The Draken: One of Sweden's finest fighters

When it was conceived in the early 1950s, Saab’s Draken was a very radical and unusual machine. Its unorthodox design allowed it to easily surpass the speed of sound, making it Sweden’s first supersonic fighter aircraft and one of Europe’s best performing fighters. The Draken had a successful career with a number of air forces and remained in service 50 years after its maiden flight – quite an achievement, especially considering that two successors have been built!

Two Flygvapnet Drakens banking in unison (Saab) A stunning shot of two Austrian J35OE Drakens flying over the Austrian Alps. The aircraft on the left is painted in unique aerobatic markings. (K Tokunaga/Saab)

History
Saab 210
The Draken
J35A
J35B
SK35C
J35D
S35E
J35F
J35J
Proposed variants
Danish Drakens
Finnish Drakens
Austrian Drakens

History

The inception of the Draken (Dragon) dates back to September 1949 when the Royal Swedish Air Material Board of the Swedish Air Force (FMV) issued a requirement for a new single-seat all-weather interceptor to replace the Saab J29 ‘Tunnan’. The endeavour was named Project 1200 and called for a new supersonic aircraft that would have a speed of at least Mach 1.4, be able to operate off specially-built sections of public roadway (under the Swedish BASE 90 distributed airfield scheme), be rugged, easy to maintain and cheap to operate. One of the most important requirements was that it had to have a very high rate of climb in order to catch the emerging threat of fast, high-altitude jet bombers travelling at around Mach .9. Sweden was a neutral country and was determined to defend its independence against any threat, especially that of Cold War bombers from the Soviet Union.

In November 1949 a Saab engineering team under designer Erik Bratt examined a number of different options to meet the demanding specifications. The conventional way to achieve the desired high performance was to fit the most powerful engine into the smallest airframe with the lowest drag. Bratt preferred a single-engine configuration because it saved weight and cost and reduced complexity. Instead of designing the airframe first and then trying to fit in all the essential equipment, Bratt’s team did the opposite. The first part was easy: the radar, cockpit and engine were arranged in a straight line. But the more difficult part was how to fit in everything else like the landing gear, avionics, systems, fuel and weaponry.

In order to achieve supersonic flight, the wing had to be quite thin and have a low thickness to chord ratio (chord is the shortest distance between the leading and trailing edges of a wing). To achieve Mach 2.2 speed on the contemporary F-104 Starfighter, Lockheed had crammed everything into a long slim fuselage and made the wings little larger than the vertical tail! Although such thin, sharp wings gave impressive speed, they resulted in very high wing loading, very high takeoff and landing speeds and severely limited agility. Bratt and his team briefly considered this configuration, but noted its considerable shortcomings and took a totally different approach.

If the wing was made thick, a low thickness to chord ration could still be obtained by making the chord very long. This is where Bratt came up with a unique and highly successful wing planform that would be thick enough to hold large items like the landing gear and systems, yet still have a low drag coefficient. Saab initially envisaged a long, pure delta-winged aircraft with an incredibly large wing sweep angle of 70 degrees and a nose air intake.

As handling problems were foreseen with such a radical and advanced layout, the design was modified. The cranked delta wings began at the air intakes and were swept at 76 degrees, but halfway along the wings this was reduced to 57 degrees for the outer portions. The inner wing was very thick in order to accommodate the fuel and landing gear, while the outer portion was thinner and provided lift for short-field and low-speed operation while still keeping drag low enough for supersonic flight. This configuration was frozen under Saab’s Project 1250, a follow-on to the original Project 1200.

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Saab 210

Project 1250 met the requirements of the FMV, but it was an extremely radical design that could easily have ended up a disaster. Rather than risk the whole programme by building a full-scale prototype, Saab first decided to test the design’s handling characteristics by building a small demonstrator, the Saab 210. But before building this aircraft, ground testing was done on the double-delta configuration. This included wind tunnel experiments using pulse-jet-powered models. As results showed no major problems, the Saab 210 70% scale demonstrator aircraft was built.

The aircraft originally had an oval nose intake, separated in the middle by a nosecone in the shape of a pyramid/chisel. In this form it was designated 210A. But since flight testing revealed that the intake did not provide enough airflow, the forward fuselage was redesigned and a proper nose was introduced, with the intakes moved back to each side of the cockpit. In this, the final configuration, it was designated 210B. The aircraft was powered by an Armstrong Siddeley Adder turbojet producing just 480 kg (1 048 lb) of thrust, which was barely enough to get it into the air but served the purpose. Like the Draken, the Saab 210 had a single vertical tail and double-delta wings, of which the inner wing was blended into the fuselage to almost function like a big wing leading edge root extension. There was no horizontal tailplane, even though Saab engineers had considered fitting one. A few wind tunnel models were built with tailplanes, but during wind tunnel testing it was found that this configuration was unstable, and so the tailplane was dropped.

Construction of the aircraft, nicknamed ‘LillDraken’ (Little Dragon), began in May 1950 and in December 1951 it made a small hop, although this was unintentional. Saab test pilot Bengt Olow made the 210’s maiden flight on 21 January 1952 and kept the little aircraft in the air for 25 minutes. Although flight controls were manual, the 210 performed very well and revealed no undue problems, except the need for a redesigned nose and the need for autostabilisation on the full-scale model. The double-delta configuration combined the best of both worlds, as it was good for high-speed flight and relatively low takeoff and landing speeds. The Saab 210 made around one thousand test flights until it was donated to the Flygvapnet (Swedish Air Force) museum.

