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Saab 37 Viggen: The Forgotten Fighter Jet

Written by Matthew Copes

Imagine this…

1986 – somewhere over the Baltic Sea. 

After making a 2,000+ mile per hour (3,200 km/h) reconnaissance run over Northern Europe and around the edges of the Soviet Union, an American SR-71 Blackbird – the world’s fastest known aircraft – was speeding homeward on the return leg of its mission. 


It goes without saying that the Yanks love knowing what everybody else is up to, but safe in their supposed invulnerability, somewhere along the line they slipped into casual sloppiness. 

Known as the “Baltic Express,” the Blackbird’s routes and schedules had become laughably predictable.

As a result, the revolutionary spy planes were particularly vulnerable while in a tiny slice of international air space between various friendly and not-so-friendly countries, one of which had spent much of the previous two decades developing one of the world’s most capable and technologically advanced aircraft.  

Not surprisingly, this unnamed country had a state-of-the-art air defense radar system too, and it didn’t like it when its turf was encroached upon.  

Privy to the Blackbird’s course and speed, jets on the ground were scrambled.  

Barreling down short runways, climbing into the air and hurtling skyward under power from their deafening turbofan engines, they accelerated toward a point well ahead of their intended target at speeds approaching Mach 2. 

Each was armed with air-to-air missiles capable of locking onto high and fast-flying aircraft like Blackbirds even from head-on, but despite heavy active jamming from the SR-71, at least one of the pilots was able to acquire missile lock.  

Then, when the adversary was in range he reached for the red trigger on the stick, and…

OK, so truth be told, missiles probably aren’t even fired by red triggers, and though it would’ve made for a dramatic ending and possibly marked the beginning of World War III, the pilot never launched his weapons. 

By now you’re probably thinking it must’ve been a MiG-25, but there dear reader, you’d be wrong. 

In fact the warbird in question was a Swedish Saab Viggen – by some accounts the only aircraft to ever officially achieve radar lock on an SR-71, though some Russian interceptor pilots might vehemently disagree with this assertion.

But perhaps most ironically of all, in the early going the Viggen wasn’t even meant to be an interceptor.  



The Saab 37 Viggen was a single-seat, single-engine, multi-role combat aircraft developed between the early ‘50s and late ‘60s. 

With the Draken the Swedes already had a capable fighter-interceptor, though their Saab 32 Lansen attack planes were rapidly becoming obsolete. 

Viggens would ultimately replace both. 

Featuring distinct double delta wings and large canards jutting from the engine inlets below the cockpit, Viggens featured tailless designs with no horizontal stabilizers.

Known for a lengthy development period, blistering performance, high-tech avionics and the wide array of lethal weapons they could carry, when Viggens entered service in 1971 they were among the most lethal military aircraft in the world.

In English, Viggen has at least two distinct translations. 

Loosely, the first is “thunderbolt,” referring to the magical hammer wielded by the Thunder god Thor. 

The second is simply, tufted duck. 

It’s probably safe to say that since no Scandinavian waterfowl ever stood a chance of intercepting an SR-71, designers had the former translation in mind when they named their new warbird. 

Dozens of different concepts featuring single and twin-engines as well as traditional and delta wing configurations were considered. 

Ultimately however, double delta wings and a single engine were deemed to be the best combination.  

VTOL (vertical takeoff and landing) capabilities were also considered, but testing revealed that this would’ve required even more development time, and the necessary lift engines would have increased weight, cost and complexity, while severely limiting range. 

From the outset, Viggens were to be integral parts of Sweden’s national defense, and due to the country’s relatively small defense budget they’d need to be capable of performing a variety of missions. 

Part ground attack platform, part fighter and part interceptor, to survive the rigors of aerial combat, Viggens would need to exceed Mach 2, outmaneuver the world’s best dogfighters, and take off and land on short unfinished airstrips and highways.

In addition, they’d need to be relatively inexpensive, serviceable by minimally trained groundcrews, and have the ability to operate from dispersed air bases in remote areas far away from military installations and supply hubs. 

Factor in low stall speeds, complex thrust reversers for post-landing deceleration and high thrust-to-weight ratios to get them airborne in less than 500 meters, and it’s not surprising that initial estimates pointed to a development period exceeding a decade. 

