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Flaming T-34s - 8/11/2013 6:24:53 PM   
Mobius


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For PCO we changed it from all knocked tanks exploding to only a percentage being killed that way. Maybe we reduced that chance too far.

I found this report about looking for the causes of a high number of exploding T-34/76s experienced at Kursk. It appears to have been robo-translated from the original Russian. I tried to correct some of the wording.
quote:


Report of special laboratory NKV No. 101-1 on theme:
Examination of hitting features of T-34 tank fuel tanks with armor-piercing/high-explosive and cumulative (armor-burning) shells of German fascist army.
Resp. executors: Rozov, Kaminsky, Shchurov
Superviser: Sarafanov

1. History of question
In the battles of spring-summer 1943 tank army, tank corps and tank brigades commanders begin to note that cases of T-34 tanks combat losses with catastrophic explosions of fuel tanks or fire in engine compartment became more frequent. For instance, cases of burnt out T-34 tanks in battles of summer 1943 near Kursk exceeded those of T-70 tanks by 4 – 9%...
By order of chief of BTU GBTU of Red Army engineer-colonel Afonin, 11 Sept. 1943 a commission was formed to study this problem.
Our group studied possibilities of T-34 fuel tank explosion with various armor-piercing tools and valuation of its probable impact on crew and inner equipment.

2. Target setting
Commission's survey of 72 destroyed during Kursk battle tanks on SPAM {field repair} bases have shown that most of them (68%) were destroyed by fire originated in result of fuel tank depressurization with subconscious inflammation of diesel fuel.
All mentioned tanks have breach in hull side or underskirt by AP, armor-burning shells or field charge.

About 1/3 above mentioned tanks lack one or two front fuel tanks and have demolition inside or partial, or even complete destruction of hull's welded seams, caused by internal explosion.
Only small part (8%) of tanks have signs of inner explosion with signs of flames, whereas 24% of machines were destroyed by explosion without any signs of inner flames. Often even ordinance was completely unharmed in chest. According given order our group researched this particular type of destruction - fuel tank explosion.
Members of commission engineer-colonel Gurov and MVTU associate professor Krutov assumed after inspection of exploded tanks that given damage was caused by explosion of front fuel tanks placed inside crew compartment of T-34 after impact of some specific German ammunition.
Engineer-major Firsov expressed opinion that such explosion could happen in result of burst of high temperature caused by ammunition based on thermite or electron.

Group of com. Sarafanov received a task personally from chief of GBTU to explore the possibility of T-34 fuel tanks detonation after hit by various types of armor-piercing ammunition of German fascist army
{part missing}

4. Study equipment.
To verify assumptions of comm. Gurov, Firsov and Krutov, three sections layouts of 35mm thick armoured steel with 135 liters fuel tank established inside were built by NII-48 and Uralmashzavod. Also according to cover letter No.312-a from 21/4/1944. a T-34 hull with turret and equipment but without weapons was put to testing ground by BTU.
{part missing again}

5. Experimenting on location.
First shelling of layouts was on 12/12/1943. from ballistic cannon m.40 from 30 meters distance.
1. During the test fuel tank was full of diesel fuel, received by cover letter of com. Afonin from 5/12. Total spent 8 m.38 shells, 5 m.39/40 shells and 5 armor-burning shells.

The m.38 shell might be the Gr.38 shell. This was the earliest model 75mm HEAT round but maybe compared to the pzgr 38 Hl/B HEAT shell it seemed to be something else. I can't find this listed as part of the PaK 40's 1942 ammo catalogue.
The m.39/40 might be a single kind of AP shell or maybe either/or pzgr.39 APHE and pzgr 40 APCR rounds.
Armor-burning shells. These must be HEAT shells as the ‘88mm recoilless cannon’ (Panzerschreck 43) fires 88mm ‘armor-burning’ mines.
trotyl – probably TNT.

quote:


The results are the following:
During tests fuel tank was completely destroyed 3 times, diesel fuel was flamed 4 times. Explosions were not recorded.
When the fuel tank was hit by fragments of m39/40 shell they were abruptly dragged. Many of fragments did not break through.
Conclusions: 100% filled fuel tank of T-34 tank cannot be a source to inner explosion of T-34 tank, but even serves as protection from fragments of armor and cores of m.39/40 shells.
2. Since com. Krutov expected that gasoline cannot explode either if tank is full, with comm. Fedin sanction a tank of gasoline was installed into section. 3 shots was fired with m.38 shell and one armor-burning. Explosions were not recorded, in 2 tests gasoline caught fire.

