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Dumpshock Forums _ Shadowrun _ When missiles and bullets COLLIDE!

Posted by: nezumi Jul 3 2006, 11:01 PM

Alright, a quick question I'm not sure how to address...

A player plans on spraying a GMC banshee with his ingram valiant (loading EX Explosive rounds). Knowing the banshee is armored to no end (how does something with that much armor fly again??), he's calling shots on the front turret and the side loaded missiles.

So what happens when a missile or rocket (or grenade, for that matter) is sprayed with automatic fire, especially when using explosive bullets? I assume missiles have something to prevent them from going off accidentally, which means they're inert until active. I also assume the missile doesn't have any ammo worth mentioning. So the bullet spray would simply destroy tracking computers and firing pins in the nose of the missile, and otherwise make it non-aerodynamic and unworthy of flight. This means that, with sufficient machine gun fire, all the missiles will be incapacitated and the t-bird will be left with the nose turret only, but will otherwise be largely safe from anything the gunner might attempt to do.

Thoughts or comments on this? Am I completely misunderstanding the nature of explosives?

Posted by: Foreigner Jul 3 2006, 11:17 PM

nezumi:

Others will probably contradict me but, as I understand it, you are essentially correct.

Missiles and bombs are THEORETICALLY inert if they haven't been armed.

However, there's always a possibility that the proverbial "lucky shot" might hit a bomb's/missile's detonator, which could trigger the explosive charge even if the weapon itself hasn't been armed.

Another possibility would be damaging the parent vehicle through intense heat, which might happen if a missile's fuel supply was compromised by a bullet--some rocket fuels start to burn if they come into contact with the air, or if the separate fuel and oxidizer compounds come into direct contact with each other anywhere outside of the controlled environment of the missile's fuel intermix chamber.

For example, several Iraqi SS-1 "Scud" missiles were destroyed by long-range precision rifle fire, using Barrett M107 .50 BMG rifles, during the First Gulf War. The fuel and oxidizer combination used in those weapons is VERY unstable. What happened was that U.S. and Coalition snipers punched several holes in each missile at strategic points--in and around the fuel tanks.

When the chemicals involved in the fueling process mixed, they burst into flame, causing the missile to burn/explode, and most likely destroying ancillary equipment, such as the missile launcher truck, the fuel truck, and the vehicle carrying the control equipment.

Let's face it; when you're dealing with a missile that's roughly the size of an average municipal cell-phone tower (the SS-1 was basically a two-stage V-2, developed using captured German (World War II) technology), a few one-half-inch-diameter holes aren't going to be noticed, unless you have the time to do a REALLY thorough inspection.

Food for thought.

--Foreigner

Posted by: hyzmarca Jul 3 2006, 11:41 PM

There is no such thing as an explosive that is completely inert, the conditions of being explosive and being inert are mutually exclusive. The actual probability of an missile being prematurely detonated by a bullet depends very much on the design of the missile itself. There are so many different types of missiles that it is isn't possible to give a single answer that would be true in all cases.

Posted by: Frag-o Delux Jul 4 2006, 12:56 AM

Most portable missiles from what I have read use solid state engines, basically a solid stick of fuel in the tube of the missile body. Only really huge rockets/missles like ICBMs and possibley Scud type missiles use liquid fueled engines. I dont know the cook off temperature or how voilitale these fuels are for the solid state fuels, I have to suspect they have been made to resist accidently cooking off from incoming fire. Solid state engines can and do cook off, but not nearly as easily as liquid fuled engines.

Most high level exsplosives, such as the ones used in warheads are made of pretty robust chemicals like RDX, which need a smaller explosion to make go off. From reading, RDX is pretty hard to set off on its own, so you need a much easier to detonate explosive to set them off such as nitrocellulose. Not arming the missile is to keep these easier to detonate fuses from accidently setting off the much more powerful explosive.

Missiles are generally made "unsafe" before the platform takes them out into combat, but they still arent armed. They dont arm till the weapon is designed to arm them, sometimes in mid flight, sometimes just before impact.

Either way, shooting at a stack of missiles may not give the desired effect of blowing the roof off a Banshee, but there is certainly a cook off factor.

In fact even if he does set off the warhead chances are itll still do nothing. High exsplosive missiles and rockets will generally just go around a heavy armored vehicle. Were anti vehicle weapons need to hit pretty close to nose to body like a 90 dgree impact, to work since theyll be using a shaped charged warhead to penatrate the vehicles armor. Since the missile is on the mount and not aimed directlly at the Banshees the molten core of the AP missle will shoot off into nowhere (well not nowhere, but not at the Banshee.)

But thats my take on missiles and my limited research in missiles and rockets.