The Saab 210, the Draken's proof of concept demonstrator (Saab). The 70% scale 'mini-Draken' in flight (Saab). A beautiful shot of the Saab 210 in flight (Saab).

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The Draken

Following successful testing of the Saab 210, the layout of the Saab Type 35 Draken (Dragon) was frozen in March 1953. After some hesitation by the FMV, who were a little nervous about the radical tailless layout, an order for three prototype and three pre-production Drakens was placed in August 1953. An order was also placed for the front end of a two-seat conversion trainer.

The first of the three Draken prototypes made its maiden flight on 25 October 1955 with Bengt Olow at the controls. It was powered by a British Rolls Royce Avon Mk 21 without afterburner, built by Svenska Flygmotor as the RM5A. However, the prototype was later re-engined with the more powerful Avon Mk 43 without afterburner, one of six Avons provided by Rolls Royce. With this improved engine, the first prototype flew past Mach 1 in level flight on 26 January 1956. Unfortunately it suffered damage in a belly landing on 19 April that year, but was later repaired.

The second Draken prototype with an even more powerful Avon Mk 46 first flew in March 1956, but was also damaged in a belly landing a week before the first prototype’s accident. In September 1956 the third prototype took to the air and was later joined in an extensive flight test programme by the other two prototypes, once they had been repaired. In the end, the first prototype was sent to a museum, the second was destroyed in a ground fire in 1965 and the third landed up at a technical school where it was used for stress and fatigue testing.

Following successful testing, the Draken was ordered into production in August 1956. The first variant produced was the J 35A, the J standing for Jakt, meaning fighter and the A standing for Adam. Another two prototypes were built with J35A features (these were part of the six prototypes originally ordered, but it seems that only five were built new) and these flew in 1958. Number five, the first one built, was initially fitted with an improved Avon Mk 48A engine and later fitted with the equivalent locally built RM6B which was to be the production J35A engine. It was used for testing and evaluation purposes and was later sent to the Flygvapnet museum.

Deliveries to the Swedish Air Force began on 8 March 1960 when the first J35As were delivered to F13 Wing at Norrköping-Bråvalla where they were operated by 1, 2 and 3 Jaktflygdivisions (Squadrons). It took F13 nearly a year to phase out the J29 Tunnan and convert to the new Drakens. Delivery of the J35A variant was completed in 1962, by which time it was also operated by 1, 2 and 3 Jaktflygdivisions of F16 Wing based at Uppsala, including the Draken Conversion Unit. The J35A continued to fly with the Air Force until 1976 when the last A models were withdrawn from active service.

A pre-production J35 Draken coming in to land (Saab) The three Draken prototypes and two pre-production prototypes (Saab).

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J35A

The intended engine for the Draken was the indigenous STAL Glan but, as it was never developed, the tried and tested Rolls-Royce Avon 200 turbojet was substituted in 1952. Svenska Flygmotor (later Volvo Flygmotor) obtained a license to manufacture the British engine.

The production J35A was powered by the RM6B (Avon Mk 48A) turbojet with a Swedish EBK 65 (or type 65) afterburner. The engine developed 4 890 kg (10 600 lb) of thrust dry and 6 804 kg (15 000 lb) with afterburning, giving an outstanding top speed of Mach 1.8 in level flight. Maximum internal fuel was 2 240 litres (590 gallons), carried in the thick inner wing section together with the landing gear.

The Draken was provided with a pop-up ram air turbine to provide emergency power in case of electrical or hydraulics failure. This turbine was located just behind the nose gear and could be extended manually or automatically when the hydraulic power failed. However, it could only be retracted when the engine was running.

The circular engine air intakes were mounted on either side of the fuselage just behind the cockpit, giving the Draken its unique double-delta configuration. The inboard section of the wing trailing edge was swept forward, but the outer section was almost straight and unswept, giving an even more unusual wing plan. Flight control was provided by elevons running the width of the wing trailing edge and by a rudder. The elevons operated in unison for pitch control and in opposition for roll control. They were split, with one on the inboard section of each wing and the other on the outboard section. All flight controls were powered by a dual redundant hydraulic system.

The J35A had tricycle landing gear with a single wheel on each unit. Each main unit was hinged at the wing root to retract outward into the wing and unusually contracted to save space. The nose gear unit retracted rearwards into the fuselage and was fitted with a mudguard for rough field operations, which was especially useful when Drakens took off and landed from short sections of highway and farm road.

Taking off was relatively straightforward and presented no problems, but landing and pulling up in a short distance did. As a result, a braking parachute was added at the base of the vertical tail to reduce the landing run and a small airbrake was fitted on either side of the fuselage near the end of the wing. Without the brake parachute the J35A’s landing run was 2 657 feet (810 m), but with the parachute it was reduced to 2 224 feet (678 m).

As the only way to slow the aircraft in flight was to raise the nose, which resulted in a high nose-up attitude on landing, a tailskid was fitted to prevent damage to the rear fuselage. This created an impressive trail of sparks whenever it grazed the runway.

The pilot sat in a basic Saab ejection seat which was reclined 30 degrees to help deal with g-forces. Faired into a dorsal spine that ran the length of the airframe, the cockpit featured a clamshell canopy and was hinged at the rear. It was also pressurised and air-conditioned.

Armament consisted of two 30 mm (1.18 in) British Aden revolver type cannon, each mounted in the inboard wing section outboard of the engine air intake. They were each provided with 90 rounds of ammunition. The J35A had a single centreline stores pylon and a pylon under each wing. These two wing pylons usually each carried a single Rb 24 (licence-built American AIM-9B Sidewinder) heat-seeking air-to-air missile (AAM) while the centreline pylon could carry one Rb 24 or an external fuel tank with a capacity of 530 litres (140 gallons). A twin launch rack could be fitted to this centreline pylon, allowing two Rb 24s to be carried. The maximum external stores load for the J35A was 1 700 kg (3 748 lb).

