History of the F-106
Convair Aircraft Plant
San Diego, CA
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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 28 years, longer than most of its contemporaries. The origin of the F-106 dates back to 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. The North American F-86D Sabre, the Northrop F-89 Scorpion, and the Lockheed F-94 Starfire were all subsonic aircraft, and deemed to have insufficient growth potential to meet this new threat. The project became known as the "1954 Interceptor", named for the year the 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 the problem, the Air Force introduced the "weapons system" concept, in which components of 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 (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 of the projects design came first, known as the new WS-201A system. Project MX-1179 was the designation given to the 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, with the Hughes proposal consisting of an 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 portion of the project was designated MX-1554. Proposals were requested by the Air Force on June 18, 1950, and 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
- Single proposals were made by Chance-Vought, Douglas, Lockheed, and Convair.
On July 2, 1951, the Air Force announced designs by Convair, Lockheed, and Republic had been selected to proceed with preliminary development. All three were to proceed with their designs all the way to the mockup stage, with the design deemed most promising being awarded a production contract. Later, the USAF deemed it too costly to carry through with three concurrent development programs, so it cancelled the Lockheed project entirely. The Convair and Republic entries were given the go-ahead to proceed. Republic's entry bore the company designation of AP-57 (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. Convair's entry was closely related to the experimental XF-92A, which Convair 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 consultation with Dr. Alexander Lippisch, who had done pioneering work in Germany on delta wing 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 wing aircraft to fly, but the F-92 project had itself been cancelled before any prototype could be built.
On 11 September 1951, Convair received a contract for its delta wing design, designated the F-102. Work on the competing Republic design was also authorized, and was designated XF-103, however, the XF-103 was so far ahead of the state of the art, it was deemed too risky to be a serious contender for the 1954 Interceptor project. This made the F-102 for all practical purposes the winner of the contest.
The USAF authorized fitting a Westinghouse J40 turbojet into the first few examples of the F-102, but production aircraft were to be powered by the 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, who during the late 1940s developed a concept of an aircraft development program where the usual prototype stage would be skipped. Rather than waiting to start full-scale production until the prototypes had passed flight testing and the bugs ironed out, the Cook-Craigie plan called for delivery of a small number of production aircraft during the flight testing phase so 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, as it can produce a new combat aircraft in a hurry if everything goes right during flight testing, but can result in costly and time consuming fixes in the field if unexpected problems turn up. The Cook-Cragie plan is viable if there's a high degree of confidence that the aircraft is really going to go into production, and since the F-102 was basically a scaled-up XF-92A, the risk seemed worth taking.
F-102A F-102B F-106
By December of 1951, it was apparent the Wright J67 engine and the MA-1 fire-control system would not be ready in time, which forced the USAF to change its plans. They 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 later on. The interim version was designated F-102A, and the fully-developed advanced version designated F-102B. The F-102A would use the less-powerful Pratt & Whitney J57 turbojet, but the F-102B would retain the high-thrust J67. The F-102A would be equipped with an interim fire-control system, but the F-102B would be equipped with the highly-sophisticated Hughes fire control system under project MX-1179. Although the F-102A was considered only an interim version pending availability of the F-102B, it ran into some unexpected developmental difficulties and fell behind schedule. A lot of money originally planned for the F-102B, now had to be diverted into fixing F-102A 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 known as the MA-1) was slipping badly. 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, and the Air Force needed to consider alternative powerplants, finally settling on the Pratt & Whitney J75, which was an advanced version of the J57 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, with their serials ranging from 56-0451 t0 56-0467. The F-102B mockup was ready for inspection in December of 1955. On 18 April 1956, the Air Force finalized the F-102B production contract of the previous November, ear-marking all 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 17 June 1956, the F-102B designation was changed to F-106A, which was in affect an official 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 due to so many aerodynamic changes and far more advances to include a variable-geometry inlet design. In September of 1956, the Air Force specified that the F-106A would be available by August 1958, four years later than initially planned, and it had to be compatible with the Semi-Automatic Ground Environment (SAGE) up to a radius of 430 miles and an altitude as high as 70,000 feet. Interceptions would be accomplished at speeds of up to Mach 2 at 35,000 feet, and would 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. The aircraft with FY 1956 serial numbers had outer-wing boundary layer fences as on the F-102A, which were replaced in FY 1957 with leading edge slots. The "wet" wing used no fuel bladders, and fuel transfer was accomplished using low pressure bleed-air from engine into the tanks. It was thought, however combat damage, even a single bullet hole in the wing, could incapacitate the entire system. The major external difference was in the fuselage, which had a much more streamlined shape and a "coke-bottle" design. The variable-ramp air intakes were moved well aft of the nose and mounted closer to the engine, and the shape of the fin and rudder were changed with a clamshell-type airbrake fitted at the base of the vertical fin. A new undercarriage was fitted with steerable twin-nose wheels. On the first F-106s, the upper and lower rotating navigation beacon lights retracted when the aircraft went supersonic. They were located immediately aft of the canopy in the dorsal position and immediately behind the nose wheel on the belly of the aircraft, but the retractable feature was disabled in later years. The Pratt & Whitney J75 twin-spool, axial-flow afterburning turbojet was the same engine which powered the Republic F-105 Thunderchief, and was rated at 15,000 lbs thrust dry, and 23,500 lbs thrust in afterburner. The pilot sat well ahead of the engine air intakes. As with the F-102, the F-106 featured optically-flat windscreens which met at their forward edges. The metal strip that was located where the windscreens met was directly in front of the pilot's face and severely restricted his forward vision.
