An aircraft power system for selectively operating an aircraft device , the aircraft power system comprising: an electric accumulator comprising an ultra-capacitor for storing electrical energy from a power source ; an input connector configured to couple the ultra-capacitor to a power source through an ultra-capacitor charge circuit ; an output connector configured to couple the ultra-capacitor to the aircraft device; a sub-system controller connected to the output connector; and a power distribution controller operatively connected to the input connector and to the sub-system controller for controlling the flow of electrical energy to and from the ultra-capacitor, the power distribution controller configured to: determine, based on output from one or more sensors, power demand on the power source ; selectively close the input connector to charge the ultra-capacitor by allowing electrical energy to flow into the ultra-capacitor when the power demand is low; selectively open the input connector to restrict electrical energy from flowing into the ultra-capacitor when the power demand is high; and selectively close the output connector to power the aircraft device using the electrical energy from the power source and the ultra-capacitor by allowing it to flow to the aircraft device. wherein the power source is external to the aircraft and wherein the electric accumulator is selectively connectable to it only when the aircraft is grounded. an electric accumulator comprising an ultra-capacitor for storing electrical energy from a power source ; an input connector configured to couple the ultra-capacitor to a power source through an ultra-capacitor charge circuit ; an output connector configured to couple the ultra-capacitor to the aircraft device; a sub-system controller connected to the output connector; and a power distribution controller operatively connected to the input connector and to the sub-system controller for controlling the flow of electrical energy to and from the ultra-capacitor, the power distribution controller configured to: determine, based on output from one or more sensors, power demand on the power source ; selectively close the input connector to charge the ultra-capacitor by allowing electrical energy to flow into the ultra-capacitor when the power demand is low; selectively open the input connector to restrict electrical energy from flowing into the ultra-capacitor when the power demand is high; and selectively close the output connector to power the aircraft device using the electrical energy from the power source and the ultra-capacitor by allowing it to flow to the aircraft device. wherein the power source is external to the aircraft and wherein the electric accumulator is selectively connectable to it only when the aircraft is grounded. determine, based on output from one or more sensors, power demand on the power source ; selectively close the input connector to charge the ultra-capacitor by allowing electrical energy to flow into the ultra-capacitor when the power demand is low; selectively open the input connector to restrict electrical energy from flowing into the ultra-capacitor when the power demand is high; and selectively close the output connector to power the aircraft device using the electrical energy from the power source and the ultra-capacitor by allowing it to flow to the aircraft device. wherein the power source is external to the aircraft and wherein the electric accumulator is selectively connectable to it only when the aircraft is grounded. <EOS>