MILITARY E-2D ADVANCED HAWKEYE
AIR International looks at what makes Northrop Grumman’s E-2D Advanced Hawkeye different from, but a worthy successor to, its illustrious ancestors
When the first Grumman Hawkeye made its maiden flight from Bethpage, New York, on October 21, 1960, it was known as the W2F-1. The redesignation of US Navy aircraft in 1962 turned it into the E-2 Hawkeye and the type entered service alongside other newcomers to naval aviation, such as the F-4 Phantom II in 1960. It had been ordered to replace another Grumman product, the E-1B Tracer.
With its revolutionary radar mounted in a spinning rotodome housing above the fuselage it was a quantum leap in naval airborne early warning (AEW). A carrier group without its AEW component is virtually blind, vulnerable to air attack and unable to operate near the forward edge of battle.
At the start of this century, Operation Iraqi Freedom saw the US Navy’s E-2C Hawkeye IIs being used as littoral surveillance systems and communications nodes relaying data from rapidly advancing ground forces to commanders on land and at sea.
It’s fair to say the original Hawkeye and its successors were a stunning success. As many as 280 were built and overseas sales were made to Egypt, France, Israel, Japan, Mexico, Singapore and Taiwan. By the turn of the new century, however, it was clear something more potent was needed.
Over the preceding 40-odd years, airframes, engines, avionics, radars and other components of the various Hawkeye models had evolved in response to evolutions in technology and threats.
That worked well, but the limitations in the almost World War Two-era airframe increasingly made improving the system challenging, to say the least. To meet those new challenges, Northrop Grumman decided to redesign its new Hawkeye from the ground up with, as far as possible, an eye to making the airframe and its systems future proof.
In accordance with the Sea Power 21 concept, which itself was part of the Joint Vision 2020 doctrine promulgated in 2000, the E-2D Advanced Hawkeye was intended to be a multipurpose platform capable of integrating digitally with allies and other US weapons systems in the air, land and sea domains. Chief among its objectives was to meet AEW, surveillance, battle management and theatre missile defence needs.
Instead of a conventional 1940s form of construction comprising sheet metal, Northrop Grumman decided to make as much of the airframe as possible from single-piece machined parts. This construction method saves time in final assembly and reduces cost.
Ease of maintenance was designed in from the start, as were computerised diagnostic systems. The new airframe is cleared to land on a carrier at a higher weight than its predecessor, although it has the same overall dimensions. The flight crew of two is provided with a redesigned fully digitised glass cockpit. Either of the two pilot’s displays can be configured at the flick of a switch to replicate one of the three work stations in the back cabin of the aircraft. This increases the aircraft’s capability in its primary wartime roles of providing advance warning of approaching enemy surface units, missiles or aircraft and controlling the carrier group’s response. The facility can also be used in the aircraft’s other roles, such as providing area surveillance, acting as a communications relay or air traffic control hub or as an SAR platform.
The E-2D retains the basic configuration of its predecessor because, as a carrier-borne aircraft it needs to fit the same tight space of the original E-2 Hawkeye footprint. It was much cheaper to use the same tried and tested platform than start from scratch with all the costs associated with certification of a new design.
The aircraft is powered by two Rolls- Royce T56-A-427A turboprop engines, each rated at 5,100shp (3,803kW) and fitted with UTC Aerospace Systems NP2000 eight-bladed composite propellers.
The two powerplants, controlled by a propulsion system control, monitoring and maintenance system, can propel the aircraft up to 33,000ft and provide ample power for the aircraft’s electronics with more to spare to keep them and the crew cool.
Designed with the aim of reducing cost and facilitating ease of upgrades, Northrop Grumman engineers decided from the beginning to use commercial off -the-shelf systems where possible.
