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Short Answer
Primary Effect on Crew
The impact of a hollow charge warhead produces a narrow jet and a slug formed from the liner of the warhead. Around this is a cone of spall fragments from the armour. The cone half-angle varies from about 30 to 45 degrees.
Personnel within this spall cone will be killed or incapacitated by jet, slug or splinters.
Outside this cone, crew are unlikely to be incapacitated by blast, thermal, optical or impulse effects - so 1 or 2 crew members would be expected to perish from direct impact, although hits on ammunition could cause catastrophic fires.
Primary Effect on Tank
Despite 5 hits from a US Dart heavy Anti-Tank Guided Weapon, a heavy tank suffered only minor damage and was able to both move and fight after these insults.
A single hit from a Malkara heavy ATGW immobilised a heavy tank, the HEAT jet passing through the fighting compartment into the engine.
Secondary Effects
Unprotected ammunition within the spall cone could suffer an HE explosion or a propellant fire (‘brewing up’), either of which will probably destroy the tank. HE explosions occur so fast that escape is impossible; this does not seem to always be the case for ammunition fires.
The probability of secondary effects is a strong function of the design of ammunition stowage.
It should be noted that HEAT warheads come in a range of sizes and have been improved over the 75 plus years of use, and tank design has also progressed and hence the level of damage caused is going to vary quite a lot.
Long Answer with Supporting Data, Diagrams and References
This is a long answer, but I wanted to “bust a few myths”.
Part 1 Introduction
Hollow charge anti-tank weapons have been around since the introduction of the British No. 68 rifle grenade in November 1940 [ Ref 1]. Other countries were designing hollow charge weapons at around the same time and there is a debate about which was fielded first!
When a shaped charge is detonated, a detonation wave sweeps forward and begins to collapse the metal cone liner at its apex. The collapse of the cone results in the formation and ejection of a continuous high-velocity molten jet of liner material and a slug containing about 80% of the liner mass. The jet moves at 2–10 km/s and the jet with velocities up to 0.5-2 km/s [Ref 2].
Owing to different speeds, the jet and the slug gradually separate.
When the jet strikes a target of armour plate, pressures in the range of hundreds of MPa are produced at the point of contact. This pressure, along with the hypersonic speed of the jet produces causes the target material to flows like a fluid out of the path of the jet. This phenomenon is called hydrodynamic penetration.
Myth 1 Hollow Charge Jets melt through Armour
It is a myth (possibly caused by the acronym “HEAT”) that the jet melts its way through the armour- it is just not that hot! Some authors such as Walters and Zaloga in Ref 4 state it is 27 000 degrees. Radiometry measurements [Refs 5&6] show the maximum temperature was about 500 plus or minus 100 C compared to the melting point of steel of 1500 C.
Part 2.Experimental Tests of HEAT against a Heavy Tank
2.1 Description of Test
I shall start by dealing with some experimental work then follow up with I shall examine casualty statistics from WWII and then Middle East wars in Part 3.
The UK War Office [Ref 7] carried out six tests of the effect of large (8 inch diameter) hollow charge warheads on the Conqueror heavy tank. Initially it had been fitted with additional spaced armour, this was removed when the Dart warhead struggled to penetrate.
For the tests, “crash test” dummies were used, along with a leporine crew from the Royal Regiment of Rabbits (motto “Hare today, gone tomorrow”)*; the tanks were also fitted with a range of sensors for acceleration, temperature etc.
Five of the warheads were from the abortive US Dart missile with a 15 lb (6.8 kg) and one from the UK Anglo-Australian Malkara.
Malkara normally had a HESH warhead (see discussion at How effective would the British heavy gun vehicles FV215 and FV4005 have been if deployed in the 1950s? ] but this one had a prototype 25 lb (11.3 kg) HEAT warhead.
These are big warheads as can be seen from Table 1 and the 1967 picture of ATGWs.
Four out of five Dart and the single Malkara defeated the Conqueror armour. The results are discussed below.
Evc6 Ir2.4 Pressure Unit Cannot Be Changed Time
The images of the hits from Ref 7 are shown, I think these diagrams are very helpful. Note that there is no picture for Round 2 because it failed to penetrate. The shaded areas show the lethal zone.
2.2 Results
2.2.1 Effects on Rabbit “Crew”
There were 31 rabbits crewing the five penetrated tanks.
Five of the 31 died. All deaths were from splinters.
