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The potential benefits of digital electronic controls, including increased flexibility and lower cost, have not yet been fully applied to the small gas turbine engines of remotely piloted vehicles. For these applications, the need for low cost is a strong factor in design. To address this situation, a new, simple and inexpensive electronically controlled metering system for small gas turbine engines is proposed. The system incorporates a diaphragm type valve keeping a constant differential pressure across a stepper motor actuated metering valve. To optimize the design, mathematical models were created for computer simulation. Experimental tests performed on a prototype showed that it can adequately meet the fuel schedules of small gas turbines. The simulation models were validated against the test results and were used in design optimization.

A new family of low cost electronic fuel control units is being proposed for small gas turbine engines of remotely piloted vehicles and auxiliary power units. It has a modular design incorporating an electronically actuated metering valve which can be matched with various types of differential pressure valves controlling the pressure drop across the metering valve. Four different configurations are proposed: metering valve only, metering valve with diaphragm type differential pressure valve, metering valve with bypass valve and double valve configuration, the latter with a back-up capability. These configurations can satisfy various demands from gas turbine engine producers. Some components of automotive fuel injection system could be used to reduce the cost of these units as well as components from the DP-F2 fuel control which has been in production for a long time. This adds to the confidence of the reliability and durability of this new design.