View source for Convair XF-92

{{Short description|Experimental interceptor aircraft}}
{{Infobox aircraft
  |name= XF-92A
  |image= Convair XF-92A.jpg
  |caption= A photo of the Convair XF-92A in flight
  |type= {{Plainlist|
* [[Interceptor aircraft|Point-defense interceptor]]
* [[Experimental aircraft]]}}
  |manufacturer= [[Convair]]
  |designer= 
  |first_flight= 18 September 1948<ref name= "Winchester p. 242">Winchester 2005, p. 242.</ref>
  |introduction=
  |retired=
  |status= Canceled
  |primary_user= [[United States Air Force]]
  |more_users=
  |produced=
  |number_built= 1
  |program cost= {{US$|link=yes}}4.3 million<ref name="knaack">Knaack 1978, pp. 322–323.</ref>
  |developed_from= 
  |variants = [[Convair F-102 Delta Dagger]]
}}

The '''Convair XF-92''' (re-designated from '''XP-92''' in 1948) is an [[United States|American]], [[delta wing]], [[jet fighter generations#First generation|first-generation jet]] prototype. Originally conceived as a [[point-defence]] [[interceptor aircraft|interceptor]], the design was later used purely  for [[experimental aircraft|experimental]] purposes and only one was built. However, it led Convair to use the delta-wing on a number of designs, including the [[Convair F-102 Delta Dagger|F-102 Delta Dagger]], [[Convair F-106 Delta Dart|F-106 Delta Dart]],  [[Convair B-58 Hustler|B-58 Hustler]], the [[US Navy]]'s [[Convair F2Y Sea Dart|F2Y Sea Dart]] as well as the [[VTOL]] [[Convair XFY Pogo|FY Pogo]].

==Design and development==

===Early work===
[[File:Convair XP-92 mockup.jpg|thumb|Mockup of the XP-92.]]
[[File:XF-92A Edwards AFB.jpg|thumb|The XF-92A at [[Edwards Air Force Base]], 1952]]
Prior to August 1945, the Vultee Division of Consolidated-Vultee looked at the possibility of a swept-wing aircraft powered by a ducted rocket. Years earlier, the company had performed designs which involved liquid-cooled radiator engines.  With this design, fuel would be added to the heat produced by small rocket engines in the duct, creating a "pseudo-[[ramjet]]".<ref name="J&L p. 122">Jenkins and Landis 2008, p. 122.</ref>

In August 1945, the [[United States Army Air Forces]] (USAAF), soon to be renamed the [[United States Air Force]], issued a proposal for a supersonic interceptor capable of {{convert|700|mi/h|km/h|abbr=on}} speeds and reaching an altitude of {{convert|50000|ft|m}} in four minutes.{{Citation needed|date=July 2011}} Several companies responded, among which was Consolidated-Vultee, which submitted its design on 13 October 1945.<ref name="J&L p. 122"/> This design featured swept wings and [[V-tail]]s, as well as a powerful propulsion system. Besides the ducted rocket, four {{Convert|1,200|lbf|kN}} rockets were positioned at the exhaust nozzle, along with the {{Convert|1,560|lbf|kN}} 19XB turbojet produced by Westinghouse.<ref name="J&L p. 122"/>

A proposal by [[Consolidated Vultee]] (later Convair) was accepted in May 1946, with a proposal for a ramjet-powered aircraft, with a 45° [[swept wing]] under USAAF [[Air Materiel Command]] Secret Project MX-813. However, [[wind tunnel]] testing demonstrated a number of problems with this design.<ref name=baugher>Baughe, r, Joe. [http://www.joebaugher.com/usaf_fighters/p92.html "Convair XF-92A."] ''USAF Fighters,'' 21 November 1999. Retrieved: 11 June 2011.</ref>

