J29 Tunnan, Saab

J29 Tunnan, Saab

The Saab 29 was the first European, post WWII, swept-wing jet fighter in service (the Messerschmitt Me262 being the first ever). It had a short, barrel-like fuselage and swept wings. The J29 had high performance and heavy armament. The last versions had dogtooth wing extensions, an afterburner, and carried Sidewinder AAMs. 661 were built. Some obsolete J-29s were later sold to Austria.

Type: J 29F
Country: Sweden
Function: fighter
Year: Crew: 1
Engines: 1 * 2800kg SFA RM 2B (De Havilland Ghost)
Wing Span: 11.00 m
Length: 10.23 m
Height: 3.75 m
Wing Area: 24.15 m2
Empty Weight: 4845 kg
Max.Weight: 8375 kg
Speed: 1060 km/h
Range: 1100 km
Armament: 4*g 20 mm

SAAB 29 Tunnan, a short description

Tunnan means The Barrel, often referred to as Flygande Tunnan, The Flying Barrel.

By 1945, it was clear that in the future all Swedish combat aircraft would be jet powered, so all propeller projects were cancelled. STAL was already working on jet engines, but they wouldn't be ready until 1952, which is to say too late for any aircraft project started in 1945. As a quick fix de Havilland Vampires were purchased in 1945 and licence production of its Goblin engine was started for the jet engined variant of Saab's J 21 fighter.

It was from the outset clear that Goblin would be too small for the new "JxR" fighter beeing planned, and in December 1945 the De Havilland Ghost engine, still in the early stages of design, was selected and chosen to for licence production in Sweden. The earliest design work decided the relative merits of a "Vampire" or "Shooting Star" configuration, but finally the choice was to stand between project R 1001 "The Cigar" of a "Shooting Star" layout and R 1001 "The Barrel". December 1945 saw the latter as the victor, and it looked much like the production items, but the tail was a little bit longer and the wings had a shorter chord near the tips.

The very first "Barrel" concept in October 1945 had straight wings, but in November Saab came into possesion of German research material, via Switzerland (the same material that was handed over to USA, but we got ours in a slightly less official manner, and put it to use much earlier), which showed advantages of swept back wings. The 45 degree sweep the Germans planned was deemed to be too extreme from a standpoint of stability, likewise it would affect the weight of the wing negatively, so a 25 degree sweep back was selected, together with leading edge slots.

At first the fuselage was to have a continous curve like a barrel, but it was found that it was better to have the centre section of the fuselage cylindrical. This was area rule, a few years before the name was coined.

The first Saab 29 prototype first flew on Sept 1:st 1948. It had full span flaperons, but later prototypes and the production machines had separate flaps and ailerons, not because it worked better, but rather that the customer was more familiar with it and had required it on the second prototype. The reasoning behind the flaperons was that since the ailerons had to be powered anyway, and artificial feel introduced, combining them with flaps wouldn't change the feel of the controls, and would lower landing speed by 10 km/h.

designation     number  delivered       in service      serial numbers
Saab 29          4      1948-50         prototypes, never in AF service
J 29A          224      1951-53         -1963(65)       29101-29324
A/J 29B        361      1953-55         -(1957)         29325-29685
S 29C           76      1954-56         -1970           29901-29976
Saab 29D         1      1955            -(1954)
J/A 29E         29      1954            -(1958)
J/A 29F        308      1955-58         -1968(76)

To improve range tanks were introduced inside the wings. Ground attack capability was added, but designation seems to have depended on to which squadron an aircraft belonged.

On May 6:th 1954 a J 29B took the world record on a closed 500 km circuit with 977 km/h which were previously held by a F-86. Another F-86H took it back a year later but crashed.

S 29C

At first when the reconnaissance version was designed, the Air Staff had a very modest requirement for camera equipment, and only minimal changes to the fighter was envisioned. Luckily, a reconnaissance wing commander loaded a truck with everything he thought would be needed, and together with the chief designer and an axe, he proved that there was room for it in the wooden mock up. "You're a good designer, you'll solve the details!"

The whole front lower fuselage was redesigned, with the bottom beeing flat and the sides near vertical. Up to five cameras of different types could be carried at the same time. To begin with, only a pair of cameras salvaged from our Spitfire PR.XIXs were used, without sights even. All camera ports were covered by shutters, the forward ones opening down and forward, thus beeing usable as air brakes as well. Later on camera sights were introduced.

The use of "camouflage detecting" IR colour film was investigated, but found to be much too expensive (USD 1000 per roll was a lot of money back then). What was done was to let the left forward looking long focal length camera use black and white IR film, the right panchromatic film. By comparing the pictures, some anti-camouflage effect was attained. IR film also gave the camera a longer useful range during conditions of haze.