Second stage of trials was began 9/2/1944. For trials the same weapons were used with addition of 88mm recoilless cannon m.1943, firing 88mm armour-burning mines.
According to trials program partially filled tanks were tested. Prior to the test shootings the tank was carried on a truck for 1-2 hours on service roads on testing area. After that fuel was poured off according to test conditions and tank was being installed on layout.

As guess... Just to spill fuel around and cause vapors to accumulate like a moving tank would after a few hours.
quote:


4th series of shooting. Tanks filled to 10-25%. Tank exploded from hit of coherent jet being filled to 25% or less. Equivalent bursting power was near 30-50 gramms of trotyl. The hatch cover on roof of layout made to lift off the tanks was smashed out. In case of filling with gasoline explosiveness reducing on average 1.5 times comparing to diesel fuel. Fuel tank detonation caused hatch cover to open. Welded seams of layout remained intact.
Another picture is observed when inside almost empty tank a high explosive part of 75mm armor-piercing shell with red ring (80 grams of trotyl with detonator of 20 grams of phlegmatized tan in aluminum cup) is bursting. In this case exploding effect of the shell is greatly (several times) increased. Welded seams of underskirt was destroyed by explosion, after that shock wave ripped underskirt off and partly destroyed the roof of layout. Layout admitted off.

The shell with the red ring (rot) was a large cavity APHE round with an 80 gr. burster. The pzgr 39 had only a 17 gr burster. Which is another round I can't find it in the 1942 Pak 40 75mm ammo catalogue. It might part of the 75mm/L24 inventory or maybe it was an early issue for the Pak 40.
quote:


6. Conclusions:
The best ratio for detonation of T-34 fuel tank is when it's 10-15% full and AP shell m.38 bursting inside. Burst causes immediate detonation fuel's vapor which adds to shell's explosion, multiplying it by 2-4 times, which corresponds with effect of 105-122mm AP shell.
Even better summary effect is reached when domestic 76.2mm AP shell BR-350À which contains 150 grams of trotyl bursts. Summary effect corresponds with 152mm AP shell BR-540B type, which contains 400 grams of trotyl.
With reducing caliber of AP shell the probability of a fuel tank explosion decreases dramatically. 37mm and 45mm AP shell cause almost no detonation. It should be noted that further increasing of AP caliber does not lead to a significant increase explosive power of ammunition bursting inside the fuel tank. The presence of 75-85mm shells containing 50-100 grams of trotyl or less amount of more powerful blasting substances (for instance, 30-80 grams of A-1X-2 mixture or 25-50 grams of phligmatized gexogen) is optimal, The capacity of a fuel tank should not be less than 100 liters. 30-50 liters do not make significant increasing of AP ammunition blasting power.

Countermeasures:
1. Do not allow placing of fuel tanks in crew compartment
2. During action spend the fuel from rear tanks first as their hit is less probable
3. Try to lessen accumulation of fuel vapor and formation fuel vapor of high concentration inside tank with constructing measures.
4. Lessen volume of fuel tanks inside crew compartment at least twice.
5. Place fuel tanks behind armored leak-tight wall

Rozanov
Kaminsky
Shchurov
Chief of the group Sarafanov

Interesting in blaming this on partially filled side hull fuel tanks.
Coincidentally the British were evaluating the T-34 about the same time the Russians were testing the exploding T-34 problem. The placement of the fuel tanks were mentioned as a weakness of the T-34 in the British report. I read someplace that the Russian response to the British was a snarky ‘Well where do you want us to move the fuel tanks?”


_____________________________

All your Tanks are Belong to us!
panzer
Post #: 1
RE: Flaming T-34s - 8/12/2013 12:30:17 AM   
Yoozername

 

Posts: 1121
Joined: 3/4/2006
Status: offline
I posted that before...

quote:

Quote
Ref. № 632/3
11/IX-44 y.