===Switch to delta===
Convair found that by straightening the trailing edge and increasing the sweep of the leading edge, the characteristics of their new wing were greatly improved. Thus, contrary to suggestions that German designer [[Alexander Lippisch]] influenced it, Convair independently discovered the thin high-speed delta wing.<ref name="hallion1979">Hallion (1979)</ref> Ralph Shick, chief of aerodynamic research, later met Lippisch at [[Wright-Patterson Air Force Base]]. This helped to convince him that the thin delta was the way forward, however the influence of Lippisch provided no more than "moral support" and Convair rejected many of his ideas, such as the thick wing of the [[Lippisch P.13a]] project and the [[Lippisch DM-1|DM-1]] test glider which the US had tested.<ref name=f102>[http://www.flightglobal.com/pdfarchive/view/1957/1957%20-%200510.html "Convair F-102"], ''Flight International'', pp. 512–518.</ref><ref name="hallion1979"/>

Thrust was to be provided by a {{convert|1560|lbf|abbr=on}} [[Westinghouse J30]] jet engine assisted by a battery of six {{convert|2000|lbf|kN|abbr=on}} liquid-fueled rockets. This mixed-propulsion system required a very large intake duct, which not only fed the jet engine but also passed air around the rocket exhaust to provide [[Air-augmented rocket|thrust augmentation]]. Located centrally, the large duct left nowhere to put a traditional cockpit; in its normal location it would have projected deep into the duct. To address this, the team modified the design in a fashion similar to both the [[Leduc 0.10]] and [[Miles M.52]], placing the cockpit in a cylindrical body in the center of the intake. The design was presented to the [[U.S. Air Force]] in 1946 and was accepted for development as the XP-92.<ref name="Yenne 2009, p. 27">Yenne 2009, p. 27.</ref>

===Delta research===
In order to gain inflight experience with the delta wing layout, Convair suggested building a smaller prototype, the '''Model 7002''', which the USAAF accepted in November 1946.<ref name="Taylor 1977, p. 61">Taylor 1977, p. 61.</ref>

In order to save development time and money, many components were taken from other aircraft; the main gear was taken from a  [[North American FJ-1 Fury]], the nosewheel from a [[Bell P-63 Kingcobra]], the engine and hydraulics were taken from a [[Lockheed P-80 Shooting Star]], the ejection seat and cockpit canopy were taken from the cancelled [[Convair XP-81]], and the rudder pedals were taken from a BT-13 trainer.

Construction was well underway at Vultee Field in [[Downey, California]] when [[North American Aviation]] took over the Vultee plants in summer 1947. The airframe was moved to Convair's plant in [[San Diego]], and completed in the autumn. In December it was shipped without an engine to [[NACA]]'s [[NASA Ames Research Center|Ames Aeronautical Laboratory]] for wind tunnel testing. After testing was completed, the airframe was returned to San Diego, where it was fitted with a {{convert|4250|lbf|abbr=on}} [[Allison J33]]-A-21 engine.<ref name="Yenne 2009, p. 27"/>

By the time the aircraft was ready for testing, the concept of the [[point-defense]] interceptor seemed outdated and the (now redesignated) F-92 project was cancelled; the test aircraft was nevertheless completed as the '''XF-92A'''.<ref name="Taylor 1977, p. 61"/>

==Operational history==
[[File:USAF XF-92A.jpg|thumb|Convair XF-92A in flight with bare metal scheme]]

In April 1948 the XF-92A was shipped to [[Rogers Dry Lake|Muroc Dry Lake]] (later to become [[Edwards AFB]]). Early tests were limited to taxiing, although a short hop was made on 9 June 1948. The XF-92A's first flight was on 18 September 1948 with Convair test pilot Ellis D. "Sam" Shannon at the controls. On 21 December 1948 Bill Martin began testing the aircraft for the company. After 47 flights totaling 20 hours and 33 minutes, the aircraft was turned over to the USAAF on 26 August 1949,<ref name="Yenne 2009, p. 29">Yenne 2009, p. 29.</ref> with the testing being assigned to [[Frank Kendall Everest Jr.|Frank Everest]] and [[Chuck Yeager]].<ref name=baugher/>

