Editing Bell UH-1 Iroquois (section)

==Development==
{{main|Bell UH-1 Iroquois variants}}
[[File:Bell XH-40.jpg|thumb|Bell XH-40, a prototype of the UH-1]]

In 1952, the U.S. Army identified a requirement for a new helicopter to serve as [[medical evacuation]] (MEDEVAC), instrument trainer, and general utility aircraft. The Army determined that current helicopters were too large, underpowered, or too complex to maintain easily. During November 1953, revised military requirements were submitted to the Department of the Army.<ref name="Weinert203">Weinert 1991, p. 203.</ref> Twenty companies submitted designs in their bid for the contract, including Bell Helicopter with the ''Model 204'' and [[Kaman Aircraft]] with a turbine-powered version of the [[Kaman HH-43 Huskie|H-43]].<ref name= "remarkheuy 2016"/> On 23 February 1955, the Army announced its decision, selecting Bell to build three copies of the Model 204 for evaluation with the designation ''XH-40''.<ref>{{cite web |last= Chapman |first= S |url= http://www.airforce-magazine.com/MagazineArchive/Documents/KittyHawkChronology/kitty1954-63.pdf |title= Up from Kitty Hawk: 1954–63 |publisher= Air Force Magazine, Air Force Association |access-date= 5 October 2008 |archive-date= 24 May 2011 |archive-url= https://web.archive.org/web/20110524150207/http://www.airforce-magazine.com/MagazineArchive/Documents/KittyHawkChronology/kitty1954-63.pdf |url-status= usurped}}</ref>

===Model 204===
{{main|Bell 204/205}}

Powered by a prototype [[Lycoming T53|Lycoming YT53-L-1]] (LTC1B-1) engine producing 700 [[Horsepower#Shaft horsepower|shp]] (520&nbsp;kW), the XH-40 first flew on 20 October 1956,<ref>{{cite web |url= http://www.flightglobal.com/pdfarchive/view/1957/1957%20-%201046.html |title= Aeroengines 1957 |publisher= Flight |date= 26 July 1957 |access-date= 10 August 2009 |archive-date= 19 November 2009 |archive-url= https://web.archive.org/web/20091119192101/http://www.flightglobal.com/pdfarchive/view/1957/1957%20-%201046.html |url-status= dead }}</ref> at [[Fort Worth]], [[Texas]], with Bell's chief test pilot, Floyd Carlson, at the controls. Even prior to the first flight, the Army had placed an order for six ''YH-40'' service test helicopters. During 1957, a further two prototypes were completed.<ref name="Weinert203"/><ref name=Donald>Donald, David, ed. "Bell 204"; "Bell 205". ''The Complete Encyclopedia of World Aircraft''. New York: Barnes & Noble Books, 1997. {{ISBN|0-7607-0592-5}}.{{page needed|date=October 2015}}</ref> In 1959, the Army awarded Bell a production contract for 182 aircraft, which was designated "HU-1A" and officially named ''Iroquois'' after [[Iroquois|the Native American nations]].<ref>{{cite book |last1=Johnson |first1=E. R. |last2=Williams |first2=Ted |title=American Military Helicopters and Vertical/Short Landing and Takeoff Aircraft Since 1941 |date=29 November 2021 |publisher=McFarland |isbn=978-1-4766-4342-7 |page=123 |url=https://books.google.com/books?id=xtxSEAAAQBAJ |access-date=23 August 2023 |language=en}}</ref>

The helicopter quickly developed a nickname derived from its HU-1 designation, which came to be pronounced as "Huey". The reference became so popular that Bell began casting the name on the helicopter's anti-torque pedals.<ref name="DVHAA" /> The official U.S. Army name was almost never used in practice.<ref name="Drendel">Drendel 1983, pp. 9–21.</ref> Even after September 1962, at which point the designation for all models was changed to UH-1 under a unified [[United States Department of Defense|Department of Defense]] (DOD) designation system, yet the nickname persisted.<ref name= "remarkheuy 2016">{{cite web |url= https://vtol.org/files/dmfile/50-52HueybyFardinkSO162.pdf |title= Huey Turns 60: A Retrospective Review of the UH-1's Remarkable Military Service |publisher= vtol.org |first= Paul J. |last= Fardink |date= September–October 2016}}</ref>