A pair of S 29Cs set a world record for a 1000 km closed circuit on March 23:rd 1955 with 900.6 km/h (the old record beeing 822 km/h taken by a RAF Gloster Meteor in 1950). Well done keeping two aircraft together and still getting the fuel to stretch. The external tanks were dropped at the point were they were estimated beforehand to have run dry, as there was no separate meter for them.

S 29C was the first Swedish combat aircraft to be equipped with radar warning recievers. All were rebuilt with -E wing during 1955-56, permitting maximum speed to be raised from Mach 0.86 to 0.93, but they never got afterburners.

J 29D

This was a single J 29B that was given an engine with afterburner, shortly thereafter converted to J 29F standard.

J 29E

In order to raise the critical Mach number from 0.86 to 0.89 the leading edge slot on the outboard part of the wing was deleted and the chord of the same section increased, creating a dog-tooth that also had a small fence. In spite of the slot beeing deleted, landing performance remained the same but the load factor was increased. All -Es were rebuilt -Bs.

J 29F

All J/A 29Fs were conversions of J/A 29Bs, some directly, some had flown as -Es. 210 were rebuilt by Saab, the rest by the air force. To take advantage of the increased load factor the new wing offered, they were given new engines, licence produced Ghosts with Swedish designed afterburners. They were also given a missile option: A pair of AIM-9B Sidewinders. After 1968 the only remaining examples flew with the aggressor squadron, some as target towers.

15 A 29Fs were sold to Austria in 1961. The second batch of 15 was delivered in 1963-64. They were modified to let the left two cannon be exchanged in 30 min for a set of three 70 mm Vinten cameras in 30 minutes. There were two side facing camera ports, two down facing and one down and forward. Twelve such camera sets were delivered.

In spite of beeing purchased for their suitability for close air support, neither rockets nor bombs were ever purchased for them. Air interception was only a tertiary role, reconnaissance a secondary.

A trainer version, SK 29, was planned in 1950, but it was cancelled the same year. It was to have had side-by-side seating, no armament and reduced fuel. Aft of the cockpit it would be identical to the fighters.

Saab had a very tight delivery schedule for the fighters to the air force, which made it impossible for them to also build the required 20 trainers. The air force on the other hand, didn't think it would be a good idea to modify the aircraft into trainers themselves, which was suggested as a solution. Probably not a good idea, as there were quite a few landing accidents.

A radar equipped all-weather version was also studied and cancelled in 1950, for the same reasons as the trainer version. The favoured installation consisted of a bulge over the air intake. Wavelength were to be 3 cm with an effect of 100 kW. It was to have a spiral scan pattern. These capacity problems later on led to Saab having to cancel their Saab 90 Skandia airliner in favour of building Tunnans for the air force.

As part of a UN operation, five J 29Bs were sent to Kongo in 1961. They were followed by two S 29Cs and four additional J 29Bs in 1962. The operation, the only one involving Swedish made jet combat aircraft, ended in 1963.

Armament options for all version, except S 29C, which was unarmed:
Four 20 mm guns with 180 rounds each

Maybe on J 29A, certainly on later versions
   rrr     rrr
   rrr     rrr          12 x 7.5 cm anti-aircraft rockets
   rrr     rrr
A 29B/E/F               Same as above, also:
   rrrr   rrrr          8  x 8 cm anti-armour rockets, seldom used

   RRRR   RRRR          8 or 14 x 14.5 cm anti-armour rockets, 45 kg each;
   RRR     RRR          or 8/14 x 15 cm HE rockets, 45 kg each

  unknown pylons        2 or 4 x 18 cm HE anti-ship rockets, 125 kg each

T              T        Droptanks also usable as napalm bombs, either 400 or
                        500 litres each
J 29F                   Same as above, also:
    M       M           2 x Rb 24 (AIM-9B) Sidewinder

Technical data

                        J 29A   A/J 29B S 29C   J 29E   J 29F

All versions    Span: 11.0 m; Length: 10.23 m; Height: 3.75 m

Empty weight            4580    4640    4700    4600    4845 kg
Normal take off weight  6880    7520                    7720 kg
Max take off weight     7530    8170    8000    8170    8375 kg
Internal fuel           1430    2150    2150    2150    2150 l
External fuel            900     900     900     900     900 l (Older style drop tank 750 l)
Engine  RM 2/RM 2B      2270    2270    2270    2270    2800 kp de Havilland Ghost DGT 3
Max speed               1035    1035    1035    1035    1060 km/h
Time to 10 km           7.3     8.5     7.3             5.2 min
Max altitude            13.7    13.7    13.7    13.7    15.5 km
Take-off run            1050    1350                     790 m
Landing run              600     600                     650 m

Text : Urban Fredriksson, The Swedish military aviation page

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