On 13 October 1949 Yeager became the first Air Force pilot to fly the XF-92A.<ref name="Yenne 2009, p. 29"/> On his second flight he dove the aircraft in a 4&nbsp;g [[split-S]] dive, reaching Mach&nbsp;1.05 for a brief time.<ref name=GlobalSec>[http://www.globalsecurity.org/military/systems/aircraft/f-92.htm "XF-92A Dart."] ''globalsecurity.org.'' Retrieved: 3 July 2011.</ref> When approaching for landing on this flight he continued to pull the nose higher and higher in order to slow the forward speed to avoid the problems from his first attempt. Surprisingly, the aircraft simply wouldn't stall; he was able to continue raising the nose until he reached 45&nbsp;degrees [[Aircraft principal axes#Transverse axis (pitch)|pitch]], flying under control in that attitude to a landing at {{convert|67|mi/h|km/h|abbr=on}}, {{convert|100|mi/h|km/h|abbr=on}} slower than Convair had managed.

In 1951, the XF-92A was refitted with an Allison J33-A-29 engine with an afterburner, offering a thrust of {{convert|7500|lbf|abbr=on}}. The re-engined XF-92A was flown by Yeager for the first time on 20 July 1951. However, there was very little improvement in performance. In addition, there were maintenance problems with this engine and only 21 flights were made during the next 19 months.<ref name=baugher/> A final engine change was made to the {{convert|5400|lbf|abbr=on}} J33-A-16.

On 9 April 1953, [[Albert Scott Crossfield|Scott Crossfield]] began a series of flights on behalf of NACA. These tests revealed a violent pitch-up tendency during high-speed turns, often as much as 6&nbsp;g, and on one occasion 8&nbsp;g. The addition of [[wing fence]]s partially alleviated this problem. Crossfield flew 25 flights in the XF-92A by 14 October 1953.<ref>Yenne 2009, p. 30.</ref> After the aircraft's last flight the nose gear collapsed as Crossfield taxied off the lake bed; the aircraft was retired.<ref>Yenne 2009, p. 31.</ref>

None of the pilots had much good to say about the design. Yeager commented "It was a tricky plane to fly, but ... I got it out to 1.05 Mach." Crossfield was more direct, saying "Nobody wanted to fly the XF-92. There was no lineup of pilots for that airplane. It was a miserable flying beast. Everyone complained it was underpowered."<ref>DiGregorio, Barry E. [http://www.historynet.com/air_sea/flight_technology/3037311.html?showAll=y&c=y "Aviation History: Interview with Frank K. 'Pete' Everest Who Flew A Bell X-2 To Record Speed of Mach 3."] {{webarchive|url=https://web.archive.org/web/20070930210331/http://www.historynet.com/air_sea/flight_technology/3037311.html?showAll=y&c=y |date=2007-09-30 }} ''Aviation History,'' July 1998. Retrieved: 3 July 2011.</ref><ref>[http://www.nasa.gov/centers/dryden/news/FactSheets/FS-080-DFRC.html "NASA Fact Sheets: XF-92A."] {{Webarchive|url=https://web.archive.org/web/20141025161712/http://www.nasa.gov/centers/dryden/news/FactSheets/FS-080-DFRC.html |date=2014-10-25 }} ''NASA.'' Retrieved: 11 June 2011.</ref>

===Influence===
[[File:Convair XF-92A accident front.jpg|thumb|right|Landing accident, 1953]]

The delta wing's thin airfoil cross section, low weight and structural strength made it a good candidate for a supersonic airplane. The large surface area of 425&nbsp;ft<sup>2</sup> (39&nbsp;m<sup>2</sup>) gave a low [[wing loading]] which in turn led to good low-speed performance. Very slow landing speeds could be achieved, at the cost of extremely nose-high landing angles and the resulting poor visibility. The combination of good high-speed and low-speed characteristics was very difficult to achieve for other [[planform (aeronautics)|planform]]s. Although the XF-92 itself was not liked, the design concept clearly had promise and the delta wing was used on several Convair designs through the 1950s and 1960s.

