The Convair XF-92 (re-designated from XP-92 in 1948) was an

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

delta wing A delta wing is a wing shaped in the form of a triangle. It is named for its similarity in shape to the Greek uppercase letter delta (Δ). Although long studied, it did not find significant applications until the Jet Age, when it proved suitabl ...

, first-generation jet prototype. Originally conceived as a

point-defence Point defence (or point defense; see spelling differences) is the defence of a single object or a limited area, e.g. a ship, building or an airfield, now usually against air attacks and guided missiles. Point defence weapons have a smaller range i ...

interceptor Interceptor may refer to: Vehicles * Interceptor aircraft (or simply "interceptor"), a type of point defense fighter aircraft designed specifically to intercept and destroy enemy aircraft * Ford Crown Victoria Police Interceptor, a police car * ...

, the design was later used purely for

experimental An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a ...

purposes and only one was built. However, it led Convair to use the delta-wing on a number of designs, including the F-102 Delta Dagger,

F-106 Delta Dart The Convair F-106 Delta Dart was the primary all-weather interceptor aircraft of the United States Air Force from the 1960s through to the 1980s. Designed as the so-called "Ultimate Interceptor", it proved to be the last specialist interceptor ...

B-58 Hustler The Convair B-58 Hustler, designed and produced by American aircraft manufacturer Convair, was the first operational bomber capable of Mach 2 flight. The B-58 was developed during the 1950s for the United States Air Force (USAF) Strategic Air ...

, the

US Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage of ...

F2Y Sea Dart The Convair F2Y Sea Dart was an American seaplane fighter aircraft that rode on twin hydro-skis during takeoff and landing. It flew only as a prototype, and never entered mass production. It is the only seaplane to have exceeded the speed of so ...

as well as the

VTOL A vertical take-off and landing (VTOL) aircraft is one that can take off and land vertically without relying on a runway. This classification can include a variety of types of aircraft including helicopters as well as thrust-vectoring fixed-wi ...

FY Pogo.

Design and development

Early work

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 A ramjet, or athodyd (aero thermodynamic duct), is a form of airbreathing jet engine that uses the forward motion of the engine to produce thrust. Since it produces no thrust when stationary (no ram air) ramjet-powered vehicles require an ass ...

".Jenkins and Landis 2008, p. 122. In August 1945, the

United States Army Air Forces The United States Army Air Forces (USAAF or AAF) was the major land-based aerial warfare service component of the United States Army and ''de facto'' aerial warfare service branch of the United States during and immediately after World War II ...

(USAAF), soon to be renamed the

United States Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...

, issued a proposal for a supersonic interceptor capable of speeds and reaching an altitude of in four minutes. Several companies responded, among which was Consolidated-Vultee, which submitted its design on 13 October 1945. This design featured swept wings and

V-tail The V-tail or ''Vee-tail'' (sometimes called a butterfly tail or Rudlicki's V-tailGudmundsson S. (2013). "General Aviation Aircraft Design: Applied Methods and Procedures" (Reprint). Butterworth-Heinemann. p. 489. , 9780123973290) of an aircraft ...

s, as well as a powerful propulsion system. Besides the ducted rocket, four rockets were positioned at the exhaust nozzle, along with the 19XB turbojet produced by Westinghouse. A proposal by

Consolidated Vultee Convair, previously Consolidated Vultee, was an American aircraft manufacturing company that later expanded into rockets and spacecraft. The company was formed in 1943 by the merger of Consolidated Aircraft and Vultee Aircraft. In 1953, it ...

(later Convair) was accepted in May 1946, with a proposal for a ramjet-powered aircraft, with a 45°

swept wing A swept wing is a wing that angles either backward or occasionally forward from its root rather than in a straight sideways direction. Swept wings have been flown since the pioneer days of aviation. Wing sweep at high speeds was first investigate ...

under USAAF

Air Materiel Command Air Materiel Command (AMC) was a United States Army Air Forces and United States Air Force command. Its headquarters was located at Wright-Patterson Air Force Base, Ohio. In 1961, the command was redesignated the Air Force Logistics Command wi ...

Secret Project MX-813. However,

wind tunnel Wind tunnels are large tubes with air blowing through them which are used to replicate the interaction between air and an object flying through the air or moving along the ground. Researchers use wind tunnels to learn more about how an aircraft ...

testing demonstrated a number of problems with this design.Baughe, r, Joe
"Convair XF-92A."
''USAF Fighters,'' 21 November 1999. Retrieved: 11 June 2011.

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.Hallion (1979) Ralph Shick, chief of aerodynamic research, later met Lippisch at

Wright-Patterson Air Force Base Wright-Patterson Air Force Base (WPAFB) is a United States Air Force base and census-designated place just east of Dayton, Ohio, in Greene County, Ohio, Greene and Montgomery County, Ohio, Montgomery counties. It includes both Wright and Patte ...

