Abstract: A dual fluid injection system which comprises a liquid fuel metering device, a fluid delivery device, and apparatus providing an interface therebetween. The interface conveys liquid fuel along a flow path from the metering device to a mixing zone for mixing with air from a pressurized supply to provide an air-fuel mixture for injection by the fluid delivery device into a combustion chamber of an internal combustion engine. The flow path may involve a directional change by way of a turn section. The flow path is sized such that liquid fuel is retained therein by virtue of capillary action, whereby a quantity of liquid fuel is retained after a delivery event such that the flow path remains substantially filled with liquid fuel in readiness for the next delivery event during operation of the engine.

Abstract: An unmanned aerial vehicle has an internal combustion engine, and a fuel and lubrication system comprising a fuelling system for fuelling the engine and a lubrication system for delivering lubricating oil to the engine. The fuelling system comprises a fuel reservoir from which fuel can be delivered to the engine. The fuel reservoir comprises a main tank and a header tank. The lubrication system comprises an oil tank. The oil tank is accommodated internally within the main tank to provide an integrated assembly. The arrangement provides for warming of lubrication oil for the UAV engine using several available heat sources. Further, the arrangement facilitates a configuration and layout intended to minimise or negate any undesirable moments of inertia for the UAV during flight as fuel and oil is consumed.

Abstract: A muffler devised particularly for a small, reciprocating-piston two-stroke internal combustion engine of the type used on unmanned aerial vehicles. The muffler comprises a body incorporating an inlet, an outlet, and a plurality of chambers for exhaust gas flow from the inlet to the outlet. The body is configured to present a compact profile for installation on the engine. The chambers are so configured that adjacent chambers communicate to facilitate exhaust gas flow from the inlet to the outlet via flow passages. The various chambers comprise an inner chamber, an outer chamber, and one or more intervening chambers disposed between the inner and outer chambers. The various chambers are disposed one about another in annular formation. This arrangement creates a long flow path from the inlet to the outlet incorporating various directional changes.

Abstract: A dual fluid injection system which comprises a liquid fuel metering device, a fluid delivery device, and apparatus providing an interface therebetween. The interface conveys liquid fuel along a flow path from the metering device to a mixing zone for mixing with air from a pressurized supply to provide an air-fuel mixture for injection by the fluid delivery device into a combustion chamber of an internal combustion engine. The flow path may involve a directional change by way of a turn section. The flow path is sized such that liquid fuel is retained therein by virtue of capillary action, whereby a quantity of liquid fuel is retained after a delivery event such that the flow path remains substantially filled with liquid fuel in readiness for the next delivery event during operation of the engine.

Abstract: A muffler devised particularly for a small, reciprocating-piston two-stroke internal combustion engine of the type used on unmanned aerial vehicles. The muffler comprises a body incorporating an inlet, an outlet, and a plurality of chambers for exhaust gas flow from the inlet to the outlet. The body is configured to present a compact profile for installation on the engine. The chambers are so configured that adjacent chambers communicate to facilitate exhaust gas flow from the inlet to the outlet via flow passages. The various chambers comprise an inner chamber, an outer chamber, and one or more intervening chambers disposed between the inner and outer chambers. The various chambers are disposed one about another in annular formation. This arrangement creates a long flow path from the inlet to the outlet incorporating various directional changes.

Abstract: An unmanned aerial vehicle has an internal combustion engine, and a fuel and lubrication system comprising a fuelling system for fuelling the engine and a lubrication system for delivering lubricating oil to the engine. The fuelling system comprises a fuel reservoir from which fuel can be delivered to the engine. The fuel reservoir comprises a main tank and a header tank. The lubrication system comprises an oil tank. The oil tank is accommodated internally within the main tank to provide an integrated assembly. The arrangement provides for warming of lubrication oil for the UAV engine using several available heat sources. Further, the arrangement facilitates a configuration and layout intended to minimise or negate any undesirable moments of inertia for the UAV during flight as fuel and oil is consumed.

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: 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 two stroke internal combustion engine having at least one cylinder (1) with exhaust port means (5), the engine further including at least one supplementary passage (9) in addition to the exhaust port means (5) for allowing gas flow from the cylinder (1), and control means (7) for controlling the gas flow through the supplementary passage (9) as a function of predetermined operating conditions of the engine wherein the control means allows at least substantially unimpeded gas flow therethrough during a compression stroke of the engine when the engine is at least at idle, low engine loads and/or engine speeds, and/or during engine start-up and at least substantially prevents gas flow therethrough when the engine is at higher engine loads and/or engine speeds.