Uninhabited Air Vehicles Enabling Science for Military Systems (2000) / Chapter Skim
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6 Power and Related Technologies
6 Power and Related Technologies
Pages 71-81
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From page 71... ...
For these vehicles, the propulsion system might not provide external power or may require electric power, or the required storage life of the power system might be longer than normal. For typical aircraft, the electric or hydraulic power requirement is 100 to 1,000 times less than the power requirement for propulsion.
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From page 72... ...
The selection of a prime power source will be determined by mission requirements and platform constraints. After the prime power source has been selected, the subsystems related to power conversion, power storage, and power management must be defined.
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From page 73... ...
management and distribution subsystem links the energy generation source to the energy storage elements and to the aircraft electrical loads. This management function involves regulation, distribution and control, and fault detection and isolation, as well as point-of-load power conditioning.
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From page 74... ...
Thermal management is a systemwide issue. Actuators Traditional hydraulic systems will not be used in most future UAVs because these systems represent a substantial vehicle weight penalty, reduce available volume for payloads, and increase vehicle complexity and production costs.
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From page 75... ...
100 W-hr/kg 125 W-hr/kg Specific energy (GEO) 100 W-hr/kg 125 W-hr/kg Design life 1 yr 5 yr Primary Fuel Cell Power load 7 kW 50 kW Specific power 100 W/kg 150 kW/kg Specific cost $40/W $25/W Design life 2,000 hrs 4,000 hrs Nuclear Power Reactor Level 10 kW 10 kW Specific power 10 W/kg 10 W/kg Efficiency 10% 10% RTG Power level 2 kW 2 kW Specific power 6 W/kg 10 W/kg Efficiency 8% 12% Note: GEO = geostationary or geosynchronous earth orbit LEO = low earth orbit RTG = radioisotope thermoelectric generator
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From page 76... ...
Current programs at DARPA, including the Compact Hybrid Actuation Program, are exploring the development of EMAs and devices using smart-materials transduction elements, including piezoelectrics, electrostrictives, magnetostrictives, and shape memory alloys. TECHNOLOGY NEEDS For conventional UAV missions, electric power and related systems will not be critical or enabling for the next decade, although advances in the state of the art would certainly improve UAV performance.
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From page 77... ...
will involve trade-offs among several interacting technologies that can be used for power generation (prime power, energy storage, and power conversion [see Table 6-21~. Prime Power Sources Improvements in current integrated power-propulsion (shared-shaft)
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From page 78... ...
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From page 79... ...
These could be conventionally sized as central power units or distributed using MEMS technology. Power Management and Distribution UAV requirements for power management are similar to those for conventional aircraft.
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From page 80... ...
Also, active cooling will probably be avoided whenever possible to minimize system complexity, mass, and power requirements. Research into microchannel plates and compliant diamond-film heat spreaders could lead to more efficient heat exchangers for cooling densely packed electronics.
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From page 81... ...
Although continued development of many prime power technologies would enhance UAV capabilities, most of these technologies will evolve with little or no intervention from the UAV community. Possible exceptions to this are specialized technologies for producing solar-powered HALE UAVs and air-driven or combustion-driven microgenerators that would distribute the power generation function throughout a UAV.
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