The Grumman XF10F Jaguar was a
prototype
A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototyp ...
swing-wing
A variable-sweep wing, colloquially known as a "swing wing", is an airplane wing, or set of wings, that may be swept back and then returned to its original straight position during flight. It allows the aircraft's shape to be modified in fli ...
fighter aircraft
Fighter aircraft are fixed-wing military aircraft designed primarily for air-to-air combat. In military conflict, the role of fighter aircraft is to establish air superiority of the battlespace. Domination of the airspace above a battlefield ...
offered to the
United States 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 ...
in the early 1950s. Although it never entered service, its research paved the way toward the later
General Dynamics F-111 and Grumman's own
F-14 Tomcat
The Grumman F-14 Tomcat is an American carrier-capable supersonic aircraft, supersonic, twinjet, twin-engine, two-seat, twin-tail, variable-sweep wing fighter aircraft. The Tomcat was developed for the United States Navy's Naval Fighter Experi ...
.
Design and development
The Navy's interest in the variable-geometry wing was based on concerns that the ever-increasing weight of its jet fighters was making
aircraft carrier
An aircraft carrier is a warship that serves as a seagoing airbase, equipped with a full-length flight deck and facilities for carrying, arming, deploying, and recovering aircraft. Typically, it is the capital ship of a fleet, as it allows a ...
operations troublesome. Many of its existing aircraft already had marginal carrier performance, and the trend in weight growth was obviously upward. At the same time, the demands for high-speed performance demanded
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 ...
layouts that did not lend themselves to good takeoff characteristics. The prospect of combining the two in a single aircraft was enticing.
Originally conceived as a swept-wing version of the earlier
F9F Panther, in February–March 1948, the design was reconfigured with a T-tail and ultimately a variable-geometry wing.
[Winchester 2005, p. 294.] It featured a T-tail, with the horizontal stabilator, a small pivoting center body with a delta servo control at the nose and a larger rear delta main wing, mounted atop the vertical fin. The single
turbojet
The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...
engine was fed by cheek intakes. The high, shoulder-mounted wing could be moved to two positions: a 13.5° sweep for takeoff and landing and a 42.5° sweep for high-speed flight.
The unique horizontal stabilizer design was free-floating; the attached small foreplane was directly controlled by the pilot and pulled the stabilizer up or down; so, it was aerodynamically, not mechanically controlled, and this resulted in sluggish pitch control, increasingly so at low speeds where airflow over the small foreplane was lessened, and if the project had developed further, it probably would have been replaced by a conventional all-flying
tailplane
A tailplane, also known as a horizontal stabiliser, is a small lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters and gyroplane ...
. The unpredictable behavior of the design often caused
pilot-induced oscillation
Pilot-induced oscillations (PIOs), as defined by MIL-HDBK-1797A, are ''sustained or uncontrollable oscillations resulting from efforts of the pilot to control the aircraft''. They occur when the pilot of an aircraft inadvertently commands an oft ...
s, with the sudden and erratic deployment of leading edge slats causing the aircraft to be nearly uncontrollable much of the time.
[DeMeis 1976, p. 32.]
The XF10F-1 was not armed, but production aircraft would likely have had four 20 mm (.79 in) cannon and pylons for bombs and rockets, like other contemporary Navy fighters.
Testing
![XF10F](https://upload.wikimedia.org/wikipedia/commons/0/0d/XF10F.jpg)
The Jaguar's configuration presented many of the same handling problems as the earlier
Bell X-5
The Bell X-5 was the first aircraft capable of changing the sweep of its wings in flight. It was inspired by the untested wartime P.1101 design of the German Messerschmitt company. In contrast with the German design, which could only have its ...
experimental aircraft, with some vicious spin characteristics.
The Jaguar's development was hampered by its use of the chronically unreliable
Westinghouse J40
The Westinghouse J40 was an early high-performance afterburning turbojet engine designed by Westinghouse Aviation Gas Turbine Division starting in 1946 to a US Navy Bureau of Aeronautics (BuAer) request. BuAer intended to use the design in severa ...
turbojet, which, as on other aircraft of this period, made the Jaguar dangerously underpowered and prone to various engine-related problems. The J40 developed only 6,800 lbf (30.2 kN) thrust rather than the anticipated 11,000 lbf (49 kN), and its troubles ultimately proved to be insurmountable.
[Winchester 2005, p. 295.]
Test pilot
A test pilot is an aircraft pilot with additional training to fly and evaluate experimental, newly produced and modified aircraft with specific maneuvers, known as flight test techniques.Stinton, Darrol. ''Flying Qualities and Flight Testing ...
Corwin "Corky" Meyer, the only pilot to fly the Jaguar,
[DeMeis 1976, p. 46.] described it as entertaining to fly "because there was so much wrong with it."