The J35A had a relatively basic avionics fit, but it did have a relatively sophisticated PS-02/A radar (which was based on the French Thomson-CSF Cyrano radar fitted to the Dassault Mirage III), integrated with an Ericsson-built Thomson-CSF Cyrano S6 fire control system. Basic avionics included a VHF/UHF radio, radio altimeter, transponder, PN-793/A identification friend or foe (IFF) system and a Swedish copy of the US Lear-14 autopilot.

A number of J35As were equipped with the SB6 fire-control system between 1966 and 1967. This included an infrared search and track sensor (IRST) under the nose. The J35F2 variant also had an undernose IRST, but this was a different device and should not be confused with that of the J35A.

A total of 90 J35As were built, of which the first three were pre-series aircraft and the next 17 were operational evaluation machines lacking radar and other equipment, which was later fitted. While unarmed and without radar, these Drakens served as single seat trainers for both ground crew and pilots. The first 65 aircraft were equipped with the RM6B (Avon Mk 48A) with EBK 65 (or type 65) afterburner. The last 25 J35As were fitted with the EBK 66 (or type 66) afterburner, delivering around 300 kg (660 lb) more thrust to give a higher service ceiling and better performance. This resulted in a longer engine assembly, necessitating a longer rear fuselage. As the tailskid was not considered enough to protect the extended rear fuselage from damage during touchdown, a clever and innovate set of ‘rollerskate’ wheels was fitted in place of the skid. These two small wheels were mounted side by side and retracted into the rear fuselage.

The Drakens with EBK 66 afterburner had other modifications and could accommodate three stores pylons on each wing. Each pylon was capable of carrying two Bofors 135 mm (5.3 in) unguided rockets, giving a maximum of 12 rockets.

Although the Draken was a ‘hot ship’ it had excellent performance and was relatively easy to fly, and proved to be a good dogfighter. Its instantaneous turn rate was good, but as with virtually all delta-winged aircraft, speed and energy was rapidly bled off during tight turns. The Draken did have a few problems that needed to be solved, the worst of which was over-sensitive controls that made it unforgiving to ham-handed pilots. It also tended to pitch up and down easily, leading to rapid oscillations that caused a few crashes, but attrition remained within reasonable limits. The flight controls were modified to cure these teething problems.

The Draken was easy to maintain and service since the fuselage was bolted together in the middle of the airframe for easy engine access. In addition, the outer wing sections could be easily removed for shipping or storage. Operational turnaround time was relatively quick, as the Draken could be re-armed and refuelled in around ten minutes by a team of seven.

A Flygvapnet Draken in a vertical climb carrying Rb 27/Rb28 AAMs (I Thuresson/Saab). The Draken's cockpit (N G Widh/Saab).

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J35B

Development of the Draken was an ongoing process and many different variants were produced. The next variant after the Adam was the J35B (the B for Bertil). Work on this variant had started in 1956 even before the J35A went into production. The idea was to introduce a new Draken variant with improved avionics and a more powerful engine, but it didn’t work out exactly as planned. J35Bs were supposed to have much more powerful RM6C engines, PS-03/A radars and S7 fire-control systems. However, as none of this new equipment was ready when the airframe was, all the J35Bs were delivered with RM6B engines and no combat avionics. With the RM6C engine, the J35B would have been able to fly at Mach 2. Even so, an early J35B broke the Mach 2 barrier in level flight on 14 January 1960, but all J35Bs had a nominal maximum speed of Mach 1.9.

The first J35Bs delivered were used for training and evaluation until they were fitted with proper avionics between 1964 and 1965. These redelivered aircraft were also fitted with an air-to-ground datalink supported by the STRIL 60 (Stridesledning och Luchbevankning, meaning Intercept Control and Early Warning) network and had modified landing gear with twin ‘roller-skate’ tailwheels. The new radar and fire-control system allowed the J35B to perform collision course intercepts, instead of tail-chase intercepts. A new ejection seat allowed the pilot to eject at zero altitude, but not zero speed. Although it was not as good as a zero/zero seat, it was an improvement over the older ejection seat.

Because the Rb 24 could only be fired at an enemy aircraft’s engine exhaust, it was useless for head-on intercepts and so the J35B was fitted with two 19-round Bofors 75 mm (3 in) folding-fin unguided anti-aircraft rockets. These rockets pods were fitted on a dual stores station on the centreline fuselage pylon. In order to reduce drag a frangible cover was fitted to the pods through which the rockets were fired. 135 mm (5.3 in) rockets could also be carried for the ground attack role.

The first J35B prototype, a modified J35A, made its maiden flight on 29 November 1959 and three years later the first of the type were delivered.

F16 Wing at Uppsala received the first J35Bs in 1962, where they were operated by 3 Jaktflygdivision. They were followed by 1, 2 and 3 Jaktflygdivisions of F18 Wing at Tullinge in 1962. A total of 73 J35Bs were built, although one was kept by Saab for test and evaluation purposes so only 72 were actually delivered to the Swedish Air Force. By the time the rest of the J35B fleet was upgraded in 1964/5, there were only 69 airframes left – presumably the other three were destroyed or damaged. Retirement of the J35B began in 1974 and was completed in 1976.

