Abstract: The ignition system (10) of an engine (particularly for a UAV) has a primary (10a), and a secondary (10b) ignition system to provide redundancy for ‘get you home’ capability should the primary ignition system fail. The secondary ignition provides a lower energy or shorter duration spark than the higher energy or longer duration sparking of the primary ignition system, and is retarded relative to primary sparking. Timing of the secondary sparking can be advanced in the event of primary sparking failure. Fuelling strategy can be shifted from a leaner stratified charge to a richer homogenous charge when relying just on the secondary ignition system for ignition. The secondary ignition system can be of a lower spark energy and/or duration than the primary ignition system, avoiding the cost, complexity and weight of replicating the primary ignition system, and to improve packaging within the engine housing, particularly within the limited payload and space limits of a UAV.

Abstract: An air cooling system for an unmanned aerial vehicle including a propeller (14) driven by an engine (12) has at least one cooling air duct (22) to direct cooling air to cool a vehicle component e.g. a cylinder head. The duct has at least one air inlet and at least one air outlet. Operation of the propeller causes a pressure differential between the air outlet (24,124) and the air inlet (23,123) which draws air through said cooling air duct (22). A cowling (16) can cover at least part of the engine, and can form a plenum and have the supply of cooling air through a front face aperture (164) or side walls (17) of the engine cowl (16).

Abstract: A method of operation of a dual fluid fuel injection system arranged to supply fuel to a cylinder of an internal combustion engine, the dual fluid fuel injection system being controllable to effect fuel metering events and fuel delivery events. The method comprises operating the dual fluid fuel injection system so as to have at least one fuel delivery event during each engine cycle and to have fewer than one fuel metering event, on average, per engine cycle. An electronic control unit for implementing the method is also described. The method and control unit allow dynamic range of a fuel metering injector, where included within the dual fluid fuel injection system, to be extended.

Abstract: This disclosure describes a method of controlling operation of an unmanned aerial vehicle (UAV) having a flight control system comprising: a flight controller for implementing a flight control strategy; and an engine control unit interfaced with the flight controller for controlling engine operation. An engine speed target is set for the flight control system in response to one or more signals communicated by the flight controller to the engine control unit which controls engine operation to achieve the engine speed target by closed loop control over fueling without requiring throttle position control.

Abstract: A method for controlling controlled-auto-ignition operation in an eternal combustion engine is described. The method includes the injection of air into a combustion cylinder at an appropriate time in the combustion cycle in response to measured conditions. The injection of air acts to alter the CAI-phasing, thus providing the ability to extend the CAI operation further into a vehicle speed/load range.

Abstract: A method of operation of a dual fluid fuel injection system arranged to supply fuel to a cylinder of an internal combustion engine, the dual fluid fuel injection system being controllable to effect fuel metering events and fuel delivery events. The method comprises operating the dual fluid fuel injection system so as to have at least one fuel delivery event during each engine cycle and to have fewer than one fuel metering event, on average, per engine cycle. An electronic control unit for implementing the method is also described. The method and control unit allow dynamic range of a fuel metering injector, where included within the dual fluid fuel injection system, to be extended.

Abstract: A method of vaporising fuel in a spark-ignition engine using the supply of heat into the cylinder to wholly or partly vaporise the fuel, the heat being supplied by operation of a spark plug. One or more engine conditions can be sensed, such as engine temperature, coolant temperature, the cumulative amount of fuel supplied, engine speed or the time elapsed since start-up, and the spark plug operated to supply heat in response to such condition(s). The heat can be supplied by operating the spark plug more than once in an engine cycle or by operating the spark plug to form a spark over a time period determined in response to the engine condition. An AC circuit can be used to produce a substantially continuous spark over a defined time period or suitable angular duration. The heat can be supplied by operating the spark plug prior to engine cranking, to generate heat in the cylinder at engine start-up. A method of reducing spark plug fouling is also disclosed.

Abstract: Fuel injection apparatus comprising a solenoid coil (40); an armature (41) coupled with a valve element (34) operable to open and close a fuel valve (32) when the solenoid coil (40) is selectively energized and de-energised. The valve element (34) is biased to the closed position by a biasing device (42). Magnetic force from the energized solenoid coil moves the armature (41) and valve element (34) to open the valve to an opening position to deliver fuel reached when a controller (170) calculates opening forces balance closing forces. Such opening position control is used to control fuel flow rate to a gas fuelled engine (20) and/or reduce noise vibration harshness in varied engine types. Balance of forces control, on closing of the valve, reduces or avoids impact of the valve element (34) with a physical stop (106), thus reducing engine noise, and can be used in fuel metering.