EDIT: It maybe in better interest for your friend to shoot at the parascopes an other viewing/sensor equipment to blind the tank.

Posted by: Kagetenshi Jul 4 2006, 03:39 AM

QUOTE (hyzmarca @ Jul 3 2006, 06:41 PM)

There is no such thing as an explosive that is completely inert, the conditions of being explosive and being inert are mutually exclusive.

Only true for conventional explosives, and not even all of them (though the conventional explosives that can be kept as separated components until the last minute are generally inappropriate for weaponized use).

Or perhaps I should say "true but misleading", as they aren't actually explosive in any of the states I mention.

~J

Posted by: mfb Jul 4 2006, 04:51 AM

many missiles use explosives that require detonation to go off--eg, a blasting cap, or hot lead smashing into it. C-4, for instance, can generally be lit on fire or stomped on with no explosion, but not both. so, while i'd generally rate the probability of a missile exploding because you shot it as low, it's not impossible.

Posted by: Edward Jul 4 2006, 06:15 AM

It occurs to me that the EX Explosive ammunition may be sufficient to detonate relatively stable explososives (such as those used in weapon warheads) where other ammunition would almost certainly fail.

Edward

Posted by: Ryu Jul 4 2006, 07:01 AM

ExEx:
That would depend on the speed of the shrapnel, as the explosion would not occur "inside" the warhead. Only the kinetic energy of the shrapnel might cause the explosion (a missile trigger should only arm after a few meters of flight).

A massive bullet fired at a right angle to the surface of the warhead should fare better.

Posted by: Birdy Jul 4 2006, 08:37 AM

It is far easier to disable a missile than to explode it.

A hole through the solid fuel engine will give the gases an other way to escape, changing the trust balance and send the missile of on a wild trajectory. A hole through a fuel tank that uses either very cold or quite agressiv fuel is not something that can be easily patched on the spot.

As for "cooking off" a missile: The propellant charge of tank canons can and do explode if hit be the jet of a HEAT round. That is actually the main damage mechanism of the beast (The hole punched is rather small). Bombs/Missiles on the other hand can be build to withstand a jet fuel fire for IIRC 15 minutes, i.e on a carrier. So chances are small that an ExEx will fire them of

And finally the missiles are most likely not "out in the open" but rather in transport/launch containers inside a starter with at least the barrier rating of sheet metal. Think M2 "Coke can" IFV with the external TOW launcher

Posted by: Austere Emancipator Jul 4 2006, 08:49 AM

QUOTE (Foreigner)

However, there's always a possibility that the proverbial "lucky shot" might hit a bomb's/missile's detonator, which could trigger the explosive charge even if the weapon itself hasn't been armed.

Prior to launch, that wouldn't happen. AFAIK, most current designs only align the detonator after launch, and the detonator being set off before that would not launch the main explosive train. You'd only get a broken detonator. The detonators on most missiles are also buried deep within the missile itself, usually imbedded in the rear of the main charge.

Insensitive high explosives may become more common in the next 60 years. A new generation of IHEs has apparently already been tested with the Hellfire missile, among others, and proven to perform just as well as the compositions currently used. Either way, though, you'd have to get a mighty wallop into the main charge to set it off -- I seriously doubt LMG ammunition would manage this, even with older, more sensitive plasticized HMX compositions.

Assuming you get insanely lucky and your LMG round does detonate the main charge, since the projectile deforms the charge prior to and while it's setting it off, and because the detonation originates from another point and in a different manner than what would occur if the fuse detonated it, it would most likely fail to form a projectile from the charge liner. Which makes little difference, of course, since any armor piercing effect would be directed forward and away from the aircraft.

If the missiles are small, like the rocket/missile thingies mentioned in the SR3 core book, the effect on an armored vehicle would thus be minimal. If the missiles are a lot larger, like the naval scale missiles in Rigger 3, there might be trouble. Of course, the larger missiles are even more likely to use insensitive explosives and have even more stuff inbetween before the bullet gets to the explosives.

As Frag-o Delux said, the kind of missiles you'd expect to see mounted on aircraft use solid rocket fuels -- for example, XLDB in the case of the AGM-114 Hellfire. According to some patents relating to such propellants, they may be ignited for example when the metal casing surrounding them is cut. (You can see the layout of the Hellfire motor http://upload.wikimedia.org/wikipedia/en/4/45/Hellfire-motor-drawing1.gif.) That'd mean a pyrotechnically initiated explosive projectile may well have a shot at igniting the fuel, though whether this is something like a 1/10000 or 1/5 chance, I have no idea. If the fuel is ignited in this manner, I expect the rear of the missile would disintegrate and spew out a lot of flames. It would have little effect on surrounding armored surfaces, however.

