Patent Publication Number: US-2020283170-A1

Title: Hybrid airship and related assembly and/or maintenance method

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a U.S. National Phase Application under 35 U.S.C. § 371 of International Patent Application No. PCT/IB2017/001549, filed Nov. 13, 2017. The entire contents of which are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention concerns a hybrid airship comprising at least one buoyancy enclosure containing a gas lighter than air, a gondola attached below the buoyancy enclosure, the gondola extending along a longitudinal axis, at least one propeller configured to propel the hybrid airship and at least one generator, configured to provide power to the propeller, the generator being connected to the gondola. 
     BACKGROUND 
     The hybrid airship is in particular intended to carry heavy payloads to remote locations with a difficult access, in particular regions in which access by road is tedious or impossible. 
     For example, the payloads are used in oil and gas exploration activities in a remote region with a difficult access. The region in particular comprises a high density of vegetation, such as a forest, in particular a tropical forest. Also, the region may comprise rugged terrain such as hills (for example foothills), cliffs and/or mountains. The region may sometimes comprise dangerous to access areas, such as areas with unexploded ordinances (UXO&#39;s). 
     Generally, helicopters are used to carry payloads to such regions. Nevertheless, helicopters are expensive to operate and generate a high quantity of greenhouse gases. Helicopters are also very limited in the amount of payload they can carry. 
     SUMMARY 
     Hybrid airships of the above-mentioned type are a very efficient and environmentally friendly alternate. They are able to carry heavy payloads with minimal fuel consumption. They are silent and can be propelled with thermal generators providing electrical power to propellers. 
     Such hybrid airship nevertheless requires a regular maintenances and, in particular, maintenances of the generator which is a critical device for the good operation of the hybrid airship. The access for operators and equipment for the maintenance is difficult in the remote regions and the hybrid airships have to be continuously operational. 
     Generally, the generators are located in the gondola of the airship. An intervention on the generator requires entering the gondola and providing the maintenance inside the gondola, which is tedious and complicated. 
     DE 197 53 548 discloses an airship comprising a buoyancy enclosure and propellers, the propellers being powered by fuel cell generators which protrude, in an extension of the gondola, from a back surface of the gondola and are attached to the buoyancy element. 
     Nevertheless, such a solution is not entirely satisfactory. The generators being attached directly to the gondola and to the buoyancy element, the maintenance of the generators remain a complicated operation which is difficult to carry out in a remote location. 
     Moreover, in order to explore a region of interest, a hybrid airship sometimes comprises, in the gondola, several sensors in order to carry out measurements. These sensors are, for example, actives sensors such as electro-magnetic sensors, laser sensors (LIDAR) or infrared sensors or passive sensors measuring the gravitational field or the magnetic field. The vibrations created by the generators are directly transmitted to the gondola and may disrupt these sensitives sensors located in the gondola. 
     Also, the generators being located at the back of the gondola, they are not affected by the surrounding air flow when the airship is flying. The thermal cooling of the generator is therefore not efficient. 
     One aim of the invention is to obtain a hybrid airship allowing an easier maintenance of the generators in particular in remote places. 
     To this aim, the subject-matter of the invention is a hybrid airship of the above type, characterized in that the hybrid airship comprises an arm protruding from the gondola and connecting the generator to the gondola. 
     The hybrid airship according to the invention comprises one or more of the following features, taken solely, or according to any technical feasible combination: 
     the hybrid airship comprises two generators, the two associated arms protruding symmetrically from each side surface of the gondola; 
     each arm protrudes laterally from a side surface of the gondola along a transverse axis of the gondola; 
     each arm protrudes laterally from a top surface of the gondola; 
     each generator is configured to be reversibly assembled and disassembled from the arm in one piece and replaced as a single piece; 
     the arm comprises a fuel tank, configured to store fuel to power the generator; 
     the generator has an ovoid shape; 
     the length of the arm taken from the side surface of the gondola to the generator is greater than 0.6 m; 
     the height between the bottom of the gondola and the bottom of the generator is comprised between 0.2 m and 0.8 m; 
     the hybrid airship comprises a payload carrying apparatus deployable from the gondola to carry a payload below the gondola; 
     the at least one propeller is attached to the buoyancy enclosure with a mast structure; 
     the hybrid airship comprises a plurality of propellers, each propeller of the hybrid airship being attached to the buoyancy enclosure; 
     no propeller of the hybrid airship is attached to the arm and/or to the generator. 
     The invention further concerns an assembly and/or maintenance method for of a hybrid airship as defined above comprising: 
     immobilizing the gondola of the hybrid airship on the ground or in proximity to the ground; 
     carrying out an assembly and/or a maintenance of the generator at the end of the arm protruding from the gondola. 