Injured animals were euthanased and full autopsies were carried out*
Twelve rabbits had thermal injuries, 8 would have been incapacitated from these.
2.2.2 Blast
Most rabbits suffered burst eardrums. In WWII, about 1/3 of tank crew suffered burst eardrums after their tank was knocked out. [Ref 8]
Penetrating rounds produced 3-25 psi over-pressures.These would not be expected to incapacitate the crew, where 70 psi over-pressure is required to cause lung damage. [Ref 8 again].
This result is confirmed by US tests on a Bradley which showed that hits by RPG 7, 105 mm HEAT and TOW missiles did not produce blast injuries beyond eardrum rupture. Ref 9- Rather injuries were from penetrating jet or spall. See Diagram below based on 68 shots against a Bradley test vehicle
Myth 2. HEAT warheads kill the crew by blast
Not according to this data. Splinters do the job.
Myth 3.The crew of a tank can be killed by primary blast when a shell explodes without penetrating the tank
The blast effect of HEAT was larger than for previous tests with HE or HESH.
HESH induced ear damage rabbits in 1/3 of cases for a similar series of tests. [Ref 10]
This is unsurprising as the HEAT jet enters the tank directly when a penetration is achieved.
For the for HEAT attack, the impedance mismatch** is much than lower in the case of an HE exploding shell outside the tank, mean that blast would be transmitted much better
The non penetrating round (which almost penetrated, forming a 100 mm diameter bulge 12 mm deep) produced about 2-10 psi in the tank.
On Quora have read statements such as “a hit on a tank with a 155 mm shell would turn the buttoned-up crew to jelly owing to blast effects”
This is not supported by the above data!
2.2.3 Accelerations
Likely to cause only minor injury to crew
The Malkara shot may have caused injury although this was uncertain. [Ref 11]
2.2.4 Thermal effects
Livro concreto armado eu te amo pdf download. These were too to be incapacitating except in the spall cone. The thermal effects from Malkara were lower than for Dart. [Ref 12]. This may be a result of he copper liner in Malkara- the Dart used aluminium.
2.2.5 Flash effect
The intensity of the internal flash would cause no injury by day and only loss of dark adaption at night. [Ref 13]
2.3 Discussion of Size, Strength and Type of Tank and Warhead
The experiments reported here are of the effect of a large warhead on a well armoured and spacious tank.
US tests on an M46 tank with Dart showed blast pressures within the tank of 30-50 psi and this was thought to be a result of the warhead having to a lot more work in penetrating the heavily armoured Conqueror so having less energy to injure crew.[ Ref 14]
From a conservation of energy approach, hitting a less well protected tank with the same size warhead will do more damage as the warhead will have done less work penetrating the thinner armour. As a rule of thumb, the HEAT round needs to be able to overmatch the target armour by 1/3 and produce a 25 mm diameter hole to disable a tank-{Refs 15 and 16]
Conversely hitting a Conqueror tank with a HEAT projectile from a hand-held weapon will do a lot less damage than with, say, Malkara, even if penetration is achieved.
[There has been a seven fold improvement in penetration of HEAT warheads since the 1940s, however the laws of physics and chemistry cannot be changed for a given weight of explosives, the energy is broadly fixed].
Compact Russian tanks will suffer more casualties for the same energy entering the crew compartment, but of course are a smaller target in the first place and have thicker armour per unit mass of tank. This is discussed at Ref 17
I am aware of more modern armours and the effects of HEAT attack [Ref 18]
Ammunition Storage and Secondary Effects
Several hits caused damage to stored inert ammunition during the tests. Ammunition storage in the Conqueror was by modern standards poor and the authors of the report were of the view that round 3 and round 5 would killed the tank through ammunition fires.
Some tank types may have also contained other flammable materials such as the OHT hydraulic fluid in Patton tanks. Ref 19
Part 3. Reported Casualties from Combat.
3.1 Crew Casualties When Hit by Panzerfaust Per Hit
• 25% fatalities
• 21% wounded per hit giving
• 46% total dead and wounded when a tank was penetrated
• 27% wounded when a non-penetrating detonation,
• for non-penetrations, wounds were classed as minor. when they occurred
[Ref 20]
Detailed accounts of Panzerfaust hits on tanks in the British 4th Armoured Division in 1944–45 can be found here. This data clearly shows what happened on a tank by tank basis, with discussions of individual crew injuries.
