I don't know why, but in 1919 someone wrote a book about tanks in Swedish. It's not in a format that allows me to run it through a translator. Perhaps our resident Swedish tank expert can help us with this one?
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Lets start a thread about the CV-90. Past, present, futur.
Link to the Linström's page about the initial Stridsfordon-90 project :
An interesting SH-MM post about evolution of CV-90 :
And a summary about contenders for the forseen Czech IFV programme :
From a well known blog.
I was originally going to post this in the J35 thread (since that's turned into the general Swedish aviation thread), but I felt that it'd get more visibility here.
During the 1950s, many nations sought to develop nuclear weapons. One of these was Sweden, who hoped that nuclear weapons could help maintain their neutrality during the Cold War. However, when developing nuclear weapons, a delivery system is also needed. For Sweden, that would have been the A 36, a dedicated nuclear strike aircraft and one of the "missing pieces" in the Swedish aircraft sequence (between the 35 and 37).
Development of the A 36 began in 1952, as part of SAAB's 1300 series of projects (which included numerous other designs). The requirements for a Swedish nuclear strike aircraft were different from those of other major countries. The most likely opponent (the USSR) was less than 500 kilometers away across the Baltic, while American bombers would have to fly more than ten times as far to reach their targets. This was evident in designs such as the B-36 and B-52, which had very large wingspans and fuel capacities, as well as large payloads. Additionally, a Swedish nuclear bomber would have to be capable of operating from dispersed airfields, in accordance with Swedish doctrine. Obviously, the Swedish nuclear bomber would end up looking quite different from its American or Soviet counterparts.
Numerous SAAB engineers were involved with the A36 development (quite an undertaking, as the company was developing the J35 at the same time while also producing the J32). Among them was Aarne Lakomaa, a transplanted Finn who had gained fame for developing the Morko-Morane fighter during the Continuation War.
From the start, the Swedish bomber (at this point it had yet to be designated A 36) was designed for high speed. Numerous configurations were studied, with swept wings or delta wings on various designs. Top speed was planned to be around Mach 2, which would have made the A36 almost as fast the J35.
SAAB 1323 (or 1300-23), an early step in the A36 development.
SAAB 1371 (1300-71), a proposal which made it as far as wind tunnel testing.
As can be seen from the previous drawings, many of the designs were planned to have two engines. As with other Swedish aircraft of the time, the A36 was planned to use license built British engines. Among the engines considered were the de Havilland Gyron and smaller Gyron junior. However, at some time early in the development of the program, it was decided that the aircraft would be powered by the Bristol Olympus turbojet, the same engine that powered the British Vulcan bomber. However, for use in a supersonic aircraft, it would have required modification, such as the fitting of an afterburner, and a new intake. (The Olympus was eventually developed for use in supersonic aircraft, such as the TSR-2 and Concorde.) With such a large and powerful engine, it became apparent that only a single engine would be needed in the A36.
At such high speeds, the A36 would have experienced significant aerodynamic heating. This concerned Swedish engineers, who were afraid that the heat would damage contemporary nuclear weapons (or even lead to them detonating prematurely). As a result, it was decided that the payload would be carried within an internal weapons bay. This would reduce drag, improving performance, but it would also limit payload, while decreasing the internal volume available for fuel, avionics, and other systems. By the time the A36 design had progressed to the 1376 and 1377 configurations, payload was determined to be a single 800 kilogram nuclear weapon, carried internally. This is roughly comparable in size to the American Mark 7 bomb, deployed tactically around the same time. As far as I know, no provision was ever made for the A36 to have air-to-air capabilities.
By 1957, the design of the A36 (which had by now received a formal Swedish Air Force designation) was almost finalized.
(SAAB 1376, with chin intake)
(Drawing of SAAB 1377 with dorsal intake, similar to YF-107)
Most documents show the 1376 as the chosen design. 1376 was a moderately sized aircraft, somewhat smaller than the American F-105 (which had a similar role to the A36). The wing was a conventional delta with 62 degree sweep, which would have given good performance in the supersonic regime. I am uncertain whether the A36 would have utilized a variable geometry inlet. A fixed inlet would have had to be optimized for a certain speed; this would mean that the A36 would have been inefficient at low Mach numbers, or been had it speed limited by the inlet design. (Read more about inlet design here).
