The Saab J35 Draken was the first production fighter aircraft to feature a double delta wing, an innovation that transformed its agility and missions.
The Saab J35 Draken, developed by Sweden in the 1950s, marked a technological breakthrough by becoming the first production fighter aircraft equipped with a double delta wing. This aerodynamic configuration, unprecedented at the time, combined high-speed stability and low-speed maneuverability, two qualities rarely found in the same aircraft. The objective was clear: to design an interceptor capable of reaching Mach 2 while remaining operational from short and sometimes rudimentary runways. The Draken’s double delta wing offered a unique compromise, influencing its operational effectiveness, export marketing, and exceptional longevity, with a career spanning until the early 2000s in some European countries.
An innovative and complex design
The choice of a delta wing was already obvious in the 1950s for fast fighters. This type of wing offered good lift at high speeds and low supersonic drag. However, it had two limitations: low efficiency at low speeds and difficulties in controlling the aircraft during landing. Saab engineers, faced with the specific requirements of the Swedish defense forces, introduced a radical innovation: a double delta wing.
The Draken combined two different sweep angles on the same wing:
- A steeply swept inner delta (≈ 80°) to ensure stability and reduce drag at supersonic speeds.
- A less pronounced outer delta (≈ 57°) to improve lift and maneuverability during slow flight phases, particularly during landing approaches.
This geometry produced air vortices that were favorable for controlling the aircraft, even at high angles of attack. This made it possible to maintain effective lift without sudden stalls, a rare feature for an aircraft of this generation.
Measurable aerodynamic effects
The double delta wing generated a stabilized turbulent airflow along the wing, which increased lift. In practical terms, this gave the Draken the ability to fly at Mach 2 at high altitude while still being able to perform tight maneuvers at low speeds. Pilots quickly discovered that the aircraft could perform unprecedented maneuvers, such as the precursor to the cobra (high angle of attack followed by a controlled recovery), long before Soviet fighters such as the Su-27 demonstrated this publicly.
In practice, this aerodynamics gave the J35 versatile performance:
- A maximum speed of 2,120 km/h (≈ Mach 2) at high altitude.
- A rapid climb capability, essential for an interceptor.
- Sufficient maneuverability for close combat, an asset rarely associated with heavy interceptors.
These characteristics placed the Draken in a hybrid category, capable of competing with heavier fighters while remaining adapted to local Swedish constraints.
An aircraft designed for Swedish needs
Sweden’s military doctrine imposed unique constraints. The aircraft had to be able to operate from short runways, sometimes improvised on sections of road. This required an aircraft capable of taking off quickly, landing at low speed, and withstanding rough terrain conditions.
Thanks to its double delta wing and integrated parachute brake, the Draken could land on runways less than 800 m long, a feat for a supersonic interceptor. This flexibility strengthened the resilience of the Swedish air force in the face of a possible Soviet attack, as it allowed aircraft to be dispersed throughout the country.
Logistically, the aircraft was also designed to be easily refueled and rearmed by small crews. The compromise between supersonic performance and low-speed maneuverability was therefore perfectly suited to national needs.
The Draken’s military missions
The Saab J35 was designed as an interceptor, capable of shooting down Soviet bombers entering Nordic airspace. However, its design gradually led to it being used for multiple roles:
- Supersonic interception: rapid climb and use of air-to-air missiles.
- Close air combat: maneuverability provided by the double delta wing.
- Ground attack: carrying bombs and rockets thanks to its six hardpoints.
- Reconnaissance: some versions equipped with specialized pods.
The Draken was thus used in several variants, such as the J35F (interception), the J35D (multi-role) and the S35E (reconnaissance). This versatility stemmed directly from its aerodynamic design, which offered a much wider range of use than initially anticipated.
Operational and commercial consequences
Operationally, the Draken served in Sweden from 1960 to 1999, a period of nearly 40 years. Its efficiency and robustness convinced other European countries. Denmark, Finland, and Austria adopted it, extending its career until 2005. The export of such an innovative aircraft from a neutral country showed that the double delta wing was a strong commercial selling point.
Compared to other European fighters of the same period, such as the Dassault Mirage III or the English Electric Lightning, the Draken stood out for its versatility and interoperability. The Austrian Air Force, for example, used it as its primary interceptor for more than 20 years, proof of its reliability.
The Draken’s technological legacy
The double delta wing design paved the way for other aeronautical innovations. Saab itself continued this logic with the Viggen, then the Gripen, each adapted to the Swedish doctrine of dispersion and flexibility. The Draken also remains a textbook case in aeronautical engineering, as it demonstrated that a well-thought-out compromise between aerodynamics and operational requirements could produce a high-performance, durable aircraft.
Today, several examples still fly in private or museum organizations, proof that its architecture continues to be studied and admired. In academia, its double delta wing is still cited as a successful example of innovative design to solve a major aerodynamic dilemma.
A breakthrough that goes beyond the technical realm
The Saab J35 Draken illustrates how technical innovation can shape a national military strategy and influence international markets. The double delta wing not only improved its flight performance, it also guaranteed Swedish air sovereignty during the Cold War, while opening up export opportunities. Saab’s boldness in the 1950s led to the creation of an aircraft that, long after its operational career, continues to inform thinking about the design of modern fighter aircraft.
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