The first F-106A (56-0451) was finally available by the end of 1956. The first flight was made by Convair test pilot Richard L. Johnson at Edwards AFB on December 26, 1956. He was the same pilot who had made the maiden flight of the F-102. The flight was not entirely glitch-free as it had to be aborted early due to air turbine motor frequency fluctuations, and the speed brakes opened but would not close. Consequently, the aircraft did not go supersonic on its first flight. The second aircraft (56-0452) followed on 26 February 1957. They were both powered by the YJ75-P-1 engine.
F-106A: Serial number 56-0451, the first F-106 (F-106A) produced by Convair at San Diego CA, on 14 Dec 1956 was trucked from Convair to AFFTC Edwards AFB CA. On 22 Dec 1956 it began Taxi tests. On 26 Dec 1956 it made its first flight, which included an air abort due to air turbine motor frequency fluctuations and speed boards that opened and wouldn't close. This first take-off was performed without afterburner, which was comperable to an F-102 Delta Dagger take-off 'with' afterburner. The 20 minute flight took the aircraft to an altitude of 30,000 miles and 0.8 Mach.
F-106B: Serial number 57-2507 was the first F-106B produced by Convair, which was also trucked from Convair to AFFTC Edwards AFB CA. Taxi test runs were completed on 8 April 1958. The first B model flight was made on 10 April 1958 piloted by pilot Fitzpatrick. The first flight lasted for 50 minutes, almost twice as long as the F-106A first flight. The aircraft also reached higher altitudes and obtained faster supersonic speeds than is normal for a first flight. Your author here can only imagine that was due largely but the fact the F-106A was already a tried and true model, which the 'B' models were so much like.
Armament and Engine
As on the F-102A, the all-missile armament was housed internally in a spacious ventral weapons bay, which was closed by pneumatically-operated double-folding doors. The all-missile armament consisted of a single Douglas MB-1 (AIR-2A or 2B) Genie unguided missile equipped with a 1.5 kT nuclear warhead, plus four Hughes GAR-3 Falcon radar- homing or GAR-4 infrared-homing (later re-designated AIM-4E and AIM-4G respectively) air-to-air missiles. The unguided 2.75-inch missile armament of the F-102A was omitted.
The Genie missile was carried in the rear half of the missile bay. It was powered by a 36,600 lbs thrust Thiokol TU-389 rocket motor and was unguided, relying on its 1.5 kT nuclear warhead to ensure a kill. Launch weight was 822 pounds and maximum velocity was Mach 3.3. Snap-out fins gave the missile stability during flight. Range was about 8 miles, and flight time to target was about 12 seconds and a blast radius of about 1000 feet. The Falcons were conventional warhead adaptations of the nuclear-tipped AIM-26A Falcon. The two semi-active radar homing AIM-4E Falcons were carried in the forward half of the weapons bay, whereas the AIM-4G infrared-homing missiles were carried in the rear half of the weapons bay flanking the Genie missile. All Falcon missiles were contact fused, with the fuses located on the leading edges of all four fins, so that a direct hit on the target was needed to score a kill. The Falcon missiles could be launched in salvo or in pairs. Because the aerodynamic range of the AIM-4F was greater than the range of its seeker and tracker radar sensor, the IR-guided AIM-4G was the preferred means of attacking a fast-moving target. At high closure speeds, the MA-1 fire control system would present two separate firing solutions, one for the AIM-4G and the other for the AIM-4F. If all four missiles were to be fired, the 4Gs were fired first so that they would not inadvertently lock onto the radar guided missiles rather than the target. As a further precaution, the 4F pair was carried in the rear bay. The 4F and 4G missiles were fired in like pairs and ripple-fired so that one would always be ahead of the other. The missiles were fired in pairs because the pneumatic system had only enough high pressure stored for three cycles of the armament system. There were essentially three shots available-one Genie, one pair of AIM-4Fs and one pair of AIM-4Gs. The Hughes MA-1 fire control system incorporated the first digital computer to be built into a fire control system. A datalink with NORAD's SAGE system meant that radio silence could be maintained throughout the intercept, while an autopilot allowed the ground controllers to "fly" the aircraft during the final approach to the target. A Tactical Situation Display (TSD) between the pilot's feet showed a moving map of the route across the ground during the intercept.
