UAV Watchkeeper WK450

UAV Watchkeeper WK450

The Thales Watchkeeper WK450 is an unmanned aerial vehicle (UAV) for all weather, intelligence, surveillance, target acquisition, and reconnaissance (ISTAR) use by the British Army. It is provided under an £800 million contract with UAS Tactical Systems (U-TacS), a joint venture of Elbit and Thales UK, and is based on Elbit’s Hermes 450.


The Watchkeeper WK450 is based on the Elbit Hermes 450 UAV and is built in the UK by a joint venture company, UAV Tactical Systems (U-TacS), set up by the Israeli company Elbit Systems (51% ownership) and the Thales group. The Watchkeeper is 6.5m long, with a 10.9m wingspan. Its cruising speed is 77 knots (143 km/h), and it can operate at an altitude of 16,000 feet (4,900 m). It has a takeoff weight of 485 kg, a typical endurance of 14 hours, a payload capacity of 150 kg and uses a rotary Wankel engine provided by UAV Engines Ltd, a wholly owned subsidiary of Elbit Systems. It can operate up to 150 km from the Ground Control Station; multiple stations can be linked to extend the range. It was originally intended to enter service in June 2010, but years of delays, technical issues, hardware modifications, difficulties in training sufficient pilots and incidents means that it was not expected to be fully operational until late 2018.

A prime difference between the Hermes 450 and Watchkeeper is that the 450 is fitted only with an electro-optical/infrared sensor, while the WK450 has in addition a dual-mode synthetic aperture radar and ground moving target indication system that allows it to see through all weather conditions. The British Army was to receive 30 Watchkeepers and a further 24 due to go into store to be deployed as needed.

As of March 2018 the 47th Regiment Royal Artillery was the only unit operating the Watchkeeper.

As of August 2020 Watchkeeper had accumulated over 3,000 flying hours since the first flight in 2010.


Crew 0
Payload 180 kg (400 lb)
6.1 m (20 ft 0 in)
Wingspan 10.5 m (34 ft 5 in)
Empty weight
Maximum weight 550 kg (1,213 lb)
Powerplant 1 × UAV Engines Limited R802/902(W) Wankel engine, 39 kW (52 hp)
Maximum speed 176 km/h (109 mph, 95 kn)
Cruising speed at sea level 130 km/h (80 mph, 70 kn)
Range 300 km (190 mi, 160 nmi)
Endurance 17 hours (450LE – 30 hours)
Ceiling in service 5,500 m (18,000 ft)


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