While glowing in praise for the helicopter's advances over piston-engined helicopters, the Army reports from the service tests of the YH-40 found it to be underpowered with the production T53-L-1A powerplant producing a maximum continuous 770 [[shaft horsepower]] (570 [[kilowatt]]s).{{#tag:ref|The total power rating of the T53-L-1A is 860&nbsp;shp (640&nbsp;kW). Military engines are often derated to improve reliability of the aircraft [[powertrain]] and to provide a temporary period of higher power output without exceeding the limits of the engine.|group=N}} The Army indicated the need for improved follow-on models even as the first UH-1As were being delivered. In response, Bell proposed the UH-1B, equipped with the Lycoming T53-L-5 engine producing 960&nbsp;shp (720&nbsp;kW) and a longer cabin that could accommodate either seven passengers or four stretchers and a medical attendant. Army testing of the UH-1B started in November 1960, with the first production aircraft delivered in March 1961.<ref name="Weinert203"/>
[[File:USN 1131561.jpg|thumb|left|UH-1B cockpit view]]
Bell commenced development of the UH-1C in 1960 in order to correct aerodynamic deficiencies of the armed UH-1B. Bell fitted the UH-1C with a 1,100&nbsp;shp (820&nbsp;kW) T53-L-11 engine to provide the power needed to lift all weapons systems in use or under development. The Army eventually refitted all UH-1B aircraft with the same engine. A new rotor system was developed for the UH-1C to allow higher air speeds and reduce the incidence of [[retreating blade stall]] during diving engagements. The improved rotor resulted in better maneuverability and a slight speed increase.<ref name=Donald/> The increased power and a larger diameter rotor required Bell's engineers to design a new tail boom for the UH-1C. The longer tail boom incorporated a wider chord vertical fin on the tail rotor pylon and larger synchronized elevators.{{Citation needed|date=June 2022}}

Bell also introduced a dual hydraulic control system for redundancy as well as an improved inlet filter system for the dusty conditions found in southeast Asia. The UH-1C fuel capacity was increased to 242 [[Gallon|US gallons]] (920 [[liter]]s), and gross weight was raised to {{convert|9500|lb|kg|0|abbr=on}}, giving a nominal useful load of {{convert|4673|lb|kg|0|abbr=on}}. UH-1C production started in June 1966 with a total of 766 aircraft produced, including five for the [[Royal Australian Navy]] and five for Norway.{{Citation needed|date=June 2022}}

===Model 205===
{{main|Bell 204/205}}
[[File:Ventura County Sheriff Bell HH-1H (205) "N205SD".jpg|thumb|[[Ventura County Sheriff's Department]] Air Unit Fire Support Bell HH-1H]]

While earlier short-body Hueys were a success, the Army wanted a version that could carry more troops. Bell's solution was to stretch the HU-1B fuselage by {{convert|41|in|cm|0|abbr=on}} and use the extra space to fit four seats next to the transmission, facing out. Seating capacity increased to 15, including crew.<ref name=Apostolo_Bell_204-205>Apostolo 1984, pp. 47–48.</ref> The enlarged cabin could also accommodate six stretchers and a medic, two more than the earlier models.<ref name=Apostolo_Bell_204-205/> In place of the earlier model's sliding side doors with a single window, larger doors were fitted which had two windows, plus a small hinged panel with an optional window, providing enhanced access to the cabin. The doors and hinged panels were quickly removable, allowing the Huey to be flown in a doors off configuration.

