Abstract: A catalytic combustion chamber is provided with at least two cataleptic combustion zones arranged in flow series, In a first mode of operation fuel is supplied from first fuel injectors, positioned upstream of the first catalytic combustion zone, into the catalytic combustion chamber and is burnt in the first catalytic combustion zone in order to preheat the subsequent catalytic combustion zones. In the second mode of operation the supply of fuel to the first fuel injectors is reduced and fuel is supplied from second fuel injectors positioned between the first catalytic combustion zone and the second catalytic combustion zone into the space between the first catalytic combustion zone and the second catalytic combustion zone. This prevents the first catalytic zone becoming overheated, and reduces the possibility of the second and third catalytic combustion zones becoming overheated and allows the optimum catalyst to be selected for the first catalytic combustion zone.

Abstract: A catalytic combustion chamber is provided with at least two catalytic combustion zones arranged in flow series. In a first mode of operation fuel is supplied from first fuel injectors, positioned upstream of the first catalytic combustion zone, into the catalytic combustion chamber and is burnt in the first catalytic combustion zone in order to preheat the subsequent catalytic combustion zones. In the second mode of operation the supply of fuel to the first fuel injectors is reduced and fuel is supplied from second fuel injectors positioned between the first catalytic combustion zone and the second catalytic combustion zone into the space between the first catalytic combustion zone and the second catalytic combustion zone. This prevents the first catalytic zone becoming overheated, and reduces the possibility of the second and third catalytic combustion zones becoming overheated and allows the optimum catalyst to be selected for the first catalytic combustion zone.

Abstract: An air intake suitable for an aerospace propulsor comprises a duct which contains, in flow series, a first heat exchanger, a water separator, and a cryogen injector and a second heat exchanger. Air entering the intake is cooled by the first heat exchanger to cause the majority of the water vapor in the air to condense into water droplet form. The water droplets are then removed by the air flow by the water separator. The cryogenic injector reduces the air flow temperatures still further so that any remaining water in the air flow is converted to small dry ice crystals which do not block the second heat exchanger.

Abstract: An aerospace propulsor is powered by liquid hydrogen. The hydrogen is passed through a turbine which drives a liquid oxygen pump. During non-atmospheric flight, the liquid oxygen is directed to the propulsor's combustion chamber where it is mixed with the liquid hydrogen and combustion takes place. However during atmospheric flight, the liquid oxygen is pumped to drive a turbine which powers a fan adapted to provide additional pressurization of air entering the engine for combustion.

Abstract: An air intake suitable for an aerospace propulsor comprises a duct in which are provided two pirmary heat exchangers arranged in parallel relationship and a secondary heat exchanger downstream of the primary heat exchangers. The primary and secondary heat exchangers are arranged to place a cryogenic fluid in heat exchange relationship with the air flow through the duct. Icing of the primary heat exchangers is controlled by interrupting the flow of cryogenic fluid to each of the primary heat exchanger in turn. Thus while one heat exchanger is subject to ice accretion hereon, the temperature of the other increases sufficiently for de-icing thereof to occur.

Abstract: A marine propulsion unit which is mounted externally of a marine vessel and receives supplies of compressed air and fuel from on board the vessel, comprises a housing, a duct in the housing, containing a ventilated flow rotor, the rotor having tip blading driven by the products of combustion from combustion apparatus located in the housing.