Editing Sea Dart (section)

===SIGS===
In October 1960, the Navy launched the Small Ship Integrated Guided Weapon System project to fill this need, SIGS for short. This called for a weapon small enough to be carried on a 3,000 ton frigate and able to attack bombers, anti-shipping missiles, and other ships up to frigate size. Seaslug had taken much longer to develop than expected and was a very costly, ongoing program. There was some concern that development of a new system should not commence before Seaslug was in service. A review by the [[Defence Research Policy Committee]] agreed with the Navy that the new design represented an entirely new class of weapon and that development should be undertaken immediately.{{sfn|Friedman|2012|p=258}}

Two systems were initially considered for the role. [[Bristol Aeroplane Company|Bristol's]] RP.25 was a [[ramjet]] powered design with a long [[wing configuration#Ogival delta|ogive wing]] that was boosted to speed by two detachable booster rockets under the missile in a layout not that different from Bristol's [[Bloodhound (missile)|Bloodhound]] missile. The second was two-stage solid-fuel rocket known as SIG-15 from BAC, developed partially from BAC's work on the PT.428 which would later emerge as [[Rapier (missile)|Rapier]].{{sfn|Gibson|Buttler|2007|p=62}}

The Admiralty considered the range of the BAC entry, about {{convert|16|miles}}, to be too short to be useful. The Bristol concept offered a much more useful maximum around {{convert|50|miles}}. However, it also felt the BAC team, known as Project 502, was better able to manage the project. The Admiralty also demanded that the design be able to be moved about the ship in a fashion similar to gun ammunition, which made the winged RP.25 unsuitable. The result was a redesign effort with BAC designing the airframe and Bristol providing the engine.{{sfn|Gibson|Buttler|2007|p=63}}