A single-seat, single-engine interceptor/fighter for all-weather conditions, with low double delta wings, the Saab 35 Draken was developed in order to replace the Saab J29 Tunnan and the Saab J32 Lansen. Its first flight took place in 1955, being amongst the most advanced and remarkable fighters of its time. In 1960 it entered in service with the Flygvapnet.
Development of the Draken
Draken development started in 1949, following a requirement by the Flygvapnet for a single-seat cost-efficient interceptor with supersonic capabilities and high climbing rates, able to operate in short airstrips – or even highways, roads and unprepared runways – and easy to operate with high adaptability. As a result of both the requirements and development process, the result was a double-delta winged fighter that became the first European supersonic fighter, and also a high performance air-defence asset for Sweden. And on a similar fashion as the JAS 39 Gripen and JAS 37 Viggen, it was required the Draken to be serviced, refuelled and armed up to ten minutes by untrained ground personnel. A brake parachute was incorporated to reduce landing distance. Interestingly, a prototype was built expressly to test the double-delta wing concept: such was the Saab 210 ‘LilDraken’.
The Draken is also a product of the needs from a neutral nation willing to keep its neutrality, and geographically placed between the two block. This reason explains the requirements, but especially its high climbing rate capabilities, so to be able to engage high-altitude bombers and fighters – namely Soviet Union bombers and fighters. It also explains the need for STOL capacities, as the Flygvapnet was implementing a system of dispersed bases, asking for highways and roads to be used as airstrips from where the aircraft could be operating, and also to reduce damage and increase survival in case of attack.
Its very unique and remarkable double-delta wing design is also explained by the technical abovementioned requirements, which gave the aircraft very good high and low speed performances. This design made the Draken capable of executing the “Cobra” manoeuvre, and also to stand well against more recent designs, as air exercises in Austria evidenced. During development it was able to unintendedly exceed Mach 1 on its first afterburner flight. It could also sustain a force of 10G turning force. And it also had a safety feature, with the introduction of a ram turbine, placed under the nose, to provide emergency power.
Despite being conceptualized as an interceptor, it performed well in dogfights and was able to undertake ground attack, training, and reconnaissance missions as well. And it proved to be a very tough and resistant design, as it is among the few jet fighter designs to be in service for 50 years. Austria, Denmark, Finland, Sweden and US National Test Pilot School were the operators of the Draken.
The design was so unique that, in fact, the Draken was studied for the design and development of the F16XL experimental prototype.
Between 600 and 650 Draken were built, serving with the Flygvapnet until 1998, with the Finnish air force until the year 2000, the Danish air force until 1993, and the Austrian air force until 2005. The Draken also flew with the Flygvapnet ‘Acro Delta’ acrobatic team.
The Draken is designed as a tailless middle double-delta wing fighter, with a single tail and a single engine (A Volvo Svenska Flygmotor RM6C, bestowing a maximum speed of 2125 km/h / 1,317 mph). Its double-delta wings allow good high and low speed performances. It also provided good fuel and armament capacity. The engine air inlets are located mid-wing at each side of the cockpit, featuring a characteristic egg shape.
Considered an easy-to-fly platform, yet not suitable for untrained pilots given the high sensibility controls, and being prone to ‘superstalls’ as a very stable platform with good low flight.
Although the avionics were in principle basic, the radar was a very sophisticated one – A PS-02/A based on the French radar Thompson-CSF Cyrano – integrated with an Ericsson version of a radar Thompson-CSF Cyrano S6 fire control system. It also incorporated VHF/UHF radio, a radio altimeter, a transponder, an IFF (Identification Friend or Foe) system, and the Swedish version of the Lear-14 autopilot. The seat of the pilot was reclined 30 degrees, similarly like the Viggen, to allow the pilot to resist G-forces. And the cockpit was fitted with air-conditioning and pressurization.
The engine in combination with the design, made the Draken a very manoeuvrable and fast fighter jet, with the braking parachute assisting the aircraft in the landing, reducing the distance required to reach a full stop. Earlier version of the Draken had two 30 mm Aden M/55 cannons, with later versions having only one cannon. Also some export versions kept the two cannons configuration.
