F-106 Delta Dart, Convair


F-106 Delta Dart

Development of the F-102 with significantly higher performance. The F-106 was primarily an interceptor, integrated in the computer-radar controlled SAGE network. It was a versatile aircraft that proved to be also an excellent dogfighter; it served many years with the USAF, armed with Falcon missiles, Genie nuclear-tipped rockets, and a later added 20mm Vulcan cannon. The last was retired in 1988. 341 built.

Type: F-106A Delta Dart
Function: fighter
Year: 1959
Crew: 1
Engines: 1 * 11130kg P&W J75-P-17
Wing Span: 11.67m
Length: 21.56m
Height: 6.18m
Wing Area: 64.83m2
Empty Weight: 10957kg
Max.Weight: 18974kg
Max. Speed: 2020km/h
Ceiling: 17400m
Max. Range: 4300km
Armament: msl. A 20mm cannon was added later.
Unit cost: 3,305,435 USD


F-106A

The Convair F-106A Delta Dart is regarded by many as being the finest all-weather interceptor ever built. It served on active duty with the US Air Force for almost 28 years, much longer than most of its contemporaries.

The F-106 had its origin in an early-1949 request by the USAF for an advanced interceptor capable of supersonic performance that would surpass the speed and altitude performance of new Soviet intercontinental bombers which intelligence services warned would soon be available. The North American F-86D Sabre, the Northrop F-89 Scorpion, and the Lockheed F-94 Starfire were all subsonic aircraft, and were deemed to have insufficient growth potential to be able to meet this new threat. This project came to be known as the "1954 Interceptor", after the year that new interceptor would supposedly be entering service.

At that time, the Air Force recognized that the increasing complexity of modern weapons made it no longer practical to attempt to develop equipment, airframes, electronics, engines, and other components in isolation and to expect them to work properly when they were put together in the final product. To address this problem, the Air Force introduced the "weapons system" concept, in which components of the the new interceptor would be integrated with each other from the very beginning, making sure that the various systems would be compatible with each other when they were incorporated into the final aircraft. The project was given the designation WS-201A, where WS stood for "Weapons System". As originally conceived, WS-201A was a weapons system consisting of air-to-air guided missiles, all-weather search and fire control radar, all housed in an airframe capable of supersonic flight.

The electronics package for the new WS-201A system came first. Project MX-1179 was the designation given to that portion of the project dedicated to the armament and electronic fire-control system of the 1954 Interceptor. In October of 1950, the Hughes Aircraft Company was named the winner of the MX-1179 contract. The Hughes proposal consisted of a MA-1 fire control system acting in conjunction with GAR-1 Falcon air-to-air guided missiles. For a brief time, the Falcon missile was known as the F-98, a fighter designation.

The airframe part of the project was designated MX-1554. Proposals for the airframe portion were requested by the Air Force on June 18, 1950. When the bidding closed in January of 1951, nine proposals had been submitted by six different manufacturers. Republic submitted three separate proposals, North American submitted two, and single proposals were made by Chance-Vought, Douglas, Lockheed, and Convair.

On July 2, 1951, the Air Force announced that designs by Convair, Lockheed, and Republic had been selected to proceed with preliminary development. All three companies were to proceed with their designs all the way to the mockup stage, with the design deemed most promising at that time being awarded a production contract. Later, the USAF deemed it too costly to carry through with three concurrent development programs, and it cancelled the Lockheed project in its entirety. The Convair and Republic entries were given the go-ahead to proceed.

The Republic entry bore the company designation of AP-57, where the AP stood for "Advanced Project". It called for an extremely advanced aircraft capable of achieving a Mach 4 performance at altitudes of up to 80,000 feet. This was clearly a quantum leap in the state of the art for the early 1950s.

The Convair entry in the MX-1554 project was closely related to the experimental XF-92A which Convair had built in 1948 as a test bed to provide data for the proposed F-92 Mach 1.5 fighter. This work had been performed in consulation with Dr. Alexander Lippisch, who had done pioneering work in Germany on delta-winged aircraft during the war, and Convair had become convinced that the delta configuration provided a viable solution to the problems of supersonic flight. The XF-92A had been the first powered delta-wined aircraft to fly, but the F-92 project had itself been cancelled before any prototype could be built.