     The method according to the invention comprises one or more of the following features, taken solely, or according to any technical feasible combination: 
     the maintenance of the generator comprises accessing the generator from the outer and/or the inner lateral side of the generator; 
     disassembling at least one generator in one piece from the arm; 
     assembling a new generator in one piece on the arm; 
     the generator is disassembled from the arm and assembled on the arm by unclipping/clipping. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood, upon reading of the following description, given solely as an example, and made in reference to the appended drawings, in which: 
         FIG. 1  is a schematic view of a region of interest; 
         FIG. 2  is a side view of a first hybrid airship according to the invention; 
         FIG. 3  is a bottom view of the first hybrid airship according to the invention; 
         FIG. 4  is a schematic view of the electricity providing system of the first hybrid airship according to the invention; 
         FIG. 5  is a side view of a second hybrid airship according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     A first hybrid airship  10  according to the invention, flying above a region of interest  12 , is shown in  FIG. 1 . 
     The region of interest  12  is for example a region having an uneven terrain  14 . The uneven terrain  14  in particular comprises hills, mountains, cliffs or any type of rugged terrain. The region of interest  12  is for example located on foothills which are difficult to access. 
     The region of interest  12  further comprises vegetation  16 . The vegetation  16  is for example a forest, in particular a tropical forest. The region of interest here comprises a high density of vegetation, for example trees  18  forming a canopy  20  which covers a majority of the surface of the ground in the region of interest  12 . 
     In the region of interest  12 , the vegetation  16  defines a plurality of natural and/or artificial clearings  22 . 
     The clearings  22  are spread in the region of interest  12 , at a distance generally comprised between 100 m and 500 m, preferentially around 300 m, taken along the line of sight between two adjacent clearings  22 . 
     The clearings  22  generally have a surface area greater than 25 m 2 , at the ground level and generally greater than 900 m 2  at the top of the canopy  20 . 
     A clearing  22  is for example defined in a OGP Standard “OGP-Helicopter Guideline for Land Seismic and Helirig operations—Report 420 version 1.1 June 2013. 
     The subsurface  24  located below the ground comprises layers of geological formation and potentially oil and gas reservoirs. 
     In order to carry out an exploration or an exploitation of the oil and gas reservoirs, the region of interest  12  comprises at least a base camp  26  and a secondary camp  28 . The base camp  26  and the secondary camp  28  are separated from a distance generally comprised between 5 km and 20 km, preferentially around 10 km. 
     The base camp  26  is advantageously accessible by a road  27 . The equipment and necessities are provided to the base camp  26  for example by trucks driving on the road  27 . 
     The secondary camp  28  is closer from the clearings  22  than the base camp  26  and is not accessible by any road. 
     The secondary camp  28  and the clearings  22  are separated from a distance generally comprised between 200 m and 10 km, preferentially around 5 km. 
     The hybrid airship  10  is configured to take off from the ground, to fly in the surrounding air and to land on the ground. 
     As shown in  FIG. 3 , the hybrid airship  10  extends along a longitudinal axis A-A′. 
     The hybrid airship  10  is configured to take-off and land substantially, vertically and to move substantially along the longitudinal axis A-A′ during the flight. 
     The hybrid airship  10  is configured to carry a payload  30  from the base camp  26  to the secondary camp  28  and, vice versa, from the secondary camp  28  to the base camp  26 . 
     The hybrid airship  10  may also be used to carry the payload  30  from the secondary camp  28  to the clearings  22  and, vice versa, from the clearings  22  to the secondary camp  28 . 
     The payload  30  transported from the base camp  26  to the secondary camp  28  is for example camp equipment such as tents, water supply, fuel or food. It also comprises equipment for exploration and/or exploitation of oil and gas, such as seismic equipment and/or drilling equipment. 
     The payload  30  transported from the secondary camp  28  to the base camp  26  is for example camp wastes, or used equipment. 
     The payload  30  transported from the secondary camp  28  to the clearings  22  is for example seismic equipment for exploration and/or drilling equipment. 
     The payload  30  may include in some instances an injured or sick worker for medical evacuation. 
     The hybrid airship  10  is configured to carry a payload  30  weighing advantageously between 0 tons and to 2 tons. 
     As shown in  FIG. 2  and  FIG. 3 , the hybrid airship  10  comprises a buoyancy enclosure  32 , a gondola  34  attached below the buoyancy enclosure  32 , at least one propeller  36 , at least one generator  38  providing power to the or each propeller  36  and for each generator  38 , an arm  40  connecting the generator  38  to the gondola  34 . 
     Advantageously, the hybrid airship  10  comprises a payload carrying apparatus  41 . 
     The buoyancy enclosure  32  contains a gas lighter than air, meaning that the gas has a density lower than the surrounding air at 20° C. and 1 atm. The gas is advantageously helium. 
     When filled with the gas lighter than air, the buoyancy enclosure  32  provides positive buoyancy in air of the hybrid airship  10 . 