Report of spec.lab. NKV № 101-1 on theme:
Examination of hitting features of T-34 tank fuel tanks with armor-piercing/high-explosive and cumulative (armor-burning){HEAT} shells of german fascist army.
Resp. executors: Rozov, Kaminsky, Shchurov
Superviser: Sarafanov

1. History of question
In the battles of spring-summer 1943 tank army, tank corps and tank brigades commanders begin to note that cases of T-34 tanks combat losses with catastrophic explosions of fuel tanks or fire in engine compartment became more frequent. For instance, cases of burn T-34 tanks in battles of summer 1943 near Kursk exceeded those of T-70 tanks by 4-9%...
By order of chief of BTU GBTU of Red Army engeneer-colonel Afonin, 11 Sept. 1943 a comission was formed to study this problem.
Our group studied possibilities of T-34 fuel tank explosion with various armor-piercing tools and valuation of its probable impact on crew and inner equipment.

2. Target setting
Comission's survey of 72 destroyed during Kursk battle tanks on SPAM {field repair} bases have shown that most of them (68%) were destroyed by fire originated in result of fuel tank depressurization with subconcious inflammation of diesel fuel.
All mentiond tanks have breach in hull side or underskirt by AP, armor-burning shells or field charge.
About 1/3 abovementioned tanks lack one or two front fuel tanks and have demolition inside or partial, or even complete destruction of hull's welded seams, caused by internal explosion.
Only little part (8%) of tanks have signs of inner explosion with singns of flames, whereas 24% of machines were destroyed with explosion without any signs of iner flames. Often even ordinance was completely unharmed in chest. According given order our group researched this particular type of destruction - fuel tank explosion.
Members of comission engeneer-colonel Gurov and MVTU associate professor Krutov assumed after inspection of exploded tanks that given damage was caused by explosion of front fuel tanks placed inside crew compartment of T-34 after impact of some specific german ammunition.
Engeneer-major Firsov expressed opinion that such explosion could happen in result of burst of high temperature ammunition based on thermite or electron {aluminium or alloy powder and mixed with rust}
Group of com. Sarafanov recieved a task personally from chief of GBTU to explore the possibility of T-34 fuel tanks detonation after hit by various types of armor-piercing ammunition of german fascist army
{part missing}

4. Study equipment.
To verify assumtions of coms. Gurov, Firsov and Krutov, three sections layouts of 35 mm thick armoured steel with 135 l. {35 gallons} fuel tank established inside were built by NII-48 and Uralmashzavod. Also according to cover letter № 312-a from 21.IV-44 y. a T-34 hull with turret and equipment but without weapons was put to testing ground by BTU.
{part missing again}

5. Experimenting on location.
First shelling of layouts was on 12/XII-43y. from ballistic cannon m.40 from 30 meters distance.
1. During the test fuel tank was full of diesel fuel, recieved by cover letter of com. Afonin from 5/XII. Total spent 8 m.38 shells, 5 m.39/40 shells and 5 armor-burning shells. The results are the following:
During tests fuel tank was completely destroyed 3 times, diesel fuel was flamed 4 times. Explosions were not recorded.
When the fuel tank was hit by fragments of m39/40 shell they were abruptly dragged. Many of fragments did not break through.
Conclusions: 100% filled fuel tank of T-34 tank cannot be a source to inner explosion of T-34 tank, but even serves a protection from fragments of armor and cores of m.39/40 shells. {Guess it's the exact meaning of these fuel tanks}
2. Since com. Krutov expected that petrol cannot explode either if tank is full, with com. Fedin sanction a tank of petrol was installed into section. 3 shots was fired with m.38 shell and one armor-burning. Explosions were not recorded, in 2 tests petrol flamed.

Second stage of trials was began 9/II-44y. For trials the same weapons were used with addition of 88mm recoilless cannon m.1943, firing 88mm armour-burning mines.
According to trials program partially filled tanks were tested. Prior to the test shootings the tank was carried on a truck for 1-2 hours on service roads on testing area. After that fuel was poured off according to test conditions and tank was being installed on layout.

