United States Department of Defense - E-3 Sentry

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. The 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 contains a hydraulically rotated antenna system that 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. Generators on each of the four engines provide the 1 megawatt of power required by the radar. The Pulse Doppler radar has a range of more than 250 miles (375 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 for aerospace vehicles flying at medium to high altitudes (essentially above the radar horizon). The radar combined with an SSR subsystem can look down to detect, identify and track enemy and friendly low-flying aircraft by eliminating ground clutter returns.

Variants

EC-137D
Two prototype AWACS aircraft with JT3D engines, one fitted with a Westinghouse radar and the other with a Hughes radar. Both converted to E-3A standard with TF33 engines.

E-3A
Production aircraft with TF33 engines and AN/APY-1 radar, 25 built for USAF later converted to E-3B standard. 18 built for NATO with TF33 engines and five for Saudi Arabia with CFM56 engines.

KE-3A
These are not AWACS aircraft but CFM56 powered tankers for Saudia Arabia, 8 built.

E-3B
E-3As converted with AN/APY-2 radar and other improvements, 24 conversions.

E-3C
Production aircraft with system improvements, nine built. NATO E-3A aircraft although not re-designated have been modified to the same equipment standard.

JE-3C
One E-3A aircraft used by Boeing for trials later redesignated E-3C.

E-3D
Production aircraft for the Royal Air Force to E-3C standard with CFM56 engines and British modifications designated Sentry AEW1, seven built.

E-3F
Production aircraft for the French Air Force to E-3C standard with CFM56 engines and French modifications, four built.

Sentry AEW1
British designation for the E-3D.