On September 11, 1951, Convair received a contract for its delta winged design which was assigned the designation F-102. Work on the competing Republic design was also authorized, and that aircraft was assigned the designation XF-103. However, the XF-103 was so far ahead of the state of the art that it was deemed too risky to be a serious contender for the 1954 Interceptor project, which made the F-102 for all practical purposes the winner of the contest.

The Air Force authorized the fitting of a Westinghouse J40 turbojet in the first few examples of the F-102, but later production aircraft were to be powered by the appreciably more-powerful Wright J67 turbojet, which was a license-built version of the Bristol Olympus. The J40-powered F-102 was to be capable of a speed of Mach 1.88 at 56,500 feet, with the J67 production version capable of Mach 1.93 at 62,000 feet.

In order to expedite the development of its 1954 Interceptor program, the Air Force adopted the so-called "Cook-Craigie" program, named for its originators, Generals Laurence C. Craigie and Orval R. Cook. During the late 1940s, these two officers had developed a concept of an aircraft development program in which the usual prototype stage would be skipped. Instead of waiting to start full-scale production until the prototypes had passed flight testing and the bugs had been ironed out, the Cook-Craigie plan called for the delivery of a small number of production aircraft during the flight testing phase so that any major changes could be incorporated into permanent factory tooling in order for combat-ready aircraft to be delivered when mass production started. This program is inherently risky --- it can produce a new combat aircraft in a hurry if everything goes according to plan during flight testing, but can result in a lot of costly and time-consuming fixes in the field if unexpected problems turn up. The Cook-Cragie plan is really viable only if there is a high degree of confidence that the aircraft is really going to go into production. Since the F-102 was basically a scaled-up XF-92A, the risk was deemed work taking.

By December of 1951, it was apparent that the Wright J67 engine and the MA-1 fire-control system would not be ready in time. This forced the USAF to change its plans. At that time, the Air Force decided to proceed with an interim version of its 1954 Interceptor, one which could be introduced into service at an early date, pending the availability of the fully-developed version at a later time. The interim version was to be designated F-102A, with the fully-developed advanced version being designated F-102B. The F-102A was to be powered by the less-powerful Pratt & Whitney J57 turbojet, but the F-102B was to retain the high-thrust J67. The F-102A would be equipped with an interim fire-control system, but the F-102B would be equipped from the outset with the highly-sophisticated fire control system being developed by Hughes under project MX-1179.

Although the F-102A was considered only as an interim version pending the availability of the F-102B, the F-102A ran into some unexpected developmental difficulties and fell behind schedule. A lot of money that had originally been planned for the F-102B now had to be diverted into fixing the F-102A's problems. Consequently, the F-102B fell even further behind schedule and began to lose some of its original high priority.

By mid-1953, the MX-1179 fire control system (later to be known as the MA-1) was slipping badly, and it took another year before an experimental installation could be installed aboard a T-29B for testing. At the same time, the Wright J67 engine was experiencing difficulties of its own. The Air Force had to consider alternative powerplants, and finally settled on the Pratt & Whitney J75, which was an advanced version of the J57 which was used in the F-102A. The substitution of the J75 engine for the J67 was approved in early 1955.

Seventeen F-102Bs were ordered in November of 1955. Their serials were 56-0451/0467. The F-102B mockup was ready for inspection in December of 1955. On April 18, 1956, the Air Force finalized the F-102B production contract of the previous November, earmarking all of the 17 aircraft ordered exclusively for testing. One prototype was to be delivered in December of 1956, with the others to follow in January of 1957.

On June 17, 1956, the designation of the F-102B was changed to F-106A. This redesignation was a recognition of the past technical differences that had distorted the original F-102 program and also a recognition that the F-102B was by now a completely different aircraft from the F-102A and was far more advanced.

In September of 1956, the Air Force specified that the F-106A would be available by August of 1958 (some four years later than initially planned) and that it had to compatible with the Semi-Automatic Ground Environment (SAGE) up to a radius of 430 miles and as altitude of 70,000 feet. Interceptions would be accomplished at speeds of up to Mach 2 at 35,000 feet. It was to be capable of launching air-to-air guided missiles and rockets under the control of the Hughes MA-1 fire control system.

