Decades Ago The Navy Tested A Maritime Patrol U-2 Variant That Was Way Ahead Of Its Time

A state-of-the-art EP-Xs never came to be, but the Navy didn’t give up on the idea and it’s finally becoming a reality via the MQ-4C Triton.

byJoseph Trevithick|
MQ-4C photo


After more than six decades of service to the United States, the U-2 Dragon Lady has become an iconic design, with numerous variants acting as both a high-flying spy plane and test bed for first the Central Intelligence Agency, and then the U.S. Air Force and NASA. For a short time it looked as if another organization, the U.S. Navy, might join its short list of American operators, with aircraft Lockheed had configured as maritime surveillance platforms.

In 1972, the Navy obtained a single U-2R, known both as Article 061 and by its Air Force serial number 68-10330, as part of an experimental program called Project Highboy. In cooperation with the manufacturer Lockheed, the service made substantial modifications to the aircraft, configuring it for an all-new mission, tracking ships at sea.

The initial phase of the project cost $5.5 million at the time – more than $33 million in 2017 dollars – and lasted six months, according to Unlimited Horizons: Design and Development of the U-2, an official NASA monograph by Peter Merlin. The Navy referred to its U-2R as the “EP-X.”

Though this was the only example it ever officially took ownership of, this was not the Navy’s first experience with the U-2. To help extend the range of the aircraft and get them into more remote areas, the service had helped train CIA pilots to fly off aircraft carriers using specially modified variants, the U-2G and U-2H.

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That concept proved successful, but costly and the Navy became increasingly resistant to the idea owing to the amount of resources it had to pull away from other duties to support the flights. However, training for carrier operations using the larger and much more capable U-2Rs continued at least into the 1970s.

The Navy itself had expressed interest in joining the spy plane program as early as 1963, but the National Reconnaissance Office successfully blocked the purchase of any additional U-2s the next year in favor of more focus on spy satellites. The service’s separate plans to acquire the aircraft as airborne communications relays never came to fruition, either, according to Merlin’s monograph.

A US Air Force U-2C., USAF

The EP-X tests offered another opportunity, though, and also helped support the development of other then state-of-the-art technologies. The utility of an aircraft capable of broad maritime surveillance over a large area would have been particularly obvious to the Navy at the time.

The service had spent the better part of a decade attempting to track and monitor shipping to and from North Vietnam and interdict ships smuggling men and materiel into the South. At the same time, North Korean commandos had attempted to infiltrate into the South by sea on numerous occasions and that country’s naval forces routinely sortied out to harass allied and civilian boats. Just being able to spot and track the movements of Soviet warships and commercial vessels would have been a valuable intelligence tool, too.

The EP-X test aircraft seemed well suited to many of those requirements. The unique Dragon Lady variant had a new nose section and two equipment pods, one in the leading edge of each wing. Various specialized equipment went into the U-2R’s other modular payload bays.

The EP-X and its various systems., Lockheed via NASA

An X-band phased array AN/APS-116 radar went into the nose. Originally intended as a weather radar, the unit proved capable of performing a surface search function and it was sensitive enough to pick up submarine periscopes poking up above the water. The same system subsequently went into the EP-3E Aries intelligence, surveillance, and reconnaissance aircraft, the S-3A Viking submarine hunter, and later models of the SH-3 Sea King helicopter.

The equipment pod on the left wing held a so-called Return Beam Vidicon camera, or RBV, an early multi-spectral imaging sensor consisting of three video cameras each recording in only one spectral band – blue-green, yellow-red, and near infrared. The complete system would then merge the three sets of data into a single image. It could provide continuous, but relatively high-fidelity imagery without the need for film. The first three Landsat imaging satellites used a similar setup.

The video clip below describes the capability of Landsat 1, including its RBV sensor.

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On the right side, there was an AN/ALQ-110 radar signal tracker linked to a T-35 camera, a combination that had been inside the nose of the standard U-2Rs. A communication relay went into the aircraft’s “Q-bay,” which normally held one of a number of different types of visual cameras.

Perhaps the most important piece of equipment sat in the plane’s “E-bay.” Earlier in 1972, as part of a program called Senior Dagger, the Air Force had developed a digital data link that would allow its own U-2R pilots to send radar data to a ground station in near real time.

The NASA monograph says there was only one aircraft bailed to the Navy for conversion to this EP-X configuration, but other sources suggest there was a second aircraft. It is possible that Lockheed made up a second example for its own test purposes. This confusion could be based on the proposed transfer of two ex-CIA U-2Rs to the Navy by way of the Air Force for further EP-X tests, which may or may not have occurred.

Regardless, with the full set of systems installed, the EP-X test bed could not only monitor a wide area both visually and via radar, but it could then feed that information straight to friendly ships or shore-based headquarters within its line of sight. In 1973, the aircraft proved it could do just that during a test flight off California in which it sent data to analysts at Lockheed’s facility in Sunnydale.

A US Air Force U-2., USAF

Between 1974 and 1975, the aircraft came back out for a series of tests called Outlaw Hawk. The primary goal of these experiments was to test an experimental ship-to-shore data link setup, called the Flag Command and Correlation Facility (FCCF), on board the aircraft carrier USS Kitty Hawk.

The FCCF could provide an “integrated war-room display” of all of the information flowing into the system, according to one 1978 technical report from the Naval Ocean Systems Center. This gave the ship greatly increased situation awareness, allowing it to monitor a number of friendly ships, and other unspecified "targets of opportunity" during the day and at night, according to a now declassified 1976 Office of Naval Research report.

