The Lockheed P-3 Orion is a four-engine turboprop anti-submarine and maritime surveillance aircraft developed for the United States Navy and introduced in the 1960s. Lockheed based it on the L-188 Electra commercial airliner. The aircraft is easily recognizable by its distinctive tail stinger or "MAD Boom", used for the magnetic detection of submarines.
 

Over the years, the aircraft has seen numerous design advancements, most notably to its electronics packages. The P-3 Orion is still in use by numerous navies and air forces around the world, primarily for maritime patrol, reconnaissance, anti-surface warfare and anti-submarine warfare. A total of 734 P-3s have been built, and by 2012, it will join the handful of military aircraft such as the Boeing B-52 Stratofortress which have served 50 years of continuous use with its original primary customer, in this case, the United States Navy. The U.S. Navy's remaining P-3C aircraft will eventually be replaced by the Boeing P-8A Poseidon.

 

Development

Origins

In August 1957, the U.S. Navy called for replacement proposals for the aging twin piston engined Lockheed P2V Neptune (later redesignated P-2) and Martin P5M Marlin (later redesignated P-5) with a more advanced aircraft to conduct maritime patrol and antisubmarine warfare. Modifying an existing aircraft was expected to save on cost and allow rapid introduction into the fleet. Lockheed suggested a military version of their L-188 Electra, which was still in development and had yet to fly. In April 1958 Lockheed won the competition and was awarded an initial research and development contract in May.
 

The prototype YP3V-1/YP-3A, Bureau Number (BuNo) 148276 was modified from the third Electra airframe c/n 1003.[4] 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 metres (23 ft) less fuselage forward of the wings with an opening bomb bay, and a more pointed nose radome, distinctive tail "stinger", 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 (761 km/h) comparable to the fastest propeller fighters, or even slow low-bypass turbofan jets such as the A-10 Thunderbolt II or the S-3 Viking. Similar patrol aircraft include the Soviet Ilyushin Il-38 and the French Breguet Atlantique, while Britain adapted the jet-powered de Havilland Comet as the Hawker Siddeley Nimrod.
 

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.[3] 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.

Further developments

In 1963, the U.S. Navy Bureau of Weapons (BuWeps) contracted Univac Defense Systems Division of Sperry-Rand to engineer, build and test a digital computer (then in its infancy) to interface with the many sensors and newly-developing display units of the P-3 Orion. Project A-NEW was the engineering system which, after several early trials, produced the engineering prototype, the CP-823/U, Univac 1830, Serial A-1, A-NEW MOD3 Computing System. The CP-823/U was delivered to the Naval Air Development Center (NADC) Warminster at Johnsville, Pennsylvania in 1965, and directly led to the production computers later equipped on the P-3C Orion.
 

Three civilian Electras were lost in fatal accidents between February 1959 and March 1960. Following the third crash the FAA restricted the maximum speed of Electras until the cause could be determined. After an extensive investigation, two of the crashes (in September 1959 and March 1960) were found to be caused by insuffiently strong engine mounts, unable to dampen a whirling motion that could affect the outboard engines. When the oscillation was transmitted to the wings, a severe vertical vibration escalated until the wings were torn from the aircraft. The company implemented an expensive modification program, labelled the Lockheed Electra Achievement Program or LEAP, in which the engine mounts and wing structures supporting the mounts were strengthened, and some wing skins replaced with thicker material. Each of the survivors of the 145 Electras built to that time was modified at Lockheed's expense at the factory, the modifications taking 20 days for each aircraft. The changes were incorporated in subsequent aircraft as they were built.
 

Sales of airliners were limited as the technical fix did not completely erase the "jinxed" reputation, turboprop-powered aircraft were soon replaced by faster jets. In a military role where fuel efficiency was more valued than speed, the Orion remained in service over 50 years after its 1962 introduction. Although surpassed in production longevity by the C-130 Hercules, 734 P-3s were produced up until 1990. Lockheed Martin opened a new P-3 wing production line in 2008 as part of its Service Life Extension Program (ASLEP) for delivery in 2010. A complete ASLEP replaces the outer wings, center wing lower section and horizontal stabilizers with new-build parts.
 

In the 1990s, during a U.S. Navy attempt to identify a successor aircraft to the P-3, the improved P-7 was selected over a navalized variant of the twin turbofan-powered Boeing 757, but this program was subsequently cancelled. In a second program to procure a successor, the advanced Lockheed-Martin Orion 21, another P-3 derived aircraft, lost out to the Boeing P-8 Poseidon, a Boeing 737 variant, which is due to enter service in 2013.

Design

The P-3 has an internal bomb bay under the front fuselage which can house conventional Mark 50 torpedoes or Mark 46 torpedoes and/or special (nuclear) weapons. Additional underwing stations, or pylons, can carry other armament configurations including the AGM-84 Harpoon, AGM-84E SLAM, AGM-84H/K SLAM-ER, the AGM-65 Maverick, 127 millimetres (5.0 in) Zuni rockets, and various other sea mines, missiles, and gravity bombs. The aircraft also had the capability to carry the AGM-12 Bullpup guided missile until that weapon was withdrawn from U.S./NATO/Allied service.
 

