Weaponised victuals

The flameless ration heater that comes with every Meal, Ready-to-Eat contains a fine powder of iron, magnesium and salt, which gets hot when it gets wet.

You are supposed to put some water in the heater packet and then lean the MRE pack against, famously, a rock or something, while it warms up. The reaction shouldn't take more than a minute.

What, young soldiers with little to do have doubtless asked many, many times, would happen if you were instead to collect the powder from several ration heaters and put it in a sturdy sealed vessel, with some water?

Why, this would, thanks for asking!

Unlike relatives like the dry ice bomb, the heat of these "MRE bombs" will soften plastic, allowing the impressive inflation seen above.

If this just isn't dangerous enough for you, you could always use a metal canteen instead of a plastic bottle!

Note also the suggestion of putting the MREs' Tabasco sauce in the bomb, to add a chemical-warfare tang to the operation.

In Which I Try Not To Set A Reader's House On Fire

A reader writes:

I've been searching the internet (including your articles) for information on putting together a simple back-up power supply for my central heating system. One that when the power fails (which it will here in Greece when we get a good old storm), I just go down to the boiler room, disconnect the boiler system from the mains and hook it up to a back-up supply (for the two or three hours that it takes to get the utility repair man out of the taverna, up the pole and get my 230v back on line). Automatic systems are all very well, but isn't it nice to know what is actually going on, and also be in charge!

Most of the back-up power systems that I have found on the internet seem to be designed for computer systems (oh, and maybe a fridge). Well when it's wet and cold here and the power goes down, I am more interested in keeping warm than keeping my beer cold (although I do understand the importance of the later) and if my computer doesn't work, well, I still have my Ipod.

The reason I need back-up power is because my oil fired central heating system has a wood burning stove linked to it and must keep the system (in particular both the pump and the system controls) running. The boiler is rated at 140w, the pump 160w, 5 motorised valves 30w and the control box and lamp 70w - 400w in total.

Is there such a back-up supply suitable for my heating system or do I put up with shivering, writing unnecessary e-mails in the dark over a can of cold beer?

Bill

Anything involving monkeying with heating systems raises red flags with me, but I'm pretty sure I'm not about to give you advice that will lead to your death. I have, however, been repeatedly demonstrated to have very poor judgement in this regard. (Some friends of ours have officially notified their small children that not everything Daniel says should be accorded the same respect as things said by other adults. They were fine with this, though.)

There may also be some local law that makes this illegal, or requires a licensed electrician to install it, or something; I know nothing of Greek law.

OK, disclaimers over. If you're happy to have a setup that you have to go into the boiler-room to connect, then I think the best option would be an appropriately robust petrol-powered generator. You have to duct the exhaust outside, of course, or set the generator itself up outside. (It might be possible to plumb the generator exhaust into the boiler flue or something, but this could also be another piece of extremely dangerous advice.) Apart from the exhaust issue, though, it'd probably work nicely. Modern generators from the major manufacturers are reliable, quiet and not even all that expensive.

(Generators that serve the purpose of a UPS, cutting in automatically when power fails, are fancier and more expensive. Way more expensive, if you want one that won't give you even half a second of blackout.)

You could probably also use a suitably large off-the-shelf UPS, though, if the tromping into the basement and switching the cables and pulling the starting rope starts to pall. The wattage figures on your heating system's specification stickers are, like most such figures, likely to be over-estimates, so it's possible a quality UPS with as small a rating as 700 volt-amps (which are not quite the same as watts, as I discuss here) could do the job.

The power-rating issue is the same for generators as for UPSes, but I think generators are better at handling the initial "inrush" current when a motor starts. That can be high enough to cause a UPS to beep and shut down, even if the UPS is perfectly able to power the motor if it's already running. This is particularly the case for refrigerators, whose run power is quite low but whose compressors suck a lot of watts for a brief moment when they click on. A UPS trying to power such a motor will therefore work OK if you lose power when the motor's already running, but not if the motor needs to start from UPS power. In the same situation, a similarly marginal generator should just bog down and deliver lower voltage than it's meant to, which is in this case perfectly fine and should let the motor start up with no trouble.

