertical lift. Other means of providing vertical lift are envisaged within the scope of this aspect of the invention.

The control means of this aspect of the invention adjusts the thrust device in response to the signals from the sensing means. For example the control means may adjust the delivery of fuel to the thrust device, thereby modifying exhaust creation and vertical lift.

According to a fourth aspect of the invention there is provided a method for increasing lifting capacity of an aircraft, the method including steps of:

(a) attaching an apparatus according to according to the first aspect of the invention between the aircraft and a load to be lifted; (b) causing the aircraft to lift the apparatus;

(c) causing the apparatus to at least partially lift the load; and

(d) periodically sensing the weight of the load as it is lifted from the ground and, in response, periodically adjusting the magnitude of the vertical lift provided to the thrust device, wherein the apparatus effectively reduces the weight of the load and thereby increases the lifting capacity of the aircraft.

Preferred embodiments of the present invention provide a number of advantages over the prior art discussed above. In particular, because horizontal motion of the apparatus is provided by the aircraft the lifting force applied by the apparatus need not be diluted by having to tilt to provide horizontal motion.

Additionally, the sensor means and control unit of preferred embodiments allow for the weight of the load carried by the apparatus to be continuously sensed and the lifting force applied by the apparatus to be adjusted accordingly. This is particularly beneficial when the load is being lifted off the ground, as continually sensing the weight of the load and adjusting the lifting force allows the apparatus to progressively "take up" the weight of the load to ensure that the lifting capacity of the aircraft is at no time exceeded.

The sensors means and control unit also allow for variable loads to be lifted by the apparatus without the need to manually set the lifting force required to lift a particular weight. Additionally, preferred embodiments of the present invention allow for the total weight of the load to be apportioned between the apparatus and the aircraft.

Description of the Drawings

The invention will now be further explained and illustrated by reference to the accompanying drawing in which Figure 1 is an elevation view partly in cross-section of an embodiment of an apparatus in accordance with the invention The apparatus 1 comprises an engine IA supported within a frame 12 with the frame including an upper protection grid 6 that is connected at each opposed end to a side member 3A & 3B. A fuel tank is provided inside each side member 3A & 3B with fuel lines (not shown) extending from the tank to provide fuel to the engine IA. The engine IA is preferably a turbine engine, however other types of engines such as a reciprocating engine or a jet engine could also be used.

The engine drives a propeller 2 that comprises a hub 2A and a pair of propeller blades 2B and 2C extending radially from the hub. Rotation of the propeller 2 by the engine IA causes a difference in air pressure between the upper and lower surfaces of the propeller blades that provides a lifting force to lift the apparatus 1 into the air as understood by those skilled in the art.

The air pressure difference, and consequently the magnitude of the lifting force, can be varied by adjusting the pitch of the propeller blades, relative to the horizontal. Essentially the propeller 2 will provide zero lifting force when the propeller blades 2B, 2C are at a pitch of zero degrees relative to the horizontal, and provide an increased lifting force as the pitch of the blades is increased.

The apparatus 1 is connected to an aircraft (not shown) via first and second cables 7A & 7B, each of which is connected to the lower portion of a side member 3A & 3B through a circular connector 12. These cables 7A & 7B operate as a lifting sling for the apparatus 1. In turn, the load to be lifted (not shown) is connected to the apparatus 1 via third 8A and fourth 8B cable, each of which is also connected to the lower portion of a side member 3A and 3B through a connector 14.

Interposed between the first 7A and third 8A cable and the second 7B and fourth cable 8B is a hydraulic cylinder 4A & 4B containing hydraulic fluid (not shown) . As further detailed below, the hydraulic cylinders 4A & 4B function as sensors that sense the weight of the load and the respective portions of that weight carried by the aircraft and the apparatus 1.

The apparatus 1 also includes curved members 5 that are rotatably connected to frame. These members 5 act to limit the torque of the apparatus 1 when suspended from the aircraft by the cables TA & 7B by directing the flow of air from the rotating propeller 2 in the direction shown by the arrows, as it exits from the base of the apparatus 1.

In use, the pilot of the aircraft attaches the apparatus 1 to the aircraft via the cables TA & 7B, attaches the load (not shown) to the apparatus via the cables 8A & 8B and starts the engine IA from the cockpit of the aircraft either before or after starting the engine of the aircraft. The propeller blades 2A and 2B then enter idle mode where they rotate with the hub at a predetermined speed. During idle mode, the pitch of the propeller blades 2A & 2B is zero degrees relative to the horizontal so that the rotating propeller 1 does not applying any lifting force.

The aircraft will generally be a helicopter that allows a vertical take-off and landing, and as the aircraft lifts from the ground, it climbs into the air firsuy carrying only the weight of the first and second cables TA & 7B. Tension is then progressively applied to the cables 7A & 7B as the aircraft lifts the apparatus 1 into the air until a maximum tension is reached when the apparatus is fully supported by the aircraft. The total weight of the apparatus 1 is around 10% of the aircraft's maximum lifting capacity.

During this lift-off process, the engine IA is caused to accelerate from the predetermined idle engine speed to a predetermined full operating speed that is reached when the cables 7A & 7B are at maximum tension. At this stage the aircraft has not yet lifted any portion of the load and will accordingly be well within its lifting capacity. Also the pitch of the propeller blades 2A & 2B remains zero so that no lifting force is applied.

Tension in the cables 7A & 7B causes compression of the hydraulic fluid in the hydraulic cylinders 4A & 4B so that the weight of the apparatus 1 can be determined by measuring the pressure of the hydraulic fluid.

The aircraft continues to lift the apparatus 1 and begins to lift the third and fourth cables 8A & 8B and eventually the load (not shown) into the air. Progressive tensioning of these cables 8A& 8B as the load is lifted off the ground also caused further compression of the hydraulic fluid in the hydraulic cylinders 4A & 4B. The pressure of the hydraulic fluid in the hydraulic cylinders 4A & 4B is then periodically measured over short time intervals, so that a series of values approximating the instantaneous weight bared by the apparatus, as the load is lifted into the air are determined. In the preferred embodiment the pressure of the hydraulic fluid is measured around 256 times per second. These values are electronically or mechanically transmitted to a controller 13 associated with the propeller 2. In response to the received values the controller 13 causes the pitch of the propeller blades to be increased to thereby increase the magnitude of the lifting force applied by the apparatus 1 to the load. Of course the controller 13 can be calibrated

so that a particular pitch adjustment causes the application of a sufficient lifting force in response to a specific pressure/weight value.

By the time the load has been fully lifted into the air the controller 13 has adjusted the pitch of the propeller blades to provide a sufficient lifting force so that the maximum lifting capacity of the aircraft is not exceeded. Since the lifting force acts in the opposite direction to gravitational forces acting on the load when suspended from the aircraft, the apparatus effectually reduces the weight of the load and enables the aircraft to carry a greater load than would otherwise be possible.

The total weight of the load may be apportioned between the aircraft and the apparatus 1 by measuring the pressure of hydraulic fluid in the hydraulic cylinders 4A & 4B. to sense the tension of the first and second cables 7A & 7B. In a similar manner to that described above, the pressure can be transmitted to the controller 13 to adjust the magnitude (either up or down) of the lifting force by adjusting the pitch of the propeller blades. Generally the aircraft will lift a percentage of total weight greater than about 51%. The word 'comprising' and forms of the word 'comprising' as used in this description and in the claims do not limit the invention claimed to exclude any variants or additions. Modifications and improvements to the invention will be readily apparent to those skilled in the art. Such modifications and improvements are intended to be within the scope of this invention.