Following
World War II, modified attack aircraft, including the
AD-3W Skyraider and
TBM-3W Avengers, filled the airborne early warning role. In 1955, engineers at
Grumman Aircraft Engineering Corporation began studies on how to accommodate a new radar being developed by
Hazeltine (which became the AN/APS-82) aboard a carried-based aircraft, and concluded that a design based on the Tracker would be the best option. When, later that year, the US Navy's
Bureau of Aeronautics (BuAer) developed requirements for a new AEW aircraft, Grumman proposed a development of the Tracker, and began detailed work on the project. The E-1 was designated
WF under the
1922 United States Navy aircraft designation system; the designation earned it the nickname "Willy Fudd". The Tracer was derived from the
C-1 Trader, itself a derivative of the
S-2 Tracker carrier-based antisubmarine aircraft, known as S2F under the old system, nicknamed "Stoof", leading to the WF/E-1, with its distinctive
radome, being known as "Stoof with a Roof." The E-1 featured folding wings of a very particular design for compact storage aboard aircraft carriers; unlike the S-2 and C-1 in which the wings folded upwards, the radome atop the fuselage required the E-1's designers to re-adopt an updated version of the Grumman-patented "
Sto-Wing"
folding wing system, pioneered on their earlier
Grumman F4F-4 Wildcat piston-engined fighter of the early-WWII period, to fold its wings aftwards along the sides of the fuselage. Its prototype made its first flight on December 17, 1956. Just over fourteen months later the first WF-2 (E-1B) Tracer made its maiden flight. With
carrier operations being a necessity for the aircraft, various features are geared towards providing stability and control when launching from and landing on an aircraft carrier. The distinct
twin-tail found on the E-1 allows for greater rudder control and stability on the
yaw axis without the implementation of one large unwieldy space-taking vertical stabilizer. It also provides a degree of
redundancy, allowing a pilot to maintain some yaw control if one rudder is damaged. The positioning of the rudders also place them on the edges of the
prop wash generated by the spinning propellers of the aircraft, creating additional stability as the fast wind flowing over the stabilizers creates a stronger rectifying force for any
sideslip or rudder input than if the vertical stabilizers were placed out of the prop-wash zone. While this placement would lead to a yawing moment on most smaller aircraft, as the helical motion of the prop wash would collide with only one side of the vertical stabilizer, the dual propellers on the E-1 create opposing yawing
torques on the aircraft of the same magnitude, leading to approximately net zero yaw as a result of prop wash. The E-1, despite having a set of landing gear mounted under its nose, is a
tail-dragger aircraft. This configuration provides the airframe with a distinct "nose-up" appearance when taxiing, and allows for the wings to generate more
lift on launch from a
catapult than if the aircraft was level due to the higher angle-of-attack (AoA) of the aircraft.
Radar The Tracer was fitted with the
Hazeltine AN/APS-82 in its radome and fuselage, a substantial upgrade to its predecessor the
AN/APS-20. The AN/APS-82 featured an airborne moving target indicator (AMTI), which compares the video of one pulse time to the next in
reflected radar energy to distinguish a flying aircraft from the clutter produced by wave action at the ocean's surface. The energy reflected from an aircraft changes position rapidly compared to the energy reflected from the surrounding sea. The radar was also capable of ground stabilization and target height determination. An airfoil-shaped dome protects the parabolic dish antennae, mounted above the fuselage. ==Operational history==