Defence

Israeli unmanned air vehicle manufacturers are attempting to make their aircraft quieter following operations over the Gaza strip and the recent war in Lebanon, writes Arie Egozi.

UAV operations over urban areas in Gaza and low flying missions in Lebanon to detect rocket launchers have highlighted that noise emissions are crucial to mission success, despite the fact that for many years the noise emissions of Israeli UAVs were not considered a problem.

Israel Aircraft Industries (IAI) has already replaced the Wankel engine powering its Searcher 2 UAV with a four-stroke engine. Systems in service with the Israeli air force are being re-engined, but export examples are already equipped with the quieter powerplant.

Yair Dubester, general manager of IAI’s Malat UAV division, says the new engine and a bigger propeller have reduced the noise footprint of the Searcher 2 “dramatically”. He says that from an altitude of 4,000ft (1,200m), the UAV cannot be heard.

IAI’s larger Heron UAV was originally equipped with a four-stroke engine and larger propeller. A special gearbox allows the propeller to operate at a lower rpm.

Elbit Systems’ Hermes 450 tactical UAV has also been in regular use over Gaza and Lebanon. The aircraft’s rotary engine emits a distinctive noise that can be heard from a significant distance. Company sources say that mufflers are being adopted to lower the noise.

The Hermes 450 is also the baseline vehicle for the UK Ministry of Defence’s Thales UK-sourced Watchkeeper programme. Its WK450 vehicles will receive several enhancements, but will keep the UAV Engines AR801 powerplant.