View source for Grumman E-1 Tracer

{{Short description|United States Navy airborne early warning aircraft}}
{{More citations needed|date=March 2008}}
<!-- This article is a part of [[Wikipedia:WikiProject Aircraft]]. Please see [[Wikipedia:WikiProject Aircraft/page content]] for recommended layout. -->
{{Infobox aircraft
| name = E-1 (WF) Tracer
| image = File:E-1B VAW-121 CVW-6 CVA-42.jpg
| caption = E-1B Tracer
| type = [[Carrier-based aircraft|Carrier-based]] [[airborne early warning]]
| national_origin = United States
| manufacturer = [[Grumman]]
| designer = 
| first_flight = 17 December 1956
| introduction = 1960
| retired = 1977
| number_built = 88
| status = 
| unit cost = 
| primary_user = [[United States Navy]]
| more_users = 
| developed_from = [[Grumman C-1 Trader]]
| variants = 
}}

The '''Grumman E-1 Tracer''' ('''WF''' prior to 1962)  was the first purpose-built [[airborne early warning]] aircraft used by the [[United States Navy]]. It was a derivative of the [[Grumman C-1 Trader]] and entered service in 1960. It was replaced by the more modern [[Grumman E-2 Hawkeye]] by the mid-1960s-1970s.

==Design and development==
Following [[World War II]], modified attack aircraft, including the [[Douglas A-1 Skyraider|AD-3W Skyraider]] and [[TBM Avenger|TBM-3W Avengers]], filled the airborne early warning role.<ref name=":0" /> In 1951, the US Navy, seeking a replacement for the TBM-3W, asked Grumman and [[Vought]] for new AEW aircraft based on their competing designs for a carrier-based anti-submarine aircraft, the [[Grumman S-2 Tracker|Grumman XS2F Tracker]] and the [[Vought XS2U]]. Grumman's design, Design 95, which was designated XWF-1 under the  [[1922 United States Navy aircraft designation system]], used the same [[fuselage]] and wings as the XS2F, with an [[AN/APS-20]] radar mounted on a pylon over the forward fuselage. The arrangement was chosen to not require changes to the Tracker's wing folding design. Two prototypes were ordered, but the project was cancelled late in 1952.<ref name="frgrummp554">Friedman 1989, p. 554</ref>

In 1955, engineers at [[Grumman Aircraft Engineering Corporation]] began studies on how to accommodate a new radar being developed by [[Hazeltine Corporation|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.<ref name="frgrummp4012">Friedman 1989, pp. 401–402</ref>

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."<ref name=":0" /><ref name=":1">{{Cite web |title=Airborne Command & Control and Logistics Wing, Command History |url=https://www.airpac.navy.mil/Organization/Airborne-Command-Control-and-Logistics-Wing/About-Us/History/ |access-date=18 August 2024 |website=Naval Air Force, U.S. Pacific Fleet ([[United States Navy]])}}</ref> 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 "[[Grumman Sto-Wing|Sto-Wing]]" [[folding wing]] system, pioneered on their earlier [[Grumman F4F Wildcat#F4F-4|Grumman F4F-4 Wildcat]] piston-engined fighter<ref>{{cite web |url=http://www.aviation-history.com/grumman/f4f.html |title=The Aviation History Online Museum - Grumman F4F Wildcat |last1=Dwyer |first1=Larry |date=19 February 2014 |website=aviation-history.com |publisher=The Aviation History Online Museum |access-date=April 2, 2016 |quote=The F4F-4 was the first version of the Wildcat to feature a Grumman innovation, the ''Sto-Wing''. The ''Sto-Wing'' used a novel approach using a compound angle folding-wing that was unique to Grumman...It was a successful design that was later used on the F6F Hellcat and TBF Avenger.}}</ref><ref>{{cite web |url=https://www.asme.org/getmedia/2d64abc8-3fa3-4d29-92d4-40db4777e8b2/238-Grumman-Wildcat-Sto-Wing-Wing-folding-Mechanism.aspx |title=WING-FOLDING MECHANISM OF THE GRUMMAN WILDCAT - An American Society of Mechanical Engineers Historic Mechanical Engineering Landmark |author=<!--Not stated--> |date=May 15, 2006 |website=asme.org |publisher=American Society of Mechanical Engineers |access-date=April 29, 2017 |quote=The  innovative  wing  folding  mechanism  (STO-Wing), developed by Leroy Grumman in early 1941 and first applied to the XF4F-4 Wildcat, manufactured by the Grumman Aircraft Engineering Corporation, is designated an ASME Historic Mechanical Engineering Landmark. |archive-url=https://web.archive.org/web/20151021083204/https://www.asme.org/getmedia/2d64abc8-3fa3-4d29-92d4-40db4777e8b2/238-Grumman-Wildcat-Sto-Wing-Wing-folding-Mechanism.aspx |archive-date=October 21, 2015 |url-status=dead }}</ref> of the early-WWII period, to fold its wings aftwards along the sides of the fuselage.<ref>Jackson, David D. [http://www.s2ftracker.com/ "Surviving Grumman S2F Tracker Information Repository."] {{Webarchive|url=https://web.archive.org/web/20141218075943/http://www.s2ftracker.com/ |date=2014-12-18 }} ''s2ftracker.com.'' Retrieved: 29 October 2011.</ref>

