Monthly Archives: January 2014

TLP and pvkv fm/48: the story of a cancelled project

This small collection of documents (letters, memos, minutes of meeting and blueprints) tells the short and sad story of the Landsverk TLP, which was to be a 30-ton tank destroyer armed with a 105 mm gun. It lived a very brief life on paper at Landsverk and Bofors for a few short months in 1947, until the army changed its mind and decided it didn’t want AFV’s in that weight class after all. Before cancelling the project entirely, the possibility of improving the protection of the existing pvkv m/43 by angling its armor plates better and potentially upgunning it to 105 mm was investigated (that part of the project was called “pvkv fm/48” by Landsverk), but the conclusion was that the protection would not be improved and the entire thing came to nothing.

Archive reference: SE/KrA/0062/D/01/016:H/F I/13

Memo regarding guidelines for new AFV development (1944)

Original title: VPM med förslag till riktlinjer för planering och utprövning av nya stridsvagnar mm.

This memo (dated 1944-11-29) suggests guidelines for future AFV development. It starts off with discussing foreign developments, and states that the general opinion seems to be that anti-tank weapons have reached such a degree of efficiency that merely building more heavily armored tanks no longer seems cost-efficient. At the same time, the demand for “support tanks” (self-propelled guns and tank destroyers) is on the rise.

With this in mind, the memo suggests a number of new developments, mostly improvements of existing designs, and suggests that using the new “split” turret with an automatic gun rammer (currently under development at Bofors) might be a good idea.

Archive reference: SE/KrA/0062/D/01/016:H/F I/4

Minutes of meeting (1941-04-30) regarding development of new AFV’s

Original title: Sammanträde ang. strv m.m. å MB3 den 30 april 1941

This document contains minutes of a meeting held on 1941-04-30, where the requirements for a new tank and/or tank destroyer are discussed. The decisions made at this meeting led to the development of the strv m/42.

The meeting starts off with an overview of the tanks currently available to the Swedish army (48 strv m/37, 16 strv m/38 and 20 strv m/39), as well as the ones ordered but not yet delivered (100 strv m/40 to be delivered before the end of 1941 and 116 license-built TNH with deliveries starting summer 1942). The meeting participants conclude that neither current tanks nor current towed anti-tank guns (mostly 37 mm Bofors) are sufficient to fight modern German or Russian tanks, and that it is necessary to develop either a new, heavier tank or a self-propelled anti-tank gun of some kind, and quick.

Three current Swedish tank development alternatives are presented: the Landsverk Lago (originally intended for Hungary), the Landsverk Terro (a 14 ton tank with a 57mm gun and 50 mm frontal armor) and an unnamed design proposal for a 22 ton tank with a 75mm gun and about 70mm frontal armor.

Weight restrictions are brought up. If strategic mobility is disregarded, tanks suited to Swedish terrain should weigh max 30 tons, but since tanks have to move along roads and over bridges, the meeting concludes that a new AFV (tank or TD) must not weigh more than abut 20 tons in order to retain sufficient strategic mobility.

Some discussion follows, with several different proposals from the meeting participants. Someone proposes a 20 ton TD with a 75mm gun and 70mm front armor, but is met with opposition and the counter-argument that Swedish terrain is better suited to more mobile anti-tank guns, and that the Swedish military attache in Berlin reports that tanks are the best weapon for fighting tanks. Someone else then proposes an 18 tank with a 105mm short-barreled howitzer, but this idea is not received favorably since both the precision and the rate of fire would be low.

In the end the meeting decides that development should focus on a 20 ton tank with 60 mm of frontal armor and armed with a 57mm gun (or alternatively a 75mm or 105mm gun), with a max speed of 40 km/h.

Archive reference: SE/KrA/0062/D/01/016:H/F I/1 a

A brief history of Swedish tanking (as of February 1943)

Original title: Anteckningar från orientering för Överingenjör Lundborg den 13/2 1943 i stridsvagnsfrågan

This document contains notes from an orientation (held on 1943-02-13) on the Swedish tank development and tank purchasing thus far. It takes the form of a pretty informal briefing that relates a number of amusing anecdotes; among other things it’s revealed that the reason that there were two different engine options for the strv m/42 was that Volvo (which built a number of tanks) absolutely could not accept installing an engine from their competitor (Scania) and had to be threatened with government sanctions in order to accept a compromise where they’d mount Scania engines in early tanks while developing their own engine option.

Archive reference: SE/KrA/0062/D/01/016:H/F I/1 a

Memo regarding the quality of homogenous armor plates

Original title: PM angående kvaliteten i homogen pansarplåt

A memo (dated 1944-03-21) regarding the properties of various types of steel, particularly with regard to the capability of withstanding hits from armor-piercing rounds of various types. Contains a lot of data from test firings with various guns against various armor plate configurations.

Archive reference: SE/KrA/0062/D/01/016:H/F I/3

Minutes of meetings regarding a better gun for strv m/42

Minutes from three 1944 meetings, regarding equipping the strv m/42 with a better gun. The existing 7,5 cm kan m/41 strv has insufficient penetration, and a replacement is clearly necessary considering the tank development seen so far during the war. A 57 mm option is considered, but in the end it is decided to let Bofors fit the 75 mm pvkan m/43 for trials.

