The Racer-class sloop also known as the Cordelia class of swift cruisers was an 11-gun wooden screw sloop class of five ships built for the Royal Navy between 1855 and 1860.
Built of a traditional wooden construction, the Racer class were a lengthened version of the , which in turn had been intended as "type of screw vessel below the Cruizer". The extra length gave greater speed, and combined with a considerable increase in power, this gave a speed of about , rather more than the of the previous class.
The class were armed with a single 32-pounder gun (58 cwt) gun on a pivot mount and ten 32-pounder (25 cwt) carronades on the broadside. These guns were all smoothbore muzzle-loading, and were little changed from the standard guns of Nelson's era.
Propulsion was provided by a two-cylinder horizontal single-expansion steam engine developing and driving a single screw. At maximum power under steam, top speed was about . A barque rig of sails was carried, which meant the ships of the class had three masts with a square rig on the fore and main masts.
The first three ships were ordered on 3 April 1854, although both Cordelia and Gannet were ordered as Swallow-class sloops, with the design being changed before construction. Icarus was ordered on 3 February 1855 and Pantaloon was ordered on 1 April 1857.