Abstract: A fuel cell system configured to provide electrical power to an electrical motor producing propulsive thrust for an aircraft includes a plurality of fuel cell stacks radially arranged about a central cavity. Fuel cell plates within each of the fuel cell stacks are oriented such that major surfaces of the fuel cell plates are parallel to an airflow created by the aircraft as it moves through the air. The fuel cell system further includes a plurality of cooling devices disposed in radial cavities located between at least two fuel cell stacks in the plurality of fuel cell stacks.

Abstract: An all-electronic print rate control system for a high-speed column sequential dot matrix printer, using a permutation code input signal, an input storage register with a capacity of at least three code words, for storing the input data and a print timing oscillator. The control system comprises a print clock, including a plurality of countdown circuits connected to the oscillator, for generating a normal print rate timing signal and a fast print rate timing signal; the print clock can also generate a variable print rate timing signal in which the initial column intervals are longer than in the normal print rate timing signal and the concluding column intervals are preferably shorter than in the normal signal. A print clock control selects one of these print rate timing signals to control the printing speed in each print cycle, depending on printer conditions in the prior cycle; the variable signal is used whenever the printer has actually come to rest for any appreciable interval.

Abstract: An all-electronic control system for a high-speed column sequential dot matrix printer, using a permutation code signal of given pulse rate p comprising a series of individual code words each including a fixed number of data pulses preceded by a start pulse; the control system comprises a plural-stage FIFO storage register with a capacity of at least three, and preferably four or more, code words, for storing input data, as during a carriage return of the printer. A print timing oscillator having a frequency f is coupled to countdown means that develops a normal print rate signal f/n and a fast print rate signal f/m, where f >>p and n>m. A print rate selector selects one of the print rate signals, to control the printing speed of the printer, depending on whether a code word is stored in a given stage of the storage register.