NASA PLANS TO AWARD contracts in October under its general-aviation propulsion (GAP) programme to develop power plant technology for next-generation light aircraft. The GAP programme aims to reduce the price of "intermittent combustion" (IC) engines by half and small turbine engines by a factor of ten.

The IC element of the GAP programme will demonstrate a propulsion system for a single-engine, four-seat aircraft capable of less than 300kt (550km/h). Under consideration are two- and four-stroke diesel and two- and four-stroke spark-ignition reciprocating; and rotary engines.

Aims include increased reliability and maintainability; meeting future emission and noise requirements; running on fuels free of lead or other toxic additives; simpler engine controls; easier cold-weather starting; and reduced cockpit noise and vibration. The IC engine will have a low parts count, integrated subsystems and drive advanced low-speed propellers.

The turbine element of the GAP project will demonstrate a propulsion system for a higher-performance light aircraft - single-engine, with six or fewer seats and capable of more than 200kt. Goals include engine simplification and a reduction in parts count; operating temperatures low enough to avoid expensive materials and cooling techniques; and the minimum number of bearings and stages.

The GAP turbine engine is expected to have foil and magnetic bearings to reduce or eliminate the need for foil systems; direct-drive generators and all-electric accessories to eliminate the need for accessory drives; and high-speed machining and near-net or net-shape casting and forging to reduce manufacturing costs.

NASA's Advanced General Aviation Transportation Experiments (AGATE) programme, meanwhile, plans to demonstrate single-lever control of current light-aircraft power plants at the Aircraft Owners and Pilots Association convention in San Jose, California, in October.

Teledyne Continental and Textron Lycoming are modifying engines with full-authority digital engine-controls (FADEC) for flight demonstrations in a Cirrus SR20 and Cessna 182RG, respectively. First tests, runs of a Lycoming engine with single-lever power control were conducted in late June. The FADEC replaces five controllers with one and ten gauges with one integrated engine-information display.

The programme is developing an electronic-engine-control architecture for new and existing GA aircraft. AGATE officials forecast a retrofit market exceeding $15 million by 2006, with FADEC "paying its way" on to existing aircraft with a 25% increase in engine-overhaul interval and a cut in fuel consumption of over 10%.

Source: Flight International