The solution to this whole problem is, of course, to just get a UPS or generator with a higher volt-amp rating, or with a specific high surge capability that it may only be able to deliver for one second, but that'll do. A "home"-model UPS or small generator rated for a genuine 1500 VA (as opposed to the suspiciously high numbers on suspiciously cheap off-brand UPSes) might be adequate; if you turn out to need more than that, and decided to go with a UPS, then you'd have to pay extra for a commercial-market one.

Easy enough to find out what works, of course, if you can get a local dealer to let you borrow likely-looking generators and/or UPSes and try them out. Overload won't actually damage any half-decent UPS or generator; at worst, they'll just complain and shut down.

The real killer for a UPS solution would be run time. Generators can run for as long as you have fuel, of course, but three hours is a long time for a home-or-small-office UPS to be delivering a few hundred watts. Smaller UPSes may even overheat and die in such a situation.

If we presume the constant draw is, say, 400 watts, then that for three hours is 1200 watt-hours, and the battery-to-UPS-to-appliance chain is not 100% efficient, so you'd need more than 1300 watt-hours of batteries to get it done. The capacity of the standard little sealed-lead-acid brick batteries in small UPSes is maybe 90 watt-hours. Less, actually, if you don't want them to die young; standard lead-acid batteries don't like being run flat.

Commercial UPSes can usually be had with extended batteries, but regular readers will know that I recommend just hooking up some car batteries instead. The very cheapest car batteries are still good for 240 watt-hours or more, so it'd be inelegant but feasible to build an array out of them that could meet your needs.

Drop some extra dough on quality "deep-cycle" batteries that are actually meant to do this kind of job and you can easily get well over a thousand watt-hours from one 12V battery that two normal humans can probably move. Graduate to proper industrial batteries that only strongman contestants can move by themselves and you probably won't actually get a whole lot more capacity per kilogram, but probably will get a setup that'll work for many, many years with no more maintenance than an occasional distilled-water top-up. Industrial batteries and a commercial UPS should actually easily outlive a generator.

The smallest batteries in the current Trojan Industrial Line, for instance (PDF here), are six-volt with a 355-amp-hour rating even if you're running them flat over only five hours; two of those in series will give you 4000 watt-hours at 12 volts even into quite a large load.

But, again, none of this is necessary if a generator's acceptable to you. Since you specifically asked for a system that requires you to switch it over manually, a standard, quite inexpensive pull-start generator looks like just what you want.

(I invite commenters to point out the many ways in which I have, in the above, unknowingly endangered Bill's life.)

Peace breaks out in Caustic Valley

Yep, 'Mechs again.

Me: Three-Streak-SRM-2 Commando, which is a surprisingly dangerous build now that the most recent patch has made Streaks both more accurate and more damaging. My 6-Streak Commando now consistently gets more kills per match than my 40-LRM Awesome.

Him: A Catapult with a lot of LRMs.

The scene: My side's base in Caustic Valley, where after finding myself the last alive on my team and facing an enemy medium and two heavies capturing our base, I have been running in frantic circles, managing heat, shooting big 'Mechs in the back, and being highly successful. Two enemy big boys dead, and my total kill count is four. (From, I remind you, the smallest 'Mech in the game. With, because I'm in Australia, also easily the worst ping.)

But the Catapult remains, 65 tons to my 25, and has 95% health.

I have about 12 missiles left.

I fire them all, bringing him down to 87% or something, and then park myself in front of him and await the inevitable.

Nothing happens.

It turns out he's a Catapult with a lot of Long-Range Missiles and... nothing else.

No close-range armament at all.

You can shoot LRMs at targets closer than 180 metres in MechWarrior Online, but they don't arm before they hit the target, and bounce off harmlessly.

He could try to move a couple of hundred metres away from me so his missiles would work, but I'm more than twice as fast as him; he'd never manage to escape my affectionate, cat-like rubbing on his legs.

I could bolt for the enemy base and try to capture it, probably without dying to his missiles on the way, but there's no way I'd get there before he captured our base by just staying where he was.

So we just stood there and stared at each other, while the match's 15-minute timer ran out.

I was pretty sure that when the timer ran out the other team would win (either because they'd partially captured our base, or because they had more tonnage still alive), but they wouldn't get a capture win, worth more to them than an ordinary military one.

There was some conversation in the chat, mostly about the effectiveness of the Streak-Commando, the foolishness of not fitting even one Small Laser or SRM of some sort to supplement your long-range armament, and other amusing situations people had encountered in this game.