Posted by: nezumi Jul 4 2006, 12:27 PM

Thank you for the replies. So it sounds like, barring an absolutely awesome success, even EX Explosive ammo will not set off the rockets. It's good to be right now and again : )

As for the rockets being out of LOS, I'm going off the pictures like this:

http://static.flickr.com/77/179594055_3af4dab5ed.jpg

Where there are at least two obvious missiles. The Banshee is listed as "scout" sized vehicle, so I assumed there were no dedicated missile bays.

Posted by: Austere Emancipator Jul 4 2006, 12:37 PM

I believe Birdy meant having a rocket/missile launcher encased in light armor, like the one on the M2/M3 Bradley, seen http://www.globalsecurity.org/military/systems/ground/images/bm2-2.jpg in firing mode and http://www.globalsecurity.org/military/systems/ground/images/m2-bradley-ds.jpg disengaged. Such mounts are less common on aerial vehicles because aircraft are not normally expected to take withstand large significant amounts of non-armor piercing projectiles like ground vehicles are -- but the extremely heavy armor on Shadowrun "thunderbirds" imply quite different design principles, which might make the Bradley a more likely comparison.

Posted by: Foreigner Jul 4 2006, 12:57 PM

A.E.:

I'm probably way off-base here, but i've always pictured a T-bird as similar in design and/or appearance to the dropship in ALIENS.

Am I anywhere close to being correct?

Pardon the brief OT excursion.

--Foreigner

Posted by: Austere Emancipator Jul 4 2006, 01:01 PM

They do share several characteristics: thick, rather unaerodynamic body, often of very blocky design, with short stubby wings. Of course the dropship is massive, and designed for different kind of flight than T-birds. I'm not familiar enough with any other aspects of the Aliens dropship to compare those, but the aesthetics are certainly similar.

Posted by: Frag-o Delux Jul 4 2006, 04:48 PM

I think I seen a Banshee picture in one of the later 3rd edition books, but it seems no one knows what it looks like.

Sorry about the bad scans, but the Riggers Blackbook I have is really old and in rough shape, I was trying to be gentle with it.

http://i5.photobucket.com/albums/y181/ackam/gmcbanshee.jpg

And because it was on the next page over

http://i5.photobucket.com/albums/y181/ackam/stonewall.jpg

Posted by: Rock Jul 4 2006, 04:57 PM

There's a Banshee picture in SR1 page 131. It's the page with a Mitsubishi Nightsky as well and is a page behind the Eurocar Westwind 2000 (pg 130) and a page before the Yamaha Rapier (page 132).

I knew thumbing through my 1st Edition this morning would come in handy for something other than a trip down memory lane.

Posted by: nezumi Jul 4 2006, 05:08 PM

Holy carp, that's it? Boy, it's awfully phallic shaped. So whats the little thingy I linked to? A baby?

Posted by: Frag-o Delux Jul 4 2006, 05:15 PM

Yeah thats the Banshee, and I guess if you want to call it phallic shaped, you can, I mean it is meant to penetrat into opposing territory and possibly deliver troops.

The problem with a lot of art in SR is its made up. I know its all made up, but in general a lof of the vehicles in the art are not things described by the books. That picture you linked to could just as well be a LAV from a rival corp.

Posted by: ShadowDragon8685 Jul 4 2006, 06:24 PM

That art looks like they described Shadowrun to the Battletech art guy in about four sentances, gave him an additional sentance about the Banshee, and said "We need a picture of it in about ten hours. Good luck."

If you want a REAL vector-thrust aircraft, you can do no better than to look to the Pelican, from Halo.

http://www.france-fps.com/images/halo/pelican.png

Posted by: Frag-o Delux Jul 4 2006, 06:53 PM

Well actually if you want to look at REAL vectored thrust vehicles youll have to look at the F35B and the AV-8B.

If you want to see another persons idea of what futuristic vector thrust vehicles will look like. Look at the Pelican.

Posted by: Birdy Jul 4 2006, 07:37 PM

The "Hovertanks" from 2300AD are an other (and pre SR-1) example of Vector trust Armored fighting vehicles. Despite the Hover and the Skirts they are actually jet-driven using the skirt as an additional means of generating lift. Some http://www.users.globalnet.co.uk/~dheb/2300/Equipment/EG/AC12/AC12EG.htm for the germans can be seen here.

And there's always the http://www.salute.co.uk/slammers3/index.htm the "Blowers" from David Drakes excellent "Hammer's Slammer's" universe. The second best tanks in existence. Right after the ones that introduce themselfs with http://en.wikipedia.org/wiki/Bolo_(self-aware_tank)