The Saab J35 Draken was a Swedish-designed multi-role fighter aircraft that was ahead of its time, featuring a revolutionary double-delta wing configuration. The J35 Draken, translated to “Dragon” in English but meaning “Kite” due to its angular resemblance to a kite, was one of the most outstanding aircraft designs to emerge during the Cold War. It proved to be a viable solution to Sweden’s need for a high-performance interceptor, equal or superior to anything used in the world at the time. The Draken served from 1960 to 2005 and proved its worth in over 640 serial examples. The double delta wing configuration proved to be revolutionary and undoubtedly contributed to the aircraft’s flight capabilities.
In the late 1940s, the Swedish government was considering the inevitable replacement of the Saab J29 Tunnan range. A specification was established in 1949, requiring a new aircraft to provide a maximum speed half again as fast as any other platform entering service in the world. This aircraft also had to offer exceptional climb rates, as it was tasked with intercepting transonic enemy bombers. The already demanding specifications also called for high weapons capacity, long operational endurance, and the ability for the platform to operate on short runways as well as on roads. This last requirement was more or less a permanent requirement for all future Swedish-designed aircraft, as it was always intended that these aircraft would be responsible for defending the country by any means necessary – meaning the aircraft could be flown from short stretches of Swedish highways for optimal range of its combat capabilities.
Erik Bratt led the Saab design team to meet the specifications of the specification. The selected shape became a double-delta wing arrangement, more specifically known as a “double delta” (or even “compound delta”) wing design. The double delta design was exactly the same: two paired delta wings working in conjunction with each other. One pair was placed at the front and had a steeper sweep angle and smaller area than the rear pair, which had a gentler sweep angle. This pairing allowed the new aircraft to promote good maneuverability at both high and low speeds, with each pair of wings benefiting from these flight speeds. Delta wings, in their essence, allowed for greater fuel capacity, low-speed stability, and a greater weapons load. In comparison, the contemporary Lockheed F-104 Starfighter used short and thin wings, forcing the fuel and landing gear to be stored in its tubular fuselage. Furthermore, the Starfighter was relatively limited in its munitions carrying capacity, though its minimalist and rocket-focused approach allowed it to achieve record-breaking speeds.
The new Saab’s double-delta wing was paired with a circular fuselage adorned with a single vertical fin, successfully tested on the Saab 210 “Lilldraken” (“Little Kite”) – essentially a scaled-down version of what would become the J35 – on January 21, 1952. A Rolls-Royce Avon afterburning turbojet engine (series 200/300) was chosen to power the new aircraft, and an agreement was reached for the licensed production of the engine in Sweden under the name Svenska Flygmotor RM 6B/C. Three prototypes followed, all equipped with the Avon 200 series (the first prototype without afterburner), and the first flight took place on October 25, 1955. The second prototype is notable for unintentionally breaking the sound barrier during ascent, an achievement that nonetheless illustrates the exceptional design principles of the aircraft. The seats allowed for a single operator to be positioned in the front of the fuselage with excellent forward and side views.
The Saab J35 Draken was designed from its inception as a specialized interceptor aircraft. Traditionally, this required an aircraft with high top speed, exceptional climbing ability, and the capacity for pursuit and weapon delivery at range, with maneuverability being a secondary concern. Despite its origins, the Draken proved to possess more than adequate air combat capabilities due to its large wing area. With good turning performance and a powerful engine capable of Mach 2, the J35 Draken could keep pace with any modern fighter of its time. This made the Draken not only an exceptional interceptor but also a competent air defender when employed as specialized fighters.
Variants of Saab J35 Draken:
J35A – Early Production Models:
The J35A was the first production model dedicated to the interceptor role, with around 90 units built. Deliveries began in 1959 and continued until 1961. Two subvariants of the A model, known as “Adam kort” (short Adam) and “Adam lang” (long Adam), were differentiated by the addition of a new afterburner system in an elongated rear section to improve thrust performance. This modification occurred after the 66th production of the J35A and required the use of an additional set of landing wheels along the rear part of the lower fuselage. This new landing gear arrangement, combined with the Draken’s large wing area, also allowed for “tail low” landings.
J35B – Improved Avionics:
The J35B, produced in 73 units between 1962 and 1963, featured a revised targeting system and a fully integrated radar in the digital STRIL-60 combat management system. Additionally, it had a collision course radar and a data link system.
SK 35C – Converted Trainer Aircraft:
The SK 35C comprised up to 25 J35A production models converted into two-seat trainer aircraft. These trainers were equipped with tandem seats for the instructor and student, and were unarmed. The modification was such that the aircraft could be relatively easily reconverted to A-type combat models if needed.
J35D – New Engines:
The J35D was the third Draken model in the series, featuring new Rolls-Royce Avon 300 engines (RM 6C under Flygmotor production label) with afterburner. Production lasted from 1963 to 1964, with 120 units delivered.
S 35E – Reconnaissance Variant:
The S 35E became 60 production units of reconnaissance aircraft, delivered without armament or associated radar systems to make room for five cameras in the nose. While most were built new, nearly half of the operational batch was converted from existing J35D production models.
J35F – Ultimate Interceptor:
The J35F, produced in about 230 units between 1965 and 1972, became the definitive Draken interceptor. The cannon armament was reduced to a single 30mm M-55 ADEN to accommodate more significant avionic equipment. A revised avionics, radar, and weapons suite, along with improved electronics, welcomed the new Draken variant. The weapons system included an automatic control system designed by Hughes, a pulse-Doppler radar, and provisions for the Hughes Falcon air-to-air missile family. The J35F-II represented the J35F model with a Hughes infrared sensor. The F models eventually gave way to the much more advanced Saab JAS Gripen multirole fighters.
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