E-2A Hawkeye

Since the days of the earliest weapons, dating back to the time when man fashioned his first club, the underlying fear of all tactical commanders has been the “surprise attack.” History is dotted with the routs and overwhelming defeats of superior forces by an alert and aggressive foe who took full advantage of the element of surprise and was able thereby to deliver an initial, demoralizing, and destructive blow. Early warning of impending attack, in order to prepare an adequate defense or implement retaliatory measures, has therefore always been a requirement in waging successful land warfare.

Until World War II, however, navies were not so vulnerable to surprise attack due to their mobility and the hiding places that the vast oceans afforded. Striking forces could roam far and wide and go undetected for long periods of time. This is well illustrated by the German “raiders” which in the first stages of World War II preyed upon merchant shipping practically unmolested. The entry of the United States and Japan into the war, however, brought many rapid changes to naval warfare. Two great navies, both of which emphasized carrier aviation, were now pitted against each other. The “eyes” of the fleet became the airplane and the oceans began to shrink in size.

Radar, at that time, was in its early stages of development and confined primarily to shipboard use which extended the “eyes” of task forces only about 50 miles or so to the horizon. This afforded a brief reaction time to prepare for defense against attacking aircraft. However, even against the relatively slow-flying aircraft of this era, intruders inflicted extensive damage on naval task forces.

In 1944, the Japanese were making telling use of their kamikazi tactics in attacks on the Allied navies in the Pacific. This created the urgent demand for an effective and immediate countermeasure. This project of providing early warning detection of these kamikaze aircraft was, for a time, assigned a priority second only to that given the atomic bomb.

While Aircraft Early Warning (AEW) aircraft were not available in time to be used against the kamikazis, the development of AEW has continued, and today it plays a vital role in both U. S. continental and Fleet defense.

The first operational carrier-based AEW system was installed in a TBM-1 Avenger aircraft. This development progressed via the AD-3W, -4W and -5W Skyraider series, and WF-1 (now E-IB) Tracer. The AD-5W (now EA-1E) and WF-1 are being operational on board aircraft carriers today.

Even in the early 1950s, however, it had become clear that in an era of supersonic aircraft, nuclear warheads, and stand-off misses, the policy of using existing airframe designs for the AEW mission would not satisfactorily counter the threats of the 1960-to-1970 time period. The “eyes” of the Fleet had to be extended. An airborne picket, providing an umbrella-type radar coverage, and able to Perform air battle direction, was mandatory for successful protection of principal Fleet forces. The defense tactics demanded sufficient lead time to permit detection, identification, and destruction of attacking aircraft Prior to their penetration of the task force’s Perimeter of air-to-surface missile launch. Command, control, and deployment of defensive weapons had to be unerring and swift. Task forces could no longer relax in the sanctuary of the vast oceans.

An operational requirement was specified in 1955, and for the first time the Navy began development of an AEW system wherein the aircraft would be designed exclusively for the carrier-based AEW mission. The Grumman Aircraft Engineering Corporation of Beth- page, Long Island, New York, was awarded the contract to develop and produce this aircraft which unquestionably represents the most complex airborne weapon system that has ever been introduced to the Fleet. Initially designated the W2F-1, the E-2A is an all- weather carrier and shore-based airborne early warning and intercept control aircraft. Its primary mission is to maintain a duty station at a predetermined altitude and distance from a task force, alert the force of approaching hostile aircraft, and control and vector interceptors into attack positions. In the selection of a popular name for an aircraft assigned such a mission, it was only fitting that “Hawkeye” was chosen in memory of the Indian scout famed for his farseeing eyes.

The E-2A features a high wing and is distinguished by a rotating, disc-shaped “roto- dome” which houses the radar and IFF antennas. (The rotodome can be lowered for hangar deck stowage.) The cylindrical fuselage is divided into four main sections: cockpit, forward equipment compartment, combat information center compartment, and aft equipment compartment. All compartments are fully pressurized and air-conditioned. These spaces are normally manned by a crew of five—pilot, co-pilot, and three electronic equipment operators.

The Hawkeye incorporates two “firsts” in carrier-based aircraft: the turbo-prop engine and nose-tow catapult equipment. The Allison T-56 engine is the same as is used on the commercial Lockheed Electra. The constant-speed, twin turbo-prop engines permit a rapid transition from approach power to takeoff power as fast as change of propeller blade pitch angle can be accomplished, thus facilitating rapid wave-off during carrier approaches.

The nose-tow catapult feature represents a radical innovation in that the tow-link and the hold-back fitting are integral parts of the nose-wheel. This simplifies the alignment of the aircraft with the catapult centerline, and eliminates the previous time-consuming and risky hook-ups required by flight deck personnel for most other aircraft.

Other principal aircraft characteristics are:

At operating altitude, normally 30,000 feet, the cabin pressure remains under the 5,000- foot level. On station, all turns are made “flat” in a skid in order to provide proper attitude for most efficient antenna scan. The autopilot performs this flat turn maneuver when desired. It is in the avionics equipment area, however, that the E-2A is truly representative of the latest “state of the art” developments.

As the airborne platform for the Air Tactical Data System (ATDS), it is the data gathering and processing extension of the ship-based Naval Tactical Data System (NTDS), and also acts as an autonomous detection and command/control system. In order to fulfill this dual role the functions performed semi-automatically are: detection, acquisition and identification of targets, evaluation of tracked targets in terms of threat potential, transmission of control data to interceptors, transmission of tactical data among the various elements of the Fleet, and accurate navigation computations.

In order to perform these functions, more than 10,000 pounds of electronic equipment are installed in the aircraft. All mission-essential equipment represents new developments incorporating the latest advances at the time their design was commenced. Following through the block diagram (Figure 1), the first item is the antenna. Since the radar operates at UHF, a large antenna aperture was required, and the 24-foot dome represents the largest practical size that could be used on a carrier-based aircraft. The radar uses pulse compression techniques and an airborne moving target indicator to allow 30,000-foot operation without fear of sea-clutter. The automatic detector converts the analog radar information into a digital message containing X and Y co-ordinates and height of the target. Also processed at this point is IFF information. The main data processing equipment actually consists of six digital computers which use a common magnetic drum for primary storage. Over 2,000 module cards are used in this equipment, each of which contains up to 200 individual components. Tracking, intercept control, navigation, NTDS reporting, interceptor data transfer, and display symbol generation functions are performed by these computers. The two data links—one to NTDS and the other to data-link-equipped interceptors and highly accurate doppler/inertial navigation sensors—complete the primary equipments. Standard voice communications, Tacan, and IFF are included.

In order to keep the operators advised as to the status of the system an in-flight performance monitor is included. This device is a computer-controlled trouble shooter which instantly alerts the radar operator of any malfunction and allows him to test level of performance as well as isolate malfunctions down to a replaceable black box.

Fleet introduction of the E-2A took place in January 1964 with delivery of the first aircraft to Carrier Airborne Early Warning Squadron 11 at San Diego. Even though the aircraft is still undergoing Navy evaluation, it was considered mandatory that the indoctrination and training of Fleet personnel commence as early as possible prior to Fleet employment.

These technological advances, represented in the E-2A, will unquestionably require highly trained personnel in both the operational and maintenance areas. However, the contribution that this aircraft offers in defense of the Fleet is of immeasurable value.