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The Convair F-106 Delta Dart: The Ultimate Interceptor

The day after Christmas in 1956, a state-of-the-art interceptor that’d been under development for years was finally rolled out at Edwards Air Force Base in Southern California’s high desert. 

Featuring a long pointy fuselage and razor thin delta wings, conspicuously absent were the horizontal tail surfaces common on more traditional aircraft. 

The sleek supersonic Convair F-106 Delta Dart had been built with one mission in mind – to intercept long-range nuclear-armed Soviet bombers flying over the North Pole, Northern Europe Canada and Alaska enroute to targets in the United States.  

Powered by a Pratt & Whitney J75 afterburning turbojet that produced more than 16,000 pounds of dry thrust, the aircraft was jam-packed with high-tech avionics, and it boasted one of the highest power-to-weight ratios of the era. 

Then when the various systems and flight controls had been checked, test pilot Richard Johnson lined up along the runway’s centerline, eased the throttle forward, hurtled down the tarmac and climbed into the sky. 

Development

Nicknamed “Ultimate Interceptors” for their ability to fly high and fast, Delta Darts were in service between the late ‘50s and early ‘80s. 

CONVAIR F-106A DELTA DART by D. Miller is licensed under CC-BY

But though F-106s were intended to be front line missile-armed interceptors during the dark days of the Cold War, they never technically saw combat, and perhaps even more ironically, they were the last dedicated interceptors ever produced in America.  

The F-106 story began in the early ‘50s when the relationship between the United States and Soviet Union was – to put it mildly – tense.   

In schools across the country frantic children responded to ear splitting sirens by scrambling from their chairs, dropping onto the polished tile floor and climbing under their flimsy stamped steel and plywood desks. 

Known as “duck-and-cover” drills, in the event of a thermonuclear exchange between the world’s superpowers, the children were constantly reminded that the speed and efficiency with which they performed these tasks may have a direct impact on their survival.

The threat of Russian ICBMS and fast intercontinental bombers was creating a nightmare security scenario for American politicians and military brass, and behind the scenes a new breed of interceptor was already on the drawing board.  

The aircraft that would ultimately become F-106s were conceived when the Air Force submitted RFPs to various manufacturers for a high-altitude, all-weather, supersonic interceptor that would be capable of flying the pants off anything in the air.  

However, of the designs put forth, most were too heavy, too expensive, or relied too heavily on untested technology. 

That said, they all had one thing in common – lackluster performance. 

Ultimately Convair’s F-102 Delta Dagger – from which the F-106 Delta Dart would be derived – was deemed to be the most competent aircraft, but only because the planes against which it was competing weren’t particularly impressive.  

But though 102s looked fast even when they were standing still, the first prototype was barely capable of pushing its way through the sound barrier on its way to an anemic top speed of just Mach 1.25 (825 mph / 1,327 km/h). 

In addition, it was both larger and heavier than the original specifications called for, and with a service ceiling of just 53,000 feet (16,150 m), it wasn’t exactly a high flier. 

At about the same time 102s were coming online, the Soviets were tinkering with the Tupolev Tu-125 supersonic medium bomber concept. 

Though the project was scrapped before a prototype was ever built, the idea alone was deeply disconcerting to the US and Canadian air forces. 

Resembling the SR-71 Blackbird, the Tu-125 had a theoretical top speed of 2,000 miles per hour (3,220 km/h) and an estimated service ceiling of 83,000 feet (25,300 m). 

Needless to say, had they been built, it would have been impossible for even the most advanced F-106 variants to intercept them.  

However, despite this glaring performance gap Daggers were ordered into production, but they were given the unflattering designation “interim interceptor,” because everyone conceded that they were little more than stopgap measures until more capable aircraft could be delivered. 

Later variants did benefit from improved aerodynamics, more powerful engines and upgraded avionics, but in the end they never lived up to the Air Force’s expectations. 

But even as F-102 production got underway, Convair and the Air Force were focusing their attentions on yet another variant that would remedy the 102’s performance shortcomings, thanks to the addition of a new engine – the Wright J67 – a license-built version of the English Bristol Olympus. 

With more power, better range and improved avionics, the new bird might have become the interceptor the Air Force wanted all along, but Wright was having serious manufacturing issues, and as a result production was more than a year behind schedule. 

With no end to the delay in sight, the Air Force approved another power plant switch, this time to the Pratt & Whitney J75.