The wing of the F-106A was virtually identical to that of the F-102A, but the fuselage had a much more streamlined shape. The variable-ramp air intakes were moved well aft of the nose and mounted closer to the engine. The shape of the fin and rudder were changed and a new undercarriage was fitted with steerable twin-nosewheels. As on the F-102A, the all-missile armament was housed internally in a spacious ventral weapons bay. The all-missile armament consisted of a single Douglas MB-1 (Air-2A or 2B) Genie unguided missile equipped with a nuclear warhead plus four Hughes GAR-3 radar- homing or GAR-4 infrared-homing (later redesignated AIM-4E and AIM-4G respectively) air-to-air missiles. The Falcons were equipped with conventional high-explosive warheads and could be launched in salvo or in pairs. The unguided 2.75-inch missile armament of the F-102A was omitted.

The first F-106A (56-0451) was finally available by the end of 1956. The first flight was made by Richard L. Johnson at Edwards AFB on December 26, 1956. The second aircraft (56-0452) followed on February 26, 1957. They were both powered by the J75-P-9 engine. Early testing reached a speed of Mach 1.9 and an altitude of 57,000 feet, but this was still below expectations. In addition, the F-106A's acceleration was well below Convair's estimates, and it took almost 4 1/2 minutes to accelerate from Mach 1 to Mach 1.7 and another 2 1/2 minutes to accelerate to Mach 1.8. With such poor acceleration, it was felt that Mach numbers above 1.7 would not be tactically usable.

The poor speed and acceleration was cured by altering the aircraft's air intake cowling and charging ejectors. The capture area of the intake ducts was enlarged and the duct lips were thinned down. There were also problems with the reliability of the J75-P-9 engine. Eventually, the more powerful J75-P-17 engine was substituted, which was rated at 17,200 lb.s.t. dry and 24,500 lb.s.t. with afterburner. There were further problems with the MA-1 fire control system and with the cockpit layout. Originally, the control column had occupied the traditional center location, but was later moved to the side at USAF insistence in order to ensure an unrestricted view of the Horizontal Situation Indicator. This arrangement turned out not to be viable, and the control column was later moved back to the center and provided with a two-handed grip for both radar and aircraft control.

Initial aircraft had boundary layer fences as on the F-102, but production aircraft had wing leading-edge slots instead. The first twelve aircraft were temporarily designated JF-106A for flight tests, but a total of thirty-seven (including the first two aircraft) were used for flight test development.

In mid-1957, the F-106A was given the popular name Delta Dart.

Originally, the Air Force had planned to acquire 1000 Delta Darts to equip some forty Air Defense Command (ADC) squadrons. However, by 1957 the delays in the F-106 program and the problems with the engine and the fire control system had resulted in the necessity of other interceptors such as the McDonnell F-101B Voodoo having been ordered as a stop-gap measure, and the F-106 had lost some of its urgent priority. For a while, serious consideration was given to cancelling the entire F-106 program, or else to redesigning the aircraft as a long-range interceptor. Although the F-106 survived intact, shortages of funds caused a drastic cutback in the number of F-106As on order. By September 1958 the total order of F-106 interceptors had been cut by a factor of three, enabling only fourteen squadrons and a training unit to be equipped. As a result, only a further 260 F-106As were ordered. Since the cutback was so drastic, a decision mas made in August of 1959 to convert all of the existing 35 F-106A test aircraft to operational status (Model 8-24 standards) and turn them over to the interceptor squadrons.

In September of 1958, an early F-106A (serial number 57-0235) was allocated to Ames Research Center at Moffett Field in California for tests of the MA-1 fire control system.

The first deliveries of the F-106A were made in May of 1959, initially equipping the 498th Fighter Interceptor Squadron based at Geiger AFB in Washington. This was no less than five years later than originally planned. Even then, numerous problems kept the Delta Dart from being declared fully operational until October 31, 1959. The remaining 13 squadrons were re-equipped with the F-106A by the end of 1960.

Initial operational deployment turned up all sorts of problems --- generator defects, fuel-flow deficiencies (particularly acute in cold weather), and fuel-combustion-starter malfunctions. In December of 1959, after a canopy had been accidentally jettisoned in flight, all F-106s were temporarily grounded until the problem could be fixed.

