Lockheed's proposal was based on the Electra's basic fuselage, wings, empennage, and four turboprop engines. Major changes made to transform the Electra into the Orion included:

• Revised nose contour to house forward search radar antenna.
• Revised tail contour to house aft search radar antenna.
• Lengthened fuselage forward of the wing to house bomb bay.
• Extension aft of tail to house magnetic anomaly detection (MAD) equipment.

The initial production version of the P3 Orion was designated "P3V-1". The first test Orion had its maiden flight on April 15th 1961. After a brief evaluation period, US Navy ordered 157 P3V-1 aircrafts from Lockheed. Deliveries began in August 1962 with Patrol Squadron 8 receiving the very first batch which replaced all of their P2V-7 aircraft. Around November 1962 the US Navy revised and changed all aircraft designations. In the process the P3V-1 was redesignated "P3A".

Early P3A aircraft were equipped with a variety of sensors and weaponry. Sensor equipment included radar, sonar (Jezebel/Julie), identification friend or foe (IFF) device, electronic sensing measures (ESM), a diesel exhaust sniffer, a magnetic anomaly detector (MAD), and a powerful searchlight. A typical first generation P3A crew consisted of three pilots, two flight engineers, a radio operator, an electronic technician, an ordinance specialist, four sensor operators, a tactical coordinator (TACCO), and a navigator. Weaponry included sonobuoys, mines, depth bombs, and torpedoes. Typical ASW or patrol missions would last 8 to 10 hours.

Several early P3As were in action during the Cuban Missile Crisis. The aircraft was used to help enforce President Kennedy's Cuban blockade. Afterwards, P3As monitored the movement of Russian ships removing strategic missile hardware from Cuban bases.

In 1964 Lockheed came up with an improved version of the P3 which was designated "P3B". The P3B featured improved engines (no water injection), an updated sensor suite, and the capability to fire the Bullpup air to surface missile. The diesel exhaust sniffer, which had been notoriously unreliable, was not installed in the P3B and was eventually removed from all of P3A models. One sensor operator, the man who operated the diesel sniffer, was removed from the Orion's typical tactical crew.

Many P3A and P3B Orions took part in the Vietnam War. They were used to monitor ships movements around North Vietnamese coast. P3s played a major role in "Operation Market Time".

On September 18th 1968 the first P3C Orion took off. The P3C shown more sensors and weapon system improvements over the P3A and P3B. The P3C introduced dramatically new radar and ESM systems. Many P3C aircraft were fitted with low light television (LLTV) or an infrared detection system (IRDS) which permitted visual searches in near or complete darkness. The P3C aircraft was configured to fire the Harpoon air-to-surface missile. However, the most dramatic improvement over previous versions of the Orion was that the P3C integrated sensor and tactical data using a Univac CP-901 digital computer. The P3C's computer system dramatically improved the efficiency of the aircraft's tactical crew. The P3C's navigator took the duties of the radio operator, removing another man from the Orion's typical tactical crew.

From 1979 all of US Navy P2 Neptune aircraft had been replaced by the P3 Orion. During mid 1980s, all active duty US Navy patrol squadrons were equipped with the P3C while reserve outfits operated the P3A and P3B. The end of the Cold War during the late 1980s brought to force reductions which permitted many reserve units to replace their P3A and P3B aircraft with P3Cs released from active duty service.

Many P3C Orions saw combat action during operation Desert Storm. The Orions were used to monitor ships movements in the Persian Gulf and passed target information on to tactical aircraft.

Updated versions of the P3C offer greatly improved sensor capabilities over previous versions of the Orion. One major improvement is the new inverse synthetic aperture radar system (ISAR) which presents nearly pictorial views of targets from great distances away. Other significant improvements have been made in later years to the Orion's sonar and ESM capabilities.

In recent years active duty and reserve P3 Orions have seen service in support of United Nations actions off the coasts of former Yugoslavia and Haiti. P3 Orions are also at the forefront of America's war on drugs.

With an operative range of 17 hours, the Orion satisfy the specific demands for patrol and ASW missions: it has a cruise speed high enought and, at the meantime, is able to orbit near the target for seven hours to a maximum distance of 1850 kms from the home base.
With regard to the offensive ability, the Orion has a wide bomb load bay, where is possible to load a wide range of weapons like mines, depth charges and torpedoes; Other ammunitions, like antiship missiles, air-to-surface AGM-84 Harpoon, can be loaded under the wings, in the latest versions.
For the localization of enemies submarines, it also transports a lot of sonobuoys. On P-3C are loaded 48 type 'A' sonobuoys: they can be loaded and unloaded from the launch tubes, under the fuselage, just behind the wings,when the aircraft is at base.
The sonobuoys can be loaded also from the inside of the aircraft into 4 more launch tubes during flight.
During a typical mission, an Orions can cover a vast area of sea, and even if P-3 is more commonly used for antisom war, a big part of its job consists in overseeing. Accordingly, the crewmembers use different systems of sensors (radar,sonobuoys, magnetic anomalies detectors) every of which ouputs data directly to the main computer that elaborates and visualizes them through many CRTs at the crewmember stations and in the pilot cockpit.
Eliminating the need to perform mathematical calculations as well as the routine recordings, the computer has really changed the course of antisom missions, and perhaps the most important advantage is that the crew can devote exclusively the attention to the tactical situation of the moment.

Also valuable is that the mission profile software can be prepared in advance, starting from known navigation data and from the latest intelligence reports, it is loaded in the computer of the Orion just prior the departure and, once in flight, can give an accurate picture of the situation that will be probably encountered in the operation area. The data link system allow the reception and the transmission of updated informations during the mission from other ASW aircraft or from surface ships.
Once that the Orion has reached its zone of operation, the position of the tactical coordinator becomes the focal point of the activities of the mission; he has a big multipurpose screen on which are displayed many data like direction and speed of the winds, position of sonobuoys, aircraft speed and relative position, and individuation of suspect tagets. This mess of data is stored on magnetic tape, and analyzed when the aircraft returns to base. So, the profile mission can be reviewed, giving the crew the possibility to understand and correct possible errors. The computer data are also analyzed by the TACCO (tactical Coordinator), that has the reponsability to interact with the pilots, giving them indications on the direction to follow.

With regard to the discovery capabilities, the radar is the main sensor for monitoring of surface ships, while the sonobuoys are used for submarine hunting, in conjuction with the MAD (Magnetic Anomalies Detector) that reveals the variations of the earth magnetic field due to the presence of a submerged vessel or a wreckage.

The computer determines what type of sonobuoys has to be launched and automatically selects one of the 31 VHF channels for the monitoring of signals uttered by these sensors. The buoys position informations also comes from the computer before showing them on the TACCO's multipurpose screen; the computer is also dealt with some weaponry, selecting the weapon that must be used and giving information to the crew for the launch.

This brief look to some aspects of the electronic devices on board of the large fleet of Orions in service with US Navy could bring to the belief that crewmembers don't have very much to do during a mission,
but such a supposition is wrong; the job load still remains very heavy: much time will pass before the ASW systems can become totally automatic.

The P3C still remains the most up-to-date version of the P3 Orion. A successor aircraft from Lockheed was planned during the early 1980s which would have been designated the P7. Funding dried up for this project causing it to be canceled in 1989. Thus, the P3 Orion will probably continue on as the US Navy's premier antisubmarine warfare and maritime patrol aircraft through the first decades of the 21st century.

.Orion known variants

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Further data and images

The P-3C Update III Anti SUrface Warfare Improvement Program (AIP)