US Navy’s Triton UAS – Poseidon’s perfect partner

Northrop Grumman is developing the MQ-4C Triton unmanned aircraft system (UAS) for the US Navy to provide long-endurance maritime surveillance. The biggest UAS ever operated by the navy, Triton will fly missions of up to 24 hours scouting out large areas of the ocean, working hand-in-hand with the manned Boeing P-8 Poseidon which can fly in for a closer look at targets of interest.


Triton

When it takes to the skies in 2017, Triton will cast an imposing shadow over the world's oceans. Its 131ft wingspan is even greater than that of a 737, supporting a slender 40ft body bristling with the latest sensors. Built more like a glider than a fighter jet to support extensive missions, it will be able to fly at high altitudes over huge expanses of ocean providing maritime awareness and a common operating picture and data to navy bases around the world, dipping down low through clouds to take a closer look at objects of interest.

The navy intends to operate Triton from five bases around the world where it will provide a 24/7 picture of activity in blue water, littoral zones and harbours to pinpoint enemy locations. Flying missions of up to 24 hours, it cruises at around 300 knots within a 2,000 nautical mile radius, carrying a huge maximum internal payload of 3,200 pounds, with a planned capability to carry 2,400 pounds more externally. While its main purpose will be to provide persistent maritime intelligence, surveillance, and reconnaissance (ISR), it will also be able to support overseas contingency operations, and civilian and humanitarian efforts, as necessary.

The US Navy selected Northrop Grumman's MQ-4C Triton for its Broad Area Maritime Surveillance programme having trialled the terrestrial UAS on which it will be based, Northrop's RQ-4 Global Hawk. The established UAS proved its high-altitude, long-endurance capability to offer the navy an 'unblinking eye' over the oceans it watches over, and Northrop is developing a bespoke Multi-Function Active Sensor (MFAS) to provide a 360-degree maritime awareness capability.

Flight testing

On 23 October 2014, the second system development and demonstration (SDD) Triton aircraft arrived at the Naval Air Station Patuxent River testing ground after completing its inaugural 11-hour cross-country ferry flight, validating that the hardware and software performed as advertised and marking the transition from initial flight test to operational capability testing. It had previously undergone a successful first flight.

"That mission was a little over six hours and performed flawlessly, in fact it came back with no discrepancies whatsoever," says Mike Mackey, who has been Northrop Grumman's Triton programme manager for two years, says . "We took the jet to altitude, performed various turns, did a communications check and checked flight control stability during that flight."

Compared with the relatively simple operational envelope of the Global Hawk, Triton required a few tweaks to navalise it. In operation, it will fly up to the same altitude of around 50,000-plus feet, and when operators identify an object of interest through the MFAS it will perform a manoeuvre called 'the dip'. It will descend down through any cloud cover to use its electro-optical/infrared (EO-IR) cameras and other sensors to give a positive ID of a target.



The US Navy's new maritime warfare aircraft, the Boeing P-8A Poseidon, will reach Initial Operational Capability by the end of year.


This presents a challenge; at the higher altitude wind and weather are very stable and benign. But as occurs in commercial airliner, there can be a lot of turbulence at lower altitudes. Northrop had to strengthen Triton's wings, vertical tails and fuselage and add all-weather features, including ice protection systems on the wing, empennage (tail assembly), and engine inlet, and lightning protection.

Internal changes include new communications systems to enable world-wide operations, and the MFAS sensor suite, which incorporates the ZPY-3 radar capable of simultaneously imaging selected targets while searching for new ones.

The concept of operations, or CONOPS, of Triton is that it will work in conjunction with the P-8 Poseidon to provide unprecedented intelligence, surveillance and reconnaissance data for navy operations. Later in the programme, the two aircraft will be able to share information directly over a networked environment that transmits near-time information to wherever it is needed around the world to provide a common operating picture.

"Say the Triton is out doing a mission somewhere in the world and defines a target of interest and we decide we want to explore that further," says Mackey. "You have the perfect scenario where you can stay on target, then call in or direct a P-8 to that area to do more work with different sensors. It takes the best capabilities of each and puts them together in the first manned/unmanned programme of its kind."

Flying experience

According to Captain Jim Hoke, the US Navy's Triton programme manager, Triton pilots, or air vehicle operators (AVOs), prepare for a flight in a similar manner to a manned flight.

"Triton pilots, or air vehicle operators (AVOs), prepare for a flight in a similar manner to a manned flight."

"While the AVOs have similar displays and system performance data available to them as a manned system, the actual operation of the air vehicle is much like working on a multi-display computer workstation," says Hoke.

Described as a man-on-the-loop environment, the pilot has three main displays which can be switched between as needed. One gives a cockpit-like display of airspeed, altitude and any warnings, the second displays a map of where Triton is going and the third is a comms panel.

"The pilot has some additional capability to diagnose problems as data comes down from the jet to tell him performance," adds Mackey. "In that regard, there's more data in terms information from sensors than maybe a manned aircraft would have."

It has not always been plain sailing for Triton. According to Hoke, prior to Triton's successful first flight in May 2013, the programme experienced technical challenges associated with system integration and developmental testing which delayed entry into flight test. These included aircraft flight control computer software issues, an aircraft ruddervator control surface coupled flutter issue, and communications system link stability issues, all of which have been resolved.

"They were concerned about some vibration that could be induced. We resolved that by adding a stabilising counterbalance," adds Mackey. "We've never seen that now have we seen that on other jets so it was precautionary."

While manned aircraft require hundreds of hours of flight tests to validate new capabilities, UAS like Triton can be tested in a laboratory environment with reliably predictable results.

"An example is the initial envelope expansion testing that we predicted we'd do in 13 flights. We did it in 13 flights," says Mackey. "We tested over 568 test points, and of those there was only one that we re-ran in that whole time. There were no re-flies; it was just a condition that we were trying to get into that caused us to have to do it one extra time."



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Next stages

With two of the three SDD Tritons based in Patuxent River, ground testing, sensor integration, and detailed sensor and payload testing will now continue. Northrop recently released the second software batch bringing the communication suite up to its full complement of five, which were all used on Triton's cross-country flight. The next release will bring MFAS and the EO-IR systems online.

"We expect that same kind of performance; the jet is solid, and now it's about fine-tuning and tweaking the sensor capabilities and exploiting that data down through the network to all the entities," says Mackey.

The next stage will see Northrop load up a corporate jet with Triton's sensor software in the first part of December to begin testing ready for an operational assessment planned for next spring. That will be followed by one last software release that adds some advanced mission capabilities late next summer, working towards early operational capability in 2017, and initial operational capability in 2018. The US Navy is also working on getting Triton and Poseidon to collaborate through common communication and data dissemination pathways.

The US Navy's programme of record is planned for 68 aircraft, and Triton is also expected to attract the interest of international navies.

"We're going to see strong pull to get Triton out there in the real world, because it's a revolutionary product and it's what we need for our warriors," concludes Mackey.

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