- Rolls-Royce PWR 2 reactor
- MTU 600 kilowatt diesel generators
- Thales Sonar 2076
- Atlas DESO 25 echosounder
- 2 * Thales CM010 optronic masts
- Raytheon Successor IFF
- 6 * 21 in (533 mm) torpedo tubes with stowage for up to 38 weapons:
- Tomahawk Block IV cruise missiles
- Spearfish heavyweight torpedoes
HMS Audacious is the fourth Astute-class nuclear-powered fleet submarine of the Royal Navy. Several previous vessels of the Royal Navy have borne the name. She was formally named on 16 December 2016 and was launched on 28 April 2017. Audacious is stated to be handed over in January 2021. A parliamentary written answer stated that Audacious was commissioned on 3 April 2020.
Audacious's nuclear reactor will not need to be refuelled during the boat's 25-year service. The submarine can purify water and air, and will be able to circumnavigate the planet without surfacing. However, she will only carry three months' supply of food for 98 officers and ratings.
Audacious will have provision for up-to 38 weapons in six 21-inch (533 mm) torpedo tubes. The submarine will be capable of using Tomahawk Block IV land-attack missiles with a range of 1,000 miles (1,600 kilometres) and Spearfish heavyweight torpedoes.
Long lead items for her construction were ordered on 28 August 2006 although the actual order was not placed until 21 May 2007. Launch was expected in the fourth quarter of 2016, and the submarine was due to leave the yard in 2017. She was eventually formally named on 16 December 2016, and floated out on 28 April 2017, and was due to leave in 2018 for sea trials. The original budget was £1,279m but by 2015 this had risen to £1,492m.
The submarine and its crew have formally forged links with the City of Leeds (which had previously had an association with HMS Ark Royal) by meeting the people at Elland Road in the city and marching in the Armistice Day parade in November 2016.
Audacious completed her first dive at Devonshire Dock over two days in January 2018. She eventually sailed from Barrow on 4 April 2020, and commenced sea trials on 6 April 2020.