[''Air International'', VG Special Issue, 1977.]
Examples of the "wrongness" encountered by Meyer during the test flight program included:
*Jamming of the wing sweep mechanism as
hydraulic fluid
A hydraulic fluid or hydraulic liquid is the medium by which power is transferred in hydraulic machinery. Common hydraulic fluids are based on mineral oil or water. Examples of equipment that might use hydraulic fluids are excavators and backhoe ...
congealed into a gelatinous state from poor maintenance, resulting in a substance with "a consistency of
Jell-O
Jell-O is an American brand offering a variety of powdered gelatin dessert (fruit-flavored gels/jellies), pudding, and no-bake cream pie mixes. The original gelatin dessert (genericized as jello) is the signature of the brand. "Jell-O" is a reg ...
". Despite this failure, the aerodynamicist's assertion that the wing would unsweep itself in case of a mechanical failure proved entirely correct, to Meyer's relief.
*Regular inflight failures of the equally experimental Westinghouse XJ-40 turbojet. The reason for its unreliability within the Jaguar was traced ultimately to an extraordinary case of sloppy manufacture; an engine electronics box access panel had a screw nearly 5 in (127 mm) long mangling the delicate circuits within, in sharp contrast to the other three panel screws which were barely .4 in (10 mm) long.
*The "aerodynamically balanced" canard-actuated pendulum elevator, whose ineffectiveness and poor contribution to stability was already apparent in free-flight development models. The instability was dismissed as a "model effect", but this proved to be a fallacious judgement. Initial fixes consisted of a set of triangular horizontal fins on the rear fuselage, but ultimately Grumman admitted defeat and retroactively fitted the horizontal surfaces from the earlier
Grumman F-9 Cougar swept-wing fighter. By this time the program was nearing its end, and it was at this stage unlikely that the U.S. Navy would adopt the Jaguar.
*During a flight the canopy opened and could not be closed, nor could it be ejected. At the same time, the less-than-trustworthy engine began losing power at an alarming rate, but, due to the problems with the canopy, Corky Meyer could not eject. He did manage to land safely. It was just after this flight that the aforementioned grossly oversized screw was found.
He found the translating wing-sweep mechanism, similar to the
Bell X-5
The Bell X-5 was the first aircraft capable of changing the sweep of its wings in flight. It was inspired by the untested wartime P.1101 design of the German Messerschmitt company. In contrast with the German design, which could only have its ...
's, (which was much more complicated than the one later adopted by the F-111, F-14 and
Panavia Tornado
The Panavia Tornado is a family of twin-engine, variable-sweep wing multirole combat aircraft, jointly developed and manufactured by Italy, the United Kingdom and West Germany. There are three primary Tornado variants: the Tornado IDS (inter ...
''et al.''), to be the only feature that worked flawlessly. The Navy was not encouraged by the results, and the development of larger carriers with
angled flight deck
The flight deck of an aircraft carrier is the surface from which its aircraft take off and land, essentially a miniature airfield at sea. On smaller naval ships which do not have aviation as a primary mission, the landing area for helicopter ...
s and steam-driven
catapult
A catapult is a ballistic device used to launch a projectile a great distance without the aid of gunpowder or other propellants – particularly various types of ancient and medieval siege engines. A catapult uses the sudden release of stored p ...
s made the swing-wing configuration unnecessary.
The prototype XF10F-1 first flew on 19 May 1952. It was used for some 32 test flights throughout the year,
but in April 1953, the Navy canceled the program, and with it, the 112 production aircraft that had been ordered. The sole flying aircraft and the uncompleted second prototype were shipped to
Naval Air Material Center
A navy, naval force, or maritime force is the branch of a nation's armed forces principally designated for naval and amphibious warfare; namely, lake-borne, riverine, littoral, or ocean-borne combat operations and related functions. It inc ...
in
Philadelphia
Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...
for barricade testing, and the static test aircraft was later used as a gunnery target.
Specifications (XF10F-1)
See also
References
Notes
Bibliography
*DeMeis, Richard. "No Room to Swing a Cat." ''Wings'', Volume 6, No. 4, August 1976.
*Jones, Lloyd S. ''US Naval Fighters 1922 to 1980s''. Fallbrook, California: Aero Publishers, 1977. .
*Francillon, Rene. ''Grumman Aircraft Since 1929''. Annapolis, Maryland: Naval Institute Press, 1989. .
*Winchester, Jim. ''The World's Worst Aircraft: From Pioneering Failures to Multimillion Dollar Disasters''. London: Amber Books Ltd., 2005. .
{{USN fighters
F10F Jaguar
Grumman F10F
Single-engined jet aircraft
High-wing aircraft
Variable-sweep-wing aircraft
Carrier-based aircraft
T-tail aircraft