4th series of shooting. Tanks filled to 10-25%. Tank exploding from hit of coherent jet being filled to 25% or less. Equivalent bursting power was near 30-50 gramms of trotyl. The hatch cover on roof of layout made to lift off the tanks was smashed out. In case of filling with petrol explosiveness reducing on avearge 1.5 times comparing to diesel fuel. Fuel tank detonation caused hatch cover to open. Welded seams of layout remained intact.
Another picture is observed when inside almost empty tank a high explosive part of 75mm armor-piercing shell with red ring (80 gramms of trotyl with detonator of 20 gramms of phlegmatized tan{I don't know how to translate it, it seems to be acronym. Pretty sure some one of military or defence professionals would recognize it, but I' not} in aluminium cup) is bursting. In this case exploding effect of the shell is heavily (several times) increasing. Welded seams of underskirt was destroyed by explosion, after that shock wave ripped underskirt offand partly destroyed the roof of layout. Layout admitted off.

6. Conclusions:
The best ratio for detonation of T-34 fuel tank is when it's 10-15% full and AP shell m.38 bursting inside. Burst causes immediate detonation fuel's vapour which adds to shell's explosion, mmultiplying it by 2-4, which corresponds with effect of 105-122mm AP shell.
Even better summary effect is reached when domestic 76.2mm AP shell БР-350А which contains 150 grmms of trotyl bursts. Summary effect corresponds with 152mm AP shell БР-540Б type, which contains 400 gramms of trotyl.
With reducing caliber of AP shell probability of fuel tank explosion decreases dramatically. 37mm and 45mm AP shell cause almost non existing detonation. It should be noted that further increasing of AP caliber do not lead to significant increase explosive power of ammunition bursting inside the fuel tank. The presence of 75-85mm containing 50-100 gramms of trotyl or less amount of morre powerful blasting substances (for instance, 30-80 gramms of A-1X-2 mixture or 25-50 gramms of phligmatized gexogen) is optimal, The capacity of fuel tank should not be less than 100 litres. 30-50 litres do not make significant increasing of AP ammunition blasting power.

Countermeasures:
1. Do not allow placing of fuel tanks in crew compartment
2. During action spend the fuel from rear tanks first as their hit is less probable
3. Try to lessen accumulation of fuel vapour and formation fuel vapour of high concentration inside tank with constructing measures.
4. Lessen volume of fuel tanks inside crew compartment at least twice.
5. Place fuel tanks behind armoured leaktight wall

Rozanov {such as in document}
Kaminsky
Shchurov
Chief of the group Sarafanov

(in reply to Mobius)
Post #: 2
RE: Flaming T-34s - 8/12/2013 12:31:27 AM   
Yoozername

 

Posts: 1121
Joined: 3/4/2006
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http://www.matrixgames.com/forums/tm.asp?m=2800982&mpage=1&key=fuel%2Ctank%2Cexplosion�

I was thinking about this the other day after seeing pics of t34 with the large external fuel drums. they must have used the fuel in these first, getting to the battlefield, and then went into battle using full interior fuel tanks.

In any case, the issue is actually a fuel-air explosion. These are a 'long' duration pulse and in the confines of a tank, very deadly to the crew.

< Message edited by Yoozername -- 8/12/2013 12:38:51 AM >

(in reply to Yoozername)
Post #: 3
RE: Flaming T-34s - 8/12/2013 1:34:40 AM   
Mobius


Posts: 10339
Joined: 6/30/2006
From: California
Status: offline
quote:

ORIGINAL: Yoozername
I posted that before...

Well, I guess you did.

I was recently looking into conflicting Soviet reports (ala WOT blogs) and actual US and British reports and found that. Another one was where the US stated that the T-34 armor was too hard and brittle and the Russians dismissed it as the US engineers measuring wrong. That is a little hard to square when the US examined specimens in 1942, 1945 in Berlin and in Korea and came to the same conclusion. And so did the British.

(in reply to Yoozername)
Post #: 4
RE: Flaming T-34s - 8/17/2013 2:45:15 PM   
Yoozername

 

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Joined: 3/4/2006
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T34's certainly had other volatile issues. Probably all Soviet weapons shared the HE 'cookoff' problem. When these AFV were hit and burned, the high explosive would eventually detonate and result in a catastrophic destruction of the vehicle through a ripple explosion. T34's also had compressed air tanks on board. These were used as auxiliary starters for getting the diesels to start. Well, fire and explosions need air, and having compressed air could make a small fire get stoked.

As far as the hard armor, I am not sure if it was because of face hardening or not. I know the Panther eventually dropped it's FH glacis and then its other FH armor requirements. Sloped armor does not really benefit from FH. The well known 'Panther Shoots' conducted in the ETO, where the three Panthers were catagorized as poor/good/best, may actually have had 'left-over' FH glacis armor on one or two.