The J35B, together with the J35A, was flown by the Flygvapnet ‘Acro Delta’ aerobatic team which was formed in 1963 to replace the ‘Acro Hunter’ team flying Hawker Hunters. These Drakens were fitted with smoke generators and painted white with a blue and yellow tailfin. The team was disbanded in 1966, but Drakens flew for public displays until 1982. After that, special display teams were put together.

A Flygvapnet Draken carrying four Rb 24 (Sidewinder) AAMs (I Thuresson/Saab).
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SK35C

The SK35C (the SK standing for Skol, meaning Trainer and the C standing for Caesar) was a trainer variant of the Draken. It’s not clear how the two-seat version originated. The front fuselage of a two-seater was originally ordered with the prototype Drakens, but the Flygvapnet used de Havilland 28C Vampire trainers and Draken simulators up until the early 1960s. Saab test pilots didn’t think the Draken was hard to fly, but Flygvapnet pilots did – but it’s not clear whether their demands prompted the development of a trainer. In any case, a two-seater was developed. It had an extra seat for the instructor behind the student pilot, separated by a windblast screen to protect the instructor if the canopy shattered. The instructor’s seat was raised so he could see over the student pilot’s head, but the instructor was also provided with a 3-D stereoscopic periscope to improve forward visibility. Although fitting the second seat reduced internal fuel, the two Aden cannon (together with the radar) were deleted, thereby allowing extra fuel to be stored in the wings as compensation.

The first SK35C made its maiden flight on 30 December 1959 and between 1962 and 1963 a total of 25 SK35Cs were delivered, excluding the prototype. They went to the Draken Conversion Unit (DCU) of F16 Wing at Uppsala. These aircraft were all converted from early production J35As with the EBK 65 afterburner and short fuselage. In 1966 all SK35Cs were upgraded with improved radios, a navigation radar and other minor changes. A small fin was added under each wing to improve yaw stability, which had been degraded by the large new canopy. In Flygvapnet service the SK35C served until 1985. However, a few remained in service to train Austrian pilots (see below).

A Royal Danish Air Force TF35/Sk35XD Draken (A Anderson/Saab).

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J35D

Although the J35B and SK35C were fitted with the RM6B engine, the much more powerful RM6C eventually became available. Installing this engine created a new Draken variant designated J35D (the D standing for David). The new engine was a copy of the Rolls Royce Avon 300 (Avon Mk 60) fitted with EBK 67 afterburner. It provided substantially more thrust than the original and delivered 5 750 kg (12 700 lb) of thrust dry and 7 761 kg (17 110 lb) with afterburner. Because of the new engine the air intakes were extended slightly forward of the cockpit canopy. As the RM6C burnt more fuel than the RM6B, fuel capacity was increased to around 2 920 litres (770 gallons) while two 530 litre (140 gallon) tanks could be carried externally on two new side-by-side underfuselage pylons which replaced the single dual-capacity pylon. A fuel tank could also be carried on each underwing pylon.

Performance was greatly improved and the J35D was the first variant to have a top speed of Mach 2 in level flight. The new engine also allowed the aircraft to carry a maximum of 2 200 kg (4 850 lb) of external stores. It is quite interesting to note that the J35D achieved roughly the same performance as the contemporary English Electric Lightning and used only one Avon 300 while the Lightning used two. And the Draken had a much better range as it burned up half the fuel of the Lightning, which was notorious for its short range when using afterburner.

A number of other changes were made to the J35D and these included a new Saab FH5 autopilot, Ericsson PS-03 radar coupled to a Saab S7A fire-control system and a new Saab 73SE-F ejection seat. This worked from zero altitude, but required a minimum forward speed of 100 km/h (62 mph). It was later replaced by the superior Saab RS35 zero/zero ejection seat that could eject the pilot while sitting stationary on a runway. All other Drakens were later upgraded with this seat.

The first J35D, which was actually a modified J35A, made its maiden flight on 27 December 1960, but deliveries to the Flygvapnet only began two years later. The first 30 J35Ds were delivered in 1962, but as these aircraft were delivered without radars (which weren’t ready for service), they were mothballed until 1966. Deliveries of the next 90 took place between 1964 and 1965, bringing total J35D production to 120 aircraft.

It appears that the mothballed J35Ds without radar were later upgraded with radar and ejection seats and delivered between 1966 and 1968. However, the first 30 (some sources suggest 28) were converted to the reconnaissance version (see below).

The J35D was flown by ten squadrons of the Royal Swedish Air Force. These were 1, 2 and 3 Jaktflygdivisions of F3 Wing at Linköping-Malmslätt, 1 and 2 Jaktflygdivisions of F4 Wing at Östersund-Frösön, 3 Jaktflygdivision of F10 Wing at Ängelholm-Barkåkra, 1, 2 and 3 Jaktflygdivisions of F13 Wing at Norrköping-Bråvalla and 2 Jaktflygdivision of F21 Wing at Luleå-Kallax. The J35D variant was retired in 1969.

Four J35Ds of the Flygvapnet (Swedish Air Force) in tight formation in 1965 (I Thuresson/Saab).

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S35E

After the J35D, the next Draken variant was the S35E reconnaissance platform. In Flygvapnet service it was designated S35E, the S standing for Spaning, meaning reconnaissance and the E standing for Erik. These aircraft had a total of seven French OMERA/Segid cameras mounted throughout the airframe: one vertical looking SKa 24-600 long focal length camera in the nose; one forward-looking long focal length SKa 16B in the nose; one downward/vertical looking wide-angle SKa 24-44 in the nose and two sideways-looking long focal length SKA 24-100 cameras (looking left and right out of the nose). In place of the cannons were two SKa 24-600 long focal length vertical cameras, which focused through periscopes just inside and forward of the outer wing sections.

