Adolph Saurer GT15 Gas Turbine Engine
In 1966 probably the World’s smallest production gas turbine engine built long before model RC type power-plants! The heavy industry, truck and bus company Adolph Saurer of Arbon Switzerland developed a small single shaft gas turbine the GT15. In the 1960s there was much engineering optimism and of course the cold war also that fuelled the requirements for precision technologies such as aircraft turbo-machinery. It is understood only 32 units were ever built, a number of them were installed in the Hansa HFB320 business jet. The GT15 was uses as an APU for electrical power and also compressed air of air-cycle air conditioning. (See jet beer cooler) other GT15 units served as portable generator sets for various military applications.
The GT15 consists of a simple centrifugal compressor impeller driven by a radial in flow turbine supported on ball bearings. The combustion system consisted of a disc shaped radial combustor with rotating atomiser. Fuel was fed to the atomiser along the centre of the engine shaft. Fuel was passed to the shaft by a special solenoid controlled valve that under electronic control metered the fuel flow to the combustor.
An innovative feature of the engine was the lubrication system. The engine did not use a conventional oil system but instead utilised the Jet A1 fuel flow around the bearings and gears to serve as lubrication and cooling. Fuel flow requirements in excess of the burning requirements would flow around the engine and then be returned to the fuel tank via a cooler. In Saurer documentation no mention of any additives are mentioned and so standard fuel must have presented sufficient lubricity for acceptable engine life.
Another innovation especially in the 1960s was the provision of a transistorised electronic control unit that accompanied the engine and also provided basic instrumentation.
Saurer GT15 Specification
Output.....................................….……..............…………………………..................15 Bhp
RPM............……………………..………….….......………………………….......................85,000
Compressor.....................….…………..........………………............Centrifugal Impeller
Combustion Chamber..….…..…………………….........Radial with Rotary Atomizer
Turbine......................…...……………..........…………................Radial Inflow Impeller
Layout..............….…………..……………....…........Single Spool with Reduction Gear
Ignition...........….……………..………….........….............................High Energy Igniter
Fuel System.………………….…….......Gear Pump with Electronic Control System
Lubrication………………………………………………………….……..fuel serves as lubricant
Starting..….…………………………............Electric Starter/Generator or Pull Cord
Lubrication .......Fuel Supplied by Gear Pump, Scavenge Pump, Fuel Cooler
Application...................................Hansa HF320 Biz Jet APU, Ground Genset
