These grenades, of course, need no introduction. But still...
General technology overview
At first glance, a tin can with a trotyl type, such as WP-42 and its predecessor WP-41, looks simpler to produce than the F-1. Work with sheet material does not require particularly complex equipment. Cutting the body blank, cutting or stamping blanks for the bottom and the lid, connecting them with a folding seam on a fairly simple rolling machine (such are widely used in the manufacture of cans), making a flange for the fuse and fixing it by soldering or welding. Indeed, the corps for the RG-42 during the war were made in very many factories, including canning, in various workshops. Shells were sent to the equipment factory.
A sealing machine connecting the folding seam to the wall of the can with a bottom and a lid. With a similar technology made body grenades RG-42
The case of the F-1 is manufactured by casting from iron or steel cast iron, which requires at least a minimally equipped foundry with a furnace for smelting iron and a section for the production of flasks and cores. During the casting, the hollow core formed the internal cavity of the housing; it was made from chamotte, kaolin or sand-clay mixture. I did not manage to find descriptions of the casting technology for the F-1 casings, but apparently, the molds were made immediately to the batch: six, eight, ten pieces, which depended on the performance of the iron-smelting furnace and available casting equipment.
Casting iron looks like this: assembled forms into which molten iron is poured from the ladle
After the casting was cooled, the mold was broken, the rods were knocked out of the garnet, and the mold mixture was cleaned. Shells were machined (point bore and threading) and sent to a special factory for equipment. Sometimes the equipment factory received untreated hulls and completed their processing.
The main thing in casting is to properly prepare the mold. This required specialists, model makers and molders, without whom not a single foundry could cast anything. The rest of the work did not require skilled labor. In addition, the foundry required fuel for the smelting of iron and therefore had to be supplied with coke or charcoal. WG-42 did not require furnaces, coke, skilled foundry workers. Enough was enough to simply equipped a mechanical workshop and hastily trained workers. If there is a workshop with equipment and a master, then you can train the necessary operations for a day or two. Moulder need to learn longer.
So everything is obvious? Do not hurry.
How much metal and explosives do you need?
The other side of the issue is metal consumption for a grenade. WP-42 consumes much less metal than F-1. It is not so difficult to determine if the weight of the charge and the weight of the UZRG (55 grams) are subtracted from the weight of the grenade. The F-1 weighs 600 grams, and minus the 60 grams of charge and fuse, it turns out 485 grams is the weight of the case. WP-42 weighs 440 grams, and minus 150 grams of charge and fuse it turns out 235 grams.
The housing of the WP-42 is almost exactly twice as light as the F-1. It should be borne in mind that the weight of the body also includes a fragmentation element. Without it, the grenade body will be even lighter. This is a very significant point. The conditional million WP-42 grenades will require 235 tons of metal, and the conditional million F-1 - 485 tons. Of course, in a big war, when the metal is consumed on the scale of millions of tons, it is not that much. But still, in a warring economy, metal is a deficit, and from this point of view, WG-42 looks more preferable.
The lack of metal in the war can go to the extreme. This photo is, of course, staged, but in the UK really beautiful lattices were cut into scrap metal
However, WG-42 has a much larger charge weight, 2,5 times more than F-1. The conditional million WP-42 will require 150 tons of trotyl, whereas F-1 will require only 60 tons. This is where the first ambiguous situation arises in deciding what kind of grenades to produce. What to choose? Increased metal consumption or increased explosive consumption? Within the framework of a warring economy, this issue is already being solved on the basis of the balance sheets of income and expenditure of both. According to the experience of the Second World War, it can be judged that explosive was the bottleneck. Specialized enterprises, special equipment, trained personnel and a whole range of raw materials and chemicals were needed for its production. The production of the same TNT was limited not only by the capacities of the special plants, but also by the capacities for the production of toluene, nitric and sulfuric acids. In general, if there is not enough trotyl, then it is more expedient to use a grenade with a smaller charge, that is, F-1.
And there is again an ambiguous moment. If the decision is made to equip hand grenades with ersatz-explosives such as ammonium nitrate, it is more expedient to use WG-42. The TNT equivalent of saltpeter is 0,35, that is, 150 grams of charge will be equivalent to 52,5 grams of TNT, and WP-42 with such a charge will be roughly equivalent to F-1 in TNT equipment. Mixed explosives based on ammonium nitrate are more powerful (igdanite, say, has the TNT equivalent of TNN), but in this case a larger capacity case, like the WP-0,8, is an advantage.
Thus, already in this difficult situations arise with non-obvious choice. In general, it can be said that the type of grenade and its equipment by one or another type of explosive are determined primarily by available capacities for the production of explosives and the general development of the chemical industry. For example, in Germany during the World Wars there was little oil and, consequently, little toluene, but there were good capacities for the production of synthetic ammonia and ammonium nitrate. Because the Germans were to use saltpeter in hand grenades, and therefore used a sheet metal housing.
What kind of metal?
Metal is also different. F-1 is made of cast iron, and WP-42 is made of sheet steel. The technological difference is quite large. Cast iron is the first product obtained from iron ore by smelting in blast furnaces. Although nowadays the technology of nondomain production of iron is developing quite rapidly, nevertheless, the blast furnace process still dominates in the world metallurgy.