An Advanced Cold Warrior
The Draken can boast not only being a radical and new design thus making it a very advanced one by the first decades of the Cold War. It was among the first fighters in incorporating an on-board radar and the earlier version of the data-link system, whose enhanced version was incorporated in the J 37 Viggen and the JAS 39 Gripen. Indeed, the Draken incorporated the STRIL 60 ground-control network that enable Draken pilots a firing guidance through the on-board instruments, being the system also capable to resist electronic jamming. Aside the fact of being the first European supersonic jet fighter, the Draken was the first fighter to have STOL capacities, and it was an aircraft that gathered valuable intelligence by producing photographic material of many new Soviet aircraft during the 70’s and 80’s. It also had a superior service ceiling in comparison with fighters of its times. Being a very resisting and long-endurance fighter, many pilots of the Draken stated that it was able to take on much newer designs.
- J 35A – The first version of the Draken. Capable of performing fighter tasks. A small retractable wheel was placed on the rear fuselage as the angle of the nose was required to be elevated during landings to stop the airplane. But the wheel was also placed as the fuselage was enlarged, as the EBK 66 afterburner was incorporated. This version had 2 Aden 30mm cannons, installed on each engine air take, 2 to 4 Rb 24 (Swedish version of the AIM-9B Sidewinder missile) and a central fuel tank or an additional Rb 24. The afterburner installation allowed the Draken 35A to carry Bofors 135mm rockets (up to 12) in rocket pods. This version had basic avionics, being upgraded with the SB6 fire-control system, which included an infrared search and track sensor (IRST). 90 aircraft produced.
- J 35B – Interceptor and fighter version. Its development began in 1956, before the J 65A was developed. It initially performed training task until better engines and avionics were available. This model then incorporated the air-to-ground STRIL 60 system, and new radar and fire-control systems that enhanced collision course interceptions. It had an ejection seat that allowed the pilot to eject at zero altitude. This version was armed with two 75mm Bofors cannons, folded-fin air-to-air unguided rockets, and for ground-attacks, 135mm rockets. 73 produced.
- Sk 35C – Trainer version. Two-seat aircraft build upon J 37A airframes, being exported to Denmark and Finland. The second section was raised for the instructor’s place – being located right behind the pilot/student – and fitted with a 3D stereoscopic periscope. Upgraded with afterburners and improved avionics. The tail section was shortened, and the aircraft could be easily re-modified to its J 35A version if necessary. 25 delivered.
- J 35D – Fighter version, equipped with a better engine – a Svenska Flygmotor RM6C – that made this version the fastest (up to Mach 2), which allowed increased payload, but also meant increasing fuel capacity. Its avionics were also upgraded, receiving a Saab FH-5 autopilot, an Ericsson PS-03 radar coupled with a Saab S7A fire-control system and a new ejection seat, replaced latter with a seat that allowed ejection on zero/zero conditions. 120 delivered.
- S 35E – Reconnaissance version. It was unarmed but equipped with ECM measures. Fitted with seven cameras: a vertical-looking camera; a forward-looking camera on the nose; a downward/vertical looking with wide-angle camera and two sideways-looking cameras; and two long focal length vertical cameras. A downward-looking periscope and a voice recorder were fitted to allow the pilot to aim the cameras and make comments on the imagery. Latter improved with afterburners, chaff dispensers and two radar alerts, and the ability to carry on the central pylon a night-time Vinten Blue Baron multisensory night photography device. 60 delivered.
- J 35F – Fighter version. It had improved avionics and electronics, such as integrated radars, radios, aim, infrared target seekers, and missile systems. In fact, it had the STRIL 60 incorporated. It was the version with enhanced armament, such as two semi-active radar homing Rb 27 AAM missiles, and two Rb 28 or Rb 24 AAM missiles. As a result of the new avionics, the second 30 mm cannon was supressed. Used by 18 squadrons in the Flygvapnet. 208 delivered.
- J 35F2 – A J 35F fitted with a Hughes Aircraft Company N71 infrared sensor.
- J 35J – Fighter version that kept the Draken in the inventories of the Flygvapnet, co-operating with the J 37 Viggen. It has six pylons, which increased the payload. It incorporated enhanced fire-control systems, infrared sensors, radar, altitude warning systems, navigation systems, IFF and modernised cockpit electronics. It also had a slightly improved RM6C engine that provided more speed. 76 delivered.
