The Orion is an aircraft I'm very fond of.   From 1979 to 1982 I was a Flight engineer on this amazing Patrol Aircraft.   Being in a reserve Sqaudron VP-93.  We only had "A" models.  Some where pretty old. Plus near to the end of their careers as an Patrol aircraft.   Here is some history on the aircraft.

This Day in Naval History - April 15, 1961: First flight of a production P3V-1.

The prototype YP3V-1/YP-3A, Bureau Number BuNo 148276 was modified from the third Electra airframe c/n 1003. The first flight of the aircraft's aerodynamic prototype, originally designated YP3V-1, was on 19 August 1958. While based on the same design philosophy as the Lockheed L-188 Electra, the aircraft was structurally different. The aircraft had 7 feet less fuselage forward of the wings with an opening bomb bay, and a more pointed nose radome, distinctive tail "stinger" for detection of submarines by magnetic anomaly detector, wing hardpoints, and other internal, external, and airframe production technique enhancements. The Orion has four Allison T56 turboprops which give it a top speed of 411 knots; 473 mph comparable to the fastest propeller fighters, or even slow high-bypass turbofan jets such as the Fairchild Republic A-10 Thunderbolt II or the Lockheed S-3 Viking. .
The first production version, designated P3V-1, was launched on 15 April 1961. Initial squadron deliveries to Patrol Squadron Eight (VP-8) and Patrol Squadron Forty Four (VP-44) at Naval Air Station Patuxent River, Maryland began in August 1962. On 18 September 1962, the U.S. military transitioned to a unified designation system for all services, with the aircraft being renamed the P-3 Orion. Paint schemes have changed from early 1960s gloss blue and white, to mid-1960s gloss white and gray, to mid-1990s flat finish low visibility gray with fewer and smaller markings. In the early 2000s, the scheme changed to a gloss gray finish with the original full-size color markings. Large size Bureau Numbers on the vertical stabilizer and squadron designations on the fuselage remained omitted.
(WikipediA The Free Encyclopedia)

Photo #1: Pre-production YP3V-1 Orion = Prototype Patrol 3rd type by Lockheed Aircraft Corp (Vega, Plant A) -1st configuration.
Photo #2: Production YP3V-1. *** Photo #3: P-3A Orion from VP-9 at NAS Moffett Field circa 1964. This was my squadron from 1966-1970 with P-3B

Prototype

P-3A

P-3A

Electra the fore father of the Orion. Santaina's private aircraft