Sheet metal, by contrast, is the final product. It requires to smelt cast iron, then convert it into steel in steelmaking furnaces. According to the technology of the first half of the twentieth century, steel ingots were first rolled on blooming mills, then on several rolling mills, to produce a slab - steel plate with thickness from 75 to 600 mm. Then this billet was rolled several times on sheet mills to produce a steel sheet of the required thickness (in our case 1-2 mm). More often produced hot-rolled sheet products, which had more use than cold-rolled ones. Ready rolled sheets or rolls sent to consumers. In the second half of the twentieth century, technology has changed somewhat. The emergence of continuous casting of steel allowed to go to the cast slabs, from which a higher-quality flat products were obtained.
Here, for example, sheet rolling shop 3000 OJSC "Mariupol Iron and Steel Works named after Ilyich". Mill-3000 rolls sheet steel with thickness from 6 to 50 mm. You can see how this grand building - a large sheet rolling mill
Receiving a semi-finished product for F-1 requires only one blast furnace, and for WP-42 - a whole full-cycle steel plant, producing all types of products, from iron to finished steel. The production of steel sheet requires many operations, special equipment and qualified specialists. Therefore, it is wrong to compare only the manufacture of cases for F-1 and WP-42 grenades. The technology must be considered entirely, together with the manufacture of semi-finished products. And then the production technology F-1 is much easier.
Even more than that, the F-1 grenade can be produced at a very primitive metallurgical plant, smelting iron in a blast furnace of the 18th century sample from marsh ore and on charcoal. Casting cases can be organized immediately, pouring metal from the blast furnace directly into the form.
Blast furnace built at the Seversky plant in the Urals in 1860 year. It is quite possible to melt cast iron on such a blast furnace and immediately cast grenades
It is also interesting to note a couple of moments based on the data of Novovyatsky Mechanical Plant No. 608, which during and after the war produced the equipment of F-1 and WP-42 grenades, and also made cases for the latter. First, receiving cases from suppliers, the plant part of them was defective. For F-1, the average reject rate was 16% (out of 2,7 million cases, 451 thousand pieces were rejected), and on WP-42 - 31% (out of 3,5 million cases, 1,1 million pieces were rejected). That is, the apparent simplicity of manufacturing cases for WP-42 turned into a high reject rate and the useless consumption of valuable sheet metal. Marriage could be melted down, but it was obviously more profitable to start up the defective F-1 hulls in the smelter. Secondly, although there is no way to compare the cost of the cases of these types of grenades, yet in the materials of Plant No. 608 there is an interesting indication that WP-42 became cheap only with mass, continuous production. When the plant was just beginning to master the production of WG-42 cases, they cost 18,9 rubles apiece, and with the development of in-line production, the cost price fell to 5,5 rubles. Thus, WG-42, produced in small workshops and non-core factories, was an expensive grenade. If we assume that the F-1 case cost about 6 rubles, then for the price of a semi-hand-made WG-42, at least three cases for the F-1 could be made. This is not surprising, since the sheet metal is much more expensive than cast iron, and the machining of the WG-42 casing blanks is more.
From here one more important conclusion. The mass production of the RG-42 can be decided only if there is a developed metallurgy, which has sufficient capacity for the production of sheet metal, as well as in the presence of advanced engineering. WP-42 is a by-product of automotive development that needs a lot of sheet metal. Therefore, the countries with a developed automobile industry (in the Second World War — the USA and Germany, as well as the USSR) made sheet metal grenades.
The F-1 prototype, the French F-1 grenade, did not come from a good life. The Germans seized two-thirds of the main French coal deposits in the Pas-de-Calais area. One third remained with the French, but there the mines were located almost immediately behind the trenches. There were mines that the Germans fired with machine guns, and special armored shelters were built for the miners. Coal mining has been halved. In 1915, France mined 20 million tons of coal, 20 million tons received from the UK, although 1913 consumed million tons of coal in 64. Also, the French lost almost all of the iron ore production, production fell from 21,9 million tons in the 1913 year to 0,6 million tons in the 1915 year. Requirements were covered by the remelting of scrap metal, the supply of allies, but even so the consumption of iron fell by half compared with pre-war time. It was at this time that a new grenade appeared. In France, there were many small deposits of iron, known since the Middle Ages, in which it was possible to extract ores for smelting several tens of thousands of tons of pig iron in the simplest blast furnaces and on charcoal. Let's say 1000 tons of pig iron is enough for 2 million grenades like F-1. One blast furnace with a capacity of 50 tons per day (this is a very small furnace) could produce 15 thousands of tons of pig iron per year, which would be enough to make 30 million grenades.
So the F-1 grenade is such a garnet that can be produced even with extreme depletion of the economy, using the lowest grade iron ore, charcoal and the very minimum of qualified engineers and workers. Even if large metallurgical plants turned into radioactive ruins, there are still opportunities for the production of F-1.
And what is the verdict? If we consider the issue comprehensively, it turns out that F-1 is simpler and cheaper to manufacture than WP-42. So in the third world world, the lemon will still be in the ranks and will occupy an honorable place in the infantry armament.