The first F-106A (56-0451) was finally available by the end of 1956 and made its first flight on December 26, 1956. The second aircraft (56-0452) followed on 26 February 1957. The first two aircraft were not equipped with the MA-1 system, carrying nose ballast to compensate for the missing weight. The test and development work on the F-106 was divided into six phases. Phase I was conducted by the contractor, and Phase II was conducted by the Air Force. Phase II tests were carried out between May and June of 1957. The first 12 aircraft off the production line were devoted to tests at Edwards AFB in California. They differed from the prototypes in having J75-P-9 engines. Early testing reached a speed of Mach 1.9 and an altitude of 57,000 feet, but this was still well below expectations. In addition, the F-106A's acceleration was significantly 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.
Speed and acceleration problems
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, rated at 17,200 lbs thrust dry and 24,500 lbs thrust in 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 equipped with a two-handed grip for both radar and aircraft control. The right-hand grip was used for control of the aircraft and the left-hand grip was used for operation of the radar. A button in the middle of the yoke gave the pilot control of the radar antenna, and another button on the left grip enabled the pilot to put the pipper on the target by following directions on the radar scope. The pilot selected the missiles to be fired by using a switch on the left console, with the trigger that was used to launch the missiles being on the right hand grip.
Early test aircraft had explored both conventional round-faced instrument panels and panels with vertical-tape instruments. However, the first three squadrons of F-106As were sent to the field with analog or round instrument dials. Eventually, the vertical tape instrument set, know as Integrated Instrument Display (IID), was made standard starting with aircraft 58-0759. Some of the early aircraft were subsequently upgraded with IID, but many never got the vertical tapes. Initial aircraft had wing 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 forty plus Air Defense Command (ADC) squadrons. However, by 1957 the delays in the F-106 program and the problems with the engine and fire control system had resulted in the necessity of a stop-gap measure of ordering other interceptors such as the McDonnell F-101B Voodoo, and the F-106 lost some of its urgent priority. For a while, serious consideration was given to canceling the entire F-106 program, or else 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 260 more F-106As were ordered. Since the cutback was so drastic, a decision was 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. On 30 May 1959, the first F-106As were delivered to the Air Defense Command's 539th FIS at McGuire AFB in New Jersey, replacing the F-86L, however, the first "operational unit" was the 498th Fighter Interceptor Squadron at Geiger AFB in Washington. This was five years later than originally planned, and even then, numerous problems kept the Delta Dart from being declared fully operational until 31 October 1959. The remaining 13 squadrons were re-equipped with the F-106A by the end of 1960. On 15 December 1959, Delta Dart 56-467, flown by Major Joseph W. Rogers, set a world's absolute speed record of 1525.96 mph at 40,500 feet, which beat the previous record of 1483.83 mph, set by Georgiy Mossolov in a Soviet Ye-6/3 on 31 October that same year. 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.
MA-1 Fire Control System
Also see MA-1 and SAGE page
The MA-1 fire control system was initially quite unreliable and was subjected to a lot of in-service modifications in an attempt to fix its chronic problems. The MA-1 system was upgraded 60+ times during the Delta Dart's long service life. 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.