But although the new engine provided more thrust than the old J57, it was also larger, heavier, consumed more fuel, and required much more air.  

To fix these and other issues, fuselages were lengthened, wing area was increased, a new two-stage afterburner was added, as were variable-geometry inlet ducts that allowed the engine to operate more efficiently at various speeds and altitudes. 

Now designated the MA-1, another production contract for 17 units was awarded, and the aircraft was officially designated F-106A. 

But despite high hopes and abundant upgrades, initial test flights revealed performance that was still less than stellar. 

The new engines and avionics packages required tons of maintenance and were altogether unreliable, and various other problems seemed downright unfixable, hence the project was nearly scrapped. 

However, with no viable Plan B to fall back on, the Air Force decided to go with what it had, though the original order for 1,000 aircraft was reduced by more than half.

Specifications

70 feet (21.5 m) long, just over 38 feet (11.7 m) from wingtip to wingtip and crewed only by a pilot, F-106s had gross weights approaching 35,000 pounds (15,700 kg) which made them significantly lighter than the F-4 Phantoms and F-15 Eagles that would ultimately replace them. 

Compared to F-102s, F-106s now had maximum speeds that exceeded Mach 2.3 (1,500 miles per hour – 2,400 km/h) and the ability to climb past 60,000 feet, which meant that they were increasingly capable of performing the missions for which they’d been built. 

Internal fuel capacity wasn’t great, but combat range was a respectable 600 miles (950 km) and could be extended with wing-mounted fuel tanks. 

In addition, some later variants got in-flight refueling probes.  

Weapons loads generally consisted of four Hughes AIM-4F Falcon air-to-air missiles or one 800+ pound (362 kg) AIR-2A Genie nuclear-tipped rocket. 

The F-106’s state-of-the-art Hughes MA-1 integrated guidance and fire-control system was largely operated by a ground-based controller which allowed the pilot to focus on flying the aircraft.  

Then when within range, the onboard MG-10 system would automatically select an individual target, lock on, and fire the missiles. 

The Hughes missiles used both radar in infrared homing, and earlier tests had shown that once lock-on was achieved, the probability of making a kill was high. 

Though early variants weren’t equipped with guns, between the late ‘60s and early ‘70s some heavily modified versions got 6-barreled 20 mm Vulcan rotary cannons with more than 600 rounds of ammunition that greatly increased their potency.  

Ejection Seats

The ejection seats in early 106s were derived from the ones used in F-102s, which also got an “interim” designation because they had serious flaws.  

The system propelled the seat and pilot away from the aircraft using explosive charges, but was only capable of operating within a relatively small envelope that didn’t include exceedingly high or low altitudes or airspeeds, which left pilots feeling extremely vulnerable.

The ejection seats in later variants were replaced by a Convair design dubbed the Supersonic Rotational B-seat, or supersonic bobsled, but their big drawback was that they weren’t particularly user friendly. 

In emergencies pilots had to initiate the sequence by pulling a D-ring which jettisoned the canopy, engaged the shoulder harness and retracted limbs into the correct positions. 

But though these latter actions were automated, as they were happening the pilot was responsible for manually pulling yet another D-ring to disconnect the seat’s actuator and fire the charge – not an easy task when the stress, disorientation and G-forces associated with exiting a jet aircraft were factored in.

Not surprisingly, the system wasn’t well-liked, and more than a few test ejections resulted in deaths. 

Unsatisfied with the complexity and overall unreliability of Convair’s system, starting in the mid-’60s F-106s were equipped with Weber ejection seats that had far wider operational envelopes and were zero-zero rated, which meant they could be used at zero altitude and zero airspeed during ground emergencies. 

F-106s in Service

Though officially named Delta Darts, the men who flew F-106s referred to them simply as “The Six.”

Once the initial teething problems had been ironed out, pilots generally liked F-106s, largely because they were fast and fun to fly. 

To reduce cost and eliminate redundant aircraft types through Robert McNamara’s cross-service standardization scheme, Air Force 106s and Navy F-4s were pitted against one another in Operation Highspeed.

But though Darts were faster and more maneuverable at higher altitudes, they had a number of Achilles heels.

While F-4s could carry big bomb loads, 106s couldn’t carry any bombs, because as everybody knows, interceptors don’t need to.  

