The Lockheed P-2V (SP2-H) Neptune (click on portions of the photo below for details) P2 Merchandise and more photos The Lockheed P2V Neptune is unique in that it is the only American naval land-based patrol plane ever designed expressly for this purpose. Both the Neptune's predecessor, the PV2 Harpoon , and successor, the P3 Orion , were first built by Lockheed as transports... the PV2 as ...