The Council for Scientific and Industrial Research (CSIR) has been developing a small gas turbine engine for the last three years and is close to carrying out the first compressor test later this year.
The organisation is developing a 100 kg thrust class gas turbine engine intended for stand-off weapons, unmanned aerial vehicles (UAVs) and gliders, amongst others. There are very few engines available in this segment, with many export restrictions on those in production. For instance, the major players are the French Microturbo, American Teledyne and Williams International, Indian Hindustan Aeronautics Limited (HAL) and Russian NPO Saturn. The French and American offerings are subject to strict arms controls whereas a South African small gas turbine would make use of commercial off the shelf items and materials and therefore not be ITAR (International Traffic in Arms Regulations) controlled.
CSIR competence area manager: aeronautics systems Kaven Naidoo recently said the CSIR has been working on the project for more than three years, with trial manufacture and assembly of the engine subsystems already started in order to establish a reliable supply chain and advanced manufacturing base. The CSIR is currently in the process of completing a test facility to prove the engine’s compressor capability, with the first test of the engine compressor around March 2019.
As the compressor design is highly scalable, engines in the 60 to 150 kg thrust class are possible with only minor changes in the engine architecture. The largest of these has the potential to form the high-pressure core or a larger bypass engine family.
The engine will be about 250 mm in diameter and some 500 mm in length. Maximum thrust will be around 110 kg and maximum RPM 60 000. Fuel consumption at idle will be .384 kg/minute and at max thrust 1.536 kg/minute.
The CSIR notes that the current design can be scaled up and down and converted to larger bypass engine architectures. A shaft engine variant of the current 100 kg thrust engine would be capable of 100 kW shaft power output if modified.
At the moment the CSIR is funding the gas turbine engine project, but after the engine is tested and proven, it could be transferred to industry for commercial exploitation. Naidoo believes the project could be of benefit to the entire South African aerospace and defence industry, although foreign clients are also interested.
The CSIR has long been involved in gas turbine research and development, starting with the state-funded Project Apartment in the early 1990s. This created the 65 kg thrust APA350 engine, but this was cancelled due to budget cuts. In the 1980s, the CSIR was involved in a project to reduce the weight of the Atar 09K50 turbojet and increase thrust as part of Project Carver to develop a new jet fighter. Engineering News reports that this involved the replacement of the original turbine blades and riveted compressor with new CSIR-developed single-crystal blades and a welded compressor. Although weight was not reduced, performance increased by 10%, but the programme ended in 1991.
The CSIR and the University of Stellenbosch have worked together with Cape Aerospace Technologies on other small gas turbine projects. Cape Aerospace Technologies (CAT) has three main models: the CAT 120 produces 12 kg of thrust at 125 000 rpm and weighs just 1.4 kg while the CAT 250 produces 25 kg of thrust and weighs 2.1 kg. The largest is the CAT 400, which develops 400 N (40 kg) of thrust and weighs just 3.6 kg. All can operate between -25 and 50 degrees Celsius and at altitudes of up to 8 000 metres. They are intended for sub-sonic applications.
David Krige, MD/CEO of CAT, told defenceWeb that the CAT 120 has been in production for a number of years and the CAT 250 has just received orders and is going into production. On the CAT 400, he said there has been a lot of demand, especially as a sustainer jet for sailplanes.