At one point someone called me gay, but this did not impress the other spectators. Who, as I pointed out to the you're-so-gay guy, could just quit the match and not miss out on any money or XP.

As the last several seconds ticked away, we bowed to each other, and said our farewells.

My side did lose, but this was still the most fun I've had so far in this game.

"Bug-zapper engaged."

All the serious MechWarrior Online players use voice chat to coordinate their team. The game has some kind of voice-chat thing built in, but I don't think anybody uses it, because the obvious feature of just making an ad-hoc chat group out of everybody on the team that has a microphone does not exist.

There is a much better reason to use voice chat, though.

It allows you to have a Bitching Betty voice actor actually playing on your team.

(She's in the red Gaussapult. She's also not the one who'll actually be doing the onboard-computer voice, when it returns to the game; they've apparently retained the services of Carole Ruggier again.)

Yet more MechWarriorage

Must flush thoughts of Middle-Eastern misery out of my mind.

I know: Yet another post about imaginary Internet robots!

This right here is the MechWarrior Online wiki's Hardpoints Table. All the basic stats for all of the 'Mechs in the game so far.

Also: Don't walk your BattleMech off a cliff.

This is not as easy as it sounds, especially if you're in a fast 'Mech; it's normal for high-speed light 'Mechs to suffer a few points of leg damage just by running across largely level ground. Cut the throttle when you're running downhill, or you'll leap out into the air and fall. (If you've got jump jets, you can of course use them to cushion your fall.)

One of the ways to destroy a 'Mech is by shooting off both of its legs. Thus far the legs do not actually detach from the 'Mech as blown-off arms do, but the effect of losing a leg on your locomotion is about what you'd expect; even super-fast 'Mechs drop to a top speed under 20km/h. But, for whatever reason, people tend not to shoot legs very much. So you can economise on armour there, if you're not a speedy light 'Mech, in which case skimping on leg armour is very false economy.

Winning by capturing the enemy base (in an "Assault" game, which is the only game mode that exists as I write this) gets you more money and experience points than winning by killing all of your enemies. So if the enemy team is no longer a threat, and you're a feasible distance from the enemy base at whatever your 'Mech's top speed is, head over there and start "capping". In random pick-up games the rest of your team may or may not respond to a chat suggestion that they cap rather than kill, but it's worth a try.

Oh, and while capping, don't shoot the complicated widget in the middle of the base area. Some newbies appear to think you have to blow that thing up, in case it is in league with a gazebo.

(The complicated widget also has an array of what look rather like nodding-donkey pumps. That's right - this whole war could be for oil!)

Many mechs come from the factory with too little armour, especially the small ones. The trial Atlas-K (which, once again, I implore new players to not use) has 608 of its maximum possible 614 points of armour, but the trial Commando-1B has only 128 points, of a maximum possible 178. The factory loadouts for the Commando 1D and 3A include only 96 points of armour, making them susceptible to damage from well-thrown baseballs, wind-blown leaves, and woodpeckers. (Two models of Jenner come with less than 130 points of armour, too. Their maximum is 238.)

If you die by a means other than suicide ("suicide" here means "wandering out of bounds, or shooting lasers and aborting shutdown until you explode from overheating"), and then quit out of the match rather than spectate on the rest of it, you'll get all - or at least almost all - of the money and XP rewards you'd get if you spectated until the end. The money and XP won't be awarded until the end of the match, which is also when 'Mech you were driving "unlocks" - the "in match" feature was added to deal with serial suiciders. I think you won't get any Kill Assist money and XP for kills that happen after you quit the match, but everything else, you'll still get. So you don't have to watch those two bozos in trial Atlases get pecked to death by high-speed 30-ton ducks, when you've seen it a hundred times before.

I'm not sure if there's a time or damage limit of any sort on Kill Assists, either. A light 'Mech that runs through the enemy team Small-Lasering multiple targets for almost no damage may, for this reason, reap many kill assists if those enemies get killed later.

Weapons do not penetrate water well, or in some cases at all; Streak SRMs fired from one light 'Mech at another when you're both waist-deep in the water will probably just splash down ahead of the target. They'll still work if the target is tall enough to give them an upward trajectory, though.

And, finally, you can't convert "Mech XP" into "General XP" for a model of 'Mech you no longer own. If you want to convert XP, make sure to do so before you sell the last 'Mech you own of that type. (With any luck the developers will change this in a patch, since it costs a little real-world money to convert XP, so all this limit really does is make it harder for players to spend money.)

