Grumman E-2 Hawkeye
The first of three Hawkeye prototypes flew on October 21, 1960, the Hawkeye became the primary early warning component of the US Navy carrier air wings.
Delivery of the first member of the Hawkeye family, the E-2A (formerly known as the W2F-1) began on 19 January 1964 to the US Navy, entering service in 1965 as a replacement for the Grumman E-1B Tracer, an early-warning derivative of the S-2 Tracker. The E-1B carried its radar aerial inside a fixed oval, aerofoil-shaped radome, but the E-2 was the first AEW type to adopt the 7.32m diameter 'rotodome', with the antennae mounted rigidly inside a radome which itself rotates at 6 rpm in the case of the Hawkeye. Fifty-nine E-2As were delivered to the US Navy, and the type quickly proved its worth off the coast of Vietnam. The Hawkeyes were sent out to patrol whenever there was a risk of the naval task force being attacked by enemy aircraft or ships; by extending the force's detection range well beyond the normal horizon, even against low-flying aircraft, the E-2As reduced the need for large numbers of intercepters to be kept on alert throughout the day and night.
In addition to their defensive role, the Hawkeyes were able to relay target information from the aircraft carriers to their distant attack formations. With the E-2A the US Navy began to appreciate the many advantages of a modern AEW aircraft, but the 1950s-technology computer had to be physically modified every time the ATDS (Airborne Tactical Data System) needed new software. To overcome this problem the Hawkeyes were fitted with Litton L-304 general-purpose digital computers, and several minor modifications were also made; the E-2As thus became E-2Bs, which flew for the first time in February 1969, all having been converted by 1971.
Grumman built 56 E-2As, later updated to E-2B, before introducing the E-2C. The first of the significantly more capable E-2C series flew in January 1971. By mid-1987 97 E-2Cs had been delivered to the US Navy, plus 21 to overseas customers.
Firm orders existed for a total of 47 aircraft, with procurement of 36 more by the end of 1985. Israel has four and in 1979 Japan released funds for the first four of an eventual total of about 15 for the JASDF. The E-2G has an advanced radar that is capable of detecting airborne targets anywhere in a three-million-cubic-mile surveillance envelope. It first entered service with the US Navy in November 1973 and went to sea on board USS Saratoga in late 1974. A training version is designated TE-2C.
By this time the first E-2Cs were flying, the prototype first flew in January 1971. Although virtually identical to its forebears externally, the E-2C is a very different under the skin. The improved APS-120 radar' can detect and track aircraft over land as well as above the sea, and the APS-125 ARPS (Advanced Radar Processing System) is being incorporated in all E-2Cs to give long-range detection of very small targets and automatic overland tracking. The APS-125 also incorporates a digital airborne moving target indicator (AMTI) in place of the E-2B's analogue unit. Communication equipment has been improved, and the E-2C has better hot-day and single-engine performance than its predecessors, and is four times as reliable.
The E-2C entered service in 1974, it arrival more or less coinciding with the introduction of the US Navy's new generation of carrier-based aircraft: the F-14 Tomcat, S-3 Viking, EA-6B Prowler and A-6E Intruder.
The latest APS-138 surveillance radar was introduced on the E-2C airborne early warning aircraft built in 1983, and will be retrofitted to earlier E-2Cs in place of the original APS-125. APS-138 has a low-side-lobe active-element-array antenna, an enhanced passive detection system with triangulation and exotic emitter recognition, together with expanded computer memory allowing the simultaneous and automatic tracking of up to 600 targets. At an operating height of 9,150m (30,000ft), a Hawkeye can detect and assess any approaching aircraft over a range of 480km (260 nm) in all weathers.
From 1988 new E-2Cs will be fitted with uprated Allison T56-A-427 engines, and will receive the improved APS-139 radar system which can transmit on any one of ten UHF channels. General Electric is also developing an APS-145 radar for service in 1990 which will counteract the problem of overland clutter.
The Hawkeyes work closely with the Tomcats, orbiting on station between 110 km (68 miles) and 185 km (115 miles) from the carrier at heights of 4600 m to 9150 m (15000--30000 ft); a typical orbit begins at 7000 m (23 000 ft) and rises to 8500 m (28000 ft) as fuel is burnt off. At a height of 7600 m (24 930 ft) the radar has a horizon range of 375 km (235 miles) and can detect high-flying aircraft out to 460 km (285 miles).
The radar can detect and track more than 200 targets simultaneously, supplying alti-tude, range and velocity information. The crew of five includes three operators in the combat information centre, each of which has a main 25-cm (10-in) radar display and a 12.5-cm (5in) screen giving alphanumeric information. Targets detected by the AWG-9 long-range fire-control radar in the F-14 can be notified to an E-2C by data link; they are then correlated with the appropriate return on the Hawkeye's own radar displays or are used to feed in new information, thus effectively extending the range of the AEW coverage. The intercepter may then be vectored automatically on to the rear of the target for a visual identification, or it can be manoeuvred into the optimum firing position. The US Navy claims that the use of an E-2C for airborne control can double the number of kills made by the intercepter force while substantially reducing losses of friendly aircraft.
Hawkeyes can also control a carrier's attack force, supplying navigation and turning instructions by data link.
Northrop Grumman undertakes production of E-2C Hawkeye in the Hawkeye 2000 form (first flown April 1998).
Engine: 2 x Allison T56-A-425 turboprop, 4910 shp.
Installed thrust: 6800 kW.
Span: 24.6 m.
Length: 17.5 m.
Wing area: 699.66 sq.ft / 65 sq.m.
Height: 18.34 ft / 5.59 m
Empty wt: 17,265 kg.
MTOW: 23,560 kg.
Max speed: 600 kph.
Cruising speed: 269 kts / 498 kph
Service Ceiling: 30840 ft / 9400 m.
Initial climb rate: 2519.69 ft/min / 12.80 m/s
T/O run: 609 m.
Ldg run: 439 m.
Fuel internal: 7050 lt.
Range: 320 km.
Endurance: 4 hr on station.
Air refuel: Yes.
Engines: 2 x turbo-prop Allison T-56 A-8, 2980kW
Max take-off weight: 22450 kg / 49494 lb
Empty weight: 16358 kg / 36063 lb
Wingspan: 24.6 m / 80 ft 9 in
Length: 17.2 m / 56 ft 5 in
Height: 5.6 m / 18 ft 4 in
Wing area: 65.0 sq.m / 699.65 sq ft
Max. speed: 600 km/h / 373 mph
Cruise speed: 500 km/h / 311 mph
Ceiling: 9660 m / 31700 ft
Range w/max.fuel: 3000 km / 1864 miles