A Spear, a Robot, a Lightning Strike and a Sea Serpent

Initially, the goal of the Swedish military nuclear program was only the tactical nuclear weapons and the fact found its reflection both in the power of designed warheads and in the potential means of their delivery. Cruise missiles and jet planes were considered in the role of the latter – both “common” and specially designed. The final Swedish waiver from its nuclear program buried some interesting samples of military equipment and weapons.

The choice of delivery means

In the relation to the USSR – the country, which the Swedes considered the most likely enemy in a probable war from the mid-40s, — Sweden had a quite favorable military geographical location. Sweden had no land border with the USSR, but even in the case of a possible Soviet troops passing from the Finnish or/and Norwegian territories, the North part of Sweden was quite suitable for its defense – it was impassible, swampy, mountainous with a poorly developed road network and huge forests. And the successful Soviet intrusion from the side of the Baltic Sea implied the conduction of operation compared in its scale to the Allied Normandy landings in 1944.

First of all, the Swedes planned to use their nukes against Soviet naval bases that could be the most likely places of troop concentration before the upcoming landing in the case of war. With timely and successful (for the Swedes) application of a nuclear ammunition against such an object it was possible to annihilate booth the troops and the transport vessels meant for their carriage. That is why the necessary range of action of the potential WMD (Weapons of Mass Destruction) carriers should have been comparable to the Baltic Sea width.

If the design of nuclear weapons by the Vikings’ descendants was rapid and successful then at first the combat jet plane Saab 32 Lansen (“The Spear”) could be quite suitable as a carrier in its A 32A modification. The first such ground-attack aircrafts entered the army in 1955 and their payloads capacity reached up 3 tons. They had units for bombs and missiles suspension, in particular for Anti-ship missile (AShM) Rb04. Saab 32 flying range was around 2000 kilometers and its max speed — about 925 km/h.

However, the quantity of nuclear warheads should have remained quite moderate in the Swedish Army even according to the most optimistic forecasts. Therefore, there was a huge demand in carriers, which obtained the maximum ability to overcome the Air defense system of a likely enemy. And the USSR had very strong Air defense forces. Two samples of such carriers, the development of which was actively conducted in the 50s in Sweden, will be the main topic of the article. It should be noted that like the Swedish nuclear weapons, the above-mentioned samples were stopped literally seconds away from the construction stage but they also never were created. Nevertheless, if the Swedes brought their nuclear program to the end, the bomb wouldn’t be left without a suitable carrier — about this at the very end.

Cruise missile Robot 330

In 1957 on the basis of already existing developments on cruise missile creation, Saab started designing the cruise booster rocket for nuclear weapons carrying under the name of Robot 330. It should have been a two-staged rocket. It supposed to start from a mobile launch complex with the help of a solid-fuel rocket engine that was discarded after the complete fuel spent. The first stage (with its mass of a ton and a half and its length of 4.1 m) should have accelerated RB-330 to the supersonic speed, on which two cruising ramjet engines (CRE) of the second stage (with its mass of 2.8 tons and its length of 4.1 m) could work effectively. They also had to accelerate the rocket to a speed of Mach 3.6 (about 4,400 kilometers per hour). This means that with a range of 500 kilometers, the approach time when launching to the maximum distance should have been 6-8 minutes.

US intercontinental cruise missile SM-64 Navaho had a similar scheme. The important difference of the US missile was the usage of a liquid-fuel stage as a booster rocket accelerator. In other respects, the concept was the same: the first stage accelerated a cruise missile to Mach 3 speed, disconnected after the complete fuel usage and then a CRE came into action. The US missile was much bigger (it had 20.7 m length and almost 30 tons of mass) and its max flight distance reached up quite “strategic” 6.5 thousand kilometers. In addition, unlike its Swedish “paper” equivalent, SM-64 Navaho was embodied in metal and had more than 10 launches in 1956-57 – but to tell the truth, the launches were mainly unsuccessful.

By the way, intercontinental cruise missile projects, M-40 “Buran” and La-350 “Burya”, also existed in the USSR, and the latter reached the test phase in 1957. Both the US and the Soviet intercontinental cruise missile projects were “buried” by the rapid development of ballistic missiles in the beginning of the 60s.

But let us come back to Robot 330. The Swedish missile should have flown quite high (23-24 km) and on the final segment made “a dive” down. Such a trajectory combined with the huge speed would have made the missile low vulnerable for the Air defense means of that time.

The targeting system of Robot 330 would have been a weak point in the case of its creation. The system would have been based on gyroscopes. On the max flight distance, such an autonomous inertial targeting system gave a circular probable deviation from the target of 2-3 kilometers that was far too bad even for a nuclear warhead (the Swedes planned the power of that time-designed nuke to be around 20 kilotons). The planned missile equipment with the system of radio beacon orientation Decca Navigator would improve the accuracy but not much – the circular probable deviation would still make up 1.8 km.

The problem was so serious that for the missile guidance Saab created the first Swedish transistor computer Sank (“SAABs automatiska navigeringskalkylator” that in translation means – “Automatic navigation calculator SAAB”). After the work completion over the missile project Robot 330, Sank was unsuccessfully tried to sell to the civilians under the name of Datasaab D2, but the work on this direction was not done in vain. In the particular, on the D2 basis CK 37 (Centralkalkylator 37) was created – the onboard computer of a supersonic jet fighter Saab 37 Viggen.

