I haven't found an appropriate thread where to put some interesting rare stuff related to WW2 development, be it industrial one or makeshift field modifications.
Let's start with two things. The first one is a relatively recently found rarity from Swedish archives - a drawing of ČKD/BMM V8H-Sv tank. The drawing and a letter was found by WoT enthusiasts in Swedish archives in 2014 (the original announcement and the drawing source is here). The drawing is from a message dated 8th September 1941. One of the reasons why this drawing was not known before may be that the Czech archives were partially destroyed by floods in 2002. Anyway it is an export modification of the V-8-H tank accepted into Czechoslovak service as ST vz.39 but never produced due to the cancelation of all orders after Münich 1938 (for the same reason negotiations about licence production in Britain failed). Also later attempt to sell the tank to Romania failed due to BMM being fully busy with Wehrmacht priority orders. The negotiations with Sweden about licence production of V8H-Sv lasted till 1942, at least in May 1942 Swedish commission was present in Prague for negotiations. The tank differed compared to the base ST vz.39 in thicker armor with different front hull shape (armor 60 mm @ 30° on the hull front and also 60 mm on the turret; all sides were 40 mm thick). The tank was heavier (20 tons) and had the LT vz.38 style suspension with probably even larger wheels. The engine was still the same Praga NR V8 (240-250 Hp per source). The armament was unchanged with 47 mm Škoda A11 gun and two vz.37 HMG. The commander's cupola was of the simple small rotating type similar to those used on AH-IV-Sv tankettes. It is known that the Swedes officially asked to arm the tank with 75 mm gun, replace the engine with Volvo V12 and adding third HMG to the back of the turret. In the end the Swedes decided to prefer their own Strv/m42.
Source of the drawing
The second is makeshift field modification found on Balkans. It appears Ustasha forces (and possibly some SS anti-partizan units) used several Italian M15/42 medium tanks with turrets from Pz.38(t). There are several photos of such hybrids but little more is known. On one photo it is possible to see Ustasha registration number U.O. 139.
Few more photos of such hybrid.
It appears that the source of all those photos to be found on the internet is this book, Armoured units of the Axis forces in southeastern Europe in WW2 by Dinko Predoevic.
I am sure there are many very interesting stories to share about this topic. Let's start with couple of articles about the weird and sometimes downright crazy history of Czechoslovak assistance which helped Israel to survive its early days. It's true that Czechoslovakia asked a lot of money for bypassing the UN embargo but it doesn't change the fact that it helped in the critical time - before the change of course was ordered from Kremlin in 1949. It's also worth mentioning that the arms-smuggling to Israel brought up to 1/3 of all foreign currency income of Czechoslovakia at that time! It's all in Czech but well understandable with the google translate.
Here in short the story of the secret Czechoslovak operation DI - the military asistance to Israel from the website of the Czech Institute of the military history. The article contains rare historical photos from the covert military training for army specialists (pilots, tankers, mechanics and even an infantry brigade made of volunteers from the former Czechoslovak Army Corps in USSR).
If you really like the topic, you can learn many more details from these six chapters of this superlong article (sure worth studying for anyone interested in the topic).
After that we have the totally crazy story of the Cairo bombing raid actually performed from the communist Czechoslovakia in 1948. Why don't we have yet any movie about three B-17s smuggled from USA, crewed by American-Jewish airmen, armed with former German machineguns and bombs and operating from an airfield located in then communist Czechoslovakia? If that doesn't deserve to be filmed than what does?
Most of you likely know that the first combat aircraft of the Israeli airforce were Czechoslovak Avia S-199 fighters. This stillborn stop-gap modification of the leftover Bf-109G airframe was rather useless in fact (Czechoslovakia had loads of Bf-109 airframes but no spare DB-605 engines whose reliability was absurdly low due to bad late-war steel, so the engines were replaced with Jumo-211 bomber units - completely unsuitable but available) but nevertheless it helped to stop the Egyptian attack on Tel Aviv and brought a very important psychological advantage on the Israeli side. More about these planes here.
To add to the absurdity of that time... the man behind the support for the Israel was Czechoslovak FM Vladimír Clementis who was executed just few years later as a result of an intra-communist power struggle.