. 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 DM-1 test glider which the US had tested."Convair F-102"
''Flight International'', pp. 512–518. Power was to be provided by a

Westinghouse J30 The Westinghouse J30, initially known as the Westinghouse 19XB, was a turbojet engine developed by Westinghouse Electric Corporation. It was the first American-designed turbojet to run, and only the second axial-flow turbojet to run outside German ...

jet engine assisted by a battery of six 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 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 The Leduc 0.10 was a research aircraft built in France, one of the world's first aircraft to fly powered solely by a ramjet. Design and development Designed by René Leduc in 1938, it was built at the Breguet Aviation factory after a protracted, ...

and

Miles M.52 The Miles M.52 was a turbojet-powered supersonic research aircraft project designed in the United Kingdom in the mid-1940s. In October 1943, Miles Aircraft was issued with a contract to produce the aircraft in accordance with Air Ministry Sp ...

, placing the cockpit in a cylindrical body in the center of the intake. The design was presented to the

U.S. Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Sign ...

in 1946 and was accepted for development as the XP-92.Yenne 2009, p. 27.

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.Taylor 1977, p. 61. 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 North American FJ-1 Fury was the first operational jet aircraft in United States Navy service, and was developed by North American Aviation as the NA-135.Bell P-63 Kingcobra, the engine and hydraulics were taken from a

Lockheed P-80 Shooting Star The Lockheed P-80 Shooting Star was the first jet fighter used operationally by the United States Army Air Forces (USAAF) during World War II. Designed and built by Lockheed in 1943 and delivered just 143 days from the start of design, prod ...

, the ejection seat and cockpit canopy were taken from the cancelled

Convair XP-81 The Consolidated Vultee XP-81 (later redesignated ZXF-81) is a development of the Convair, Consolidated Vultee Aircraft Corporation to build a single seat, long range escort fighter that combined use of both turbojet and turboprop engines. Altho ...

, 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 North American Aviation (NAA) was a major American aerospace manufacturer that designed and built several notable aircraft and spacecraft. Its products included: the T-6 Texan trainer, the P-51 Mustang fighter, the B-25 Mitchell bomber, the F ...

took over the Vultee plants in summer 1947. The airframe was moved to Convair's plant in

San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eigh ...

, and completed in the autumn. In December it was shipped without an engine to

NACA The National Advisory Committee for Aeronautics (NACA) was a United States federal agency founded on March 3, 1915, to undertake, promote, and institutionalize aeronautical research. On October 1, 1958, the agency was dissolved and its assets ...

Ames Aeronautical Laboratory The Ames Research Center (ARC), also known as NASA Ames, is a major NASA research center at Moffett Federal Airfield in California's Silicon Valley. It was founded in 1939 as the second National Advisory Committee for Aeronautics (NACA) laborat ...

for wind tunnel testing. After testing was completed, the airframe was returned to San Diego, where it was fitted with a

Allison J33 The General Electric/Allison J33 is a development of the General Electric J31, enlarged to produce significantly greater thrust, starting at and ending at with an additional low-altitude boost to with water-alcohol injection. Development Th ...

-A-21 engine. By the time the aircraft was ready for testing, the concept of the

point-defense Point defence (or point defense; see spelling differences) is the defence of a single object or a limited area, e.g. a ship, building or an airfield, now usually against air attacks and guided missiles. Point defence weapons have a smaller range in ...

interceptor seemed outdated and the (now redesignated) F-92 project was cancelled. They also decided to rename the test aircraft as the XF-92A.

Operational history

In April 1948 the XF-92A was shipped to Muroc Dry Lake (later to become

Edwards AFB Edwards Air Force Base (AFB) is a United States Air Force installation in California. Most of the base sits in Kern County, but its eastern end is in San Bernardino County and a southern arm is in Los Angeles County. The hub of the base is E ...

). 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,Yenne 2009, p. 29. with the testing being assigned to Frank Everest and

Chuck Yeager Brigadier General Charles Elwood Yeager ( , February 13, 1923December 7, 2020) was a United States Air Force officer, flying ace, and record-setting test pilot who in October 1947 became the first pilot in history confirmed to have exceeded the ...

. Yeager was the first Air Force pilot to fly the XF-92A on 13 October 1949. On his second flight he dove the aircraft in a 4 g

split-S The split S is an Aerobatic maneuver and an air combat maneuver mostly used to disengage from combat. To execute a split S, the pilot half-rolls their aircraft inverted and executes a descending half-loop, resulting in level flight in the op ...

dive, reaching Mach 1.05 for a brief time."XF-92A Dart."
''globalsecurity.org.'' Retrieved: 3 July 2011. 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 degrees pitch, flying under control in that attitude to a landing at , 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 . 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. A final engine change was made to the J33-A-16. On 9 April 1953,

Scott Crossfield Albert Scott Crossfield (October 2, 1921 – April 19, 2006) was an American naval officer and test pilot. In 1953, he became the first pilot to fly at twice the speed of sound. Crossfield was the first of twelve pilots who flew the North America ...

