Posts Tagged: drawings
The beginnings of the bkan 1 program
In the same 1949 army headquarters memo mentioned in the previous post, the army also saw the need for a 15 cm self-propelled autoloaded artillery gun (the 10,5 cm gun was intended for smaller formations, while the 15 cm SPG would be a division or corps-level asset). Development of this artillery piece was contracted to Bofors, with deliveries planned to start in spring 1956 (in reality, the production version of this SPG finally entered service in 1967, delayed over 10 years).
These documents describe the original intentions and requirements for the SPG, and a preliminary drawing is attached. It was originally intended to weigh 30 tons; the production version would eventually enter service weighing 52 tons. A large part of the increased weight was due to a requirement added later, namely that the entire fighting compartment and the external ammunition storage must be armor protected and sealed against NBC weapons.
Archive reference: SE/KrA/0062/D/01/016:H/F I/17 and SE/KrA/0062/D/01/016:H/F I/18
Considerations regarding self-propelled 105 mm howitzer (1949)
A few documents from 1949 regarding the development of a self-propelled 105 mm howitzer. This project has been seen before on this blog, but these documents seem to be where the project first originated, namely with a memo from the army headquarters regarding replacement of older artillery pieces.
The documents mention that Bofors proposes to mount a modernized version of the existing haubits m/40 on the chassis of the lvkv fm/49 SPAAG, but to save costs KATF is ordered to investigate if it’s possible to mount the same artillery piece on a very light tankette chassis that is being developed at Landsverk. Bofors is said to be skeptical, but the investigation proposes three alternatives for doing so (called a, b, and c; drawings are attached). Alternative a is notable for having the gun mounted backwards on the chassis, but alternative c is considered to be the most suitable.
For whatever reason the project never got off the ground and a self-propelled 105 mm artillery piece would continue to be discussed for several years until the project was ultimately cancelled for cost reasons at some point in the 60’s.
Archive reference: SE/KrA/0062/D/01/016:H/F I/17
List of Landsverk tanks as of April 1949
A letter from Landsverk to KAFT (dated 1949-04-09), containing data and drawings of some of the then-modern tanks produced there, as well as proposed data and drawings for a number of planned tanks developed by the company at their own expense.
It may be worth mentioning that most of the tanks have “motyl 25” listed as their fuel. Motyl 25 is a mixture of ethanol (that is to say, alcohol) and regular gasoline in the proportions 25% ethanol and 75% gasoline. During WW2 this was used extensively to help offset the Swedish oil shortages, but in those times both motyl 50 (50% ethanol) and motyl 75 (75% ethanol) were common. Today, we see the same thing in the form of the commercial E85 fuel available at many gas stations.
The reason this is in an archive volume dated 1948 is that apparently the same list was sent over in September that year, but KAFT seems to have misplaced some pages so it was sent over again and apparently the bureaucracy found it appropriate to place both the letter and the complete list together with the original list. Most of the pages are present twice in the archive volume.
Archive reference: SE/KrA/0062/D/01/016:H/F I/15
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
Technical specification, S-tank type A
Original title: Teknisk bestämmelse för stridsvagn S, typ A
Incomplete; I only photoed the 60 or so pages I found most interesting (out of a total of 144). Dated 1964-10-04. Note the wax seal on the first page.
Archive reference: SE/KrA/0266/005/01:H/F II/5