By 1963, Saab had settled on an aerodynamic design for their new jet. The design was radical, featuring an aft-mounted double delta wing plus small, high-set canards. The canards were especially distinct, and the Viggen would be the first mass-produced airplane to ever feature canards. Canards have since come to be relatively common, appealing in modern aircraft like the Dassault Rafale, IAI Kfir, Eurofighter Typhoon, and Saab’s newest offering, the JAS 39 Gripen.

In the Viggen, the inclusion of the canards, along with the delta wings, were to satisfy the various, often conflicting, program requirements set forth by the Swedish government. The jet was to be capable of short take-offs and landings (STOL), to enable operation from Sweden’s Bas 60 dispersal system, which repurposed reinforced public roadways as military airfields during war time. Additionally, the jet needed to be able to break the sound barrier, while also having high maneuverability (and low turbulence sensitivity) at subsonic, low-level flight.

The Saab 37 Viggen was designed to be an attack aircraft, rather than an interceptor, as the Saab 35 Draken already served as an adequate interceptor. Accordingly, Saab hoped to make the Viggen capable of low fuel consumption at high subsonic speeds, something with excellent range. Intending to build such an aircraft, Saab originally planned to power the Viggen with a single Rolls-Royce Medway engine. However, when the Medway engine development was canceled, Saab instead licensed the Pratt & Whitney JT8D engine, producing a modified version, the Volvo RM8. Whereas the original JT8D was used for commercial airliners, the RM8 was quite different from the source engine, featuring updated materials to allow operation at Mach 2 speeds, the addition of a Swedish-built afterburner, and a variable nozzle. The airframe also included a thrust reverse to help slow the aircraft down on landings (thus making short-runway landings possible). The thrust reverse could even be pre-set in the air to fire when the nose-wheel strut compressed upon landing.

A Saab 37 Viggen prototype first flew in 1967, with Saab’s chief test pilot Erik Dalhstrom at the controls. After the prototype’s maiden flight, Dahlstrom described the new jet as easy to control. The international aviation press noted that Sweden had made fantastic progress in aerospace development. By 1971, the Viggen was being delivered to the Swedish Air Force. In service, the jet proved reliable and safe – a relief given how complex and novel the airframe was. The finished product could perform, too. Capable of hitting 1,386 miles per hour, the Viggen could climb at 40,000 feet per minute and reach a service ceiling of 59,000 feet. For armament, the jet carried one 30 mm Oerlikon KCA cannon with 125 rounds. For hardpoints, the jet had three under each wing, plus three under the fuselage.

While the Viggen was capable and innovative, it was never exported, and never saw much action (as Swedish jets never do). The Swedish Air Force began removing the Viggen from front line service in 1994, to make way for the new Saab JAS 39 Gripen. The last Viggen was formally retired in 2005.