Lockheed SP-2H Neptune

The Lockheed SP‑2H Neptune was a twin‑engine maritime patrol and anti‑submarine aircraft built by Lockheed Corporation for the United States Navy in the early Cold War era. First flown in 1945 as the P2V‑1, the type entered service in 1947 and was continuously upgraded, culminating in the SP‑2H version that appeared in 1956. Powered by two Wright R‑2600 radial engines supplemented by auxiliary jet pods, the Neptune could cruise over 2,500 miles at 180 knots while carrying a payload of depth charges, torpedoes, sonobuoys and magnetic anomaly detectors. Its large wings housed retractable fuel tanks, extending range for trans‑oceanic patrols, and a radar dome beneath the fuselage provided surface search capability. The SP‑2H proved decisive during the Korean and early Vietnam conflicts, tracking Soviet submarines and conducting reconnaissance missions that shaped naval strategy. Its reliability, long endurance, and advanced sensor suite made it a benchmark for subsequent maritime patrol aircraft, influencing designs such as the P‑3 Orion. The Neptune’s service, lasting until 1970, marked a pivotal transition from propeller‑driven patrol boats to integrated airborne antisubmarine warfare platforms. Its legacy endures in modern ASW concepts and museum displays worldwide.

Lockheed Corporation

Lockheed SP-2H Neptune

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Design & Classification