Modern portable flame-thrower was German pre-WW1 invention. Its basic structure in all its simplicity: Three containers, two of them contained fuel and third one had flammable pressurised gas (usually nitrogen). Barrel connected with hose to containers was used to aim the flame. During WW1 portable flame-throwers become more common and gained popularity as one of the most feared and hated weapons. The weapon was dangerous also those carrying it and had short range when compared to other infantry weapons, but inside its short range it proved brutally effective. Flame-thrower operators were hated priority targets to their adversaries. During WW2 all major players had portable flame-throwers among weaponry used by their engineer corps. Originally portable flame-thrower was designed as a weapon to be used against fortifications, but they proved also somewhat suitable as antitank weapons. Finnish military had no flame-throwers when Winter War started, but soon that changed.

PICTURE: Italian made M/40 portable flamethrower. Drawing based to drawings of military manuals. Colours have been picked just to make identifying different parts easier - they are not the real colours used in this weapon. CLICK THUMBNAIL TO SEE LARGER PIC (54 KB).

When Winter War started at end of November 1939 Finnish military didn't have any flame-throwers. At the time Germany was still leading the development, but because of its treaty with the Soviets it was unwilling to deliver weaponry to Finland. So, the first flame-throwers were acquired from Italy instead. The Italians had portable flame-throwers in large-scale use (some 1,500 being used by Italian Army at 1940) and were quite willing to do business with the Finns. As a result the Finns bought 176 portable flame-throwers type "Lanciaflamme Spalleggiabile Model 35", which Finnish military named as M/40. From those 176 only 28 arrived during Winter War and it is uncertain if even they saw any battle-use during it. The other 148 arrived during the peacetime between Winter War and Continuation War. Finnish Engineer Corps used all of them during Continuation War.

The main parts of M/40 portable flame-thrower were:

The fuel tank consists two cylinder shape containers. These were divided by horizontal inner wall to two chambers, from which the upper chamber contained nitrogen gas and lower chamber contained fuel. Hose leading to the barrel was attached low to right hand side container. Nitrogen and fuel filling vents and nitrogen pipe connecting the two cylindrical containers were on top of the fuel tank. The barrel, from which the actual flame came, was quite ordinary kind. Originally the flame-thrower had Bengal-type torch containing system with flint, which had to be lighted before the battle. However the Finns made the design easier to use by adding the electric lighter system, which could be powered by either one 18-volt battery, four 4.5-volt batteries connected in series or high-voltage inductor. The empty fuel tank weighted 10 kg.

PICTURE: Barrel of M/40 portable flamethrower. Drawing based to drawings of military manuals. Colours have been picked just to make identifying different parts easier - they are not the real colours used in this weapon. CLICK THUMBNAIL TO SEE LARGER PIC (28 KB).

The fuel tank could contain 12 - 12.5 litres of flame-thrower fuel. The nitrogen gas in upper chambers of its containers could be loaded up to 20. According manuals filling of the flame-throwers tanks had to be just before use, because the pressure would leak from the tank if it was storaged for a long time. The typical way of using portable flame-thrower were short (about 1 second) bursts of fire and in this M/40 proved quite good - it could do as many as 20 - 30 bursts with one fill. However, the typical problem with short range was also quite eminent with it due to low working pressure - the maximum range of fire was only about 20 metres or so. As usual weight was also an issue and operating of the flame-thrower M/40 demanded crew of two men.

Later the Italians also developed "Lanciaflamme spaglleggiabile Model 1940" (which had electric lighting) and "Lanciaflamme spaglleggiabile Model 1941" portable flame-throwers, but according Finnish documents none of them were acquired.

PICTURE: Soviet made portable flamethrower M/41-R (ROKS-2). Drawing based to drawings of military manuals. Colours have been picked just to make identifying different parts easier - they are not the real colours used in this weapon. CLICK THUMBNAIL TO SEE LARGER PIC (82 KB).

During Continuation War Finnish troops also captured Soviet ROKS-2 portable flame-throwers, which were then adapted to Finnish use. The speciality of ROKS-2 was that the Soviets had tried to camouflage it as M/91-30 military rifle and backpack. Because of this purpose the barrel was shaped to remind rifle and fuel tanks had been attached to frame made from thin steel plate, which covered them somewhat hiding their structure. The Finns presumably captured ROKS-2 mostly at 1941 and named them as M/41-R. Captured M/41-R flame-throwers remained in battle-use with Finnish Engineer Corps to the end of WW2.

Main parts of M/41-R flame-thrower:

Like in M/40 also fuel tank of this flame-thrower had two cylindrical vertical containers. However in this flame-thrower the containers were in metal frame and had smaller cylindrical horizontal nitrogen tank under them. Each fuel container had filling valve on top of it. The hose containing fuel tank to barrel was attached low at right hand side fuel container. Pipe connecting nitrogen tank to fuel tank was at the left-hand side. The lighting system contained two special cartridges, which started the flame and could be fired by pulling trigger of the rifle-shaped barrel. The empty fuel tank weighted 8.5 kg. Length of the barrel was 111 centimetres and it weighted 3.6 kg.

The nitrogen tank placed vertically under the fuel tank contained 1.3 - 1.8 litres of nitrogen gas packed to pressure of 115 at. Using working pressure this hard had its ups and downs: The range with Finnish flame-thrower fuel was 30 metres (with Soviet developed flame-thrower fuel upto 36 - 45 metres), but the high pressure also used lot of fuel real fast. The weapon could only produce 6 - 8 short (1 second) bursts of fire without refill. The nitrogen tank weighted 2.8 kg. Effectiveness of camouflage used with ROKS-2 in real battles is highly questionable. The nitrogen tank was not covered by steel frame and hose leading from fuel tank to the barrel was still in plain view. And once the flame was ignited the true nature of weapon must have been quite obvious. Like with M/40 also M/41-R demanded crew of two to operate it.

PICTURE: Barrel of Soviet made portable flamethrower M/41-R. Drawing based to drawings of military manuals. Colours have been picked just to make identifying different parts easier - they are not the real colours used in this weapon. CLICK THUMBNAIL TO SEE LARGER PIC (37 KB).

Finnish military used two kinds of flame-thrower fuel mixes with these flame-throwers:

Summer-mix:

Winter mix:

Flame-thrower fuel was readily mixed for 50-litre tanks, in which it was both transported and storaged.

During WW2 flame-throwers remained rather rare weapons for Finnish military. Typical Finnish Continuation War era Engineer Battalion had first separate Flame-thrower Platoon and later Jaeger Engineer Battalion, which each had 6 flame-thrower crews (total of 12 men). But this was very little considering that by the book TO&E strength whole Finnish Engineer Battalion of that time was close to 600 men.

SOURCES:

Liekinheitinopas (M/40), (Printed by Otava in 1941)

Liekinheitinopas, kalustot m/40 ja M/41-R. 4. (Printed 1942)

Jatkosodan historia, part 1

Brassey’s Infantry Weapons 1950 - 1975