This requires a redesigned turret; blueprints for that are attached. These presented my small camera with some problems since they’re huge (they portray the entire tank – 6.2 meters long in reality – at scale 1:5, which means the tank is about 1.2 meters long on the blueprint) so I’ve had to photograph them in parts.

Archive reference: SE/KrA/0062/D/01/016:H/F I/3

Report (May 1958) from the 2nd Equipment Planning Study Group

Original title: Rapport maj 1958 från studiegrupp 2 för fortsatt tygmaterielplanering

The 2nd study group for further equipment planning was responsible for figuring out what kind of requirements would be reasonable to expect from next-generation direct-fire AFV’s (tanks and APC’s, mostly) that were to enter service around 1965. In order to do this, the group considered what the Soviets were doing, what everyone else was doing, current bleeding edge research, where tank development was right now and where it was heading. In May of 1958 the group issued this report, which is a bit over 90 pages long.

The report discusses current trends in tank development, and designates three general lines of development called the A-tank, the T-tank and the S-tank.

  • The A-tank (A for America, probably) is the expected result from current US and UK design philosophy. It weighs about 40-45 metric tons and is frontally protected against sub-caliber kinetic penetrators fired from guns of up to 120 mm caliber, with mobility somewhat impaired by its weight. (In reality, this alternative later resulted in the M60 Patton and the Chieftain.)
  • The T-tank (T for Tyskland – Germany) is the expected result from current German and French design philosophy. It weighs about 30-35 metric tons and has very high specific engine power (25-30 hp/t or more), but only has frontal protection against (the equivalent of) 57 mm guns. (In reality, this alternative later resulted the Leopard 1 and the AMX-30.)
  • The S-tank (S for Sweden) is a proposed turretless Swedish design that has the same protection as the A-tank against kinetic weapons, while weighing only about 30 metric tons. Additionally, since the gun is fixed in the chassis, it can be fitted with screens or lattices that will protect it from all currently known anti-tank missiles and other HEAT penetrators.

The report then goes on to reason about the importance of low tank weight with regards to strategic mobility. For Swedish conditions, tanks should ideally weigh less than 37 metric tons. Based on this and other factors, the authors argue that the army should not purchase upgunned Centurions from the UK, as they are too heavy and an insufficient upgrade over the 84 mm variant. Instead, it is recommended that future Swedish tank development should focus on a) testing the S-tank concept in practice to see if it’s a workable solution, b) start development on a domestic A-tank equivalent (reusing the existing Krv chassis for experiments as necessary), using an autoloader instead of a manual loader to keep the weight down, and c) keep an eye on developments in the US and UK with the intention of purchasing complete tanks if something better/cheaper than the domestic alternatives comes up.

The report also features about a metric ton of appendices, which I have photographed but not published here because they are mainly used as support for the recommendations outlined in the main report and thus not really all that interesting on their own. If you see one you want in the table of contents, leave a comment and ask for it and I’ll post it.

Archive reference: SE/KrA/0266/002/01:H/F III/1

Minutes of meetings with the armor committee of 1941

The “armor committee of 1941” (1941 års pansarkommitté) was a working group tasked to develop a satisfactory Swedish medium tank, with severe time constraints and a strict requirement that it must not weigh more than 22 tons. The result was strv m/42, which basically was an improved Landsverk L-60.

These four documents contain minutes of meetings with the committee in 1941 and 1942.

Archive reference: SE/KrA/0062/D/01/016:H/F I/1 a

Memo regarding considerations for series production of akv 151 (KV 155)

Original title: PM rörande akv 151, överarbetning av konstruktionen med hänsyn till planerad tillverkning i serie

This memo (dated 1960-01-04) discusses series production of the akv 151 SPG (aka. KV 155, the bkan 1 prototype) and some of the project history. The author notes that since the original suggestion in the second quarter of 1949, eleven years have passed and series production has not yet started. A number of reasons for this is mentioned (lack of engineers, changes in the specification, doubts whether the project is viable at all). The author concludes that because of the changes in the specification and the fact that the current prototype is based on a chassis (the Krv) that is not likely to be mass produced, the vehicle (and its chassis in particular) will need to be reworked before it can enter series production.

The author also mentions that it would be desirable to reduce the weight of the vehicle; the prototype weighs 45 metric tons but according to a 1958 report Swedish AFV’s should weigh no more than 37 metric tons, and if possible weigh less than 25 tons. A note in the margin exclaims “-18% !” in red next to this paragraph; someone who read the memo probably doubts that this is possible (and they would be right, because the series production version turned out to weigh 52 metric tons in the end).

Finally, four alternatives are presented; two conventional and two using the suspension to help with gun elevation. The weight for all four alternatives is claimed to be less than 37 tons, which seems like a pipe dream in retrospect. Rough drawings of the alternatives are attached.

Archive reference: SE/KrA/0266/002/01:H/F I/43