In order to ease access to the cameras, the nose cone was mounted on rails that enabled it to slide out for servicing. The pilot had a downward-looking periscope sight to help aim the aircraft/cameras and a cockpit voice tape recorder to comment on the imagery. Apart from the addition of the cameras and deletion of the radar and cannons, the S35E featured a few changes from the J35D from which it was derived. Plumbing was added to the wings, enabling the S35E to carry four 530 litre (140 gallon) fuel tanks, giving a significantly longer range than the J35D. A chaff/flare dispenser could be carried in place of one of the wing-mounted fuel tanks.

Early production S35Es had the RM6C engine with the less powerful EBK 66 afterburner, but later S35Es had the improved EBK 67 afterburner. These later models were also fitted with a bulged canopy to improve the pilot’s view.

The first S35E, a converted J35D, took off on its maiden flight on 27 June 1963 and the first production variant flew for the first time on 13 May 1965. Between 59 and 60 S35Es were produced with deliveries beginning in 1963 or 1964. It appears that between 28 and 30 were converted J35Ds and the rest (most likely 32) were newly built.

The S35E was operated by three Reconnaissance Squadrons and these were 1 and 2 Spaningsdivisions of F11 Wing at Nyköping-Skavsta and 1 Spaningsdivision of F21 Wing at Luleå-Kallax.

In the early 1970s the Flygvapnet’s S35Es were upgraded and given a modernised film/camera suite and the ability to carry the Vinten Blue Baron multisensor night photography pod on a centreline pylon. They also had more sophisticated countermeasures including chaff/flare dispensers attached to the sides of the engine exhaust and two radar warning receivers the outer wing pylons. The S35Es served until 1979.

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J35F

The definitive Draken variant was the J35F (the F for Filip), which had greatly improved avionics and weaponry. As with the J35D, the J35F had the same RM6C engine with EBK 67 afterburner, but had a new bulged canopy and new avionics. The principle improvement was the Saab S37B collision-course fire-control system coupled to Ericsson PS-01/A radar. The fire-control system was integrated with the STRIL 60 ground-control network over a datalink to help the J35F find and attack its target/s.

A whole new weapons suite was fitted, the primary change being the ability to carry two semi-active radar homing (SARH) Rb 27 AAMs and under each wing a single heat-seeking Rb 28 AAM or an Rb 24. Both the Rb 27 and Rb 28 were Swedish-built copies of the American Hughes AIM-4 Falcon, but featured a number of improvements compared to the American missile. Because the RB 27 was too heavy to be carried on the wing pylons, only two could be attached to the underside of the fuselage. Although the J35F had a top speed of Mach 2, this was limited to Mach 1.4 when four AAMs were carried. Because of the extra avionics, which included an upgraded radio and sighting system, the port Aden cannon was deleted and the J35F only had one Aden M/55 with either 90 or 100 rounds in the right wing. Maximum weapons load was considerably increased to 4 082 kg (9 000 lb).

Further changes on the J35F included a revised cockpit with updated navigation, autopilot and communications systems. Later production J35Fs were fitted with S-71N infrared target seekers, which were Hughes AN/AAR-4 infrared detectors built under license by Ericsson.

The first J35F, which was actually a modified J35A, made its maiden flight on 22 December 1961 and was later joined by three other modified J35As in the Filip development programme. On 26 June 1964 the first of 230 production examples took off on its maiden flight. These were the last new-build Drakens for the Flygvapnet. Deliveries began to F13 Wing at Norrköping in mid-1965 and then to F1, F3, F10, F12, F13, F16 and F17 Wings. Production and deliveries were completed in mid-1972 and the F35F served with the Flygvapnet until 1989.

The J35F was the most widely used Draken variant and was operated by 18 squadrons. J35 operators are listed below:

Wing

Swquadron Base
F1 1 Jaktflygdivision Västerås-Hässlö
  2 Jaktflygdivision  
  3 Jaktflygdivision  
F3 1 Jaktflygdivision Linköping-Malmslätt
  2 Jaktflygdivision  
F10 1 Jaktflygdivision Ängelholm-Barkåkra
  2 Jaktflygdivision  
  3 Jaktflygdivision  
F12 1 Jaktflygdivision Kalmar
  2 Jaktflygdivision  
F13 1 Jaktflygdivision Norrköping-Bråvalla
  2 Jaktflygdivision  
  3 Jaktflygdivision  
F16 1 Jaktflygdivision Uppsala
  2 Jaktflygdivision  
  3 Jaktflygdivision  
F17 1 Jaktflygdivision Ronneby-Kallinge
  2 Jaktflygdivision  

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J35J

The Draken fulfilled the Flygvapnet’s requirements up until the late 1970s, but as time went by the Draken seemed a little less effective than the Saab Viggen that began replacing J35As and J35Bs. Even so, the Flygvapnet was reluctant to withdraw the Draken as it was still a capable fighter. To keep the Draken effective, especially in the air defence role, it was proposed that the J35F be upgraded. In 1985 the Swedish Government accepted the upgrade and a new variant was born – the J35J (J for Johan). Although the next designation would logically have been J35G, the upgraded aircraft were all to go to three squadrons (1, 2 and 3) of F10 Wing at Ängelholm-Barkåkra. Since J is the tenth letter of the alphabet and the upgraded Drakens would go to the 10th Wing, they were designated J35J.