The P-3 is equipped with a magnetic anomaly detector (MAD) in the extended tail. This instrument is able to detect the magnetic anomaly of a submarine in the Earth's magnetic field. The limited range of this instrument requires the aircraft to be near the submarine at low altitude. Because of this, it is primarily is used for pinpointing the location of a submarine immediately prior to a torpedo or depth bomb attack. Due to the sensitivity of the detector, electro-magnetic noise can interfere with it, so the detector is placed in P-3's fiberglass tail stinger (MAD boom), far from other electronics and ferrous metals on the aircraft.

Crew complement

The crew complement varies depending on the role being flown, the variant being operated, and the country that is operating the type. In U.S. Navy service, the normal crew complement was 12 until it was reduced to its current complement of 11 in the early 2000s when the in-flight ordnanceman (ORD) position was eliminated as a cost-savings measure and the ORD duties assumed by the in-flight technician (IFT). Data for U.S. Navy P-3C only.
 

Officers:

• three Naval Aviators

o Patrol Plane Commander (PPC)

o Patrol Plane 2nd Pilot (PP2P)

o Patrol Plane 3rd Pilot (PP3P)

• two Naval Flight Officers

o Patrol Plane Tactical Coordinator (PPTC or TACCO)

o Patrol Plane Navigator/Communicator (PPNC or NAVCOM)
 

NOTE: NAVCOM on P-3C only; USN P-3A &and P-3B series had an NFO Navigator (NAV) and an enlisted Airborne Radio Operator (RO)
 

Enlisted Aircrew:

• two enlisted Aircrew Flight Engineers (FE1 and FE2)

• three enlisted Sensor Operators

o Radar/MAD/EWO (SS-3)

o two Acoustic (SS-1 and SS-2)

• one enlisted In-Flight Technician (IFT)

• one enlisted Aviation Ordnanceman (ORD position no longer used on USN crews; duties assumed by IFT.)
 

The senior of either the PPC or TACCO will be designated as the aircraft Mission Commander (MC).

Engine loiter shutdown

Once on station, one engine is often shut down (usually the No. 1 engine – the left outer engine) to conserve fuel and extend the time aloft and/or range when at low level. It is the primary candidate for loiter shutdown because it has no generator. Eliminating the exhaust from engine 1 also improves visibility from the aft observer station on the port side of the aircraft.
 

On occasion, both outboard engines can be shut down, weight, weather, and fuel permitting. Long deep-water, coastal or border patrol missions can last over 10 hours and may include extra crew. The record time aloft for a P-3 is 21.5 hours, undertaken by the Royal New Zealand Air Force's No. 5 Squadron in 1972.

Operational history

Developed during the Cold War, the P-3's primary mission was to track Soviet Navy ballistic missile and fast attack submarines and to eliminate same in the event of full scale war. At its height, the U.S. Navy's P-3 community consisted of twenty-four active duty "Fleet" patrol squadrons home based at air stations in the states of Florida and Hawaii as well as bases which formerly had P-3 operations in Maryland, Maine, and California. There were also thirteen Naval Reserve patrol squadrons identical to their active duty "Fleet" counterparts, said Reserve "Fleet" squadrons being based in Florida, Pennsylvania, Maryland, Michigan, Massachusetts (later relocated to Maine), Illinois, Tennessee, Louisiana, California and Washington. Two Fleet Replacement Squadrons (FRS), also called "RAG" squadrons (from the historic "Replacement Air Group" nomenclature) were located in California and Florida. The since-deactivated squadron in California provided P-3 training for the Pacific Fleet, while the squadron in Florida performed the task for the Atlantic Fleet). These squadrons were also augmented by a test and evaluation squadron in Maryland, two additional test and evaluation units that were part of an air development center in Pennsylvania and a test center in California, an oceanographic development squadron in Maryland, and three active duty "special projects" units in Maine, Texas and Hawaii, the latter being slightly smaller than a typical squadron.
 

Reconnaissance missions in international waters led to occasions where Soviet fighters would "bump" a U.S. Navy P-3 or other P-3 operators such as the Royal Norwegian Air Force. On 1 April 2001, a midair collision between a United States Navy EP-3E ARIES II signals surveillance aircraft and a People's Liberation Army Navy (PLAN) J-8II jet fighter-interceptor resulted in an international dispute between the U.S. and the People's Republic of China (PRC) called the Hainan Island incident.
 

More than 40 combatant and noncombatant P-3 variants have demonstrated the rugged reliability displayed by the platform flying 12-hour plus missions 200 ft (61 m) over salt water while maintaining an excellent safety record. Versions have been developed for the National Oceanic and Atmospheric Administration (NOAA) for research and hurricane hunting/hurricane wall busting, for the U.S. Customs Service (now U.S. Customs and Border Protection) for drug interdiction and aerial surveillance mission with a rotodome adapted from the Grumman E-2 Hawkeye or an AN/APG-66 radar adapted from the General Dynamics F-16 Fighting Falcon, and for NASA for research and development.
 

The U.S. Navy remains the largest P-3 operator, currently distributed between a single fleet replacement (i.e., "training) patrol squadron in Florida, 12 active duty patrol squadrons distributed between bases in Florida, Washington and Hawaii, two Navy Reserve patrol squadrons in Florida and Washington, two active duty special projects patrol squadrons in Florida and Washington, and two active duty test and evaluation squadrons. Two additional active duty fleet reconnaissance squadrons operate the EP-3 Aries signals intelligence (SIGINT) variant.