- 35H – Proposed export version for Switzerland. None built or delivered
- 35XD – Export versions for Denmark. It comprised the F-35 strike aircraft, TF-35 two-seat trainer and the RF-35 reconnaissance jets. Overall the 35XD were the heaviest aircraft of the Draken family, as they were optimized for strike missions. 51 delivered.
- 35XS – Export version for Finland, some of which were locally assembled by Valmet under license in Finland. The received/assembled aircraft were the interception, fighter-bomber and training versions. 48 delivered.
- 35BS – Used J 35B bought by Finland
- 35FS – Used J 35F bought by Finland
- 35CS – Used Sk 35C bought by Finland.
- 35Ö – Version for Austria. Used J 35Ds that were refurbished and modernised by Saab, with extra 1000 flying hours, radar warning receivers, the radar of the J 35D, and chaff dispensers. Like the earlier version of the Draken, it was armed with the two 30 mm Aden cannons. 24 delivered.
- Sweden – The Flygvapnet had 544 Draken: 90 J 35A; 73 J 35B; 25 Sk 35C; 120 J 35D; 60 S 35E; 208 J 35F; and 76 J 35J. Many were upgraded or modified airframes, so the number is an approximation. Many were sold to other countries.
- Austria – The last exporter of the Drakens. The Österreicher Luftstreitskräfte received 24 J 35Ö – ex-Swedish J 35D – to replace the J 29F Tunnan in 1987. Initially many Draken (5 Sk 35C) remained in Sweden for training purposes, being replaced later by a simulator. The Austrian Draken were originally armed with two 30mm Aden cannons, as AIM missiles were restricted by a treaty after WWII. But as the crisis escalated in former Yugoslavia by 1993, deeming that cannons were not enough to protect the airspace, Austria acquired AIM 9P3 and AIM 9P5 Sidewinder missiles from the US and equipped them on the Draken.
- Finland – The second exporter of Drakens, receiving 12 all-weather J 35XS interceptors, 7 ex-Swedish J 35BS, 24 ex-Swedish J 35FS and 5 ex-Swedish Sk 35CS, all to serve with the Suomen Ilmavoimat. Most of the received aircraft were delivered in kit form and assembled by Valmet in Finland, and had also two Aden 30 mm cannons. Finland used the Draken as interceptors and fighter-bombers, and retired them in 2000.
- Denmark – The first country in exporting the Draken, with units being received in 1970. As the original version was the least favoured during the competition for a new Danish fighter, Saab created a new version (J 35XD), based on the J 35F. the structure was strengthened in order to allow more payload – 9 reinforced pylons – with simultaneous use possible. The landing gear was reinforced with an added arrestor hook, and had two Aden 30 mm cannons, as well as extra fuel capacity. Being a European cost-effective platform, plus the improvements, made the Kongelige Danske Flyvevåben to choose the Draken. 20 A 35XD ground attack fighters (denominated F35), 30 S 35XD reconnaissance (denominated RF35), and six Sk 35XD training (denominated TF35) were purchased. 7 additional aircraft were purchased to be cannibalized. Danish training and reconnaissance versions were fitted with cannons and pylons to carry weapons, thus having secondary combat capabilities. 5 further Drakens (TF35) were purchased. Receiving upgrades in the following years, the Draken were retired from Danish service in 1993.
- US National Test Pilot School – Operated 6 Drakens, formerly Danish Air Force jets training and reconnaissance versions.
|Wingspan||9.42 m / 30 ft 10 in|
|Length||15.20 m / 49 ft 10 in|
|Height||3.8 m / 12 ft 7 in|
|Wing Area||49.22 m² / 529.8 ft²|
|Engine||1 Svenska Flygmotor Turbofan RM6B|
|Maximum Take-Off Weight||10,089 Kg / 22,200 lb|
|Empty Weight||6.590 kg / 14,500 lb|
|Loaded Weight||16,000 kg / 35,273 lb|
|Maximum Speed||1,900 km/h / 1,200 mph|
|Range||3,250 Km / 2,020 miles|
|Maximum Service Ceiling||18,000 m /59,100 ft|
|Climb Rate||200 m/s ( 12,000 m/min / 40,000 ft/min )|
|Armament||• 1 Aden 30mm Cannon
• 6 hardpoints that could allow 1700 kg of payload. A pod for a 135mm Bofors M70 rockets; air-to-air Rb 24, Rb 27 or Rb 28; external fuel tank; iron bombs; cameras.
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