The Johan had an extensively upgraded airframe to keep the type in service until the end of the 1990s until deliveries of Saab JAS39 Gripens (Griffins) began. J35Js received a comprehensive avionics upgrade which included an improved radar, fire-control system, infrared search and track sensor, navigation system, IFF and modernised cockpit electronics. An altitude warning system was also added.

Two new stores pylons were added to each inner wing section, giving a total of six. Four 530 litre (140 gallon) fuel tanks could be carried as well as four air-to-air rocket pods each with 19 75-mm (3 in) rockets. The wing was strengthened, allowing the aircraft to easily carry its maximum ordnance load of 4 082 kg (9 000 lb). The J35J had a slightly more powerful RM6C turbojet developing a maximum of 7 830 kg (17 262 lb) of thrust in afterburner. The extra thrust was certainly needed to offset the increased weights.

The Swedish Government initially planned to upgrade just 54 J35Fs to Johan standard, but in 1987 another 12 J35Fs were added to the conversion programme. Most converted airframes were J35Fs with low airframe hours. The first aircraft were delivered in 1987 and in August 1991 the last upgraded aircraft was delivered to F10 Wing. By March 1997 only one squadron - 2 Jaktflygdivision – operated the type with just 22 aircraft. This squadron made the last scheduled flight with the J35J on 8 December 1998. After that, all Drakens had been retired from the Flygvapnet.

A Swedish J35J Draken armed with two Rb 27 radar-guided and two Rb 28 heat-seaking AAMs (I Thuresson/Saab). A Flygvapnet J35J Draken carrying Rb 24 AAMs and  four drop tanks (H O Arpfors/Saab).

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Proposed variants

In the late 1960s Saab proposed a new-build interceptor/attack variant of the Draken, designated JA35. This would have been a multirole variant with a new infrared seeker and more powerful radar in an enlarged nose. Wind tunnel test results showed that the larger nose dramatically increased drag and reduced yaw stability and this would require a number of aerodynamic changes. However, the Flygvapnet was committed to the more capable and modern Viggen and the JA35 was cancelled.

A variety of upgrades for the Draken were studied at various times. In 1971 there were plans for an AS35X Draken which would have a needle-point nose, larger outer wings with dog-teeth and an American General Electric (GE) J79 engine delivering around 8 000 kg (17 640 lb) of thrust with afterburning. Another study attempted to increase pitch stability at low speeds, yaw stability at all speeds and supersonic turn performance. In the 1980s it was considered converting Drakens to ground attack aircraft and adding new stores pylons, new avionics, a larger braking parachute and new wheels and brakes. However, as the Swedish government was pursuing the Gripen, any ideas of modifications were dropped.

The most radical Draken would have been the 35 MOD upgrade that was considered in the late 1970s. This Draken variant would have had new outer wings with one meter (3.3 feet) greater span and a dogtooth in the centre outer-wing section. The aircraft would also have additional elevon actuators and small retractable canards on the sides of the air intakes. The 35 MOD would be able to carry RBS 15F missiles, U22 and KB countermeasures pods, Rb 24s, Rb 28s, 135 mm (5.3 in) rocket pods and AGM-65 Maverick air-to-surface missiles. However, the 35 MOD project was not approved as the Viggen was pursued instead.

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Danish Drakens

In 1968 Denmark became the first of three export customers for the Draken. Ever since 1966 the Danish government had started looking for an aircraft to replace two squadrons of Republic RF-84F Thunderflash reconnaissance aircraft and North American F-100 Super Sabre fighter/ground attacker aircraft. A number of candidates were considered and these were: the Douglas A-4F Skyhawk, Northrop F-5 Freedom Fighter, Vought A-7 Corsair II, Lockheed F-104 Starfighter, Dassault Mirage III/5 and Saab’s Draken. The F-5 and Mirage 5 were the favourites while the Draken was one of the least popular since it had poor payload/range performance and could not carry heavy weapon loads. In response to the Kongelige Danske Flyvevåben’s (Royal Danish Air Force’s) initial dislike, Saab decided to create a new Draken variant that would put it on the top of the competition shortlist.

The new variant was designated Saab 35XD (the X standing for export and the D for Denmark) and was loosely based on the J35F. In order to improve range, internal fuel capacity was increased by 40% through changes to both the front and rear fuselage. The entire structure was strengthened to allow a maximum of 4 540 kg (10 000 lb) of ordnance to be carried on nine re-enforced pylons, including under new outer wings. Each stores pylon was rated at 454 kg (1 000 lb), allowing all of them to be used simultaneously. The landing gear was strengthened to handle the increased weights and a runway arrestor hook was added. Oddly, the arrestor hook had been part of the Draken airframe from the beginning of the programme, but Saab never fitted the hook to Flygvapnet aircraft. The 35XD was fitted with two Aden cannons, as opposed to the single Aden on the J35F.

After considering the greatly improved 35XD the Danish government decided to buy the aircraft. A number of factors resulted in the Draken being chosen, notably because the 35XD filled the Royal Danish Air Force’s requirements, was relatively cheap and was a European, not a foreign, aircraft. The Royal Danish Air Force bought 20 A35XD ground attack fighters (designated F35 in Danish service), 20 S35XD reconnaissance aircraft (designated RF35 in Danish service) and six Sk35XD (designated TF35 in Danish service) trainers. In addition, the Danes acquired five S35Es and two J35Fs (all ex-Flygvapnet machines) to be cannibalised for spare parts.