From that perspective it wasn’t a fair fight, but mock aerial combat showed that “the Six” would’ve made a reasonably good dogfighter, but overall it wasn’t nearly as well-rounded as the F-4. 

In addition, Phantoms had more powerful radars, could carry larger numbers of more effective AIM-7 Sparrow and AIM-9 Sidewinder missiles, and the second crewman allowed F-4 pilots to focus on flying their aircraft. 

Hence, 106s never saw combat in the skies over Vietnam, though older and slower F-102s did. 

But though they’d lost out to McDonnell-Douglas’ F-4, later F-106s got additional upgrades including modified wings, improved avionics, updated tracking systems, and more streamlined external fuel tanks that had virtually no effect on performance. 

In addition to receiving Vulcan rotary cannons near the end of the war, later variants also benefited from optical gun sites and improved visibility canopies. 

Nevertheless, in the early ‘80s the remaining F-106s were replaced by F-15 Eagles, though some remained in service with Air National Guard units until about 1988. 

Bears, Badgers and Bison

During the Cold War few scenarious placed American and Soviet armed forces in more dangerous proximity than when aircraft like Delta Darts were scrambled to intercept reconnaissance planes and bombers like Tu-95 Bears, Tu-16 Badgers and M-4 Bison. 

This played itself out hundreds of times between the early ‘60s and early ‘90s, and in many cases the aircraft flew within just a few meters of one another.

Airmen on both sides often took pictures to document the historic and hair-raising encounters, but the Soviets were particularly careful not to fly within United States airspace. 

As we’ve already stated, F-106s never officially served in combat, but this assertion warrants some clarification. 

Perhaps it’d be more accurate to say they never fired on enemy aircraft, but they did frequently intercept them, and there are tons of photos of F-106s flying alongside their Soviet counterparts over Alaska, Canada, Iceland and the North Pole. 

F-106s based in Alaska made more than 300 individual intercepts between the ‘60s and ‘80s, but though the vast majority took place in the north, a few were made over the Caribbean and Gulf of Mexico by units based in the American South.  

Both F-102s and 106s were on the vanguard of these defensive efforts for years until being replaced by Air Force F-4s and later F-15s. 

F-106 Milestones

In late December of 1959 US Air Force pilot Charles Myers set a new world speed record by pushing his F-106 to 1,544 mph (2,484 km/h). 

Then in early February 1970, another pilot, Gary Foust, became famous under far less flattering circumstances. 

After entering an unrecoverable spin high over Montana, Foust ejected from the aircraft.

However, the sudden change in weight and balance actually righted the aircraft, after which it resumed level flight before gliding downward and eventually landing “wheels up” in a cornfield sustaining only minor damage.  

Aptly christened the “Cornfield Bomber,” Foust never lived the incident down, but the aircraft was recovered, repaired and eventually returned to service, and it’s now on display at the National Museum of the United States Air Force in Riverside, Ohio. 

Drone Conversion and Retirement

Between 1983 and 1988 F-106s that had remained in service were steadily retired. 

Like many aging and obsolete American warbirds, most eventually ended up baking under the brutal Arizona sun at Davis-Monthan Air Force Base’s Military Storage and Disposition Center near Tucson, more commonly known as the Boneyard.  

However, despite bleak futures, many were once again called out of storage when the Air Force needed full-size aerial target drones in the late ‘80s. 

Ultimately more than a dozen F-106s went out with a bang as flying targets. 

The last was destroyed in the late ‘90, after which F-4 Phantom-based QF-4E drones replaced them. 

Six surviving examples were also pressed into service as research aircraft to test everything from new engines and weapons systems to avionics packages and radar.  

In the mid-’80s, one old F-106 was modified to act as a lightning strike research platform that apparently survived more than 700 individual “zaps” without being damaged.

“Trolling” for lightning at 350 miles per hour (560 km/h) and 40,000 feet (12,200 m), during one short flight in 1984, the aircraft was struck more than 70 times. 

All told nearly 350 F-106s of different variants were built, but though they served across North America,  Alaska, Germany, South Korea and Iceland, they led relatively uneventful lives by military aircraft standards. 

With an average unit cost of about 3.3 million USD – about 31 million USD when inflation is taken into account – they were nearly 30% more expensive than F-4s, 

Looking back on his days in the cockpit of an F-106, one retired Air Force pilot recently opined that in terms of speed and range, the old Delta Darts would be more than a match for newer and more expensive aircraft like F-22s. 

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