F-106 "Delta Dart"
The F-106 began development as an improved version of the F-102 Delta Dagger all-weather interceptor. Originally known as the F-102B, extensive structural and system changes resulted in the aircraft being redesignated as an F-106. The delta wing remained substantially unchanged, but the fuselage was modified to accommodate more powerful Pratt & Whitney J-75 turbojet. Engine intakes were re-located behind the cockpit and were variable for optimum engine performance at all speeds. The cockpit was moved forward relatively, and the shape of the fin and rudder changed. A new undercarriage was fitted, with steerable twin nose wheels. First flight was December 26, 1956, and delivery began to Air Defense Command units in July 1959. The F-106 attained initial operational capability with ADC in October 1959. The F-106 remained the mainstay of the U. S.'s air defense until 1988 when the last Delta Darts were withdrawn from service.
Convair F 106, like the preceding F-102, grew out of the company's delta wing XF-92A an American application of Germany's wartime theories and preliminary testing. The F-106 and F-102 in fact originated as only one aircraft, the so called "1954 Ultimate Interceptor." The F-102E designation of the ultimate interceptor was changed to F-106. The redesignation symbolized the past technical differences that had distorted the original F-102 program. It also recognized that further changes could be forthcoming. Two months after the F-102B's redesignation, the Air Force practically re endorsed the production policy originally outlined for the "1954 ultimate interceptor." On 18 August 1956 it issued a system development directive calling for concurrent development and production of the new F-106, a procedure responsible for several later problems.
Convair test flew the F-106 for the first time on 26 December 1956, 38 months after the F-102A (the Air Force's first supersonic deltawing interceptor) made its first flight. The second F-106 prototype, after being also transported from its San Diego plant to Edwards AFB, was initially flown on 26 February 1957.
The F-106 was fitted with the sophisticated Hughes MA-1 electronic and fire control system and worked in conjunction with the SAGE (Semi-Automatic Ground Environment) defense system. The MA-1 took over control of the plane shortly after takeoff and guided it to the proper altitude and attack position. The system would then lock on and fire the F-106 weapons at the intruder aircraft, and return the plane to the vicinity of its air base, where the pilot took over control for landing.
Instant recognition features of the F-106 are the distinctive low-mounted delta wing, fuselage-mounted inlets just forward of the wing and absence of a horizontal tail. The F-102A can be distinguished from the F-106 by its pointed vertical tail and by inlets located farther forward and lower down on the fuselage than on the F-106. As with the F-102A, the F-106 was carefully area ruled to reduce the drag rise accompanying an increase in Mach number from subsonic to supersonic values. This careful attention to drag reduction, together with the large 24 000-pound-thrust (with afterburning) Pratt & Whitney J75 turbojet engine, gave the Delta Dart a maximum speed of 1525 miles per hour (M=2.31) at 40000 feet and the capability of climbing to its combat ceiling of 51 800 feet in 6.9 minutes; service ceiling was 52 700 feet. Together with excellent handling qualities, the high maximum speed and good climb characteristics of the F-106 have made it an outstanding interceptor that first began to replace the F-102 in 1960.
Roll and pitch control of the F-106 is provided by elevons, which are flaplike movable surfaces on the trailing edge of the wing. Working in phase in response to fore and aft motions of the control stick, these surfaces provide longitudinal control moments about the pitch axis; differential deflection of the surfaces in response to lateral movement of the stick gives roll control. The lack of a horizontal tail for pitch trim prevents the use of high-lift flaps on the wing. The landing speed of the 34 510-pound-gross-weight airplane is maintained at an acceptable value (173 mph) by the large wing area of nearly 700 square feet, which gives a relatively low wing loading of 49.5 pounds per square foot.
Primary armament of the F-106 consists of a Genie missile with nuclear warhead and four Falcon, radar-homing, infrared, heat-seeking missiles. Immediately after takeoff on an interception mission, control of the aircraft passes from the pilot to a ground controller who, by radio signals to the autopilot, directs the aircraft to the vicinity of the enemy intruder as displayed on a radar scope. Once within range of the enemy aircraft, the radar on board the Delta Dart locks onto the intruder, guides the interceptor to a favorable attack position, and initiates firing of the missiles. Then ground control again takes over and flies the aircraft back to its base where the pilot performs the landing. Throughout this automatic mission, the pilot can at any time assume manual control of the aircraft.
Only 340 of the much more capable F-106's were built, the last of which came off the production line in 1961. The relatively few F-106's manufactured, as compared with the number of F-102A's, reflects the changing nature of the threat from enemy bombers to ballistic missiles that took place in the 1960's. Although still in use after more than 20 years, the F-106 was gradually replaced in the air-defense role by an interceptor version of the McDonnell Douglas F-15 Eagle. In contrast with most fighter aircraft adapted to a variety of missions, the F-102A and the F-106 were never employed for any role other than interception.
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