Of particular interest to aircraft designers was the unexpectedly good low-speed behavior Yeager had noticed on his second flight. The aircraft continued to remain controllable at very high [[angle of attack|angles of attack]] (alpha), where a conventional layout would have stalled. The reason for this turned out to be the unexpected creation of a large [[vortex]] over the top of the wing, generated by the airflow between the fuselage and leading edge of the wing at high alpha. The vortex became "attached" to the upper surface of the wing, supplying it with air moving at speeds much greater than the aircraft's forward speed. By controlling the flow in this critical area, the [[performance envelope]] of the delta could be greatly expanded, which led to the introduction of [[canard (aeronautics)|canard]]s on most delta-wing designs in the 1960s and 1970s. More recently [[leading edge extension]]s have become common on most fighter aircraft, creating the vortex over a more conventional wing planform.

==Operators==
;{{USA}}
*[[United States Air Force]]

==Aircraft on display==
[[File:XF-92A at USAF Museum.jpg|thumb|XF-92A at the [[NMUSAF]] on August 31, 2017.]]
*46-682 – Research & Development Gallery at the [[National Museum of the United States Air Force]], [[Wright-Patterson Air Force Base]], near [[Dayton, Ohio]].<ref>[https://web.archive.org/web/20130330025037/http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=585 "XF-92A Dart/46-682"] National Museum of the United States Air Force Retrieved: 9 July 2017.</ref>

==Specifications (XF-92A)==
[[File:Convair XF-92A EG-0102-01.svg|right|300px|Orthographically projected diagram of the XF-92A.]]

{{Aircraft specs
|ref= ''Fighters of the United States Air Force''<ref>Dorr and Donald 1990, p. 149.</ref>
|prime units?=imp
<!--
        General characteristics
-->
|crew=1
|length ft=42
|length in=6
|length note=
|span ft=31
|span in=4
|span note=
|height ft=17
|height in=9
|height note=
|wing area sqft=425
|wing area note=
|aspect ratio=<!-- sailplanes -->
|airfoil=[[NACA airfoil|NACA 65-006.5]]<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=9078
|empty weight note=
|gross weight lb=14608
|gross weight note=
|max takeoff weight lb=
|max takeoff weight note=
|fuel capacity=
|more general=
<!--
        Powerplant
-->
|eng1 number=1
|eng1 name=[[Allison J33-A-29]]
|eng1 type=afterburning turbojet engine
|eng1 lbf=4500
|eng1 note=
|eng1 lbf-ab=7500

<!--
        Performance
-->
|max speed mph=718
|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=
|range miles=
|range note=
|ferry range miles=
|ferry range note=
|endurance=<!-- if range unknown -->
|ceiling ft=50750
|ceiling note=
|g limits=<!-- aerobatic -->
|roll rate=<!-- aerobatic -->
|climb rate ftmin=8135
|climb rate note=
|time to altitude=
|wing loading lb/sqft=34
|wing loading note=
|fuel consumption lb/mi=
|thrust/weight=0.51

|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=
}}

==Popular culture==
[[File:XF-92A MIG-23.jpg|thumb|Convair XF-92A painted as a fictional [[MiG-23]] for the movie ''[[Jet Pilot (film)|Jet Pilot]]'']]
An unusual application of the XF-92A was as a movie model, stepping into the role of the "MiG-23" in the Howard Hughes film, ''[[Jet Pilot (1957 film)|Jet Pilot]]'', starring [[John Wayne]] and [[Janet Leigh]]. Due to the lengthy delay in releasing the film, by the time it appeared in 1957, the XF-92A's role had been left on the cutting room floor.<ref>Winchester 2005, p. 243.</ref> It did appear in the film ''[[Toward the Unknown]]'' (1956) starring William Holden, again in the guise of another aircraft, this time as its descendant design the F-102 Delta Dagger.<ref>Watson 1997/1998, p. 9.</ref>