Though these projections proved accurate, the program got a boost in 1960 when the United States pledged to intervene militarily in the event that Sweden was attacked or invaded by the Soviet Union. 

Thanks to this agreement, the US transferred advanced technology that allowed Saab to develop the new airplane more quickly and inexpensively than would’ve been possible otherwise. 



Saab got the formal go-ahead to develop the new aircraft in the early ‘60s. 

It was such a massive undertaking that by the middle of the decade the program purportedly accounted for nearly 10% of all of the country’s research and development expenditures – both military and non-military.

During the first few years various teams weighed the pros and cons of each proposed configuration, but by 1963 it had become clear that powerful but fuel efficient turbofan engines, double delta wings, canards and thrust reversers provided the best all-around performance, especially when it came to STOL (short takeoff and landing) capabilities. 

Saab originally intended on using a variant of Rolls-Royce’s Medway engine, but development issues necessitated that a license-built Volvo manufactured version of the Pratt & Whitney JT8D engine be used instead. 

Called the RM8, the engine was optimized for high supersonic speeds and fitted with a Swedish-built afterburner and variable exhaust nozzle. 

RM8s were the first engines to be equipped with both afterburners and thrust reversers, the latter of which are more common on large commercial and military aircraft like airliners, bombers and transports. 

Of the seven prototypes built, the first flew in early February of 1967. 

The flight lasted less than an hour, after which Saab’s chief test pilot Erik Dahlström reported that the plane was a joy to fly.  

Though they’d briefly considered buying McDonnell Douglas F-4 Phantom IIs instead of developing their own indigenous aircraft, Saab and the Swedish Government concluded that based on initial testing, Viggens would be less expensive and superior to F-4s in many respects. 

The following year Saab was awarded a contract to build 175 Viggens, and in the spring of 1969 the first production unit made its public debut at the Paris Air Show. 

Specifications and Performance


Nearly 54 feet (16.5 m) long and 34 feet 9 inches (10.6 m) from wingtip to wingtip, Viggens had maximum takeoff weights of about 40,000 pounds (18,150 kg), which put them squarely between heavier F-4 Phantoms and lighter MiG-21s. 

With approximately 16,000 pounds of dry thrust and 28,000 pounds when the afterburner was lit, the Volvo turbofans were capable of propelling Viggens to 59,000 feet (18,000 m) and to top speeds approaching 1,400 miles per hour (2,250 km/h). 

Using only their 1,300-US gallon (5,000 liter) internal fuel loads, they were capable of flying more than 1,000 miles (1,600 km), and range could be extended significantly by adding a 400-US gallon (1,500 liter) external tank. 

Though twin-crew configurations were considered as well, the Viggen’s central computer, heads-up-display and ergonomic controls allowed pilots to comfortably handle all mission tasks in addition to flying the plane.  

The elimination of a second crew member made Viggens lighter, less complex and less expensive to build and operate, but unlike other aircraft of the era, cockpits also included old school mechanical gauges and cathode-ray display screens, because in addition to being cheaper and more reliable, most experienced pilots were already familiar with them. 

Viggens were also equipped with a host of electronic countermeasures including a radar receiver warning systems both fore and aft, as well as jamming and chaff/flare pods that could be carried depending on mission parameters. 

Of total aircraft weight, nearly 1,300 pounds (600 kg) was electronics and countermeasure equipment.  

Early Viggens were equipped with Saab-made ejection seats that were optimized for low altitude, high-speed emergencies.

Though manually initiated, the subsequent ejection sequence including canopy discharge, seat firing and parachute deployment were all automatic. 

Airframe and Wings


Because Viggens needed massive turbofan engines to meet performance requirements, their airframes were surprisingly bulky. 

Double delta wings – those in which the outer portion of the leading edge is swept at more of an angle than the inner portion – were chosen over traditional delta wings because they provided greater lift and better performance at various speeds and altitudes. 

The large canards that took the place of the horizontal stabilizers were positioned behind the inlet openings and sat slightly higher than the main wings, and they were used during takeoffs and landings to provide lift and drag respectively.  

To minimize weight and increase strength, Saab made extensive use of aluminum honeycomb structures in Viggen airframes, and much of the rear fuselage was built with titanium that acted as a giant shield which protected pilots and sensitive components from the immense heat generated by the engine. 