Production continued until December of 1960, the last aircraft off the line being delivered as Model 8-31s. which were equipped with improved MA-1 fire control systems, supersonic ejector seats, vertical instrument displays, wings with revised camber (first tested on 57-0246), and with provision for 230 US-gallon external fuel tanks mounted on pylons underneath the wings. The last 37 F-106A production aircraft were provided with a better supersonic ejector seat that would also work safely at low speeds. This new seat featured a dual timing system one for low-altitude/low-speed ejection and one for high-altitude/high-speed ejection.

Flight testing continued until early 1961, with each phase of the test program turning up a whole host of problems which required important engineering changes. Each change had to be defined, engineered, reviewed, and approved for production before modification of aircraft off the assembly line could begin. The Cook-Cragie production policy only made problems worse, and by 1960, the Air Defense Command had so many different F-106 configurations out in the field that maintenance support was a nightmare.

A major modification project named Wild Goose was initiated in September of 1960 to bring the earlier F-106s up to the latest production standard. Early in 1960, ADC could list 63 changes in the F-106A's fire control system and 67 changes in the airframe that would be required to make early F-106s equivalent to the machines currently coming off the production line. Lasting a full year, the program involved roving AMC field assistance teams supported by ADC maintenance teams working at ADC bases.

The last Delta Dart was delivered to the Air Force on July 20, 1961. On December 15, 1959, a Delta Dart flown by Major Joseph W. Rogers set a world's absolute speed record of 1515.6 mph at 40,500 feet.

Throughout its long service life, the F-106A was continually upgraded and improved. The Broad Jump modification program started in late 1960 was a long-term program for general improvements in the F-106A. This program was carried out by people at the Sacramento Air Material Area, and it extended through early 1963. Among the changes introduced by this program was the fitting of an infrared search-and-track sight that could operate at low altitudes and against varied backgrounds. The Dart Board program was another retrofit and modification program which took place in 1961-62. This program added a thermal flash blindness protection hood and a new Convair-designed ejector seat which rotated into a horizontal position so that the pilot was on his back before he ejected. In addition, the Dart Board program finally fixed a problem with flame-outs from fuel starvation which had affected earlier Delta Darts.

The MA-1 fire control system carried by the F-106A was initially quite unreliable and was subjected to lots of in-service modifications in an attempt to fix its chronic problems. In 1960, devices for long-range detection and electronic counter-countermeasures equipment were added, along with the capability for using angle chaff, silent lobing, and pulse-to-pulse frequency techniques. Anti-chaff devices were added in an effort to defeat enemy attempts to confuse the fire control system by dropping bits of radar-reflective strips. The modification programs involved 314 F-106As and were completed by the end of 1963.

In 1962, F-106As were fitted with a Sheaffer Spring Hook arrester system designed to engage wires at the end of the runway in the event of an landing overshoot, becoming the first USAF combat aircraft to be so equipped. The F-106A was definitely NEVER intended for carrier- based operations! :-)

In 1965, an new TACAN system was installed which used microelectronic circuits and was one-third the size and weight of the existing system. Zero-zero ejector seats were installed. Inflight refueling capability via a probe receptacle mounted on the fuselage behind the pilot was added in 1967. The ability to carry 360 US-gallon supersonic fuel tanks was added at the same time. In 1972, a clear canopy was fitted for improved vision.

The F-106A operated in conjunction with the SAGE (Semi-Automatic Ground Environment) network which was linked via the Hughes MA-1 fire-control system to the F-106. The MA-1 system was upgraded no less than 60 times during the Delta Dart's long service life. It operated by plotting the course needed to intercept an enemy aircraft, automatically sighted the target, fired the air-to-air missiles, and then automatically placed the F-106 on the correct course to disengage. The F-106 could actually be fully computer-flown during most of its mission, the pilot actually being needed only for takeoff, landing, or in case something went wrong with the automation.

The F-106A surprised everyone by having a good maneuverability and showing potential as being an excellent dogfighter. Consequently, an internal 20-mm M61A1 rotary cannon was fitted internally to some aircraft under the aegis of project Sharp Shooter. The cannon replaced the Genie nuclear-tipped missiles in the weapons bay. However, this innovation was not provided for the F-106B two-seater.