==See also==
{{Portal|Aviation}}
{{Aircontent
|related=
* [[Convair F-102 Delta Dagger]]
* [[Convair F-106 Delta Dart]]
|similar aircraft=
* [[Boulton Paul P.111]]
* [[Leduc 0.10]]
* [[Nord 1500 Griffon]]
|lists=
* [[List of experimental aircraft]]
* [[List of fighter aircraft]]
|see also=
* [[Lippisch P.13a]]
* [[Lippisch DM-1]]
}}

==Notes==
{{Reflist}}

==Bibliography==
* Bradley, Robert E. ''Convair Advanced Designs II'', Crecy Publishing, 2013.
* Dorr, Robert F. and David Donald. ''Fighters of the United States Air Force''. London: Temple, 1990. {{ISBN|0-600-55094-X}}.
* Hallion, Richard P. "Convair's Delta Alpha". ''Air Enthusiast Quarterly'', No. 2, n.d., pp.&nbsp;177–185. {{ISSN|0143-5450}} 
*Hallion, Richard P. "Lippisch, Gluhareff, and Jones: The Emergence of the Delta Planform and Origins of the Sweptwing in the United States", ''Aerospace Historian'', Vol.26, No.1, Spring/March 1979. pp.&nbsp;1–10. ([https://www.jstor.org/stable/44524912 JSTOR copy]).
* Jenkins, Dennis R. and Tony R. Landis. ''Experimental & Prototype U.S. Air Force Jet Fighters.'' North Branch, Minnesota, USA: Specialty Press, 2008. {{ISBN|978-1-58007-111-6}}.
* Knaack, Marcelle Size. ''Encyclopedia of US Air Force Aircraft and Missile Systems: Volume 1 Post-World War II Fighters 1945–1973''. Washington, DC: Office of Air Force History, 1978. {{ISBN|0-912799-59-5}}.
* Pace, Steve. ''X-Fighters: USAF Experimental and Prototype Jet Fighters, XP-59 to YF-23''. St. Paul, Minnesota: Motorbooks International, 1991. {{ISBN|0-87938-540-5}}.
* Taylor, John W. R. & Michael J. H. ''Jane's Pocket Book of Research and Experimental Aircraft''. Collier Books: New York, 1977 {{ISBN|0-356-08405-1}}.
* Watson, Heidi. "Daddy of the Deltas." ''The Friends Journal'', U.S. Air Force Museum, Winter 1997/1998.
* Winchester, Jim. ''X-Planes and Prototypes''. London: Amber Books Ltd., 2005. {{ISBN|1-904687-40-7}}.
* Yenne, Bill. ''Convair Deltas from SeaDart to Hustler''. Specialty Press: North Branch, MN, 2009. {{ISBN|978-1-58007-118-5}}.

==External links==
{{Commons category|Convair XF-92}}
*[http://www.dfrc.nasa.gov/Gallery/Photo/XF-92A/index.html Curry, Marty. "XF-92A". ''Dryden Flight Research Center,'' 16 May  2006.  Retrieved: 4 September 2006. Numerous images of the XF-92.]
*{{Internet Archive short film | gov.archives.arc.66653 | Research Tests of Convair Model 7002 Airplane }}

{{Convair aircraft}}
{{USAF fighters}}
{{Authority control}}

{{DEFAULTSORT:Convair Xf-92}}
[[Category:Convair aircraft|F-092]]
[[Category:1940s United States experimental aircraft]]
[[Category:1940s United States fighter aircraft]]
[[Category:Single-engined jet aircraft]]
[[Category:Tailless delta-wing aircraft]]
[[Category:Aircraft first flown in 1948]]
[[Category:Mid-wing aircraft]]
[[Category:Aircraft with retractable tricycle landing gear]]