# US 12,110,102 B2 · Mass distribution method and apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,110,102 B2 - Document ID: US12110102B2 - Status: Granted - Kind: B2 - Application number: 18/022,384 - Filed: 2021-08-23 - Published: 2024-01-25 - Granted: 2024-10-08 - Earliest claimed: 2020-08-21 - Assignees: Hill Group Technologies Limited - Applicants: Hill Group Technologies Limited - Inventors: Jason Hill - Web page: https://patentgrep.com/patent/US12110102B2 ## CPC - B64C 17/10: Transferring fuel to adjust trim - B64C 27/06: with single rotor - B64C 17/00: Aircraft stabilisation not otherwise provided for - B64D 37/04: Arrangement thereof in or on aircraft - B64D 41/00: Power installations for auxiliary purposes - H01M 8/04201: {Reactant storage and supply, e.g. means for feeding, pipes} - H01M 8/04753: {of fuel cell reactants} - B64D 2041/005: {Fuel cells} - H01M 2250/20: Fuel cells in motive systems, e.g. vehicle, ship, plane - B64C: AEROPLANES; HELICOPTERS - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY ## Abstract Disclosed is a helicopter having a longitudinal axis, a lateral axis and a vertical axis, a helicopter centre of mass and a maximum gross mass of less than 5000 kg, the helicopter comprising a fuselage elongate along the longitudinal axis, the fuselage comprising an aerodynamically shaped shell defining a front, a rear, a top and a bottom of the fuselage and a passenger cabin therein having two forward-facing front seating positions for the pilot and a co-pilot or a passenger, and forward-facing rear seating positions for at least 2 passengers, optionally 3 passengers; a primary fuel cell mounted substantially behind the passenger cabin; the front seating position for the pilot having a centre of mass at a first location substantially in front of the rotor hub location, and the primary fuel cell having a centre of mass at a second location substantially behind the rotor hub location; a landing gear arrangement; a power plant mounted substantially above and behind the passenger cabin, wherein the primary fuel cell is arranged to provide fuel to the power plant; and a secondary fuel cell having a centre of mass at a nose location in front of the rotor hub location by at least 1500 mm. ## Claims ### Claim 1 A helicopter having a longitudinal axis, a lateral axis and a vertical axis, a helicopter centre of mass and a maximum gross mass of less than 5000 kg, the helicopter comprising; a fuselage elongate along the longitudinal axis, the fuselage comprising an aerodynamically shaped shell defining a front, a rear, a top and a bottom of the fuselage and a passenger cabin therein having two forward-facing front seating positions for the pilot and a co-pilot or a passenger, and forward-facing rear seating positions for at least 2 passengers, optionally 3 passengers; a primary fuel cell mounted substantially behind the passenger cabin; a tail boom assembly extending from a tail boom bulkhead at the rear of the fuselage and including a tail rotor; a main rotor assembly comprising a hub, at least two main rotor blades mounted by a rotor mast to the top of the fuselage to permit the main rotor blades to rotate with respect to the fuselage; the front seating position for the pilot having a centre of mass at a first location substantially in front of the rotor hub location, and the primary fuel cell having a centre of mass at a second location substantially behind the rotor hub location; a landing gear arrangement; a power plant mounted substantially above and behind the passenger cabin, wherein the primary fuel cell is arranged to provide fuel to the power plant; and a secondary fuel cell having a centre of mass at a nose location in front of the rotor hub location by at least 1500 mm. ### Claim 2 (depends on 1) The helicopter according to claim 1 wherein the secondary fuel cell is maintained to a fill level to keep the helicopter centre of mass within 150 mm, preferably within 100 mm of a position directly below the rotor hub location. ### Claim 3 (depends on 1) The helicopter according to claim 1 wherein the forward-facing rear seating positions have a centre of mass arranged substantially below the rotor mast. ### Claim 4 (depends on 1) The helicopter according to claim 1 wherein the primary fuel cell has a greater length along the lateral axis than along the longitudinal axis. ### Claim 5 (depends on 1) The helicopter according to claim 1 wherein the primary fuel cell has a greater height along the vertical axis than length along the longitudinal axis. ### Claim 6 (depends on 1) The helicopter according to claim 1 further comprising a baggage compartment directly aft of the primary fuel cell along the longitudinal axis. ### Claim 7 (depends on 1) The helicopter according to claim 1 wherein the secondary fuel cell is arranged to provide fuel directly to the power plant. ### Claim 8 (depends on 1) The helicopter according to claim 1 wherein the secondary fuel cell is arranged to transfer fuel to and from the primary fuel cell via a fuel supply line. ### Claim 9 (depends on 1) The helicopter according to claim 1 further comprising a pressure balancing valve arranged between the primary fuel call and the secondary fuel cell. ### Claim 10 (depends on 1) The helicopter according to claim 1 wherein the secondary fuel cell is positioned entirely in front of the first location. ### Claim 11 (depends on 1) The helicopter according to claim 1 wherein the helicopter has a maximum gross mass of less than 2000 kg and an empty mass of less than 1000 kg. ### Claim 12 (depends on 1) The helicopter according to claim 1 wherein the helicopter has an occupant capacity of at least 4 occupants and at most 6 occupants. ### Claim 13 (depends on 1) The helicopter according to claim 1 wherein the primary fuel cell has a fuel capacity of at least 400 litres, preferably 600 litres or more. ### Claim 14 (depends on 1) The helicopter according to claim 1 wherein the secondary fuel cell has a fuel capacity of at least 50 litres, preferably 70 litres or more. ### Claim 15 (depends on 1) The helicopter according to claim 1 wherein the secondary fuel cell has a fuel capacity of less than 20% of the primary fuel cell, preferably around 15% or around 10% of the primary fuel cell. ### Claim 16 (depends on 1) The helicopter according to claim 1 further comprising a fuel pump for transferring fuel between the primary fuel cell and the secondary fuel cell, further optionally the fuel pump is operable to transfer fuel between the primary fuel cell and the secondary fuel cell during flight. ### Claim 17 (depends on 1) The helicopter according to claim 1 further comprising a mass distribution controller for receiving information relating to the loading of the helicopter and controlling the fuel pump to transfer fuel between the primary fuel cell and the secondary fuel cell to adjust the centre of mass of the helicopter, optionally wherein the information relating to the loading of the helicopter includes passenger cabin centre of mass information and fuel centre of mass information. ### Claim 18 (depends on 1) The helicopter according to claim 1 wherein the rotor mast has a length of less than 1500 mm, preferably less than 1000 mm.