E-3 Sentry

Overview:

The Boeing E-3 Sentry is an American military airborne warning and control system (AWACS) aircraft that provides all-weather surveillance, command, control and communications, to the United States, United Kingdom, France, Saudi Arabia, and NATO air defense forces. Production ended in 1992 after 68 had been built. The E-3 Sentry is a modified Boeing 707-320B Advanced commercial airframe. Modifications included a rotating radar dome, single-point ground, and air refueling points, and a bail-out chute. The unpressurized dome is 30 feet (9.1 m) in diameter, six feet (1.8 m) thick at the center, and is held 14 feet (4.2 m) above the fuselage by two struts. It is tilted down six degrees to reduce drag on take-off, and while flying endurance speed (which is corrected electronically by both the radar and SSR antenna phase shifters). The dome uses both bleed-air and cooling doors to maintain ambient temperature. The hydraulically rotated antenna system permits the AN/APY-1/2 passive electronically scanned array radar system to provide surveillance from the Earth's surface up into the stratosphere, over land or water. Other major subsystems in the E-3 are navigation, communications and computers (data processing). Consoles display computer-processed data in graphic and tabular format on video screens. Console operators perform surveillance, identification, weapons control, battle management and communications functions. The radar and computer subsystems on the E-3 Sentry can gather and present broad and detailed battlefield information. Data are collected as events occur. This includes position and tracking information on enemy aircraft and ships, and location and status of friendly aircraft and naval vessels. The information can be sent to major command and control centers in rear areas or aboard ships. In times of crisis, data can be forwarded to the National Command Authority in the United States via RC-135 or Naval Carrier Groups. Generators on each of the four engines provide the one megawatt of power required by the radar. The Pulse Doppler radar has a range of more than 250 miles (400 km) for low-flying targets at its operating altitude (essentially to the radar horizon), and the Pulse (BTH) beyond the horizon radar has a range of approximately 400 miles (650 km) for aerospace vehicles flying at medium to high altitudes (essentially above the radar horizon). The radar combined with an SSR subsystem thus providing a look down to detect, identify and track enemy and friendly low-flying aircraft while eliminating ground clutter returns. In support of air-to-ground operations, the Sentry can provide direct information needed for interdiction, reconnaissance, airlift and close-air support for friendly ground forces. It can also provide information for commanders of air operations to gain and maintain control of the air battle, whilst as an air defense asset, E-3s can detect, identify and track airborne enemy forces far from the boundaries of the United States or NATO countries and can direct fighter-interceptor aircraft to these targets. The E-3 as equipped in USAF and NATO service can fly without refueling for 8 hours or 4,000 miles, while newer examples in British, French and Saudi service, equipped with CFM56-2 engines can fly for 10 hours or 5,000 miles without refuelling. Its range and on-station time can be increased through inflight refueling and the crews can work in shifts by the use of an on-board crew rest area. The range and loiter time can be adjusted to alter the flight plan as required for operational reasons.

Specifications:

Role

• Airborne Warning and Control System (AWACS).

Avionics

• Northrop Grumman (radar).

First Flight

• 25 May 1976 (E-3A with full mission avionics).

Introduction

• March 1977

Primary Users

• United States Air Force.
• Royal Air Force.
• Royal Saudi Air Force.
• NATO.

Produced

• 1977–1991

Number Built

• 68

Crew

• 4

Mission Crew

• 13-19

Length

• 152 ft 11 in (46.61 m).

Height

• 41 ft 4 in (12.6 m).

Empty Weight

• 185,000 lb (73,480 kg).

Loaded Weight

• 344,000 lb (with aerial refueling) (147,400 kg).

Max Takeoff Weight

• 325,000 lb (take off restricted weight) (156,000 kg).

Powerplant

• 4× Pratt and Whitney TF33-PW-100A turbofan.
• 21,500 lbf (93 kN) each.