The F-106 served mainly in the continental United States, in Alaska, Iceland, and in Canada, but it did serve for short spells in Germany and South Korea. Although the F-106 was briefly deployed to Osan AFB in Korea in March of 1968 to provide air defense during the Pueblo incident, the Delta Dart never saw combat.

From 1972 onwards, the McDonnell Douglas F-15 Eagle gradually began to replace the Delta Dart in ADC squadrons. As they were removed from Air Force service, they were passed along to the Air National Guard, serving with ANG squadrons in California, Florida, Massachusetts, Michigan, Montana, and New Jersey. The last Delta Dart-equipped Air Force squadron, the 119th FIS based at Atlantic City, New Jersey flew its final alert duty on July 7, 1988. The ANG units continued to fly the last few Delta Darts for a few months longer after the USAF had relinquished the type.

In March of 1982, F-106A serial number 59-0123 was transferred to NASA's Langley Memorial Aeronautical Laboratory to serve as a spare for NASA's NF-106B #816 (ex-USAF serial number 57-2516).

During its long service life, the F-106A had the distinction of recording the lowest single-engined aircraft accident record in USAF history. As F-106As were withdrawn from active duty, they were ferried out to Davis-Monthan AFB in Arizona where they were placed in storage. In 1986, a contract was awarded to Flight Systems Inc. to modify 192 surplus Delta Darts stored at Davis-Monthan AFB in Arizona to QF-106A target drone configuration. This program came to be known as Pacer Six, and the first flight of a converted drone took place in July of 1987. Most of these drones were expended at Tyndall and Holloman AFB from the year 1989 onward.

Specification of F-106A:

One Pratt & Whitney J75-P-17 turbojet, 17,200 lb.s.t. dry and 24,500 lb.s.t with afterburning. Maximum speed: 1525 mph at 40,000 feet (Mach 2.31), 1327 mph at 35,000 feet. Landing speed was 173 mph Initial climb rate was 42,800 feet per minute. Service ceiling was 57,000 feet. Normal range was 575 miles. Maximum range with maximum external fuel was 1809 miles. Weights were 23,646 pounds empty, 38,700 pounds combat weight, 35,500 pounds gross, and 41,831 pounds maximum takeoff. Dimensions: wingspan 38 feet 3 1/2 inches, length 70 feet 8 3/4 inches, height 20 feet 3 1/4 inches, wing area 697.8 square feet. Maximum fuel load was 1440 US gallons. Armament consisted of one Douglas MB-1 (AIR-2A or 2B) Genie unguided missile with a nuclear warhead and four Hughes GAR-3 or GAR-4 (later redesignated AIM-4E and AIM-4G respectively) radar or infrared-homing missiles. All these missiles were housed within the internal weapons bay. In later installations, a single 20-mm M61A1 rotary cannon replaced the Genie nuclear-tipped missile in the internal weapons bay.

F-106B two-seater

The F-106B (Model 8-27) was a two-seat combat trainer version of the Delta Dart. 63 examples were ordered on August 3, 1956. The aircraft was originally intended as a pure trainer and was initially designated TF-102B and then later redesignated TF-106A. The designation F-106B was eventually chosen when in late August of 1956 the Air Force specified that full combat capability was to be provided for the two-seater.

In order to avoid the problems experienced with the side-by-side TF-102A trainer version of the Delta Dagger, a tandem seating arrangement was chosen. The two crew members sat under a large, single-piece clamshell-type canopy. The fitting of the aft seat reduced the fuel capacity and displaced some of the avionics to the weapons bay. The external dimensions of the F-106B were exactly the same as those of the F-106A single-seater. The F-106B was equipped with the Hughes AN-ASQ-25 fire control system which was equivalent to the MA-1 of the F-106A. The armament capability was the same as that of the single-seat F-106A, namely a quartet of Falcon air-to-air missiles plus one Genie rocket equipped with a nuclear warhead, all housed in the internal weapons bay. Procurement of the F-106B was included in the third F-106A contract, but the F-106B definitive contract was not finalized until June 3, 1957.

The first flight of the F-106B was made on April 9, 1958. The first eight aircraft off the production line were temporarily designated JF-106B for flight tests. The first delivery to the USAF was made in February of 1959. However, the F-106B suffered from the same development problems as the F-106A single-seater, and was not declared fully operational until July of 1960.