The trainers were similar to Swedish SK35Cs and had a tandem cockpit with periscope for the instructor in the rear, but they had RM6C engines with EBK 67 afterburners and a single Aden cannon, making them combat capable. They could also carry A-38K jammer pods and were later upgraded with new weapon delivery and navigation systems, including a laser ranger and marked target seeker in a modified nose.

Unlike Sweden’s reconnaissance Drakens, the Danish RF35s retained the two Aden cannons in the wings, at the expense of two cameras. They had stores pylons, giving them a secondary attack capability and allowing them to carry Red Baron reconnaissance pods. Along with the other Danish Drakens, the RF35s received a weapon delivery and navigation system upgrade in the 1980s, but did not receive the laser ranger and marked target seeker that the other Drakens did. The RF35s replaced the ageing RF-84F Thunderflashes.

The F35 could carry 1 275 litre (332 gallon) external fuel tanks in order to considerably increase range. Some of these tanks were modified as pilot baggage pods. After the Drakens were retired from the Royal Danish Air Force the tanks were bought back by Saab and, after some minor modifications, used on Flygvapnet JAS 39 Gripens.

The first Danish Draken delivery took place on 1 September 1970 when three F35s were delivered to Karup Air Base. They were later followed by another 17 F35s and six TF35s. Since the F35s lacked radar they replaced F-100Ds in the ground attack role. However, Sidewinder AAMS could be carried for self-defence. The six trainers were delivered between 1970 and 1972 and the F35s were delivered between 1970 and 1971.

Between 1970 and 1971 the Danish considered buying 23 to 46 more Drakens for one or two extra squadrons. It was considered fitting these new aircraft with modern Ericsson radars and avionics. Very cheap refurbished J35Fs with new avionics, to be designated J35FD, were also proposed, but budget cuts eliminated any chance of a purchase. However, another five TF35s were ordered in 1973 and these were delivered between 1976 and 1977. Saab assembled them from spares since the Draken was no longer in production – it had been replaced by the Viggen on Saab’s production line.

Danish Drakens have been upgraded several times due to their good service record with the Royal Danish Air Force. During the 1970s they received new altimeters, US AN/ALR-45 radar warning receivers (later upgraded to AN/ALR-65) and chaff and flare dispensers in their tail cones.

In the 1980s they received a much more comprehensive weapons delivery and navigation system upgrade. This included addition of a new radar altimeter, Lear-Siegler navigation/attack computer, Singer-Kearfott inertial navigation system, Marconi Series 900 head-up display and British Ferranti laser rangefinder and marked target seeker. EW capability was improved when the Drakens were fitted with ALR-69 radar warning receivers (with six antennas on the vertical fin, two on each wingtip and two under the nose) and the ability to carry AN/ALQ-162 jammer pods. The last upgrade was completed in 1986 and brought the Draken’s weapon aiming and navigation accuracy close to that of the Danish Air Force’s General Dynamics F-16 Fighting Falcons.

Danish Drakens served with 725 and 729 Squadrons at Karup Air Base from 1970 until 1993 when the last RF35s and TF35s were withdrawn and 729 Eskadrille (Squadron) was disbanded. Although originally intended to serve well into the 1990s, the end of the Cold War led to defence cutbacks and the elderly aircraft were withdrawn. However, that was not the end of the Danish Drakens. One TF35 and one RF35 were handed over to the Scandinavian Historic Flight and six Drakens were sold to the National Test Pilot School (NTPS) in the USA. The school operates two single-seat F35s and four TF35 two-seaters that carry practice bombs and camera pods and are used for stall/spin training. As they are the most advanced and fastest aircraft in the NTPS inventory, they are destined to have a long service life with the school.

A Danish Air Force TF35 trainer of Eskadrille 729 at Karup (A Anderson/Saab). Danish TF35 Draken trainer (A Anderson/Saab).

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Finnish Drakens

The second Draken export order (which was the last new-build export) came from Finland in 1970. In April of that year the Suomen Ilmavoimat (Finnish Air Force) ordered 12 all-weather Saab 35XS interceptors, where the X stood for export and the S for Suomi, meaning Finland. They were delivered in kit form and assembled by Valmet in Finland, where they were locally designated J35S. (Assembly of these aircraft from kits is a little more in depth than putting together a model airplane or adding luxury bath accessories to your bathroom. These aircraft were assembled by skilled professionals who spent many hours laboring over these incredible machines.) They were basically similar to the J35F, but had the twin Aden cannons and a revised avionics suite. The first of these kit-built aircraft was delivered in April 1974 and by 1975 all had been delivered.

In preparation for the newly built Drakens, six Swedish J35Bs stripped of their all-weather avionics were leased to the Finnish Air Force in 1972 and designated Saab 35BS. After one was badly damaged in 1974 and subsequently grounded, the Finns leased another J35B to replace it. In 1976 the Finnish Air Force bought the seven aircraft outright and at the same time, six refurbished ex-Swedish J35Fs (designated 35FS in Ilmavoimat service) and three Sk35Cs (35CSs) were bought as well.

This purchase was followed up by a second batch of 18 ex-Swedish J35Fs and two ex-Swedish Sk35Cs in 1984. With the arrival of the two-seat trainers, pilot conversion could take place in Finland instead of Sweden. In total, the Finnish Air Force bought 48 Drakens. This amount consisted of: seven former Swedish J35Bs, 12 35XSs newly built, 24 ex-Swedish J35Fs (18 plus 6) and five ex-Swedish SK35Cs (3 plus 2).

