A new study by James Large and Apostolos Pesyridis of Brunel University examines the ongoing research into the improvement of micro-gas turbine propulsion system performance, as well as the suitability for its application.
The study also focuses on propulsion systems for small tactical UAVs (with a weight less than 600 kg) and the concept of converting existing micro turbojet engines to turbofan with the use of a continuously variable gearbox.
Transforming from Propellers to Propulsion Systems
As the paper begins, a lot of unmanned air vehicles (UAVs) nowadays are still driven by propellers, mainly in order to maintain the low speed and low endurance of the applications. However, the use of advanced gas turbine propulsion systems could improve this – and enable faster flight speeds with increased efficiency.
Still, the use of these systems is only found in the larger military and medium-altitude long endurance (MALE) as well as high altitude long endurance (HALE) UAVs. This architecture commonly utilizes the existing turbine engines leveraged from small light aircrafts – mainly to perform the role of commanding, controlling, communicating and other functions.
Improving the Performance of Existing Turbojet Gas Engines
Micro gas turbine engines (MTE) are commonly classified under 1 kN thrust of different configurations such as turbojet, turboprop and turbofan can all be ideal for achieving this requirement. The turbojet, however, is the most common configuration of MTE that is available right now, mostly because of its simplicity of manufacture for home builders and hobbyists.
Therefore, the paper investigates the potential of improving the performance of existing turbojet gas turbine engines, mainly through the conversion to turbofan for application in the small tactical military UAVs, resulting in increased speed and improved endurance.
However, the authors of the paper also outline the single main challenge that needs to be addressed in order to validate the need to study the methods of improving the performance of MTEs, which is the following:
“Is there a requirement for small UAVs and their respective mission profiles to utilise the potential advantages MTE’s offer over current propulsion systems?”
Citation: Large, J.; Pesyridis, A. Investigation of Micro Gas Turbine Systems for High Speed Long Loiter Tactical Unmanned Air Systems. Preprints 2018, 2018100608 (doi: 10.20944/preprints201810.0608.v1). – https://www.preprints.org/manuscript/201810.0608/v1