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.<ref name=":0">{{Cite web |title=E-1B Tracer |url=https://www.history.navy.mil/content/history/museums/nnam/explore/collections/aircraft/e/e-1b-tracer.html |access-date=18 August 2024 |website=[[Naval History and Heritage Command]], National Naval Aviation Museum |language=en-US}}</ref>

With [[Aircraft carrier|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|twin-tail]] found on the E-1 allows for greater rudder control and stability on the [[Aircraft principal axes|yaw axis]] without the implementation of one large unwieldy space-taking vertical stabilizer. It also provides a degree of [[Redundancy (engineering)|redundancy]], allowing a pilot to maintain some yaw control if one rudder is damaged.<ref>{{Cite web |title=Grumman WF-2 / E-1 Tracer |url=https://www.militaryfactory.com/aircraft/detail.php?aircraft_id=708 |access-date=2024-01-30 |website=www.militaryfactory.com}}</ref> The positioning of the rudders also place them on the edges of the [[Slipstream|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 [[Slip (aerodynamics)|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 [[Torque|torques]] on the aircraft of the same magnitude, leading to approximately net zero yaw as a result of prop wash.<ref>{{Cite web |date=14 February 2024 |title=Effect of Propeller on Airplane Dynamics |url=https://www.aircraftspruce.com/catalog/pdf/13-09032.pdf |access-date=14 February 2024 |website=aircraftspruce.com}}</ref>

The E-1, despite having a set of landing gear mounted under its nose, is a [[Conventional landing gear|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 (force)|lift]] on launch from a [[Aircraft catapult|catapult]] than if the aircraft was level due to the higher angle-of-attack (AoA) of the aircraft.<ref>{{Cite web |title=Grumman WF-2 / E-1 Tracer |url=https://www.militaryfactory.com/aircraft/detail.php?aircraft_id=708 |access-date=2024-01-30 |website=www.militaryfactory.com}}</ref>

===Radar===
The Tracer was fitted with the [[Hazeltine Corporation|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 [[Reflection (physics)|reflected]] [[radar]] energy to distinguish a flying aircraft from the clutter produced by wave action at the ocean's surface.<ref name=":0" /> 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.<ref name=":1" /><ref name=":0" />

A airfoil-shaped dome protects the {{Convert|17 x 5|ft|meters}} parabolic dish antennae, mounted above the fuselage.<ref name=":1" />

==Operational history==
[[File:Grumman E-1B 147223 RVAW-110 JAX 19.07.76 edited-2.jpg|thumb|right|Grumman E-1B Tracer of RVAW-110 after service aboard USS ''Franklin D. Roosevelt'' in 1976, showing the Grumman-patented ''Sto-Wing'' wing folding arrangement]]
As one of the first carrier based early warning aircraft, the E-1 Tracer served from 1960 to 1977,<ref name=":0" /> although considered only an interim type, being replaced by the [[Grumman E-2 Hawkeye]] in the mid-1960s.<ref>{{Cite web |last=Jacobs |first=Brian K. |date=June 2000 |title=Warranty/Cannibalization Issues: Disruptive Forces in the Production and Maintainability of the E-2C Aircraft |url=https://apps.dtic.mil/sti/tr/pdf/ADA379444.pdf |access-date=18 August 2024 |website=[[Defense Technical Information Center]] (DTIC) |publisher=[[United States Navy]]}}</ref> First deployed with [[VAW-11]] on board [[USS Constellation (CV-64)]].<ref name=":0" /> During the early years of the Vietnam War, E-1s saw extensive service, providing combat air patrol (CAP) fighters with target vectors, and controlling Alpha strikes over North Vietnam. With a radius of 250–300 miles, the E-1B served as an early warning to strike aircraft of enemy MiG activity.<ref>Sullivan 1990, p. 7.</ref> Tracer-equipped VAW squadrons logged 56 deployments in support of operations over Southeast Asia.<ref name=":0" />

By May 1973, most E-1Bs were retired, with only four [[VAW-121]] Tracers based at [[NAS Norfolk]], Virginia, still in service. These aircraft were soon retired during mid-summer 1977 following a final cruise on board {{USS|Franklin D. Roosevelt|CV-42|6}} and were ferried to the [[Davis–Monthan Air Force Base|Davis-Monthan]] storage facility. The E-1B Tracer was struck from the inventory by 1977.