     The buoyancy enclosure  32  extends along the longitudinal axis A-A′. 
     The buoyancy enclosure  32  here has a wing shape with an ovoid contour, taken in a plane transverse to axis A-A′. The ovoid contour limits the aerodynamic drag. 
     When the airship  10  is horizontal, the ratio between the maximal vertical height of the buoyancy enclosure  32  taken perpendicularly to axis A-A′ and the maximal length of the buoyancy enclosure  32  taken along the longitudinal axis A-A′ is comprised between 20% and 35%. 
     In a horizontal section, the ratio between the maximal transverse width of the buoyancy enclosure  32  and the maximal length of the buoyancy enclosure  32  is comprised between 25% and 35%. 
     The buoyancy enclosure  32  advantageously comprises at least one rudder  42  protruding from the buoyancy enclosure  32  and located at the back of the buoyancy enclosure  32 . 
     The rudder  42  is configured to stabilize and improve the directional control of the hybrid airship  10 . 
     The gondola  34  extends along the longitudinal axis A-A′. 
     Advantageously, the horizontal section of the gondola  34  is oval in order to have an aerodynamic shape limiting the aerodynamic drag. 
     The gondola  34  is advantageously made of a composite material. For example, the gondola  34  is made of carbon fiber sandwich panels. 
     The length of the gondola  34  is comprised between 5 m and 10 m, preferentially 7 m. 
     The width of the gondola  34  is comprised between 1 m and 3 m, preferentially 2 m. 
     This allows the gondola  34  to be easily inserted in a standardized container. 
     The height of the gondola  34  is comprised between 1.5 m and 3 m, preferentially 2 m. 
     The gondola  34  advantageously comprises a cockpit for the pilot of the hybrid airship  10 , a cabin to transport passengers or a load, at least one side door and on-board electrical systems  43 . 
     Each propeller  36  is configured to propel the hybrid airship  10 . 
     The propeller  36  is advantageously attached to the buoyancy enclosure  32  by a mast structure  44  protruding laterally from the buoyancy enclosure  32 . 
     The hybrid airship  10  advantageously comprises at least two propellers  36 , for example four propellers  36  placed symmetrically on each side of the buoyancy enclosure  32 . Each propeller  36  here comprises an electrical motor  45 , a rotor  48  and several propeller blades  50  protruding from the rotor  48  in a tubular guide. When the generator  38  provides electrical power to the electrical motor  48 , the electrical motor  48  is rotating the rotor  48  and the blades  50  to create an air flow along the tubular guide. 
     The propellers  36  are able to propel the hybrid airship  10  at an air speed up to 100 km/h, and generally at a cruise air speed of substantially 60 km/h. 
     The hybrid airship  10  is said “hybrid” because its lift is ensured by aerostatic lift due to the buoyancy of the buoyancy enclosure  32  comprising a gas lighter than air, advantageously aerodynamic lift due to the specific wing-like shape of the buoyancy enclosure  32  and potentially vertical thrust due to the propellers  36 . 
     The generator  38  provides electrical power to each propeller  36 . It is remote from each of the propellers  36 . 
     The generator  38  and each associated propeller  36  are electrically connected through electrical cables running within the arm  40  and the gondola  34 , via the electrical power distribution system  58 , along the external surface of the buoyancy enclosure  32 . 
     The generator  38  is deprived of propeller attached to the generator  38 . 
     Advantageously, the generator  38  extends along the longitudinal axis A-A′, apart from the gondola  34 . 
     The generator  38  here has an ovoid shape, the ovoid shape limiting the aerodynamic drag. 
     The generator  38  comprises an inner lateral side and an outer lateral side. The inner lateral side is defined as the side of the generator  38  located facing the gondola  34 . The outer lateral side is defined as the side of the generator  38  located opposite to the gondola  34 . 
     The length of the generator  38  is comprised between 1 m and 3 m, preferentially 2 m. 
     The width and the height of the generator  38  are, advantageously, substantially equal and are comprised between 0.6 m and 1.2 m, preferentially 0.5 m. 
     The generator  38  comprises a housing  52 , at least one motor  54  and at least one alternator  56 . Each motor  54  and each alternator  56  are located inside the housing  52 . The motor  54  is preferably a thermal motor. It is fueled by oil, gas or hydrogen. In a variant, the generator  38  is a chemical generator such as a fuel cell. The motor  54  is configured to produce mechanical energy from the chemical energy of the fuel. 
     Each alternator  56  is connected to one of the motors  54 . The alternator  56  is configured to produce electrical energy from the mechanical energy provided by the motor  54 . 
     Each alternator  48  is connected to a primary electrical power distribution system  58  located in the gondola  34 . The primary electrical power distribution system  58  is configured to provide electricity powering the on board electrical systems  43  and to each motor  45  of the propellers  36 . 