On V-2s, Qassams, and conditional probability

A reader writes:

Re "If it looks random, it probably isn't"; can I presume that I can apply the same logic instead of lightning to missiles ?

Meaning if a missile falls in a location is it highly probably that another will fall in the same area?

R.

From Israel.

Right at the top, I'm just going to say that I'm not going to say anything about the politics of this situation which has been particularly in the news, yet again, in the last few days, and I'd appreciate it if commenters didn't either. I sure do have opinions on this subject, but there are a million places people can have arguments about the Heroic Downtrodden Palestinians versus the Stoic Peace-Loving Israelis, and this blog post is not the time nor the place.

(Readers who feel an uncontrollable need to argue about something are encouraged to do so on that post about a free book that some guy argued against without even looking at the free book, that post about the existence or otherwise of "copper bullion" where a lady turned up to hotly argue that buying copper by the ounce is a great idea, and the few posts that sort of ended up being about Jock Doubleday and the floridly preposterous conditions of his "vaccine challenge". Bonus points for anybody who manages to persuade me to their religion, or that climate change isn't happening, or that every man secretly craves sex with other men.)

Speaking of time and place, though, both things are important here, because impacts of artillery over time have a distribution both in space and in time. This is a problem which has been addressed before, most famously in analyses of where the thousands of V-1 and V-2 missiles landed in and around London in World War II.

(That, by the way, is one of the approximately 300 themes of Thomas Pynchon's Gravity's Rainbow, which I read once, and finished, purely because I am susceptible to the sunk-costs fallacy. Forget Israelis and Palestinians - if you want to see true hatred, ask me what I think of Gravity's Fucking Rainbow. How can such dazzling ability to paint a whole scene with ten words be used to create such an indigestible housebrick of a book?!)

The British analysts in WWII wanted to know how good the guidance systems of the V-2, in particular, were. Since it turned out that V-2 hits conformed quite well to a random Poisson distribution, the analysts reached the correct conclusion that the V-2 did not have a guidance system capable of targeting particular areas of the city.

Even the V-1s did have some kind of guidance system, though. There's a popular belief that V-1s "flew until their fuel ran out", but they actually had an autopilot that counted the revolutions of a little propeller on the nose of the missile, and put the bomb in a dive after a predetermined flight distance. That dive happened to cut off the fuel flow and stop the engine in early V-1s, creating the out-of-fuel legend; this bug was fixed in later V-1s, most of which therefore managed to do their final dive under power, as originally designed.

Aaaaanyway, if you abstract it all out and presume that any arbitrary square metre of Sderot is as likely to be hit by a rocket from the Gaza Strip as any other over a given hour, then the lightning-strike conditional-probability situation applies. Whichever square metre you're standing in is, by these assumptions, as likely to be hit over the next hour as any other, but in order for a missile to next hit your particular square metre two hours from now, there must by definition not be a hit in the next hour. So, as in the lightning-strike example, you multiply the probability of no-hit next hour by the probability of a hit the hour after that, and get a slightly lower number. The probability of a hit in any given spot in any given hour is the same, but the probability of the next hit being separated from now by one, or ten, or a million, hours gets lower and lower as time wears on.

This is of no use whatsoever in determining what location's going to be hit next, though; we assumed right at the start of our abstraction that the missiles were falling randomly. It just explains why clusters of hits, close in time and/or space, can and will occur - and encourage the statistically untutored to explain them in terms of aim and guidance systems - even if the actual distribution of events is random.

In the real world, of course, the distribution of Palestinian missile hits on Israel is only partially random. The basic garage-built missiles have no guidance system at all and variable performance characteristics, which predisposes them to land in a Poisson distribution just like the V-2s in WWII. But there are many launch sites and several other kinds of missile...

Ranges of different Palestinian missiles in Israel
image source: Meir Amit Intelligence and Terrorism Information Center)

...making the overall situation extremely complex.

Many Palestinian missiles are just shot in the right general direction (in the opinion of the people launching them, of course). In videos of the Iron Dome missile-defence system in operation...