The F-106A operated in conjunction with the SAGE (Semi-Automatic Ground Environment) network linked via the Hughes MA-1 fire-control system to the F-106. 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 being needed only for takeoff, landing, or in case something went wrong with the automation. 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. In September of 1960, due to the numerous modifications to the MA-1 fire control system made during production, a major modification project named "Wild Goose" was initiated 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 roaming AMC field assistance teams supported by ADC maintenance teams working at ADC bases. The 277th and last F-106A was delivered on 20 July 1961. The production run also included 63 F-106B two-seaters, for a total of 340 aircraft. In late 1961, Secretary of Defense Robert S. McNamara spoke of reopening the F-106 production line to build another 36 aircraft (rather than the 80 originally budgeted for in FY 1961). However, the ADC had heard so much about the capabilities of the Navy's F4H-1 Phantom two-seat interceptor that it thought that it might be a better idea to purchase some F4H-1s rather than buy additional F-106s. The USAF called for a competition-named Project High Speed-between the F-106 and the Navy's F4H-1 Phantom. It was designed to evaluate the capabilities of these two aircraft to perform similar missions. During the competition, the Phantom's APQ-72 radar was more reliable and had longer detection and lock-on ranges than the MA-1 system of the F-106. However, in many sorties F-106 pilots "shot down" their F4H adversaries in visual range combat situations. In the event, neither aircraft got the nod for additional ADC interceptor orders, and in December of 1961, the USAF announced that the F4H/F-110 would be acquired for the Tactical Air Command and that ADC would get no new interceptors. Even after all aircraft had been delivered, reliability problems continued to plague the MA-1 and ASQ-25 systems. Throughout its long service life, the F-106A was continually upgraded and improved to correct these problems. 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 unit retracted into a fairing in front of the cockpit. 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 never intended for carrier-based operations. The F-106 had to be grounded again on 26 September 1961 to make repairs to the fuel system which had caused two crashes. This order did not affect the F-106s that were on alert with ADC, but it did affect those used for training and transition flying. In response to this grounding, the "Dart Board" retrofit and modification program took place in 1961-62. This program finally fixed the problem with flame-outs from fuel starvation which had affected earlier Delta Darts. A thermal flash blindness protection hood was also fitted. Perhaps the most significant of these changes, however, was the revision of the ejection system.
The ejection seat fitted to early F-106s was a Weber-built variation of the seat used by the F-102. It was an open, catapult-only seat, which used an explosive charge to throw it out of the aircraft. It was thought that this seat would be inadequate for ejections at supersonic speeds, and it was replaced by a Convair-designed "B" seat. It's not clear what the B designation stood for, but pilots believed that it was so named because it resembled a bobsled. It was designed with supersonic ejection specifically in mind, and was demonstrated in 15 sled tests and 11 flight tests. The first live test ejection with the Convair-designed seat took place when Technical Sergeant James Howell Note 1 ejected safely from an F-106B piloted by Major James Hendrix on 6 June 1961.
The ejection sequence with the Convair B-type seat was quite complicated. The pilot initiated the sequence by pulling a D-ring, which jettisoned the canopy, retracted and locked the shoulder harness, retracted the occupant's feet, and raised the foot pans, seat pan and leg guards. While all this was happening, the pilot had to pull the D-ring a second time to disconnect the seat actuator and fire the vertical thruster, which propelled the seat up on its rail. The rotational thrusters then fired, causing the seat to rotate into a horizontal position on top of the aircraft. Once there, gas-operated stabilization booms extended, attachment bolts fired, and the rocket motor ignited to propel the seat away from the aircraft. The new Convair-designed ejector seat was not very popular with F-106 pilots, and there were some unsuccessful ejections that resulted in pilot fatalities. Frustrated with the complexity and unreliability of the Convair B-seat, the USAF contracted in 1965 with the Weber Aircraft Corporation for the design of a "zero-zero" seat. It was recognized that high-altitude supersonic ejections were actually quite rare, and that the high-runner cases were more likely to be ejections at relatively low altitudes and low speeds. Weber delivered the first seat in only 45 days. The new Weber seat was quite effective, and was quickly retrofitted through the entire F-106 fleet. In 1965, an new TACAN system was installed which used microelectronic circuits and was one-third the size and weight of the existing system.
M61A1 20-MM Cannon
The F-106A surprised everyone by having good maneuverability and showing potential as being an excellent dogfighter. There were some thought to using the F-106 for top cover in Vietnam. Among suggestions were to apply tactical camouflage, fit a clear-view canopy, and add internal cannon armament. Although the F-106 never actually did serve in Vietnam, the suggestion of the addition of a gun was taken seriously. The gun was not intended for air-to-air combat against enemy fighters, but was primarily intended to provide extra firepower for a better close-in kill potential against enemy bombers, but it was thought that it might also be useful in attacking bombers flying at low altitude.
