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The Bell D-188A (unofficial military designations XF-109/XF3L) was a proposed eight-engine
Mach The Mach number (M or Ma), often only Mach, (; ) is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a Boundary (thermodynamic), boundary to the local speed of sound. It is named after the Austrian physi ...
2–capable
vertical take-off and landing 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-wing ...
(VTOL) tiltjet fighter that never proceeded past the mock-up stage.


Development

In 1955, Bell Aircraft was requested by both the USAF and the US Navy to develop a VTOL/STOVL supersonic, all-weather fighter-bomber and defence interceptor. The project was highly ambitious and was designed to fulfill a multitude of roles for two different services. The aircraft was designated the Model 2000, and was offered in two different versions – the D-188 for the Navy and the D-188A for the Air Force. Bell had rather optimistically called the Navy version the XF3L-1 and the Air Force version the XF-109, although neither of these designations were official. In 1959, Bell teamed with
Convair Convair, previously Consolidated Vultee Aircraft Corporation, 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 ...
to form a joint weapon
systems management Systems management is enterprise-wide System administration, administration of distributed systems including (and commonly in practice) computer systems. Systems management is strongly influenced by network management initiatives in telecommunic ...
team in order to push the XF-109 program.Industry Observer
// ''Aviation Week & Space Technology'', February 9, 1959, v. 70, no. 6, p. 23. On 5 December 1960, Bell publicly showed off the design as the XF-109 – the Air Force version, as the Navy had lost interest the year earlier, however in the spring of 1961, the US Air Force canceled the program and no examples were built.


Designation

The military designations were not official and were speculative on the part of Bell. The Navy's XF3L-1 was not assigned, but would have been the D-188's designation had the aircraft been built, as this was the next in the US Navy's number series. The Air Force XF-109 designation had previously been assigned to a proposed Convair F-106B variant, however, had subsequently been left blank and Bell assumed – if the D-188A had been built – that this would have been assigned to the aircraft. Many reference works refer to the D-188A by its assumed experimental series number, but in fact the XF-109 designator was never assigned.


Design

The aircraft was unconventional, and consisted of a long, thin,
area rule The Whitcomb area rule, named after NACA engineer Richard Whitcomb and also called the transonic area rule, is a design procedure used to reduce an aircraft's drag at transonic speeds which occur between about Mach 0.75 and 1.2. For supersoni ...
d fuselage with a large fin and all-moving
stabilator A stabilator is a fully movable aircraft horizontal stabilizer (aircraft), stabilizer. It serves the usual functions of longitudinal stability, control and stick force requirements otherwise performed by the separate parts of a conventional hori ...
s in the tail. The single seat
cockpit A cockpit or flight deck is the area, on the front part of an aircraft, spacecraft, or submersible, from which a pilot controls the vehicle. The cockpit of an aircraft contains flight instruments on an instrument panel, and the controls th ...
was in the extreme nose and the small-span wing was mounted high on the
fuselage The fuselage (; from the French language, French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds Aircrew, crew, passengers, or cargo. In single-engine aircraft, it will usually contain an Aircraft engine, engine as wel ...
. At the ends of each wing were pods that contained two
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 ...
s each. These pods were designed to swivel through an arc of 100° (horizontal to 10° past vertical) to allow for both horizontal and vertical flight. To take off vertically, the pods were rotated to direct the engine's
thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that ...
downward, while for horizontal flight the pods were rotated back to the horizontal. The pods were capable of directing thrust slightly forward as well for enhanced landing maneuvers. In addition to the four wing engines, four engines were also mounted in the fuselage – two in the rear directed out of two separate tail ducts, and two liftjets directly aft of the cockpit and positioned vertically to aid in VTOL operation, exhausting out of two ventral ducts. The D-188A featured an engine bleed system to assist in vertical lift and maneuvering. Bleed air from the fuselage engine compressors would have been directed to a pair of thrusters in the nose and two more in the tail to aid in pitch, roll and yaw movements. Armament would have consisted of two 20mm cannon in the fuselage, an internal weapons bay and eight wing hard points for missiles and other ordnance.


Specifications (D-188A, as designed)


See also


References


Bibliography

* Jenkins, Dennis R. and Tony R. Landis. ''Experimental & Prototype U.S. Air Force Jet Fighters''. Minnesota, US: Specialty Press, 2008. . * Townend, David R. ''Clipped Wings – The History of Aborted Aircraft Projects'', Markham, Ontario, AeroFile Publications, 2007, .
Designation system





External links


USAF Museum Bell XF-109
*
Picture of the mock-up
{{DEFAULTSORT:Bell D-188a Cancelled military aircraft projects of the United States Tiltjet aircraft D-188 Aircraft with auxiliary jet engines