==Variants==
[[File:Grumman WF-1 Tracer prototype NAN5-89.jpg|thumb|The WF-2 prototype.]]
[[File:Grumman WF-2 Tracer of VAW-11 Det. L aboard USS Hancock (CVA-19) on 23 August 1962.jpg|thumb|WF-2 of VAW-11 on the catapult of USS ''Hancock'' in 1962]]
; XWF-1: Proposed AEW derivative of the S2F-1 equipped with the AN/APS-20; not built.<ref name="frgrummp554"/><ref>{{cite journal|last=Andrews|first=Hal|title=C-1A/TF Trader|journal=Naval Aviation News|volume=71|number=4|year=1989|issn=0028-1417|pages=14–15|url=https://www.google.com/books/edition/Naval_Aviation_News/TetT3Dkmc4UC|via=University of Illinois at Urbana-Champaign}}</ref>
; G-117: Company designation for WF-2. One TF-1 (BuNo 136792) converted into aerodynamic prototype for WF-2 without electronics, later rebuilt as a standard C-1A, retaining the twin tail.
; WF-2: Production Airborne Early Warning version of the [[Grumman C-1 Trader|TF-1 Trader]], redesignated E-1B in 1962, 88 built.
; E-1B: WF-2 redesignated in 1962.

==Operators==
;{{USA}}
*[[United States Navy]]
**[[VAW-11]]<ref name=":0" />
**[[VAW-12]]<ref name=":0" />
**[[VAW-121]]<ref name=":0" />


==Aircraft on display==
[[File:E-1B BuNo 147225 at Patriots Point.jpg|thumb|E-1B 147225 at Patriots Point Naval & Maritime Museum]]
There are five E-1 Tracers preserved at museums throughout the United States:
*E-1B, BuNo 147212: [[Intrepid Sea, Air & Space Museum]], [[New York City]]<ref>{{Cite web|url=http://www.warbirdregistry.org/trackerregistry/tracer-147212.html|title = Warbird Registry - Grumman Tracker/Trader/Tracer - A Warbirds Resource Group Site}}</ref>
*E-1B, BuNo 147217: [[New England Air Museum]], [[Windsor Locks, Connecticut]]<ref>{{Cite web|url=http://www.neam.org/index.php?option=com_content&view=article&id=897|title = New England Air Museum}}</ref>
*E-1B, BuNo 147225: On board the {{USS|Yorktown|CV-10}}, [[Patriots Point]], [[Mount Pleasant, South Carolina]]<ref name="s2ftracker.com">{{cite web |url=http://www.s2ftracker.com/usatracers.htm |title=USA E-1B Tracers |access-date=2015-05-21 |url-status=dead |archive-url=https://web.archive.org/web/20150716073435/http://s2ftracker.com/usatracers.htm |archive-date=2015-07-16 }}</ref>
*E-1B, BuNo 147227: [[Pima Air & Space Museum]], adjacent to [[Davis-Monthan AFB]] in [[Tucson, Arizona]]<ref>{{Cite web|url=http://www.pimaair.org/visit/aircraft-by-name/item/grumman-e-1b-tracer|title = Grumman E-1B}}</ref>
*E-1B, BuNo 148146: [[National Naval Aviation Museum]], [[Naval Air Station Pensacola]]<ref name=":0" /><ref>{{cite web |url=http://www.navalaviationmuseum.org/attractions/aircraft-exhibits/item/?item=e-1_tracer |title=E-1 Tracer {{!}} National Naval Aviation Museum |website=www.navalaviationmuseum.org |url-status=dead |archive-url=https://web.archive.org/web/20140502075605/http://www.navalaviationmuseum.org/attractions/aircraft-exhibits/item/?item=e-1_tracer |archive-date=2014-05-02}} </ref>

Another 11 E-1 Tracers are in storage at United Aeronautical, an aircraft surplus yard located just outside [[Davis–Monthan Air Force Base]] in Tucson, Arizona.<ref name="s2ftracker.com"/> At least one of those aircraft (E-1B, BuNo 148922) was sold to a private collector in 2011 with the intent to restore to fly, although no updates on the project have been posted since 2012.<ref>{{cite web |url=http://www.s2ftracker.com/unitedaerotracerphotos.htm |title=United Aeronautical Corporation Tracer Photos |access-date=2015-05-21 |url-status=dead |archive-url=https://web.archive.org/web/20150530051600/http://www.s2ftracker.com/unitedaerotracerphotos.htm |archive-date=2015-05-30 }}</ref><ref>{{cite web |last=Jackson|first=David D.|url=http://www.s2ftracker.com/trackerupdates.htm |title=Surviving Grumman S2F Tracker Information Repository|access-date=2015-05-21 |url-status=dead |archive-url=https://web.archive.org/web/20150711073031/http://s2ftracker.com/trackerupdates.htm |archive-date=2015-07-11 }}</ref>