The Ilmavoimat’s Drakens were operated as follows:

Wing Squadron Base Type
HävLLv 11

1 Flight
2 Flight

Rovaniemi

35S
35FS
35CS

HävLLv 21 1 Flight
2 Flight
Tampere-Pirkkala

35S
35FS

KoeLtue   Kuorevesi-Halli

35S
35FS

Finnish Drakens served in both the interceptor and fighter-bomber roles into the 21st century - although all 35BSs and four of the five 35CSs had been retired by 1995. On 16 August 2000 the last Draken flight took place and Finnish Drakens were subsequently withdrawn, being replaced by 64 McDonnell Douglas (now Boeing) F/A -18 Hornets.

A Finnish Air Force J35BS fighter reveals its unique double delta configuration (I Thuresson/Saab). Finnish J35BS of HavLv 11 at Rovaniemi (I Thuresson/Saab).

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Austrian Drakens

In 1972 the Österreichische Luftstreitskräfte (Austrian Air Force) retired its fleet of Saab J29F Tunnans and for the next 13 years was without a dedicated interceptor. After considering a number of replacements for the Tunnan, the Austrians settled on purchasing ex-Flygvapnet J35Ds. In May 1985 24 Saab 35ÖEs (the Ö standing for Oesterreich, meaning Austria) were ordered. After Saab bought them back from the Flygvapnet, they were refurbished and modernised by Saab/FFV Aerotech and then delivered. Each airframe gained an extra 1 000 flying hours, a bulged canopy, Radar Warning Receiver and chaff/flare dispenser. They also had two 30 mm (1.18 in) Aden cannons and the original J35D radar.

The first aircraft was handed over on 25 June 1987 and deliveries commenced later in the year. Initially most Drakens were kept in Sweden for pilot training at Ängelholm with squadron deliveries only taking place in 1988 and finishing in 1989. They were assigned to two squadrons of Fliegerregiment (Wing) 2 of the Austrian Air Force, and these were: 1 Staffel (Squadron) at Zeltweg and 2 Staffel at Graz-Thalerhof.

The 35ÖEs were used primarily as interceptors and two Saab 105s or Drakens were permanently held on quick reaction alert to intercept unidentified aircraft approaching the Austrian border. However, reconnaissance pods were also acquired for a secondary reconnaissance role.

Like Finland, Austrian military forces are restricted by a peace/neutrality agreement that resulted from the Second World War (but was only signed in 1955). This limits the maximum number of Air Force personnel to 5 000 and defensive combat aircraft to just 70. As part of the neutrality agreement, Austrian Drakens were initially just armed with two Aden cannons since AAMs or any other guided missiles were forbidden. However, after the fall of the USSR the rules were relaxed and in 1993 the Austrians bought surplus AIM-9P3 and AIM-9P5 Sidewinders from Saab.

The Austrians didn’t buy any two-seat Draken trainers as training was done in Sweden as part of the sales deal. For this purpose around five SK35Cs were kept in operation at Angelhom in Sweden after all other Flygvapnet Drakens had been retired. Training finished in 1997 after the conclusion of the Austrian deal with Saab. Training was then carried out with a Draken simulator at Zeltweg.

Austrian Drakens were planned to be withdrawn from service in 1998, but finding a suitable replacement was time-consuming and complicated. The competition for a new air defence fighter began in 1998 and the F-16, F/A-18, Dassault Mirage 2000-5, Gripen and Eurofighter Typhoon were all considered. In October 2001 a request for proposals for up to 30 new fighters was issued and the Gripen was seriously considered while Dassault and Boeing pulled out. However, Austria selected the Eurofighter Typhoon on 2 July 2002. The 1.79 billion euro ($2.15 billion or £1.16 billion) deal was intended to buy 24 aircraft. The Austrians preferred buying the more expensive Eurofighter because the deal would strengthen ties with the European Union and would deliver twice the deal’s value of offsets to Austrian industry over 15 years.

After the devastating European floods in early August 2002, the Austrian government decided to use some of the Eurofighter funds for flood relief and so the order was cut back to 18 aircraft. But in September 2002 the ruling coalition government collapsed and the whole deal was thrown into doubt. An amended 1.9 billion euro contract for 18 single-seat Typhoons was eventually signed on 1 July 2003, with deliveries set to commence in the second quarter of 2007. However, in June 2007 the order was reduced to 15 aircraft. Deliveries commenced in July that year.

As previously mentioned, the Drakens were intended to be retired in 1998. However, the delay in finding a replacement meant that the Draken had to soldier on in Austrian Air Force service. But in 2005 maintenance contracts with Saab expired and the Drakens had few airframe hours left. On 25 November 2005 the Austrian Air Force officially retired its 35OE Drakens at a formal ceremony at Zeltweg Air Base. A specially painted Draken flew a last display before landing for the last time.

During 18 years of operations the Austrian Drakens accumulated over 23 500 flight hours and performed a total of 250 ‘Priority A’ quick reaction scrambles in defending the countries airspace. Twelve Northrop F-5E Tigers were leased from Switzerland as a stopgap until Eurofighter Typhoon deliveries began. The first F-5E began operating in June 2004.

The retirement of the Drakens on 25 November 2005 was not just a milestone for the Austrian Air Force – it was the last time the Draken was flown as an operational combat aircraft and so ended the Draken’s long career.

A J35OE Draken of the Austrian Air Force (A Anderson/Saab).

For such a radical aircraft the tailless double-delta Draken was amazingly successful. Many unique and innovative aircraft have ended up performing poorly, but the Draken was almost faultless. Its large production run and export orders are testament to its quality and effectiveness. As the air forces of Sweden, Finland, Austria and Denmark would probably agree, it was one of Saab’s finest jet fighters.

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