To handle the punishment associated with operating from unfinished airstrips, Viggens had tall heavy-duty landing gears that lessened the likelihood of debris being sucked into the engines and allowed them to takeoff carrying anti-ship missiles or external fuel tanks slung under their fuselages. 

Though tall, vertical stabilizers could be folded downward to facilitate storage in small hardened hangars which were employed to limit damage from preemptive aircraft, artillery and cruise missile strikes.



Weapons loads of up to 15,500 pounds (7,000 kg) could be carried on nine hardpoints located under the fuselage and wings. 

The centerline hardpoint was typically used for an external fuel tank, but it could also accommodate an anti-ship missile when additional fuel wasn’t needed.

Ground crews logged munitions data into the Viggen’s central computer, after which it automatically made calculations and adjustments pertaining to fuel consumption, tracking, fire control and avionics. 

Available weapons included various types of explosive and armor-piercing rockets, smart and dumb bombs, air-to-air, air-to-ground and air-to-ship missiles, and 30 mm cannon pods, each of which held 150 rounds of ammunition.   


Both nuclear and chemical weapons were also considered on later variants, though in the end Sweden produced neither. 



The first production Viggen was delivered to the Swedish Air Force in the summer of 1971. 

Before flying solo however, pilots had to accumulate at least 450 flight hours in Saab 105s, Lansens and two-seat trainers. 

With production ramping up, by late 1973 a number of units had attained full operational status, and the following year despite normal teething issues and the aircraft’s complexity, Viggens across the country were operating safely and efficiently.

That said, one commonly encountered and potentially fatal safety issue was that Viggens were notoriously susceptible to ingesting birds into their engine inlets, largely because they typically operated in remote and forested areas.

To ensure that no human lives or multi-million dollar warbirds were lost, the Swedish Air Force began keeping an eye on seasonal migration patterns and forwarding vital ornithological information to ground crews in the hinterlands. 

For nearly a decade Viggens were the backbone of the country’s extensive air defense network, and compared to aircraft operated by other western powers, they had lower operating costs, quicker refueling, repair and rearming times, and were capable of operating to and from unfinished airfields.  

By the mid-1980s Viggens were routinely intercepting SR-71s, some of which were returning to RAF Mildenhall in the United Kingdom. 

During the ‘60s and ‘70s, Viggens also entered into the United States Air Force’s Air Combat Fighter competition, the aim of which was to find a suitable replacement for its aging and accident prone F-104 Starfighters. 

In early 1975 however, the aircraft that would eventually go on to become the F-16 was declared the winner, and as they say, the rest is history. 

The End of the Viggen


Though Sweden originally intended to purchase nearly 800 Viggen variants, less than 350 were ever produced, thanks to inflation and the introduction of Saab’s JAS Gripen in the late ‘80s. 

By late 2005 nearly all remaining Viggens had been officially retired.

A few were kept operational as electronic warfare trainers, though these were phased out in mid-2007. 

All told, Viggens highlighted Sweden’s ability to develop and produce a remarkable aircraft on a relatively small budget compared to those of America, Britain and the Soviet Union. 

In fact, many NATO-aligned air forces wouldn’t have equally capable and advanced multi-role aircraft until Panavia Tornadoes were introduced in the late ‘70s. 

Had the two countries gone to war, Viggens probably would have inflicted serious damage and losses on Soviet ships, tanks, troops and aircraft. 

However, it was common knowledge that they’d sustain heavy casualties in the process, and unfortunately for the Swedes, the Soviets would have been in a much better position to absorb the losses. 

With a clear winner on its hands, Saab sales executives engaged in various worldwide marketing campaigns, targeting both European nations and developing countries in Asia, Africa and South America. 

However despite its efforts, India was the only country to show any real interest in acquiring Viggens. 

Sadly, the sale was blocked by the United States, at least officially because under the proposed agreement Volvo RM8 engine variants would have been produced under license in India. 

And as you may recall, RM8s themselves were license-produced variants of American Pratt & Whitney engines. 

Though it’s anybody’s guess why the American government blocked the sale, it probably had something to do with the fact that if India bought Swedish Viggens, it’d be one less potential customer in the market for more expensive American ones. 

Despite producing a true world-beater, Saab never sold a single Viggen overseas, though now dozens are living out their final days in museums in France, Poland, Estonia, and you guessed it – Sweden.

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