Editing Bell X-5

{{Short description|NASA experimental variable-sweep wing aircraft}}
{{Infobox aircraft
  |name = X-5
  |image = Bell X-5 USAF.jpg
  |caption = 
  |type = [[Experimental aircraft]]
  |manufacturer = [[Bell Aircraft Corporation]]
  |designer = Robert J. Woods
  |first_flight =20 June 1951
  |introduction = 
  |retired = December [[1958 in aviation|1958]]
  |status =
  |primary_user = [[United States Air Force]]
  |more_users = [[National Advisory Committee for Aeronautics]]
  |produced =
  |number_built = 2
  |unit cost =
  |developed_from=
  |variants =
}}
[[File:Bell-X5-Multiple.jpg|thumb|right|A composite photograph showing the '''Bell X-5'''’s variable-sweep wing]]

The '''Bell X-5''' was the first [[Fixed-wing aircraft|aircraft]] capable of [[Variable-sweep wing|changing the sweep of its wings in flight]]. It was inspired by the untested wartime [[Messerschmitt P.1101|P.1101]] design of the [[Germany|German]] [[Messerschmitt]] company. In a further development of the German design, which could only have its wing sweepback angle adjusted on the ground, the Bell engineers devised a system of electric motors to adjust the sweep in flight.

==Design and development==
The [[Messerschmitt P.1101]] V1 prototype was captured by United States troops in April 1945 from an experimental facility at Oberammergau, Germany. It was brought back to the United States, eventually being delivered to the [[Bell Aircraft]] factory at Buffalo, New York. Although incomplete and damaged in transit, company engineering staff studied the design closely.<ref name=":0">Winchester 2005, p. 37.</ref> The P.1101 had a wing sweep that could be adjusted on the ground from 30, 40, to 45 degrees. However, this was for testing only and never intended as an operational feature.<ref name="Christopher">{{cite book |last1=Christopher |first1=John |title=The Race for Hitler's X-Planes : Britain's 1945 Mission to Capture Secret Luftwaffe Technology. |date=1 June 2013 |publisher=History Press |isbn=978-0752464572 |pages=157–160}}</ref> The Bell team, led by Chief Designer Robert J. Woods, submitted a proposal for a similar design, but with in-flight wing adjustment capability.<ref name=":0" />

Although superficially similar, the X-5 was much more complex than the P.1101, with three sweep positions: 20°, 40° and 60°, creating an inflight "variable-geometry" platform. A [[jackscrew]] assembly moved the wing's hinge along a set of short horizontal rails, using [[disc brake]]s to lock the wing into its inflight positions. Moving from full extension to full sweep took less than 30 seconds. The articulation of the hinge and pivots partly compensated for the shifts in [[center of gravity]] and [[Center of pressure (fluid mechanics)|center of pressure]] as the wings moved.{{Citation needed|date=February 2025}}

Even so, the X-5 had vicious [[Spin (flight)|spin]] characteristics arising from the aircraft's flawed aerodynamic layout, particularly a poorly positioned tail and vertical stabilizer which, in some wing positions, could lead to an irrecoverable spin. This violent stall / spin instability would eventually cause the destruction of the second aircraft and the death of its Air Force test pilot in 1953.<ref>Hallion 1984, p. 52.</ref>

The unfavorable spin characteristics also led to the cancellation of tentative plans by the United States Air Force to modify the X-5's design into a low-cost tactical fighter for NATO and other foreign countries.<ref>Hallion 1984, p. 47.</ref>

==Operational history==
Two X-5s were built (serial numbers 50-1838 and 50-1839). The first was completed 15 February 1951, and the two aircraft made their first flights on 20 June and 10 December 1951. Almost 200 flights were made at speeds up to [[Mach (speed)|Mach]] 0.9 and altitudes of {{convert|40,000|ft|m|abbr=on}}. One aircraft was lost on 14 October 1953, when it failed to recover from a spin at 60° sweepback. Air Force Captain Ray Popson died in the crash at [[Edwards Air Force Base]]. The other X-5 remained at Edwards and continued active testing until 1955, and remained in service as a chase plane until 1958.

The X-5 successfully demonstrated the advantage of a [[Variable-sweep wing|swing-wing]] design for aircraft intended to fly at a wide range of speeds. Despite the X-5's stability problems, the concept was developed to an outboard rather than inboard hinge,<ref>{{Cite web|title=Swing Wings|url=https://www.airspacemag.com/flight-today/swing-wings-9189621/|access-date=2021-07-18|website=Air & Space Magazine|language=en}}</ref> and was later successfully implemented in such aircraft as the [[General Dynamics F-111]] and [[Grumman F-14 Tomcat]], the [[Mikoyan-Gurevich MiG-23|Mikoyan Gurevich MiG-23]] and [[Mikoyan MiG-27|MiG-27]], the [[Sukhoi Su-17|Sukhoi Su-17/20/22]] and [[Sukhoi Su-24|Su-24]], the [[Tupolev Tu-22M]] and [[Tupolev Tu-160|Tu-160]], the [[Panavia Tornado]] and the [[Rockwell B-1 Lancer]].

