What first seemed a whim of aeronautical engineers is now a very solid trend. Developers of unmanned air systems (UAS) want to extend their endurance dramatically, but that cannot be achieved with fuel saving engines – only with aerial refuelling.
It is only natural that Israel – where some of the most advanced UAS are manufactured and used – will be the focus of some development teams.
Israel Aerospace Industries (IAI) is developing an aerial refuelling systems for the company’s Heron-TP MALE+ UAS.
The programme is based on a unmanned “aerial tanker” that will be capable of refuelling an Heron-TP carrying payloads and sensors.
The Heron-TP has a max speed of 113kt (209km/h) and an endurance of 50h. The aerial refuelling will enable the large UAS to stay in the “area of interest” longer, which is an operational requirement in many missions.
In a parallel effort, the MALAT UAS division at IAI is preparing the first test flight of a UAS powered by a heavy fuel engine. The test is scheduled for the next few months.
The test will be used to understand the full meaning of such a change.
The use of heavy fuel has been evaluated for some time, first for smaller UAS like the company’s Searcher. However, the evaluation did not result in any operational decision. The newest planned test may determine the future of the adaptation on series production UAS or as an upgrade.
Sources say it is only a matter of time until many UAS will be powered by heavy fuel. This as some companies are investing heavily in the development of lightweight heavy fuel power packs.
Back to the aerial refuelling of UAS. Sources said on 23 September that the aim is to allow some of the systems that have the capacity to carry a multi-sensor to stay in the air for “very extended endurance”.
The sources were not specific, but taking into account that the Heron-TP, for example, has an average 50h endurance under “good conditions”, the development teams talk of endurance at least twice as long.