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 g, and on one occasion 8 g. The addition of

wing fence Wing fences, also known as boundary layer fences and potential fences are fixed aerodynamic devices attached to aircraft wings. Often seen on swept-wing aircraft, wing fences are flat plates fixed to the upper surfaces parallel to the wing ch ...

s partially alleviated this problem. Crossfield flew 25 flights in the XF-92A by 14 October 1953. After the aircraft's last flight the nose gear collapsed as Crossfield taxied off the lake bed and the aircraft was retired. 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."

Influence

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 ft² (39 m²) gave a low

wing loading In aerodynamics, wing loading is the total mass of an aircraft or flying animal divided by the area of its wing. The stalling speed of an aircraft in straight, level flight is partly determined by its wing loading. An aircraft or animal with a ...

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 In technical drawing and computer graphics, a multiview projection is a technique of illustration by which a standardized series of orthographic two-dimensional pictures are constructed to represent the form of a three-dimensional object. Up to ...

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

angles of attack In fluid dynamics, angle of attack (AOA, α, or \alpha) is the angle between a reference line on a body (often the chord line of an airfoil) and the vector representing the relative motion between the body and the fluid through which it is ...

(alpha), where a conventional layout would have stalled. The reason for this turned out to be the unexpected creation of a large

vortex In fluid dynamics, a vortex ( : vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in th ...

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 In aerodynamics, the flight envelope, service envelope, or performance envelope of an aircraft or spacecraft refers to the capabilities of a design in terms of airspeed and load factor or atmospheric density, often simplified to altitude. The t ...

of the delta could be greatly expanded, which led to the introduction of canards on most delta-wing designs in the 1960s and 1970s. More recently "mini-deltas", in the form of

leading edge extension A leading-edge extension (LEX) is a small extension to an aircraft wing surface, forward of the leading edge. The primary reason for adding an extension is to improve the airflow at high angles of attack and low airspeeds, to improve handling an ...

s, have become common on most fighter aircraft, creating the vortex over a more conventional wing planform.

Aircraft on display

*46-682 – Research & Development Gallery at the

National Museum of the United States Air Force The National Museum of the United States Air Force (formerly the United States Air Force Museum) is the official museum of the United States Air Force located at Wright-Patterson Air Force Base, northeast of Dayton, Ohio. The NMUSAF is the ...

, near

Dayton, Ohio Dayton () is the sixth-largest city in the U.S. state of Ohio and the county seat of Montgomery County. A small part of the city extends into Greene County. The 2020 U.S. census estimate put the city population at 137,644, while Greater Day ...

Operators

; *

Specifications (XF-92A)

Popular culture

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'', starring John Wayne and

Janet Leigh Jeanette Helen Morrison (July 6, 1927 – October 3, 2004), known professionally as Janet Leigh, was an American actress, singer, dancer, and author. Her career spanned over five decades. Raised in Stockton, California, by working-class parents, ...

. 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. It did appear in the film ''

Toward the Unknown ''Toward the Unknown'', originally called ''Flight Test Center'' and titled ''Brink of Hell'' in its UK release, is a 1956 American war film about the dawn of supersonic flight filmed on location at Edwards Air Force Base. Starring William Holden ...

'' (1956) starring William Holden, again in the guise of another aircraft, this time, the F-102 Delta Dagger.Watson 1997/1998, p. 9.

Notes

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. . * Hallion, Richard P. "Convair's Delta Alpha". ''Air Enthusiast Quarterly'', No. 2, n.d., pp. 177–185. *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. 1–10.
JSTOR copy
. * Jenkins, Dennis R. and Tony R. Landis. ''Experimental & Prototype U.S. Air Force Jet Fighters.'' North Branch, Minnesota, USA: Specialty Press, 2008. . * 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. . * Pace, Steve. ''X-Fighters: USAF Experimental and Prototype Jet Fighters, XP-59 to YF-23''. St. Paul, Minnesota: Motorbooks International, 1991. . * Taylor, John W. R. & Michael J. H. ''Jane's Pocket Book of Research and Experimental Aircraft''. Collier Books: New York, 1977 . * 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. . * Yenne, Bill. ''Convair Deltas from SeaDart to Hustler''. Specialty Press: North Branch, MN, 2009. .

External links

* {{DEFAULTSORT:Convair Xf-92 1940s United States experimental aircraft 1940s United States fighter aircraft F-092 Single-engined jet aircraft Tailless delta-wing aircraft Aircraft first flown in 1948