In one or more embodiments of the novel aircraft fuel cell system without the use of a buffer battery, the fuel cell and compressor would be sized sufficiently larger for the intended application, allowing the compressor to change speeds much faster. This in turn would allow power outputs to change much quicker. If power outputs can change as quickly as the application dictates, then a buffer battery is not necessary. In one or more embodiments, because the system is mostly electronically controlled, software can be written to protect the fuel cell from instantaneous power spikes. If a large power output is suddenly requested of the fuel cell, the software can smooth out the demand curve to provide an easier load profile to follow.

In one or more embodiments of the novel aircraft fuel cell system without the use of a buffer battery, the fuel cell and compressor would be sized sufficiently larger for the intended application, allowing the compressor to change speeds much faster. This in turn would allow power outputs to change much quicker. If power outputs can change as quickly as the application dictates, then a buffer battery is not necessary. In one or more embodiments, because the system is mostly electronically controlled, software can be written to protect the fuel cell from instantaneous power spikes. If a large power output is suddenly requested of the fuel cell, the software can smooth out the demand curve to provide an easier load profile to follow.

A power and data communication system including an inboard computer system that includes a resistor network, an outboard computer system that includes at least one current limiter and voltage limiter that receives power from the inboard computer in order to power electronics of the outboard computer, and first and second wires connecting the resistor network of the at least one current limiter.

A power and data communication system including an inboard computer system that includes a resistor network, an outboard computer system that includes at least one current limiter and voltage limiter that receives power from the inboard computer in order to power electronics of the outboard computer, and first and second wires connecting the resistor network of the at least one current limiter.

A reaction-jet helicopter having an air compressor and a power source operable to power the compressor. The air compressor is in fluid communication with a cavity in a rotor blade of the reaction-jet helicopter. The rotor blade has one or more openings for the expulsion of compressed air from the cavity thereby resulting in rotation of the rotor blade. The reaction jet helicopter further has an arrangement for manipulating airflow between the compressor and the one or more openings. This results in reduced losses of energy as the airflow travels from the compressor to the one or more openings.

An unmanned aerial vehicle according to certain embodiments generally includes a chassis, a power supply mounted to the chassis, a control system operable to receive power from the power supply, at least one rotor operable to generate lift under control of the control system, and a winch mounted to the chassis. The winch includes a reel and a motor. The reel has a line wound thereon, the line having a free end. The reel includes a circumferential channel in which a wound portion of the line is wound onto the reel. The circumferential channel includes an inner portion, an outer portion, and a passage connecting the inner portion and the outer portion. The motor is operable to rotate the reel under control of the control system to thereby cause the line to wind onto and off of the reel, thereby causing the free end of the line to raise and lower.

An unmanned aerial vehicle according to certain embodiments generally includes a chassis, a power supply mounted to the chassis, a control system operable to receive power from the power supply, at least one rotor operable to generate lift under control of the control system, and a winch mounted to the chassis. The winch includes a reel and a motor. The reel has a line wound thereon, the line having a free end. The reel includes a circumferential channel in which a wound portion of the line is wound onto the reel. The circumferential channel includes an inner portion, an outer portion, and a passage connecting the inner portion and the outer portion. The motor is operable to rotate the reel under control of the control system to thereby cause the line to wind onto and off of the reel, thereby causing the free end of the line to raise and lower.

An auxiliary power unit for an aircraft, having a compressor, an intercooler including first conduit(s) having an inlet in fluid communication with the compressor outlet and second conduit(s) configured for circulation of a coolant therethrough, an engine core having an inlet in fluid communication with an outlet of the first conduit(s), and a bleed conduit in fluid communication with the outlet of the first conduit(s) through a bleed air valve. The auxiliary power unit may include a generator in driving engagement with the shaft of the engine core to provide electrical power for the aircraft. A method of providing compressed air and electrical power to an aircraft is also discussed.

An auxiliary power unit for an aircraft, having a compressor, an intercooler including first conduit(s) having an inlet in fluid communication with the compressor outlet and second conduit(s) configured for circulation of a coolant therethrough, an engine core having an inlet in fluid communication with an outlet of the first conduit(s), and a bleed conduit in fluid communication with the outlet of the first conduit(s) through a bleed air valve. The auxiliary power unit may include a generator in driving engagement with the shaft of the engine core to provide electrical power for the aircraft. A method of providing compressed air and electrical power to an aircraft is also discussed.

A cargo hold of an aircraft having cladding elements and at least one housing element for accommodating electronic components and/or cables. The cladding elements are attached to supports, in particular structural elements, of the aircraft and have a plurality of cladding holes with predefined cladding hole spacings for attachment. The at least one housing element has at least one pair of housing holes for receiving fastening devices. The housing holes have a housing hole spacing which corresponds to at least one pair of cladding hole spacings.