...you'll occasionally see the system not bothering to shoot an interceptor missile at some of the incoming fire, because the system calculates that that rocket isn't going to hit a populated area. (See also, mortar attacks by insurgents/terrorists/freedom-fighters, strike out whichever does not in your opinion apply, on military bases and police stations and various other targets in Northern Ireland, Afghanistan, Iraq, and a dismayingly long list of other places.)

But the more sophisticated actual military rockets definitely can be aimed, at least to some extent, so the distribution of their hits will be skewed toward populated areas, military targets, or whatever else the people launching them are trying to hit. You could probably protect yourself from those rockets by a considerable amount by going and living in a tent in the middle of the desert.

As regards avoiding getting blown up in the Israeli towns within rocket range of the Gaza Strip, though, I'm afraid conditional probability has nothing to offer you. All it tells you is that it's improbable that some particular location will not be hit for an extended period of time, which you already, unfortunately, knew.

MechTrivia, continued

Herewith, a few more tips for players of MechWarrior Online who are by some cruel turn of fate even worse at it than I am.

For the complete newbie: Yes, there is teamdamage in this game. You are not Friendly Fireproof.

For this reason, shooting guns at the start of the round when you're surrounded by close-packed teammates will make those teammates nervous. Shooting weapons that require ammunition is particularly unsettling. (A certain amount of celebratory gunfire occasionally breaks out at the end of a round.)

Only once have I been one-shot-killed in the first second of the game by some doofus in an assault 'Mech who spawned right behind my humble Commando. I've been winged plenty of times, though, often when there's no enemy even in sight, let alone near me.

If you're just shooting to see whether your weapons are in chain-fire or normal mode, you don't have to; in chain fire, a little highlight box thing runs down through each weapon group in the bottom-right display. In normal-fire mode, there's no animation there.

Slightly less obviously, you should not only refrain from shooting your teammates, but also avoid forcing them to shoot you. Do not, if you can help it, run your 'Mech between a friend and the enemy he's shooting at.

And, conversely, be alert for friends running into your firing line, and if you've already got a laser or something firing, yank your crosshair up or down to try to miss them.

Trial Atlas 'Mech

Chief among the teamdamage offenders in the early game are newbies driving the trial Atlas.

As I've said before: Do not do this. That 'Mech is not for you.

On the face of it, the trial Atlas (and other big trial 'Mechs with lots of weapon systems; they switch the trial 'Mechs around from time to time) seems like a great idea. Not only is the Atlas one of the archetypal BattleMechs and as big as 'Mechs get, but this particular model is well armed, heavily armoured, and of course free. In the hands of an experienced player, the stock AS7-K is a very dangerous opponent.

But it is sloooooow. Top speed 48.6 km/h.

I think that's the worst thing about it, for newbies. Mobility is immensely important when you're not sure what you're doing, and any 'Mech with a top speed under 50 km/h is likely to be difficult for an experienced player to use well in a lot of random pick-up games, let alone a newbie. The classic situation in which a fast 'Mech runs round and round a slower one shooting it in the back without even being shot back occurs frequently with trial Atlases.

(Real newbies will drive their slow trial 'Mech in a straight line shooting at someone way over there somewhere, and completely fail to notice that there's a scout 'Mech running at 25% throttle right behind them, shooting them in the back over and over and over without even having to steer.)

And to add insult to injury, the AS7-K's anaemic little engine actually isn't very little - it's of the lighter but larger "XL" type, which means it takes up space in the left and right torso. If any part of the engine receives a critical hit, the 'Mech explodes no matter how healthy the rest of it is. XL engines make it much easier for this to happen.

Engine specs

On the subject of engines, there are engines with different ratings, but the same weight.

There is very little reason to buy a 7-ton 160 engine when you could buy a 7-ton 170. Only if the higher-rated engine needs more heat sinks than you can cram into your 'Mech should you go with a lower-rated engine of the same weight. I was wrong about that, as per Itsacon's comment below. There is actually no reason besides price to get a lower-rated engine with the same tonnage.

Selling a 'Mech

And when you sell a 'Mech, you don't have to, and shouldn't, sell all the equipment in it (the optional "Item Value" checkbox). Only sell stuff you know you're never going to use, like spare engines if you've got a pile of one size, heat sinks if you've accumulated a zillion of them, and non-Streak SRMs and autocannons if, like me, your ping is lousy.

And finally, If you're overheating, slow down. The higher your throttle setting, the slower you cool off.