The first 12 F-106Bs off the production line were initially allocated to testing, but they were eventually brought up to the standards of the rest of the F-106 fleet. The last F-106B aircraft were completed as Model 8-32s, with improved MA-1 fire control systems, supersonic ejector seats, vertical instrument display panels, Case 29 wings with revised camber, and with provision for 230-US gallon underwing tanks. Production of the F-106B ended in December of 1960 with the delivery of the last two examples.

The F-106B participated in all of the F-106A modification programs, since the aircraft were so similar. Like the F-106A, the F-106B was initially powered by the J75-P-9 turbojet which was later replaced by the more powerful J75-P-17. All 64 F-106Bs built received Convair's new supersonic ejector seats with two-stage booms.

In the field, each ADC and ANG squadron was provided with several two seaters which were used to perform combat proficiency training and checks. They were fully capable of performing normal intercept missions as required. Two F-106Bs (57-2507 and 57-2516) were supplied to NASA for use as systems development aircraft. They were redesignated NF-106B and assigned the civilian registration numbers N607NA and N616NA respectively.

F-106B 57-2516 arrived at Lewis Research Center in October of 1966, where it was assigned the NASA number 616. It was used for research and development in support of supersonic transport engine inlet design. It was later modified with two additional jet engines mounted underneath the wings. 616 was transferred to the Dryden Flight Research Facility at Edwards AFB in January of 1979, where it was renumbered 816. This plane was later loaned to Langley, where it was modified by the Langley Research Center in 1979 to evaluate the effect of lightning strikes on aircraft. In 1988, it was fitted with Langley-designed and manufactured wing leading-edge vortex flaps in connection with the Advanced Technology Fighter program. This aircraft has now been retired, and is awaiting a replacement.

In March of 1981, F-106A serial number 59-0123 was transferred to NASA at Langley to serve as a spare for 816. F-106B 57-2507 arrived at Lewis in September of 1972, where it was assigned the number 607. It was used for solar cell and ocean color scanning tests, which were designed to be used in water and land quality evaluation. In May of 1981, 607 was transferred to Langley. It was cut in half in 1984 for use in full-scale wind tunnel testing. F-106B 59-2545 arrived at Langley on January 30, 1985. It is a non-flyable aircraft used for various tests. F-106B number 57-2513 was used as a Rockwell B-1 chase aircraft by the San Antonio Air Logistics Center at Kelly AFB in Texas.

Specification of F-106B:

One Pratt & Whitney J75-P-17 turbojet, 17,200 lb.s.t. dry and 24,500 lb.s.t. with afterburning. Maximum speed: 1525 mph at 40,000 feet (Mach 2.31). Service ceiling was 57,000 feet. Normal combat radius was 575 miles. Normal loaded weight was 35,000 pounds. Dimensions: wingspan 38 feet 3 1/2 inches, length 70 feet 8 3/4 inches, height 20 feet 3 1/4 inches, wing area 697.8 square feet. Armament consisted of one Douglas MB-1 (AIR-2A or 2B) Genie unguided missile with a nuclear warhead and four Hughes GAR-3 or GAR-4 (later redesignated AIM-4E and AIM-4G respectively) radar or infrared-homing missiles. All these missiles were housed within the internal weapons bay.

F-106X, F-106C/D

The F-106C/D (Model 8-28/8-29) was a 1956 design study for a Delta Dart follow-on. This study envisaged an interceptor with a canard layout that was powered by a JT4B-22 turbojet fed by rectangular air intakes. Originally known as the F-106X, it was to have a fire control system fed by a 40-inch radar dish. The C was the single seater, the D the two-seat version. The F-106X was extremely advanced for its time --- a Mach 5 performance was envisaged. At one time the Air Force had considered acquiring 350 of these advanced interceptors, but the F-106X project was cancelled on September 23, 1958. Following the cancellation of the Model 8-28/29 project, two production F-106As (57-239 and 57-240) were modified to test the new radar housing with a five-foot nose extension. They made ten flights with this new nose in 1959.

F-106E/F

The F-106E/F was a proposed version of the Delta Dart with a look-down radar mounted in an extended nose. This project never got off the drawing board.


Text : Joe Baugher


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