The Model 205 prototype flew on 16 August 1961.<ref>McGowen 2005, p. 100.</ref><ref>Pattillo 2001, p. 208.</ref> Seven pre-production/prototype aircraft had been delivered for testing at [[Edwards AFB]] starting in March 1961. The 205 was initially equipped with a {{convert|44|ft|m|adj=on}} main rotor and a Lycoming T53-L-9 engine with 1,100 shp (820&nbsp;kW). The rotor was lengthened to {{convert|48|ft|m}} with a chord of {{convert|21|in|cm|0|abbr=on}}. The tailboom was also lengthened, in order to accommodate the longer rotor blades. Altogether, the modifications resulted in a gross weight capacity of {{convert|9500|lb|kg|0|abbr=on}}. The Army ordered production of the 205 in 1963, produced with a T53-L-11 engine for its multi-fuel capability.{{#tag:ref|The 7 January 1965-edition of ''Flight International'' magazine states that the L-11 engine is similar to the L-9 in power, but with a multi-fuel capability.|group=N}}<ref>{{cite magazine |last= Dobson |first= G |title= Helicopter powerplants: The world scene |magazine= Flight |date= 7 January 1965 }}</ref> The prototypes were designated as YUH-1D and the production aircraft was designated as the ''UH-1D''.

During 1966, Bell installed the {{convert|1400|shp|abbr=on}} Lycoming T53-L-13 engine to provide more power for the helicopter. The [[pitot tube]] was relocated from the nose to the roof of the cockpit to prevent damage during landing. Production models in this configuration were designated as the ''UH-1H''.<ref name="Drendel"/><ref name="Mutza"/>

===Marine Corps===
[[File:UH-1E's of HML-167, 1970.tiff|thumb|USMC UH-1E helicopters in formation, 1970]]
In 1962, the [[United States Marine Corps]] held a competition to choose an assault support helicopter to replace the [[Cessna O-1]] fixed-wing aircraft and the [[HH-43 Huskie|Kaman OH-43D]] helicopter. The winner was the UH-1B, which was already in service with the Army. The helicopter was designated the ''UH-1E'' and modified to meet Marine requirements. The major changes included the use of all-aluminum construction for corrosion resistance,{{#tag:ref|Earlier UH-1s had some magnesium components.|group=N}} radios compatible with Marine Corps ground frequencies, a rotor brake for shipboard use to stop the rotor quickly on shutdown and a roof-mounted rescue hoist.{{Citation needed|date=June 2022}}

The UH-1E was first flown on 7 October 1963, and deliveries commenced on 21 February 1964; a total of 192 Iroquois of this model were completed.<ref name= "remarkheuy 2016"/> Due to production line realities at Bell, the UH-1E was produced in two versions, both with the same UH-1E designation. The first 34 built were essentially UH-1B airframes with the Lycoming T53-L-11 engine producing 1,100 shp (820&nbsp;kW).{{Citation needed|date=June 2022}} When Bell switched production to the UH-1C, the UH-1E production benefited from the same changes. The Marine Corps later upgraded UH-1E engines to the Lycoming T53-L-13, which produced 1,400 shp (1,000&nbsp;kW), after the Army introduced the UH-1M and upgraded their UH-1C helicopters to the same engine.

===Air Force===
The [[United States Air Force]] (USAF) held a competition for a helicopter to be used for support on missile bases included a specific requirement to mandate the use of the [[General Electric T58]] [[turboshaft]] as a powerplant. The Air Force had a large inventory of these engines on hand for its fleet of [[Sikorsky S-61R|HH-3 Jolly Green Giant]] rescue helicopters and using the same engine for both helicopters would save costs. In response, Bell proposed an upgraded version of the 204B with the T58 engine. Because the T58 output shaft is at the rear, and was thus mounted in front of the transmission on the HH-3, it had to have a separate offset gearbox (SDG or speed decreaser gearbox) at the rear, and shafting to couple to the UH-1 transmission.<ref>{{cite web |url=http://www.cactusairforce.com/inventory_item/uh-1b-huey/ |title=UH-1B Huey |website=cactusairforce.com |access-date=January 20, 2023}}</ref>

===Twin-engine variants===
{| class="wikitable plainrowheaders" style="float: right; margin-right: 0; margin-left: 1em; text-align: right;"
|-
! scope="col" | Model
! scope="col" | Engines
! scope="col" | Rotors
! scope="col" | [[First flight|F.F.]] Year
|-
! scope="row" | UH-1/CH-118/204/5
| 1
| 2
| 1956
|-
! scope="row" | UH-1N/CH-135/212
| 2
| 2
| 1968
|-
! scope="row" | 412/CH-146/UH-2
| 2
| 4
| 1979
|-
! scope="row" | UH-1Y
| 2
| 4
| 2001
|}
The single-engine UH-1 variants were followed by the twin-engine [[UH-1N Twin Huey]] ([[Bell 212]]) and years later the [[UH-1Y Venom]].<ref name= "remarkheuy 2016"/> Bell began development of the UH-1N for Canada in 1968. It changed to the more powerful [[Pratt & Whitney Canada PT6T]] twin-engine set. The US also ordered the helicopter with the USAF receiving it in 1970. Canada's military, the U.S. Marine Corps, and the U.S. Navy first received the model in 1971.<ref name="Donald p113">Donald 1997. p. 113.</ref><ref name= "remarkheuy 2016"/>