(in reply to Mobius)
Post #: 5
RE: Flaming T-34s - 8/18/2013 1:00:47 AM   
Mobius


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The Russian report mentioned that some ammunition was unharmed in the chest. So it didn't always result in a cookoff.

(in reply to Yoozername)
Post #: 6
RE: Flaming T-34s - 8/18/2013 5:56:46 AM   
Yoozername

 

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That is because there was an explosion and not a fire. The fuel tank detonations, and the damage they did, is actually the focus of the report. A stoichiometric explosion does not create a fire.

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Post #: 7
RE: Flaming T-34s - 8/18/2013 7:04:29 PM   
Ratzki

 

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What is the reason that a "stoichiometric explosion does not create a fire" ? I know that in theory all the fuel should be used up in the explosion, but a quick look back into my fire behaviour traing texts states that this is rarely the case in real life applications. Could not the remaining fuel after the explosion, now out of the fuel tanks as well as inside what is left of the fuel tanks be subjected to heat and increased pressures caused by the explosion and ingnite? I have seen some propane BBQ tanks go up and some do just go bang while others go bang with a fireball.

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Post #: 8
RE: Flaming T-34s - 8/19/2013 4:13:50 AM   
Yoozername

 

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Some did...Did you read the report?

A cookoff of the Soviet HE occurs during a fully involved fire in the vehicle. Basically the ammunition is on fire (powder) and the resulting heat detonates the explosive in the HE or APHE. US HE would not explode like this. It basically burns also. I have personally used C4 as a cooking tablet to heat food and coffee in the military. When a cookoff happens, a HE shell within the confines of the tank can ripple fire off the HE in other shells in close proximity through sympathetic detonation. This is simply the shock wave propagating through the shells.

I suspect that the fuel air explosion is not very close to the stored ammunition. Proximity is crucial for this to occur.

The surprising find is that diesel fuel-air explosions seem more powerful than gasoline-air. Since the pressure vessel these explosions are occuring in have already been punctured by the APHE, it is quite remarkable that weld seams, hatches, etc are being blown apart.


(in reply to Ratzki)
Post #: 9
RE: Flaming T-34s - 8/19/2013 12:44:23 PM   
Mobius


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From: California
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I was thinking there could be a fire="1" or fire="-1" attribute for vehicles to up or lower the chance of fire and explosion by 10%.

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Post #: 10
RE: Flaming T-34s - 8/19/2013 11:27:28 PM   
rickier65

 

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quote:

ORIGINAL: Mobius

I was thinking there could be a fire="1" or fire="-1" attribute for vehicles to up or lower the chance of fire and explosion by 10%.


that's a very good idea

Rick

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Post #: 11
RE: Flaming T-34s - 8/20/2013 3:19:31 AM   
Ratzki

 

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I do not think that the diesel vs gasoline explosions would be too odd, I think that diesel has about 25,000 more btu per gallon gross, then does gasoline. Plus the higher that you are able to heat a fuel before ignition occurs the more energy is released, and diesel requires a much higher temperature to ignite then does gasoline.

(in reply to rickier65)
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RE: Flaming T-34s - 8/20/2013 6:05:24 AM   
Yoozername

 

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This T34 is certainly 'grenaded'. Look in the foreground next to the turret. that looks like a HE shell projectile?


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Post #: 13
RE: Flaming T-34s - 8/21/2013 2:21:05 PM   
Yoozername

 

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http://www.youtube.com/watch?v=nrSy--zUokA

Video of T34s internal explosions. Clearly, the thrown turret has fuel burning inside from the internal explosion (HE) ripping the internal fuel tanks apart also.


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Post #: 14
RE: Flaming T-34s - 8/21/2013 6:16:33 PM   
Mobius


Posts: 10339
Joined: 6/30/2006
From: California
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quote:

ORIGINAL: Yoozername

http://www.youtube.com/watch?v=nrSy--zUokA

Video of T34s internal explosions. Clearly, the thrown turret has fuel burning inside from the internal explosion (HE) ripping the internal fuel tanks apart also.



Who knows, it could be NBC's Dateline at work again.

(in reply to Yoozername)
Post #: 15
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