In support of the cannon armament program, Convair issued a proposal to re-equip the F-106 with an internal cannon, an optical gun-sight, and a clear-view cockpit canopy in a program known as Project Six Shooter. An internal 20-mm M61A1 rotary cannon with 650 rounds was fitted inside the rear half of the weapons bay, replacing the Genie nuclear-tipped rocket. However, the four AIM-4F/G Super Falcon missiles could still be carried. The gun system was installed as a package inside an enclosure mounted inside the missile bay providing an aerodynamic shield for the portion of the gun protruding below the missile bay and out into the air stream. Gun-equipped F-106As could be distinguished by a bulged fairing underneath the fuselage which provided clearance for the rotating barrels of the cannon. As part of the program, a new "clear-topped" canopy was tested, which eliminated the metal strip above the pilot's head, markedly improving the cockpit visibility. The gun installation was first tested 10 February 1969 on F-106A 58-0795 and subsequently on 59-092. A prototype gun-sight was developed at Tyndall AFB. The gun was installed only on those F-106s that had vertical tape instruments. When firing, the Vulcan was limited to only 4500 rounds per minute, compared to the 6000 rpm available when installed on the F-4E, due to limitations in the hydraulic pump which rotated the weapon. However, this innovation was not provided for the F-106B two-seater. The idea of painting the F-106 in camouflage scheme was abandoned, when it was found that there was no significant advantage in doing so seeing as the F-106 would never go to Vietnam. In the late 1960s, the F-106 was provided with newly-designed larger-capacity under-wing external fuel tanks, often called "supersonic tanks", since they could be carried underneath the wings at any speed. They were a 360 US-gallon capacity, 50 percent larger than the previous 227-gallon tanks, and were jettison able, although this was rarely used in practice. The tanks were routinely carried on all but the shortest-range intercepts. In conjunction with the new under-wing tanks, in-flight refueling capability was retrofitted to all surviving F-106s, by retrofitting a slipway receptacle in a dorsal position behind the pilot. The first refueling installations were installed in 1967. The F-106 served mainly in the continental United States, 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 February of 1968 to provide air defense during the "Pueblo" incident, the Delta Dart never saw combat.
Beginning in 1972, the McDonnell Douglas F-15 Eagle gradually began replacing the Delta Dart in ADC squadrons. As they were removed from Air Force active duty service, the F-106's were passed on to the Air National Guard. The first ANG unit to receive the F-106 was the 186th FIS of the Montana ANG, based at Great Falls, taking delivery of its first planes on 3 April 1972. Six ANG units flew the F-106 on Air Defense Command mission. The last Delta Dart-equipped Air Force squadron, the 119th FIS based at Atlantic City, New Jersey flew its final alert duty on 7 July 1988. The ANG units continued to fly the last few Delta Darts for only a few months longer after the USAF had relinquished the type. The last ANG to relinquish its F-106s was also the 119th FIS, which sent its last plane to AMARC in August of 1988.
During its long service life, the F-106A had the distinction of recording the lowest single-engine aircraft accident record in USAF history. Despite this, out of a total production of 340 aircraft, 112, including 17 two-seat F-106Bs, were lost in crashes or in ground fires during the 29 year career of the Delta Dart. As F-106As were withdrawn from active duty, they were ferried out to Davis-Monthan AFB in Arizona where they were placed in storage. The first F-106 went to storage in January 1982, and the last three F-106s, from the Atlantic City-based 119th FIS of the New Jersey ANG, departed for Davis Monthan AFB in August of 1988.
In 1986, a contract was awarded to Flight Systems Inc., later Honeywell, to modify 194 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. Following the completion of an initial batch of ten QF-106s in 1990, most of the work was transferred to the USAF itself. Much of the conversion work was done before the aircraft were removed from storage at AMARC, with further work being carried out at East St Louis, Illinois. The QF-106s began operating as a Full-Scale Aerial Target (FSAT) in late 1991 at White Sands Missile Range in New Mexico, and later at the Eglin Gulf Test Range in Florida, based at Holloman and Tyndall. A typical mission would employ the QF-106 as a target for an infrared homing missile. The aircraft had burners placed on pylons underneath the wings to act as IR sources for heat-seeking missiles, but it must be admitted that no real enemy would be so accommodating as to add these burners to make their planes better targets. However, the intention of the program was for the QF-106 to survive repeated engagements with air-to-air missiles, to make it possible for each QF-106 to last as long as possible before it was destroyed. The last shoot down of a QF-106 (57-2524) took place at Holloman AFB on February 20, 1997. Today, the QF-106 has been replaced by QF-4 Phantom drones.