During one of these tests, the EP-X, flying from Lockheed’s facilities at the U.S. Air Force’s Plant 42 in Palmdale, California, contributed to this overall picture. The crew of the Kitty Hawk received the information in near real time, even though the ship had departed from Pearl Harbor, Hawaii, and was sailing in the Pacific Ocean hundreds of miles away.

The benefits of the capability would have been obvious. A fleet of high-flying, long range EP-X aircraft could have provided invaluable information to carrier battle groups, surface task forces, and other naval assets during a conflict. With that data in hand, those commanders would have been able to better allocate their resources, perhaps taking up a more advantageous position respective to the enemy, staying out of range of their stand-off weapons, or avoiding a superior force altogether. The information could also be used to target the Navy's own standoff weaponry. Even the ability to better target Russian task forces with nuclear weapons would have been an obvious benefit of the Cold War era.

The USS Kitty Hawk much later in life., USN

It could have had important peace time applications, as well, from monitoring shipping traffic to and from potential opponents to search and rescue missions. The aircraft could have patrolled for smugglers and enemy inflitrators in certain areas, as well, something that, as we previously noted, would have been particularly useful in and around the Korean Peninsula.

Unfortunately, a combination of factors ultimately scuttled any possibility of a fleet of EP-X aircraft. After the Vietnam War ended, the Pentagon’s budget had contracted dramatically, forcing all the services to trim back various programs.

On top of that, the National Reconnaissance Office continued promoting increasingly capable spy satellites as an alternative to the high-flying U-2s. In 1974, the CIA had ended its Dragon Lady operations, turning over its remaining aircraft to the Air Force. Around the same time, the Navy shelved the EP-X in favor of using a combination of EP-3E aircraft and satellites to conduct similar maritime surveillance functions.

It’s not clear whether or not the EP-X program had an influence on the wing-mounted “superpods” that the Air Force subsequently fitted on its U-2Rs and carried over to the still-in-service U-2S models. Those 24-foot long equipment pods can hold 800 pounds of gear, making them some three times larger than those of the Navy’s experimental version, according to the NASA monograph.

A U-2S with the superpods., Lockheed Martin

The EP-X concept itself, one of a long-range, high-flying, broad area maritime surveillance platform, never went away. In the early 2000s, the Navy crafted a requirement for an unmanned system with very similar requirements as part of the Broad Area Maritime Surveillance program, or BAMS.

The initial concept called for a drone that could fly at an altitude of at least 40,000 feet and would have an overall range between 1,000 and 3,000 miles, allowing it to provide persistent coverage of a wide area. The unmanned aircraft would complement the Multi-mission Maritime Aircraft, which subsequently became the Boeing P-8A Poseidon, and ship-based manned and unmanned aerial surveillance capabilities. 

These requirements morphed into a more demanding rubric as the project proceeded. Northrop Grumman used a highly modified Gulfstream G-II test aircraft to prove the concept initially and to support further testing of the components associated with the BAMS initiative. 

The almost grotesquely modified G-II BAMS test bed., NAVAIR

To test the plan in a more mature fashion, the Navy obtained a pair of Northrop Grumman RQ-4A Global Hawk drones fitted with an active electronically scanned synthetic aperture radar, a turret with electro-optical and infrared cameras, a receiver for signals from the Automatic Identification System, or AIS, and electronic support measures to detect and track enemy electronic emissions. The AIS is an unclassified maritime transponder system that both naval ships and commercial vessels use to broadcast their position to help avoid collisions and other accidents.

These BAMS demonstrators, or BAMS-D flew in support of exercises and actual operations, including counter-piracy missions in the Indian Ocean. In 2008, the Navy selected a purpose-built variant of the Global Hawk as the winner of the formal competition for the new drones. The RQ-4N beat shared efforts by Boeing and Gulfstream, who offered an unmanned aircraft based on the G550 bizjet, and Lockheed and General Atomics with a version of the MQ-9 Reaper.

One of the BAMS-D drones., USN

The maritime surveillance Global Hawk derivative, now known as the MQ-4C Triton, has reinforced wings and fuselage, improved de-icing features, and better resistance to lightning strikes compared to the earlier models. It features the same basic sensor package as the BAMS-Ds, with Northrop Grumman’s fully matured active electronically scanned AN/ZPY-3 Multi-Function Active Sensor (MFAS) radar at the core of its capabilities. You can read more about the Triton here

That a variant of the Global Hawk won a competition for what is very much a spiritual successor to the U-2-based EP-X isn’t particularly surprising. The Air Force has itself gone back and forth about whether or not to replace its remaining Dragon Ladies with the RQ-4.

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The U-2 continues to serve owing in no small part to the fact that it can fly at a higher altitude than the Global Hawk. Lockheed Martin had pitched an unmanned version to the Air Force as one possible alternative, as well as a new drone using some of the Dragon Lady’s components, called the TR-X. Neither of those aircraft has made an appearance publicly, though it is possible that Lockheed has produced or is in the process of developing a new, high altitude unmanned surveillance aircraft in the classified sphere.

The service expects to reach initial operational capability with the MQ-4C in 2018 and full operational capability five years after that. There is already work in progress to expand existing American bases around the world to accommodate the new aircraft. 

Plans to expand the Triton’s sensor suite, to include a signals intelligence system among other equipment, could allow the drones to supplant the Navy's aging EP-3Es. The service has also conducted tests to possibly integrate a similar capability onto the P-8A.

More than four decades after the EP-X effort came to an end, the Navy now looks set to get its long-range, persistent aerial maritime surveillance platform. If anything, that is a huge testament to the original visionaries behind the little known EP-X program from so long ago.

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