Network-centric: no plane is an island
A Nimitz-class supercarrier carries around 90 of the world’s most capable aircraft. Soon, a modern US Navy carrier air wing is likely to soon have squadrons of F-35C Lightning IIs, as well as F/A-18E and F/A-18F Super Hornets and EA-18G Growler electronic warfare machines. They will soon be supported by the MQ-25 Stingray carrier-based aerial-refuelling system, the unmanned replacement for shipborne tanker aircraft.
In a major peer-on-peer conflict, nearly every available one of those jets would be launched together to operate in concert with its shipmates and other allied assets, such as surface vessels equipped with the Aegis combat system.
The US Navy’s Naval Integrated Fire Control-Counter Air method of operation relies on linking every allied combatant engaged in a particular operation via datalinks; it is dubbed NIFC-CA, pronounced nif-cah.
The resultant Cooperative Engagement Capability significantly improves the effectiveness of individual weapons systems. Weapons can be fired from a ship or aircraft without a target location; nor does the aircraft releasing or launching the weapon need to turn on its own radar. Electronic data from every helicopter, aircraft and ship in an operation is linked together into a single, real-time, composite track picture giving commanders unprecedented situational awareness.
All this will be overseen and managed by two Advanced Hawkeyes operating behind the line of advance of allied aircraft as battle managers, a critical tactic given China and Russia’s development of ever more capable and longer-range air-to-air and air-to-surface missiles; keeping E-2s out of missile engagement zones as much as possible is paramount.
Faced with such a scenario, Advanced Hawkeyes will use their tactical targeting network technology (TTNT), a modern Joint Tactical Radio System networking waveform, to provide near real-time data sharing across an ad hoc internet network.
Allied land, air and sea-based weapon systems will be automatically added to the network in seconds when they come in line of sight of another TTNT-enabled system. The swarm effect of information gathering and sharing means the loss of an individual, whether by jamming or destruction, does not significantly reduce the effectiveness of the data network. If an enemy successfully jams one of the E-2Ds, the enemy jammer can quickly be marked for destruction by other allied nodes in the cloud.
The data sharing performed by Advanced Hawkeye has another key advantage. Navy F-35Cs, supported by EA-18G electronic warfare aircraft, would be operating in as near stealth mode as possible in the crucial first days of war, probing the enemies’ air defences. Operating in near stealth mode limits the ability to carry significant numbers of kinetic weapons on outside pylons, the so-called beast mode. However, using their Multi-Function Advanced Data Link, the Lightning IIs can beam back data gathered by its suite of sensors, especially the AAQ-40 advanced electro-optical targeting system, to the E-2s, which then guide missiles launched from Super Hornets on to the targets. All the while, the Advanced Hawkeyes will be communicating with the carrier, operating as the key node in NIFC-CA.
In cooperation with Aegis-enabled warships forming a shield around a carrier strike group, the E-2D is a key line of defence against cruise missiles. Advanced Hawkeye would continuously monitor missiles as they head inbound to the fleet, providing targeting information for the ships. At the same time, the battle managers aboard the E-2 will coordinate the efforts of other intelligence, surveillance, target acquisition and reconnaissance assets, manned, unmanned, celestial and terrestrial, to pinpoint the launch site of the enemy missiles and bring about their demise.
Heart of the hunter
The rotating dish fitted on the Hawkeye’s roof is designed to make one complete rotation in either 10, 12 or 15 seconds; it can also be stopped altogether. It houses the ADS-18 group of antennas; an 18-channel UHF radar antenna array, and a 36-element identification friend or foe (IFF) antenna array, which provide a 360° mechanical azimuth scan and an electronic elevation scan, the latter co-aligned with an electronic IFF scan.
Produced by L3, the ADS-18 antenna group is part of the Lockheed Martin APY-9 radar. The UHF band system uses a wavelength between 10 and 100cm generated by frequencies higher than 300MHz, over a 90° sweep to search for airborne targets. The UHF band was chosen to enable the aircraft to detect stealth aircraft undetectable by other radar systems. The APY-9 operates in three separate modes: advanced AEW surveillance (AAEWS), enhanced sector scan (ESS), and enhanced tracking sector (ETS).