The last mission flown by an F-106 was as a participant in Project Eclipse, a joint USAF/NASA project to demonstrate the validity of a concept for a reusable launch vehicle that would carry payloads into orbit. QF-106 59-130 was towed into the air by an NC-141A Starlifter (61-2775) using a synthetic rope. The first flight was made on 20 December 1997, and the last test took place on 6 February 1998. The tests were made to explore the feasibility of having a Boeing 747 tow an RLV known as the Astroliner to 45,000 feet, where the Astroliner would fire its rocket engines and fly into orbit. On 1 May 1998, this last flyable F-106 flew from Edwards to AMARC.
The F-106B (Model 8-27) was a two-seat combat trainer version of the Delta Dart. 63 examples were ordered on 3 August 1956. The aircraft was originally intended as a pure trainer and was initially designated TF-102B and then later re-designated 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.
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 removing a fuel cell, 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. 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, and had the same armament capability, which was 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 3 June 1957.
The first flight of the F-106B (57-2507) was made on 10 April 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 under-wing 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 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. The Convair supersonic seats were, however, replaced by Weber "zero-zero" seats later in the 1960s, however, the F-106B never received the weapons bay cannon installation.
In the field, each ADC and ANG squadron was provided with several two seat "B" models, which were used to perform combat proficiency training and checks. They were fully capable of performing normal intercept missions.
F-106's with NASA
Two F-106Bs (57-2507 and 57-2516) were supplied to NASA for use as systems development aircraft. They were re-designated 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 was retired on 17 May 1991 and was the last flight having been flown on 5 March from Langley AFB in Virginia. The aircraft is now display at the Virginia Air and SpaceCenter at Hampton.
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 30 January 1985, and 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.
The F-106X (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. It was envisaged as an alternative to the Lockheed YF-12 (later SR-71), and was to have had a fire control system with "look-down, shoot-down" capability fed by a 40-inch radar dish. The F-106X was extremely advanced for its time with Mach 5 performance envisaged.
The project was later re-designated F-106C/D, with "C" being the single-seat version, the "D" being the two-seat version. At one time the Air Force had considered acquiring 350 of these advanced interceptors, but the F-106C/D project was cancelled on 23 September 1958.
Following the cancellation of the Model 8-28/29 project, two production F-106A's. 57-239 and 57-240, were modified to test the new radar housing with a five-foot nose extension. They were re-designated F-106C. Only 57-239 actually flew, and made ten flights with this new nose in 1959. The plane was later destroyed in fatigue tests. 57-240 eventually reverted to standard F-106A configuration.
Two conceptual F-106C Super Darts in 101st FIS, Massachusetts ANG colors (Image by Erik Simonsen)
On 9 February 1968, the Defense Department announced they were not going to purchase the Lockheed F-12A interceptor (later the SR-71), opting instead to remain with the F-106 as the primary interceptor to protect the continental USA from air attack.
On 3 September 1968, Convair issued a proposal for an "improved" interceptor that was to be designated F-106E/F. It was to be compatible with the upcoming airborne warning and control systems as well as with the over the horizon radar defense network. The F-106E/F would have had a longer lose, with a new and improved radar with a "look-down/shoot-down" tracking and missile launch capability. It would also have had a two-way UHF voice and datalink radio. It would be capable of launching both nuclear and non-nuclear missiles, including the AIM-26 Nuclear Falcon and the AIM-47. Unfortunately for Convair, this project never got off the drawing board.
The Delta Dart was never exported to foreign air forces. A pair of F-106's were displayed at the 25th Paris Air Show in June of 1963, but no customers were forthcoming. Convair tried to interest Canada in a Canadian version-not merely as in interceptor but also for the strike role. Nothing ever came of this idea. There were also plans for F-106 final assembly and production in Germany, but these plans never reached fruition. There was a proposal for an F-106 version for Japan with an MG-10 fire control system (the same one that was fitted to the F-102A Delta Dagger) and six Super Falcon missiles. It was also to have ground-attack capability, with a pair of pylons underneath each wing capable of carrying bombs or fuel tanks. The Japanese sale never took place and several years later Japan undertook manufacture of the F-4EJ Phantom.
Note 1 Technical Sergeant James Howell was a USAF Combat Controller on a Special Duty Assignment as a Test Parachutist located at El Centro, California. He also was part of a joint Army, Air Force High Altitude Low Opening (HALO) world record. Source: William Howell, son of Technical Sergeant James Howell, as e-mailed to the webmaster 27 June 2009