I think that possibly some of you might be interested in our interwar Czechoslovak stuff. For starter I've decided to share with you a wonderful online document about our fortification system. At the very beginning I'd like to say that I have nothing common with its creators. It's just an incredible gem that deserves to be shared with you. If you know it, sorry for that, nevertheless I think most of you don't. Since I am new here I will not waste your time debating what if scenarios. Don't worry.
Well, enough of talking. What I want to share with you is a massive interactive map of our fortification system containing nearly 11 thousand objects with information about every single one of them. You can switch on even such crazy details like cable networks or construction facilities used for building of the fortifications. The map is directly linked with an online database of the fortification buildings where more than 2000 objects are listed with detailed description (plans, 3D models, photos, weapons, crew, important dates, recent state etc.). Unfortunately this database is only in Czech language but it can be a great source of information for you anyway (especially when linked with the map). The good thing is that the map alone supports other languages and you can easily switch them.
This is the base view where I have already switched on all objects. You can change background map type, information etc. on the left side and visualise everything what You want to see on the right side.
Let's zoom in a little bit. Here You can see one of the strongest fortified places - a valey at Králíky in north-east Czechia. As you can see the object marks have different shapes, colours etc. The shape is matching the menu on the right side. Triangles are concrete pillboxes vz. (mark) 36. Small circles are pillboxes vz. 37. The letter inside means type of the object (with one firing post, two on each side, angled one etc.). The color can be decoded from the information table in the bottom right corner. Basically it shows whether the object was actually built, if it was later destroyed or the works were only started or even not so. The heavy objects are the large circles. The numbers have also a meaning. It's a resistance class (1 -> 2 -> I -> IV from the lowest to the most resistant).
You can switch on also the ground plans of the artilery groups (fortresses with underground network between the casemates). You can see it here (fortress Hůrka).
You can also switch on the firing lines. Here You can see heavy artilery coverage of the most fortified section of the line (the sad thing is that no heavy artilery pieces were installed by the time of Münich crisis - but lets leave such details aside for now).
You can switch on the firing lines even for the pillboxes as you can see here on the example from the souther border. Nearly all Czechoslovak objects were built for side fire having superheavy resistance frontal walls with stone and earth covers.
If You zoom even more and switch for satelite map you get something like this. In this case the red color shows anti tank 47 mm guns and the blue color is 7,92 mm (sometimes double) heavy machine guns of a heavy separated casemate (possible use of light machine guns in observation cupolas is not marked). The grey color shows vz.26 light machine guns of the neighbouring pillbox.
You can click on every single object and you get available details. The first icon shows detailed lines of fire including realistic range. Bellow the L: L1 M ZN 3-4 means: Left side: L1 = 47 mm anti tank gun with 7,92 mm coaxial heavy MG; M = twin 7,92 heavy MG; ZN is I think type of the cupola but I'm not actually sure about it. The codes for the weapons are shown at the table in the lower right corner (you need to keep the cursor on the question mark).
The Second icon leads to a database of objects which is unfortunately only in our weird language. Anyway you can dig a lot of information from it as well (drawings, recent state, photos, exact location etc.).
The best thing is that most of the objects still exist till today (all of those heavy ones). The Germans managed to destroy roughly 2000 light objects (and gain some 11000 tons of steels from them). They managed to damage also many heavy ones when they were testing weapons and tactics for the future use duirng the WW2. They even moved some cupolas (and of course the famous hedgehogs) to other fortifications along the Atlantic wall or elsewhere. Many of them are made into better or worse museums today (large quantity is private now). Huge number of them is just left alone and freely accessible for anyone. If you are more interested I can give you tips which ones to visit. On the Czech map portal You can use a mode panorama which is basically the same thing as Google street view but it's much more up to date and it's nearly everywhere where they got at least with a motorbike. Since the fortifications are also visible there, you check where they are for easier access.
If you are interested I can continue the fortification topic with some other information (I'm no historian but I have visited quite many of the objects myself and read some books about them).
OK, so this was my first post on the forum. I hope you find it interesting and maybe for some of you it can be a reason for a trip, who knows :-)