The three modes can be used to intensify scrutiny of a particular area or object. AAEWS is the default operational setting, providing air and ground surveillance as well as longrange radar detection. In ESS mode the crew can manually control the antenna in order to focus attention on a particular area. By locking the antenna in place in ETS mode, it can focus on and electronically track a moving target using every photon generated by the E-2Ds two 170kVa generators.
Concentrating the beam allows the radar to find nearby smaller targets or pick up larger ones a long way away.
Lockheed Martin, manufacturer of the APY-9, says the system can detect smaller targets (and more of them) at more than twice the range of the earlier radar. It claims the E-2D’s radar and IFF system can detect targets at ranges in excess of 300 nautical miles (555km).
The ADS-18 antenna works in conjunction with the APY-9 radar system and continuously scans over 360° for all radio frequency emissions.
As a rule, increased radar power means increased noise or clutter on the screen. To deal with this, Northrop Grumman has incorporated new digital low-noise receivers and processors.
Space is at a premium on the E-2D, so a technique called space-time adaptive processing was adopted. In layperson’s terms, this sorts the wheat from the chaff by using algorithms to separate moving targets from static noise and other interference, allowing the radar to detect more clearly.
Nuts and bolts
The E-2D is the same size as the E-2C, but the manufacturer says it is twice as capable. Most of the systems found in the legacy aircraft have been replaced with newer, more capable kit and even that is constantly being upgraded. In June 2018, Naval Air Systems Command awarded Lockheed Martin a $64.7 million sole-source contract to upgrade the E-2D’s existing ALQ-217 electronic support measures system. The contract covered design, development, and integration of the Advanced Digital Receiver/Processor and Active Front End (AFE) upgrades to the existing ALQ-217 receiver/processor, and AFE weapon replaceable assemblies. The ALQ-217 ESM is a passive sensor fitted to the E-2D to measure, identify and locate radio frequency emitters, and is able to detect and classify targets at distances beyond radar limits. Its antennas are mounted in the vertical stabilisers at the rear of the aircraft.
The radar system and sensors are controlled by three back-office crew. The Air Control Officer serves as the primary air controller and the datalink and SATCOM operator. The Combat Information Center Officer is the mission commander responsible for mission planning, and the Radar Operator is the weapons system operator and secondary air controller. Each sits in the rear cabin at a redesigned work station fitted with 20-inch (508mm) diagonal active matrix LCD linked to an open architecture computing environment.
Up front, the pilot and co-pilot benefit from a glass cockpit with three 17-inch (432mm) LCD primary flight displays. The pilot is the aircraft commander with responsibility for safety of flight while the co-pilot handles communication and navigation. As noted earlier, either of the three primary flight displays can be used as a fourth mission work station.
Communications equipment includes the usual HF, VHF, UHF radios, the multifunctional information distribution high-capacity, and jam-resistant digital communications system. Both voice and digital data can be exchanged via SATCOM or Link 11 or Link 16.
The Navy Program of Record for acquisition of E-2D Advanced Hawkeye states a requirement for 75 aircraft, including the two systems development and demonstration aircraft and the three pilot production machines.
The first machine was delivered to the fleet on July 29, 2010, at Naval Air Station Norfolk, Virginia. It was assigned to Carrier AEW Squadron 120 (VAW-120) ‘Greyhawks’, the Navy’s E-2 Fleet Replacement Squadron. The first aircraft has been followed into service by at least 45 more. Initial operational capability was declared on October 10, 2014.
In-flight aerial refuelling is expected to have been fitted fleet-wide by 2020.
Future plans call for 66 primary authorised aircraft out of a fleet of 75. These will be deployed among ten, five-aircraft Carrier AEW Squadrons and one 12-aircraft Fleet Replacement Squadron. Two more aircraft will be assigned to the Naval Air Warfare Center Aircraft Division at Patuxent River Maryland, and two more at the Naval Aviation Warfighting Development Center at Fallon, Nevada.