     The housing  46  preferably defines at least a hatch  60  for accessing the motor  54  of the generator  38 . 
     The generator  38  has a weight comprised between 150 kg and 300 kg, preferentially substantially equal to 220 kg. 
     The arm  40  protrudes from the gondola  34  and is configured to connect the gondola  34  and the generator  38 . 
     The arm  40  is attached on the inner lateral side of the generator  38 . 
     The arm  40  is deprived of propeller. 
     In the example of  FIG. 2 , the hybrid airship  10  comprises two generators  38  and two associated arms  40 . The two arms  40  protrude symmetrically from each side surface of the gondola  34 . In particular, each arm  40  protrudes laterally along a transverse axis of the gondola  34 . 
     The length of the arm  40  taken from the side surface of the gondola  34  to the generator  38  is generally greater than 0.6 m. 
     The height between the bottom of the gondola  34  and the bottom of the generator  38  is comprised between 0.2 m and 0.8 m. 
     Therefore, the generator  38  is easily accessible for maintenance. The operator is able to directly access the generator  38  and does not have to enter the gondola  34 . 
     Moreover, the vibrations created by the generator  38  do not affect the gondola  34 , the generator  38  being separated from the gondola  34 . The comfort of the pilot and the passengers in the gondola  34  is improved and the sensitives sensors located in the gondola  34  are not disrupted by the vibrations. 
     Finally, the cooling of the generator  38  is improved, the generator  38  being located in the surrounding air flow when the hybrid airship  10  is flying. 
     In an advantageous embodiment, the arm  40  comprises at least one fuel tank  62  located inside the arm  40 . The fuel tank  62  is configured to store fuel to power the generator  38 . The fuel is, for example, oil, gas or hydrogen. 
     Advantageously, the arm  40  comprises a pump to convey the fuel from the fuel tank  62  to the generator  38 . 
     The fuel tank  62  is configured to store up to 200 kg of fuel. Advantageously, the generator  38  is reversibly assembled and disassembled from the associated arm  40  in one piece. The generator  38  is preferably replaced as a single piece. 
     The generator  38  is advantageously clipped on the associated arm  40  when assembled on the arm  40 . Preferably, the housing  52 , the motor  54  and the alternator  56  can be dismantled as a single unit from the arm  40 , the arm  40  remaining a single unit and unclipped when disassembled 
     The arm  40  is also reversibly assembled and disassembled from the gondola  34 . The arm  40  is advantageously clipped on the gondola  34  and unclipped. 
     The maintenance of a deficient generator  38  is therefore easy and quick, as it will be explained below. 
     The payload carrying apparatus  41  is for example a hoisting system comprising at least a line deployed from the gondola  34  for example by a winch to carry a payload  30  below the gondola  34 . The payload  30  is suspended from the hybrid airship  10  by the payload carrying apparatus  41 . 
     A maintenance method of a hybrid airship  10  according to the invention will be now described. This method is for example carried out after a flight of the hybrid airship  10  to carry a payload  30 . 
     When the maintenance is needed, for example as a preventive measure or to repair a generator  38 , the hybrid airship  10  lands to the ground. The gondola  34  of the hybrid airship  10  is immobilized on the ground or in proximity to the ground, in hover flight. 
     Advantageously, the gondola  34  is immobilized at a distance less than 2 m from the ground. 
     The operator accesses the generator  38  from the outer and/or the inner lateral side of the generator  38  to carry out maintenance. 
     If needed, the operator disassembles the deficient generator  38  from the arm  40  without using any motorized equipment. 
     The operator disassembles the generator  38  from the arm  40 , advantageously by unclipping. 
     Then, the operator assembles a new generator  38  in one piece on the arm  40 . 
     The operator assembles the new generator  38  on the arm  40 , advantageous, by clipping. 
     The maintenance of the generator  38  is easily and quickly performed without any motorized equipment and without a large workforce. The maintenance method is especially advantageous in the remote region of interest  12 , the region of interest  12  having a difficult access for the equipment, lacking space for maintenance and having a limited operator workforce. 
     A second hybrid airship  110  according to the invention is shown in  FIG. 5 . 
     The second hybrid airship  110  differs from the first hybrid airship  10  in that each arm  40  protrudes laterally from a top surface of the gondola  34 . 
     Advantageously, the arm  40  has a curved C shape and extends towards the ground. 
     Thanks to the inclined shape of the arm  40 , the arm  40  does not need a pump to convey the fuel stored into the tank  62 . The gravity flow of the fuel enables a passive supply of the generator  38  which leads to a safer and less expensive fuel supply. 
     In a variant, each generator  38  comprises two motors  54  and two alternators  56 , as shown in  FIG. 4 . The motors  54  and alternators  56  are contained in the same housing  52 . Each fuel tank  62  is configured to provide fuel to the two associated motors  54 .