page_title: RIM-7 Sea Sparrow
section_title: Basic point defense missile system (BPDMS)
hierarchical_section_title: RIM-7 Sea Sparrow / History / Basic point defense missile system (BPDMS)
caption_attribution_description: A gunner's mate mans the Mark 115 SEA SPARROW fire control system director during a RIM-7 SEA SPARROW missile firing exercise aboard the nuclear-powered aircraft carrier USS DWIGHT D. EISENHOWER (CVN-69).
context_page_description: RIM-7 Sea Sparrow is a U.S. ship-borne short-range anti-aircraft and anti-missile weapon system, primarily intended for defense against anti-ship missiles. The system was developed in the early 1960s from the AIM-7 Sparrow air-to-air missile as a lightweight "point-defense" weapon that could be retrofitted to existing ships as quickly as possible, often in place of existing gun-based anti-aircraft weapons. In this incarnation it was a very simple system, guided by a manually aimed radar illuminator.
  After its introduction, the system underwent significant development into an automated system similar to other US Navy missiles like the RIM-2 Terrier. Improvements made to the Sparrow for the air-to-air role led to similar improvements in the Sea Sparrow through the 1970s and 80s. After that point the air-to-air role passed to the AIM-120 AMRAAM and the Sea Sparrow underwent a series of upgrades strictly for the naval role. It now resembles the AIM-7 only in general form; it is larger, faster and includes a new seeker and a launch system suitable for vertical launch from modern warships.
context_section_description: Quickly organizing the "Basic Point Defense Missile System", BPDMS, the then-current AIM-7E from the F-4 Phantom was adapted to shipboard use with surprising speed. The main developments were the new Mark 25 trainable launcher developed from the ASROC launcher, and the Mark 115 manually aimed radar illuminator that looked like two large searchlights. Operation was extremely simple; the operator would be cued to targets via voice commands from the search radar operators, and he then slewed the illuminator onto the target. The relatively wide beam of the radar only needed to be in the general direction of the target, the continuous wave signal being Doppler shifted by the moving target and showing up strongly even if it was not centered in the beam. The launcher would automatically follow the motions of the illuminator, so that when the missile was fired it would immediately see the signal being reflected off the target.
  In this form the Sea Sparrow was tested on the destroyer escort USS Bradley starting in February 1967, but this installation was removed when Bradley was sent to Vietnam later that year. Testing continued, and between 1971 and 1975 Sea Sparrow was fitted to 31 ships of the Knox class, hulls 1052 to 1069 and 1071 to 1083. The "missing ship" in the series, Downes (DE-1070), was instead used to test an upgraded version (see below).
  The Sea Sparrow was far from an ideal weapon. Its rocket engine was designed with the assumption that it would be launched at high speed from an aircraft, and therefore is optimized for a long cruise at relatively low power. In the surface-to-air role one would rather have very high acceleration in order to allow it to intercept sea-skimming targets as soon as possible. The power profile is also suitable for cruising in thin air at high altitudes, but at low altitudes it does not produce enough power to overcome drag and dramatically decreases range; some estimates indicate that the Sea Sparrow may be effective only to 10 kilometres (6.2 mi), about one quarter of the range of the air-launched Sparrow. An engine of much higher power would greatly improve performance, in spite of a shorter burning time.
  Another problem is that the Sparrow is steered with its mid-mounted maneuvering wings. These were used on the Sparrow because they required less energy for basic maneuvers during cruise, but this made the missile less maneuverable overall, which was not well suited to the quick-reaction weapon. Additionally, the powered wings meant that they could not easily be adapted to fold, and therefore the launcher cells were sized to the wings instead of the missile body, taking up much more room than required. Although the Sea Sparrow was meant as a small missile system that could be fit to a wide variety of ships, the launcher was relatively large and was deployed only to larger frigates, destroyers and aircraft carriers. Finally, the manually aimed illuminator was of limited use at night or in bad weather, which was hardly encouraging for a ship-borne weapon where fog was a common occurrence.
caption: Mark 115 manned director, initially used to guide a Sea Sparrow to its target as a part of BPDMS.
exif: {}