The Rb-330 project was closed in 1959, as the total design cost, estimated in $50 billion seemed too high for the Swedes. Apart from that, certain doubts in its necessity played a role in the rejection of a cruise missile – as a carrier of Weapons of Mass Destruction. Nuclear cruise missiles well suited for example for a preemptive strike on the areas of troop concentration before the loading on transport vessels. But Sweden was unlikely to be the first to use nuclear weapons even in the case of a Soviet intrusion – on such an occasion there was a serious risk of getting A-bomb strikes back on Swedish towns. And according to Swedish scientists’ opinion, supersonic jet planes fitted the best for the nuclear retaliation.

Supersonic nuclear bomber Saab 36

In 1952 within the framework of the Swedish nuclear program, Saab started designing a single-seat supersonic bomber – a nuclear weapon carrier that initially got Projekt 1300 name. In its final variant, it was given the Air Force designation A 36, although it was never built. The plane should have carried 600-800 kg free fall nuclear bombs as primary weapon. For the reasons of better aerodynamics, bombs were supposed to be placed in the internal weapon bay. The radius of action should have been about 400 km that would be quite enough to defeat targets in the Soviet Baltic States.

Everything was clear with the specified parameters of the new bomber, and then the thing was much more interesting with the means of achievement of the parameters. During the relatively short period of work, the Swedish designers offered several possible variants that were very different from one another. The aircraft project 1300-01 was a rocket plane with an extra rocket engine, it should have launched as a vertical take-off aircraft (a tail-sitter) from a ramp and landed – on the common aircraft chassis.

Aircraft projects 1300–19, 1300–25, 1300–50, 1300–72G and 1300-72H should have had two jet engines inside their bodies and a delta wing as Saab 35 Draken fighter. Project 1300-40 had a straight wing as US interceptor Lockheed F-104 Starfighter. It was supposed to reach the speed of Mach 3. Project 1300–71D had two jet engines located in the middle of its triangular wings and outwardly had to resemble US supersonic spy plane Lockheed SR-71 Blackbird that appeared however a decade later.

The final project 1300-76 got the Air Force designation Saab 36 that could also carry cruise missiles Robot 04 in addition to free fall bombs. It should have been a single engine aircraft with a chin intake. There also existed an alternative composition project 1300-77 with the intake in the upper part of the body.

British Bristol Olympics was chosen as a power unit for the perspective aircraft and the same unit was also used on the British four engine strategic bomber Avro Vulcan (a later modification was set on “Concorde” passenger airliners).

All the project works were frozen in 1957 and all the resources were concentrated on a supersonic multifunctional jet fighter “Viggen” (1400 and 1500 projects). Saab 36 project was finally cancelled in 1966.

If wishes were fishes

If the Swedish nuclear weapons had been created by the end of the 60s then the most probable carrier would be namely Saab 37 Viggen. Its first flight was made in 1967 and the Air Forces adopted it in 1971. The combat load reached up 5 tons, “Viggen” (“A lightning strike”) top speed was Mach 2.1 and its practical flight range was 2150 km.

Diesel submarines of Sjöormen (“A sea serpent”) class could have become one more possible nuclear weapon carrier. Sjöormen submarines have 1210 tons submerged displacement. Its working dive depth is 150 meters, top surface speed – 20 knots, submerged – 12 knots. Crew — 23 men.

The “Sea serpents” had torpedoes type “Torped 61” aboard, which affective firing range was 20 km, and they carried a 300 kg warhead and obviously, they could be made in their “nuclear” variant. All in all the Swedes built five such submarines in 1967-69. Nowadays the fiver has been sold to the Republic of Singapore.

Beyond that, Swedish anti-ship missiles had a possibility of nuclear charge installation, for example, RBS-15 (its range of action was around 70 km) and the fact automatically made military surface ships be the potential carriers of NW. However, the Swedish doctrine of nuclear strikes against naval bases was against the usage of both nuclear torpedoes and nuclear AShM, that aimed first if all at sea ship annihilation. In the case of real NW use threat, the fleet of a likely enemy would act dispersed and relatively low-powered Swedish nuclear warheads would have appeared ineffective. Even for the Swedes it was obviously an unacceptable luxury to sink separate ships with a few nuclear torpedoes and missiles.

As for the frequent references to the alleged plans of the Swedes to use 155-mm gun launchers as a nuclear weapon carrier, in particular the Bandkanon 1 rapid-firing self-propelled gun, they are untenable for several reasons at once. Apart from that, there are no published documents yet that could confirm that kind of “city legend” (though such documents could still be top secret), there is also a technical and economic aspect. Indeed, the Swedes could create a 155 mm artillery nuclear shell – both the USSR and the USA coped with such a task.

But there was a nuance. The US nuclear W48 caliber shell had the explosion power of 0.072 kilotons (72 tons) in TNT equivalent. Meanwhile the amount of plutonium in the shell would be enough for a “normal” bomb creation of several kiloton power. This is because of the fact that in the extremely small volume of a 155-mm nuclear shell, a less effective linear implosion scheme is used instead of the traditional spherical implosion scheme of a fissile core.

Moreover, if the USSR and the USA could afford the “ineffective” expenditure of weapon-grade plutonium for the creation of artillery shells, for Sweden such “victims” looked unaffordable because of plutonium shortage that was almost the main limiting factor for the complete nuclear program. Quite unlikely Sweden would sacrifice several nuclear aerial bombs of “normal” power for the creation of far less powerful artillery shells as the country picked the plutonium up literally for grams.

The list of the literature:

• Jonter, Thomas, dr. Försvarets forskningsanstalt och planerna på svenska kärnvapen. Mars 2001. ISSN 1104–1374
• Gyldén, Nils. Niels Bohr, de svenska kärnvapenplanerna och kopplingarna till den civila kärnenergiutbyggnaden. 2008
• Saab test missiles robotmuseum.se
• Cancelled SAAB u-fr.blogspot.com.br