Although work on the A36 was progressing well, by 1957 it was apparent that Sweden could not afford to develop the A36, nuclear weapons, and other vital defense programs. As the A36 would have been relatively lacking in conventional capability, it was decided to cancel the program. (Ultimately, the nuclear weapons program would be shut down during the 1960s as well). Some of the money saved was used to develop the A37 Viggen, which proved to be a competent multirole aircraft during the 1970s and beyond. Ultimately, while it would have been interesting from a technological standpoint to see the A36 fly, its cancellation was probably the right choice.
I have not found any documents showing that the A36 was ever given a name (such as 'Draken' for the J35). Occasionally references can be found to the A36 'Vargen' (Wolf) online, but it appears that these are the inventions of either modeling companies or someone with an overactive imagination.
A36 (1376 design) specifications (approximate):
Wing Area: 54m2
Empty Weight: 9000 kg
Max Weight: 15000 kg
Wing Loading at Max Weight: 280 kg/m2
Payload: 800 kg
Max Speed: Mach 2.1
Combat Radius: 410km (?)
Engine: 1x Bristol Olympus Turbojet
Numerous countries attempted to develop turbojet engines in the post-WW2 period. There were many failures: the J40, TR-1, and others. One of these unsuccessful engines was the Swedish STAL Dovern.
Attempts to develop an indigenous jet engine began at STAL (Svenska Turbinfabriks AB) in the late 1940s. The first engine developed by STAL was the Skuten, in 1948. This was a small, axial flow turbojet with 6 combustion chambers producing roughly 6.2 kN of thrust. The Skuten was intended primarily as a ground-run technology demonstrator, I am not aware of any attempts or plans to fit it to an aircraft. In the meantime, the Swedes used British engine designs for their aircraft, such as the De Havilland Ghost on the J29.
Work on the STAL Dovern began in the late 1940s, and from the start, the engine was intended for operational use. The intended recipient was the SAAB 32 (Lansen) attack aircraft, then under development. This would require a much more powerful engine than the Skuten, and so the Dovern was itself much larger. Like the smaller engine, the Dovern was built as an axial flow turbojet. However, additional combustion chambers were added, bringing the total to nine. This, along with a large increase in the dimensions of the engine, resulted in the Dovern having a design output of over 32 kN. This was significantly more than the De Havilland Ghost powering the J29 at the time.
The STAL Dovern was first ground tested in February 1950, roughly two years after development began. By this time, the engine had matured into an axial flow design with a nine-stage compressor section, and nine combustion chambers arranged in a circular manner. Pressure ratio was about 5.2, superior to the Ghost, but inferior to the British Avon also under development in the same time period.
(a picture from 1954 Flight Global magazine comparing the Dovern and Ghost)
After about 3,000 hours of run time, a Dovern prototype was fitted to a Swedish Avro Lancaster (Tp 80) for further testing.
Testing of the engine in this manner began in June 1951, and revealed some issues. At certain power settings, the engine would suffer compressor surging, causing a loss of power and potential damage to the engine. Numerous redesigns of the compressor section somewhat alleviated the problem, though did not manage to cure it entirely.
By 1954, the Dovern had accumulated over 4,000 hours of runtime, including about 300 on the Lancaster testbed. An afterburning variant had also been developed, producing 45 kN. However, the engine was still not fully ready, and by this point the Lansen had already flown with an Avon engine fitted. As a result, it was decided to cancel the Dovern program, and instead use the Avon engine in both the Lansen and upcoming Draken (J35). (Some sources say that the Dovern was cancelled when it caught fire and destroyed the Lancaster test aircraft. However, this actually happened in 1956 while testing the RM-6/Avon, at which point the Dovern was already cancelled.) 16 units had been produced. An advanced version, called the Glan, had been under development for use in the Draken. It was also cancelled.
From this point, Swedish aircraft designs would use foreign engines. Though the Dovern was not fully developed, it cannot be said to be a failure for the Swedish aerospace industry. Producing world-class jet engines is highly difficult, requiring large amounts of experience and supporting industry. Only a few nations are truly capable of doing so even now (US, UK, France, Russia, and arguably China). For a country as small as Sweden, having an indigenous jet engine industry would be a truly Herculean feat.