Baby boating

(Again with the MechWarrior Online. Get used to it, gentle reader; there will be more.)

If you want to play a "missile boat" in MechWarrior Online - which isn't very exciting, but is a solid way to contribute to your team and make money for yourself - you have the problem that missile boats are usually heavy or assault 'Mechs. So while you're learning, your half-baked missile 'Mech may cause MechWarrior Online's... less-than-perfect... matchmaker to add a fully perked and polished enemy heavy or assault 'Mech to the enemy team.

(This will also happen if you head out in the current trial Catapult, a 70-tonner with two LRM-15s and four medium lasers.)

MWO 'Mech customisation

The solution to this problem is The Light Missile Boat, which is mildly ridiculous but actually works pretty well, and will only be matched by another light 'Mech on the other team, with any luck. (Or by some newbie in the trial Atlas, which is often even better.)

One formula for a Light Missile Boat is:

One Raven RVN-2X, which has a missile hardpoint in its right torso and four energy hardpoints split between the left torso and right arm, and an Anti-Missile System slot in the left torso. (AMS is highly desirable for missile boats, which often find themselves copping a lot of counter-battery fire.)

Pull the engine out. Stick an LRM-15 or LRM-20 in the right torso, and an AMS and one or two tons of ammo in the left torso. Add lasers of your choice to the right arm and/or left torso. Sprinkle with LRM ammo to taste. Put heat sinks in the legs (I'm pretty sure MechWarrior Online does give you the correct cooling bonus if there are heat sinks in your legs and your legs are in water). Wind up the armour, putting plenty on the back, 'cos you're not going to be fast.

Now, add the biggest non-XL engine that still fits. Enjoy your new light 'Mech that's pretty much exactly half a Catapult.

My version of this 'Mech has an LRM 15, two Medium Pulse Lasers along with the AMS in the left torso, and a Standard Engine 140 for a not-too-horribly-bad 64.8 km/h top speed. I used to have an LRM-20, but the lighter missile rack allowed the heavier, more useful lasers. You can add even more stuff if you go for structure and armour upgrades and put in an XL engine, but this'll cost you a lot more for repairs.

(On a weight-per-missiles basis, by the way, the little LRM-5 is the best; it shoots five missiles and weighs two tons, 2.5 missiles per ton. The LRM-10 and LRM-20 both give you only two missiles per ton; if you can install two LRM-5s instead of one LRM-10, you probably should. The LRM-15 gives 2.142857143 missiles per ton.)

If you want to be tricky, you can save some weight by putting no armour at all on a Raven 2X's gunless left arm. It's probably a good idea to put all of your missile ammo in the right and centre torso, in that case.

If you go into battle with an un-armoured limb there's a very good chance it'll be blown off and then, with the standard auto-repair and auto-rearm settings, you'll have to pay to put a new un-armoured arm on your 'Mech, only to have it blown off again. If you turn off auto-repair, though, you can leave the arm as a stump, and make money faster.

(For this reason, less-honourable players who want to make money fast and don't much care about helping their team may go into battle in a "Zombie Wang", a Yen-Lo-Wang with a couple of medium lasers in the centre torso, no other armament, and no arms.)

As things stand, you also get a 75% ammunition reload for free at the end of every battle. You get this reload even if auto-rearm is turned off. So for economical missile-boating, just lay in more ammo than you really need when it's all full (for both LRMs and AMS). Now the free 75% reload will give you enough, and you can head back into battle without paying to re-arm.

In a continuation of MechWarrior Online's pleasing commitment to making different 'Mechs truly different, 'Mechs fire missiles in closely-spaced volleys according to the number of physical launch tubes present on that 'Mech. A Raven 2X has six tubes, so if you put an LRM-20 on it, it will fire four volleys (of six, six, six and two missiles, respectively) in quick succession. An LRM-15 will fire three volleys.

This isn't ideal - spacing out the missiles gives enemy Anti-Missile Systems more time to fire on them, and enemy pilots more time to duck behind cover - but it works well enough. Especially if you're missile-boating correctly, with more than one of you unloading on one target.

Apparently there's at least one 'Mech with a single missile launch tube, though I forget which one it is. Put an LRM-20 on that and it'll pee out the missiles as if it's got bladder stones.

UPDATE: Ah, here it is; it's the Raven 3L...

...whose single missile tube is meant to fire Narc Beacons, not explosives.