==Survivors==
The sole surviving X-5 is now at the [[National Museum of the United States Air Force]] at [[Wright-Patterson Air Force Base]] near [[Dayton, Ohio]]. It was delivered to the museum in March 1958. It is displayed in the museum's Research & Development Hangar.<ref>[https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/195758/bell-x-5/ "Bell X-5".] ''National Museum of the United States Air Force.'' Retrieved: 22 October 2016.</ref>

==Specifications (Bell X-5)==
[[File:Bell X-5 afg-041110-046.svg|right|300px|Orthographically projected diagram of the Bell X-5.]]
{{Aircraft specs
|ref=The X-planes : X-1 to X-29<ref name="Miller">{{cite book |last1=Miller |first1=Jay |title=The X-planes : X-1 to X-29 |date=1983 |publisher=Speciality |location=Marine on St. Croix |isbn=0933424353 |pages=56–63}}</ref>
|prime units?=imp
<!--
        General characteristics
-->
|crew=1
|length ft=33
|length in=4
|length note=
|span ft=30
|span in=6
|span note=
|swept ft=20
|swept in=9
|swept note=at 60° sweep{{citation needed|date=April 2020}}
|height ft=12
|height in=0
|height note=
|wing area sqft=175
|wing area note=
|aspect ratio=<!-- sailplanes -->
|airfoil='''root:''' [[NACA airfoil|NACA 64A011]]; '''tip:''' [[NACA airfoil|NACA 64A08.28]]<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=6350
|empty weight note=
|gross weight lb=9875
|gross weight note=
|max takeoff weight lb=
|max takeoff weight note=
|fuel capacity=
|more general=
<!--
        Powerplant
-->
|eng1 number=1
|eng1 name=[[Allison J35-A-17A]]
|eng1 type=[[turbojet]] engine
|eng1 lbf=4900
|eng1 note=at sea level
<!--
        Performance
-->
|max speed mph=705
|max speed note=
|max speed mach=<!-- supersonic aircraft -->
|cruise speed mph=
|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=750
|range note=
|combat range miles=
|combat range note=
|ferry range miles=
|ferry range note=
|endurance=<!-- if range unknown -->
|ceiling ft=42000
|ceiling note=
|g limits=<!-- aerobatic -->
|roll rate=<!-- aerobatic -->
|glide ratio=<!-- sailplanes -->
|climb rate ftmin=
|climb rate note=
|time to altitude=
|sink rate ftmin=<!-- sailplanes -->
|sink rate note=
|lift to drag=
|wing loading lb/sqft=
|wing loading note=
|fuel consumption lb/mi=
|thrust/weight=0.5{{citation needed|date=April 2020}}

|more performance=<!--<br />
*'''Take-off run:''' {{cvt||ft|0}}
*'''Take-off distance to {{cvt|50|ft|0}}:''' {{cvt||ft|0}}
*'''Landing run:''' {{cvt||ft|0}}
*'''Landing distance from {{cvt|50|ft|0}}:''' {{cvt||ft|0}}-->

|avionics=
}}

==See also==
{{aircontent
|related=
|similar aircraft=
* [[Grumman XF10F Jaguar]]
* [[Messerschmitt P.1101]]
* [[North American F-86 Sabre]]
* [[Saab 29 Tunnan]]
* [[Škoda-Kauba P14]]
|lists=
* [[List of experimental aircraft]]
}}

==References==
;Notes
{{Reflist}}
;Bibliography
{{Refbegin}}
* Hallion, Richard P. ''On The Frontier: Flight Research At Dryden 1946–1981 (NASA SP4303)''. Washington, DC: National Aeronautics and Space Administration, 1984 (revised 2003 in Smithsonian edition). {{ISBN|1-58834-134-8}}.
* Winchester, Jim. "Bell X-5." ''Concept Aircraft: Prototypes, X-Planes and Experimental Aircraft''. Kent, UK: Grange Books plc., 2005. {{ISBN|1-84013-809-2}}.
{{Refend}}

==External links==
{{Commons category|Bell X-5}}
* [https://web.archive.org/web/20200425225303/https://history.nasa.gov/monograph31.pdf  ''American X-Vehicles: An Inventory X-1 to X-50'', SP-2000-4531 – June 2003; NASA online PDF Monograph]
* {{cite magazine|magazine=Popular Science|author=Bonnier Corporation|title=Dart Shaped Plane Sweeps Wings Back In Flight|url=https://books.google.com/books?id=lyEDAAAAMBAJ&pg=PA84|date=August 1951|publisher=Bonnier Corporation|page=84}}

{{Bell Aircraft}}
{{X-planes}}
{{Authority control}}

[[Category:Edwards Air Force Base]]
[[Category:Variable-sweep-wing aircraft]]
[[Category:1950s United States experimental aircraft|X-05, Bell]]
[[Category:Single-engined jet aircraft]]
[[Category:Bell aircraft|X-5]]
[[Category:Mid-wing aircraft]]
[[Category:Aircraft first flown in 1951]]
[[Category:Aircraft with retractable tricycle landing gear]]