It seems to me that a flat steel plate, only a few millimeters thick, held a few inches away from the side of an armored vehicle by supports would be a significant aid in defeating HEAT rounds by causing them to detonate and waste the plasma jet on the air between the plate and the main armor without adding significant bulk or weight to a vehicle.
The Germans used skirts (schurzen) in WW2 to cover the lower hull and treads of tanks, but this was primarily to protect tracks from russian antitank rifles. Would such a skirt be useful in pre-detonating HEAT rounds that hit it? If so, why not use bugger skirts that would cover the whole hull?
It hasn’t been done, to my knowledge, so there’s probably a good reason for it… but I don’t know what.
for one, it would be either a ton of additional weight (the skirt plus all the supports) or very frail. Weight adds up a lot faster than one would think on a machine.
“It’s been done.” For the most modern examples, look at the new US ‘Stryker’ vehicles, a series of panels that look (to me) like the railing on an old-fashioned porch helps pre-detonate HEAT warheads. The British Warrior vehicle uses the same idea.
German tanks in WWII used them. You sometimes see photos of Soviet tanks sporting what looks like bedsprings to do that job.
Now, turning to the particulars. With an arrangement like this you have to understand the power of a HEAT warhead is pretty massive. I ran the numbers years ago for a pre-detonation shield (chain link fence) protecting an un-armored target (a helicopter). You have to put the shield over 50M from the aircraft. Or (more to the point here) have a pretty good slab of armor behind the shield.
Next, the shield would ideally do more than pre-detonate the warhead, you also want to have it detonate in the wrong orientation, that is to say so the jet does not have a 90 degree impact upon the armor.
OK, so why are these skirts not more widely used? Well, the advent of counter-charges (‘Active Armor’) is eclipsing the old classics. With active armor you need less of the real stuff and shatter the heck out of the incoming warhead. In other words it is lighter.
It seems like depot or field modification rather than part of the design, though. I was curious as to why they weren’t made straight out of the factory like that.
Do you mean schurzen? The track-covering plates? The design intention with those was to prevent 14.5mm PTRD rounds from tracking the vehicle, although it probably helped against HEAT impacts.
Well, you seem to have expertise, but I find this hard to believe. Which round are we talking about? I very much doubt the plasma jet effect lasts out to 5 meters, let alone 50. I could imagine a HEAT detonation being detectable as a blast wave at that distance, but the idea of anything taking any real damage strikes me as exceedingly unlikely.
The designs are meant to put a lot of energy in a very small space - it’s hard to believe that something 150 feet away would be damaged in any way. I don’t see how.
From what I understand of the design of HEAT rounds, it seems like only a few inches in front of the warhead will take the full force of the blast. After that, the energy dissapates quickly. It seems unlikely that a HEAT round could penetrate modern tank armor from a foot away.
This is true, but I have a hard time believing that a foot of spacing, even with a 90 degree orientation, wouldn’t save a tank. Maybe not a lighter armored vehicle.
True - but active armor has only really become effective relatively recently. I’m not sure why the designs from the 40s through the 70s didn’t integrate such armor.
Interesting. This US army report from 1943 describes them, and includes a photo of a StuG armoured to the roofline. I have also seen photos of Panzers with a skirt fitted round the turret, similar to this - so they must have been for more than track protection. However This page indicates they were for defense against anti-tank rifles. However, it also points out that the western allies did not use anti-tank rifles, so it’s fair to assume that unless the germans were totally daft,they must have been aware that they were also useful against HEAT rounds and cannon shot, otherwise they wouldn’t have bothered fitting them to tanks which weren’t going to Russia.
I tried goggling for you, but couldn’t find the video on line. Sandia National Lab had a project called “fire ant”. Autonomous ATV carrying a snare-drum sized shaped-charge device. (not rocket delivered)
Somewhere there is an unclassified video that shows this thing taking out a tank at what appears to be at least 150 yards…the tank is literally a small speck in the background while the ATV carrying the shaped charge weapon is filling about half the foreground. I know that perspective can do weird things, but I am familiar with the location and terrain where this test was done (Coyote Canyon, adjoining Kirtland AFB) so I’m pretty confident in my estimation of the range. Like you, I thought shaped charge weapons only worked up close. Not so, it seems that plasma jet has some serious legs.
It had been a long time since I saw that video. The fire ant is shooting across an arroyo, that I know to be about 50 yards wide…so need to scale down my range estimate.
Actually, the video I recall the ATV was still honda-red rather than camo, and was sitting on top of a knoll. So there may be a more impressive clip out there. I think it was shown on a NOVA episode a few years back.
150 yards is nothing on a modern battlefield (unless some DoD chucklehead decides that tanks are suitable for urban combat :rolleyes: ). M-1 series can effectively engage at 4,000 meters, terrain allowing, and we had a few gunners in the 1st Cav engaging out to 5,000 with a little Kentucky Windage.
Tanks can be used effectively in an urban environment with the proper crew and unit training, teamwork (especially with infantry and air cav support), and a few odds-and-ends of specialized gear, but the breakage is probably going to be higher than typical open-country tank warfare.
When I left the green machine in 91, no such training or coordination existed, but I realize that that was a while back, and times, and tactics, change.
The “jet” generated by a lined cavity charge (which is what a HEAT warhead is) is not a plasma. It is composed mainly of the steel or copper cavity lining, and technically it is a solid, although under such high momentary pressures that it behaves as a liquid. (It’s solid crystalline nature has been confirmed by flash x-ray diffraction, and there are some nice x-ray photographs of the liner explosively forming into the penetrator in Military Metallurgy, by A. Doig.) Apparently you can pull the stubby back ends of HEAT penetrators out of holes pierced in armour - they look like metal carrots.
I have no idea how far the penetrator will travel if a heat round detonates some distance from the target, but 50m doesn’t seem at all unreasonable to me.
Some of the shaped charge IEDs used in Iraq can apparently take out an armoured vehicle at 100 yards. While this article does not discuss range, you can be sure that the IEDs are not within a few feet of the vehicle when they go off BBC News Article on shaped charge IEDs
They seem to have been coming up with a few new tricks for that, including canister shot for the Abrams’ 120mm smoothbores, and special urban combat field-modification kits for the Abrams (the idea is that you can rig the tank in the field for urban fighting, then just as easily re-equip it for open-field combat without all the extra armor weighing it down) that include things like remote controled machine guns, extra armor plating, and an intercom telephone that lets the tank crew communicate directly with supporting infantry without a radio.
I imagine there has also been some training to go along with these new toys, but IANATD (Tank Driver).
goes to show what I know. That is awesome. As an added bonus, if a soldier ever needs to take his kid to war, he has a built-in playpen to keep him safe.
To expand a bit on this, the Fire Ant uses an explosively formed penetrator which is related, but not identical, to a normal shaped charge. The EFP doesn’t penetrate as much material but it will maintain that penetration over very long distances. Where the shaped charge projects a jet of “liquid” metal, the EFP fires a solid slug.
Gosh, and I was all ready to defend my post. You smart people did it for me. The main thing is to remember I was (on paper) protecting a helicopter, a very delicate machine, from an RPG warhead. The design was safe-sided all to heck. Still directional or not an explosion is an explosion, not a thing you want to observe close-up.