==Specifications==
[[File:Grumman WF-2 Tracker 3-view line drawing.png|300px|right|3-view line drawing of the Grumman WF-2 Tracker]]

{{Aircraft specs
|ref=Standard Aircraft Characteristics<ref>[http://www.alternatewars.com/SAC/E-1B_SAC_-_1_July_1967.pdf "Standard Aircraft Characteristics:Navy Model E-1B Aircraft: NAVAIR 00-110AW1-1."] ''Naval Air Systems Command,'' 1 July 1967.</ref>
|prime units?=imp
<!--
        General characteristics
-->
|crew=4 (2 flight crew with 2 radar/intercept controllers)
|length ft=45
|length in=4
|length note=
|span ft=72
|span in=4
|span note=
|height ft=16
|height in=10
|height note=
|wing area sqft=506
|wing area note=
|aspect ratio=<!-- sailplanes -->
|airfoil='''root:''' [[NACA airfoil|NACA 63A420]]; '''tip:''' [[NACA airfoil|NACA 63A415]]<ref name="Selig">{{cite web |last1=Lednicer |first1=David |title=The Incomplete Guide to Airfoil Usage |url=https://m-selig.ae.illinois.edu/ads/aircraft.html |website=m-selig.ae.illinois.edu |access-date=16 April 2019}}</ref>
|empty weight lb=20638
|empty weight note=
|gross weight lb=24800
|gross weight note=
|max takeoff weight lb=26600
|max takeoff weight note=
|fuel capacity=
|more general=
<!--
        Powerplant
-->
|eng1 number=2
|eng1 name=[[Wright R-1820-82A Cyclone]]
|eng1 type=9-cylinder air-cooled radial piston engines
|eng1 hp=1525
|eng1 note=for take-off

|prop blade number=3
|prop name=constant-speed reversible propellers
|prop dia ft=<!-- propeller aircraft -->
|prop dia in=<!-- propeller aircraft -->
|prop dia note=
<!--
        Performance
-->
|max speed mph=238
|max speed note=at {{cvt|4000|ft|0}}
|cruise speed mph=163
|cruise speed note=
|stall speed mph=
|stall speed note=
|never exceed speed mph=
|never exceed speed note=
|minimum control speed mph=
|minimum control speed note=
|range miles=1035
|range note=
|combat range miles=
|combat range note=
|ferry range miles=
|ferry range note=
|endurance=6 hours 50 minutes
|ceiling ft=15800
|ceiling note=
|climb rate ftmin=1120
|climb rate note=
|time to altitude=
|lift to drag=
|wing loading lb/sqft=
|wing loading note=
|fuel consumption lb/mi=
|power/weight=
|more performance=
|avionics=* '''Radar:''' AN/APS-82<ref name=":0" />
}}

==See also==
{{aircontent
|related=
*[[Grumman C-1 Trader]]
*[[Grumman S-2 Tracker]]
|similar aircraft=
*[[Fairey Gannet AEW.3]]
*[[Northrop Grumman E-2 Hawkeye]]
|lists=
|see also=
}}

==References==

===Notes===
{{Reflist}}

===Bibliography===
{{refbegin}}
* Francillon, René J. ''Grumman Aircraft since 1929''. London: Putnam, 1989. {{ISBN|0-85177-835-6}}
* Sullivan, Jim. ''S2F Tracker in Action (Aircraft in Action No. 100).'' Carrollton: Texas: Squadron/Signal Publications, 1990. {{ISBN|978-0-89747-242-5}}.
* Winchester, Jim, ed. "Grumman S-2E/F/G/UP Tracker." ''Modern Military Aircraft'' (Aviation Factfile). Rochester, Kent, UK: Grange Books plc, 2004. {{ISBN|1-84013-640-5}}.
{{refend}}

==External links==
{{Commons category|Grumman E-1 Tracer}}
*[http://www.mc.com/industries/aero/radar/amti.cfm Airborne Moving Target Indicator (AMTI) explanation provided by Mercury Computer]

{{Grumman aircraft}}
{{USN AEW aircraft}}
{{USN trainer aircraft}}
{{US EW aircraft}}

[[Category:Grumman aircraft|E-001 Tracer]]
[[Category:1950s United States special-purpose aircraft]]
[[Category:High-wing aircraft]]
[[Category:Carrier-based aircraft]]
[[Category:AEW aircraft]]
[[Category:Aircraft first flown in 1956]]
[[Category:Twin piston-engined tractor aircraft]]
[[Category:1950s United States command and control aircraft]]
[[Category:Aircraft with retractable tricycle landing gear]]
[[Category:Twin-tail aircraft]]