Gas Turbine World
Solar T62 Gas Turbine Engine
A successful small engine the Solar T62 built in the USA. The T62 is a family of compact auxiliary power units (APUs) installed in ground power units and aircraft. The T62T32 variant (shown here) has also been successfully adapted as the power plant for small single seat and two seat home-build helicopters.
The T62T32 adopts a classic small gas turbine design featuring a centrifugal compressor and radial inflow turbine. The two are mounted back to back and supported on a common shaft with outboard bearings. The bearings hold the shaft in a cantilever fashion, this arrangement has a clear advantage - both bearings are outside the hot section of the engine and so run cooler in operation. The overhung arrangement may also be found in such engines as the Garrett GTP30, Rover 2S, Lucas CT2023, H & S 250 and Solar T41 (Mars)
The combustion system fitted to the Solar T62 consists of a annular reverse-flow chamber with six vaporising burners. The operation of vaporising burners requires the presence of heat in the compositor in initiate the vaporisation process, this is provided a special small atomising burner and igniter plug.
The T62T32 version carries a heavy duty reduction gearbox that can carry a 60Kva 400Hz generator turning at 6,000 rpm. The usual accessories are also driven form the gearbox and also a heavy duty pre-engaged starter motor. Other versions of the T62 generally carry smaller lighter gearboxes and may make use of electrical starter generators or hydraulic starters.
The T62 is unusual in carrying a hybrid fuel control system. Fuel is supplied to the engine by a small gear pump, up to running speed the fuel flow is controlled by a mechanical pneumatically operated valve pressurised from the compressor delivery (P2). This arrangement ensures smooth surge free acceleration after starting. When full speed is reached an electronic governor takes over by means of a rotary solenoid actuator and fuel metering valve. The governor arrangement is not dissimilar to many diesel governors fitted to generator sets running at constant speed.
The USAF EMU30 transportable generator set was fitted with the T62T32 model, a number of these units can be found surplus from time to time in the USA. Demand for these units is likely to have been stimulated by the use of the engine as a PowerPoint in small kit built helicopters. Some modifications are carried out to reduce the weight of the substantial gearbox housing.
Solar T62T32 Specification
Power Output………………………………………..………………………………………150HP @ 60,000rpm
Compressor.……………………………………………….………………………………..single stage centrifugal
Combustor………………………………………….….annular reverse flow with 6 vaporising burners
Turbine…………………………………………………………………………………….single stage radial inflow
Layout…………………………………….…….overhung rotor single shaft with reduction gearbox
Fuel system……………………..gear pump, part hydro mechanical/part electronic governor
Ignition System………………………………………………………….……high energy plug torch igniter
Starting System………………………….…………………………………………..……………….electric starter
Oil system…………………………………………………….……………return system wet sump reservoir
Accessories……………………………………………………………………..……………..Brush-less Alternator
Application…………………………………………………..…...400Hz EMU30 Military Generator set
Similar Models………………………………………………..T16 Chinook APU, T40 Blackhawk APU