3.2 Tank Crew Casualties Yom Kippur War 1973
Per tank penetrated 0.6 of a crewman killed (15%) , 0.6 wounded (not burned) (15%) and 0.9 (22.5%) with burns giving 2.1 casualties (52.5%) of some kind per tank penetrated.
This data comes from Ref 21. Alas the document is written in a confusing style, with absolute values and percents mixed up.
This data is consistent with the experimental tests above when we consider the uncertainties and the effect of a lighter tank being hit by a smaller hollow charge.
3.3 Tank Casualties in 2006 Israeli War in Lebanon
Ref 22 Shows 18 Israeli tanks destroyed by ATGWs with 23 crew fatalities in these vehicles. This is consistent with the data above.
Phew, thanks for reading. I hope that helped!
Notes
*Ok, I made that bit up. They were Porton Down lab animals. I recall the outrage when this type of animal work was exposed in the late 1970s. Comedy series Not The Nine O’Clock News did a sketch where a Porton Down employee comes home and shoots the family pets and his wife says “I do wish you didn’t bring your work home with you, dear!”
**Do you remember the high school experiment when the alarm clock is placed in a bell jar and the air is pumped out until the bell cannot be heard?
Your science teacher may have said “this proves that sound cannot pass through a vacuum, but she was fibbing. A school pump would not produce a good vacuum here. Rather the the bell is inaudible because the impedance mismatch has increased from bell to air to jar. The impedance to a pressure wave varies with density and wave speed. For steel to air the ratio of impedances is 100 to 1! So air-steel-air 10,000 to one!
Ref 23 shows that for assessing the injuries to the occupants under a bomb attack building, the blast effect is even considered until the windows have failed allowing the blast to enter the building which is consistent with this basic physics approach.
References
- Eather R F and Griffiths N (1984) Some historical Aspects of the Development of Shaped Charges ARDE report 2/84 available from DTIC https://apps.dtic.mil/dtic/tr/fu..
- Held M (2001) Liners of Shaped Charges Journal of Battlefield Technology 4 3 pp1-7).
- Walters An Introduction to Shape Charges [https://www.arl.army.mil/arlrepo.. ]
- Zaloga S (2019) Duel: Bazooka v Panzer Osprey
- Von Holle W & Trimble J (1976) Temperature measurement of shocked copper plates and shaped charge jets by two color IR radiometry, Journal of Applied Physics, 47, p. 2391-2394.
- Flis WJ (2017) On Temperature in Shaped Charge Penetration International Symposium on Ballistics 11-15 Sep 2017
- FVREE (1956) TR2/2 Trials Against Conqueror Tanks with Additional Ballistic Protection Part 2 – The Use of large Hollow-Charge Weapons UK War Office -available from DTIC, UK National Archives and Scribd.
- Owen-Smith M S (1977) Armoured Fighting Vehicle Casualties J Roy Army Med Corps 123 p73
- Thurman M R (1986) Report to US Bradley Fighting Vehicle Hearing Subcommittee page 10 with graph from page 1204.
- FVREE TR2/2 Appendix 2 Part 3
- Ibid Appendix 2 Part 1
- Ibid Appendix 2 Part 4
- Ibid Appendix 2 Part 5
- Ibid Appendix 2 Part 3
- RARDE (1966) Report 22/66 Vulnerability of JS-3 to HEAT attack.
- Terry T W, Jackson S R et al (1991) Fighting Vehicles Brassey’s p31
- Courtney-Green P R (1991) Ammunition for the Land Battle Brassey’s p127
- Horsfall I, Petrou E & Champion SM (2007) Shaped Charge Attack of Spaced and Composite Armour 23rd Symposium on Ballistics.
- Van Brocklin C (1989) Report 2482 Single hydraulic fluid for Army Ground Combat Vehicles and Equipment sourced at https://apps.dtic.mil/dtic/tr/fu..
- OARG (1945) Report 3 The Use of Panzerfaust in the NW European Campaign Table 1
- Owen-Smith M S (1977) Armoured Fighting Vehicle Casualties J Roy Arme Med Corps 123 p65-66.
- Cordesman, Anthony H; Sullivan, William D (2007), Lessons of the 2006 Israeli-Hezbollah War, CSIS.
- Malhotra A, Carson D and McFadden S (2017) Blast Pressure Leakage into Buildings and Effects on Humans Elsevier