The Triumph of Spaced Armor

[Mobius]

It was a scientific principle that HEAT warhead increased their penetration with a good stand off distance. And many naturally assumed that this then led to space armor giving a HEAT warhead or HEAT shell help with that standoff distance. But a funny thing happen on the way to the forensic lab. Testing of the Bazooka on a captured Panther shows wheel hits with no penetrations of the side armor behind them. In fact the only damage was holes blow in the outer wheels with little or no damage to the inner wheels.

http://www.100thww2.org/support/776tankhits.html

Why no standoff increase in penetration? Obvious the outer wheel should have given the Bazooka round ample standoff to penetrate the inner wheels and the side armor behind as well.
Someone on another forum may have hit on the answer. In a HEAT warhead explosion the warhead liner undergoes plastic deformation from the pressure of the explosion around it. This produces an ever-lengthening "trumpet" that does the penetrating. But along with this trumpet there is an explosion going on. This may blow out a hole of the spaced armor. Note the 8” diameter or 3”x5” holes in the wheels.

This light material may rebound off the main armor or inner wheels and come back and disrupt the trumpet in the same manner as modern day reactive armor disrupts a HEAT warhead penetration. Well, that is as good of an explanation of why the Bazooka didn’t penetrate the light Panther wheels as I’ve come across.

[Yoozername]

Well, yes and mostly No.

The roadwheels did act as spaced armor, but they also acted as sloped armor. If you look at the Panther roadwheels, they are dished and reversable.

I largely disagree with the analysis and remarks like 'a good standoff distance'. The US bazooka is 60mm in diameter. What standoff do you think this requires?

I believe the report is very clear in regards to the bazooka against the panther. The front slope easily ricochets the rockets. They do not detonate on contact. This is easily traced to the base fuze on the rocket. Other reports claim the bazooka rockets would not detonate on ground or even on hedgerows. I know of one report that said ordanance actually modified these rockets at depot in the ETO so they would go off on hedgerows.

The rockets DO detonate when hitting very hard and nearly vertical surfaces like the turret sides. They make penetration holes as a shaped charge would. That is, they make 'pencil-thin' holes with a spraying effect on the inside of the tank.

The rockets that strike roadwheels, curved exhaust pipes, jacks, track pins demonstrate that the shaped charge effect is not taking place. The roadwheels would have small defined holes not large chunks blown out. The reason for this is that the thin front metal of the rocket, that transfers the striking force through the rocket to the rear base fuze, is deforming along with the malleable liner. the effect is not like a shaped charge when detonated but more like an odd shaped self-forging slab.

It would have been interesting if the panther had its side shields (shuerzen) and tracks on its turret. I suspect the soft-metal skirt armor would act as a disrupter on the thin bazooka rocket.

It is worth noting that the German shreck had a nose fuze and was well suited for detonating on all but the most highly sloped armor.

[Yoozername]

[Yoozername]

The cross section shows the thin walled design

[Mobius]

ORIGINAL: Yoozername

Well, yes and mostly No.

The roadwheels did act as spaced armor, but they also acted as sloped armor. If you look at the Panther roadwheels, they are dished and reversable.

I largely disagree with the analysis and remarks like 'a good standoff distance'. The US bazooka is 60mm in diameter. What standoff do you think this requires?

Nice try but. Not so much. The road wheels are no more sloped than the side turret or the side hull at location E. Yet these were penetrated. So it has to be the space and the thin mild steel wheel combination.

[Yoozername]

Why no standoff increase in penetration? Obvious the outer wheel should have given the Bazooka round ample standoff to penetrate the inner wheels and the side armor behind as well.
Someone on another forum may have hit on the answer. In a HEAT warhead explosion the warhead liner undergoes plastic deformation from the pressure of the explosion around it. This produces an ever-lengthening "trumpet" that does the penetrating. But along with this trumpet there is an explosion going on. This may blow out a hole of the spaced armor. Note the 8” diameter or 3”x5” holes in the wheels.

This light material may rebound off the main armor or inner wheels and come back and disrupt the trumpet in the same manner as modern day reactive armor disrupts a HEAT warhead penetration. Well, that is as good of an explanation of why the Bazooka didn’t penetrate the light Panther wheels as I’ve come across.

I still would want an explanation why you think there is 'ample standoff' and what you think that means in regards to a 60mm HEAT round.. This rebounding, off a sloped surface (look at the wheels) and coming back is especially curious. I think a simple analysis of the related rates is also in order. Do you have any idea how fast a shaped charge jet is? The 'blown-out' pieces will precede the jet...then rebound back...and disrupt the jet?

I suppose that one could analyze the great payload of high explosive these bazooka rockets deliver also?

[Mobius]

ORIGINAL: Yoozername
Do you have any idea how fast a shaped charge jet is? The 'blown-out' pieces will precede the jet...then rebound back...and disrupt the jet?

From MilTech issues modern HEAT jets travel at about 30,000 ft/s. I don't know if it was a lot slower in WWII HEAT. The first Bazooka rocket warheads had steel liners. They penetrated about 30% less than copper liners. Later versions had copper liners. Maybe more energy was needed to deform steel than copper?

[Yoozername]

.
Problems of the Bazooka In the Sicilian campaign, the U.S. Army's Lt. General James Gavin was to later observe
(Ref. 77) that the Bazooka lacked penetration capability and that his troops were literally
being crushed into the earth by German tanks they were unable to dcfeat. General Gavin
lamented that the weapon "could havc been tested against the German tanks captured in
North Africa, but evidently it was not." But according to other sources, the weapons had
been tested against German tanks in North Africa. In retrospect, it is possible that the
problem was not in the lack of penetration of the shaped charge, but the failure of the fuzes
to initiate the warhead quickly enough. In 1951, this writer was invited to observe infantry
training at Camp Roberts, California, where it was obvious that the 2.36-inch Bazookas
were, for the most part, failing to detonate high order and form a jet as designed. Instead,
most of the rounds were apparently functioned low order from crush-up on the target, as
evidenced by the presence of many undeformed conical liners laying about on the test field.
Further, the damage to the armor targets usually resembled that produced by a HEP or squash
head mechanism. Even the Army instructors seemed to be unaware that their Bazookas
were malfunctioning. They described the Bazooka's ternuinal effect as "discharging a
baseball sized chunk of metal from the far side of the armor." There was no mention of a
penetration hole.
Gen. Gavin's complaints about the Bazooka may have been instrumental in the Army's
development, later in World War II, of the larger and more powerful version, the 3.5-inch
"Super-Bazooka" (Fig. 34). However, the latter was not introduced into WWII but was kept
"on the shelf" until 1950. It was hurriedly introduced into the Korean War after early actions
using the older 2.36-inch Bazooka showed it to be inadequate for defeat of the Russian armor
employed by the North Korean Army. U.S. Army combat teams were reporting being
overrun by the Soviet T34-85 tanks (Refs. 72, 74, 77). Similar problems were reported by
Navy and Air Force pilots who complained that 5-inch HVAR rockets were "bouncing off"
of the North Korean tanks. The U.S. Navy response to the latter problem is discussed in
Part III of this paper.