In 1996, the USMC launched the [[H-1 upgrade program]] via the award of a contract to Bell Helicopter for development of the improved UH-1Y and [[AH-1Z Viper|AH-1Zs]] variants.<ref name="mod_battle">Donald, David. ''Modern Battlefield Warplanes''. London: AIRTime Publishing, 2004. {{ISBN|1-880588-76-5}}.</ref><ref>{{cite web |url= https://www.flightglobal.com/helicopters/retrospective-how-the-uh-1-huey-changed-modern-warfare/130259.article |title= RETROSPECTIVE: How the UH-1 'Huey' changed modern warfare |publisher= Flight International |first= Garrett |last= Reim |date= 12 December 2018}}</ref> The UH-1Y includes a lengthened cabin, four-blade rotor, and two more powerful [[General Electric T700|GE T700]] engines.<ref name="UH-1Y_guide">{{cite web |url= http://www.bellhelicopter.com/en/aircraft/military/pdf/UH1Y_PG_3-06_web.pdf |title= Bell UH-1Y pocket guide |publisher= Bell Helicopter |date= March 2006 |access-date= 20 January 2010 |archive-date= 29 December 2010 |archive-url= https://web.archive.org/web/20101229201940/http://www.bellhelicopter.com/en/aircraft/military/pdf/UH1Y_PG_3-06_web.pdf |url-status= dead }}</ref> The UH-1Y entered service with the USMC in 2008.<ref>{{cite web |last= Trimble |first= Stephen |url= http://www.flightglobal.com/articles/2008/08/18/314915/uh-1y-declared-operational-after-12-year-development.html |title= UH-1Y declared operational after 12-year development phase |publisher= Flightglobal.com |date= 18 August 2008 |access-date= 24 January 2010 |archive-date= 2 September 2008 |archive-url= https://web.archive.org/web/20080902004704/http://www.flightglobal.com/articles/2008/08/18/314915/uh-1y-declared-operational-after-12-year-development.html |url-status= dead }}</ref>

The [[Bell 412]] is an improved 4-rotor version of the twin-engined Bell 212, and while not adopted by the US, was chosen by Canada ([[Bell CH-146 Griffon|CH-146 Griffon]]), license produced in Italy as the Augusta-Bell AB412, and is going to be made for the Japan Self Defense Force in Japan by Subaru.<ref name=":1">{{Cite web |title=Bell / Agusta Bell 412 - Aerospace Technology |url=https://www.aerospace-technology.com/projects/bell-412/ |access-date=2024-04-26 |website=www.aerospace-technology.com}}</ref> It is a popular commercial and military helicopter, and it competed in the early 2000s Army Light Utility Helicopter program, but lost to what would be the [[Eurocopter UH-72 Lakota|UH-72 Lakota.]]<ref>{{Cite web |title=Bell Helicopter LUH Submission Surpasses 3.1 Million Flight Hour Milestone |url=https://verticalmag.com/press-releases/bell-helicopter-luh-submission-surpasses-3-1-million-flight-hour-milestone-html/ |access-date=2024-04-26 |website=Vertical Mag |language=en-US}}</ref><ref name=":0">{{Cite web |title=Airbus wins US Army UH-72A Lakota upgrade contract {{!}} Shephard |url=https://www.shephardmedia.com/news/air-warfare/airbus-wins-us-army-uh-72a-lakota-upgrade-contract/ |access-date=2024-04-26 |website=www.shephardmedia.com |language=en}}</ref> That program replaced aging UH-1 and OH-58A/C models being used by the National Guard.<ref name=":0" />