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I think whether a bolt round is rocket powered or conventionally balistic is moot. When it strikes its target, whether its traveling 1mph or 300mph, the negative acceleration would set off the bolt shells explosive warhead. If equipped with a sufficiently powerful explosive velocity would have a less noticable impact on performance, less bullet more grenade.

Lets assume velocity does play a part in its penetrating capability. A false assumption being made by the OP is that the "gyrojet" rocket is a linear accelerating rocket. Unlike a gyrojet bullet, a bolt shell has a built in "brain" and sensors, that supposedly help aim. Anything that sophisticated would presumably have a range finder or something equivalent. It is not a stretch to imagine a bolt shell optimizing its acceleration based on range. Though this still might not be enough for shorter ranges. The answer to this lies in the fact that Bolt rounds are shown to have a casing, that gets ejected upon firing. This insists on Bolters shell being a 2-stage projectile, where the warhead is fired from the bolter with some sort of expulsion charge like a grenade, where the rocket motor kicks in as its leaving the barrel. The expulsion charge would likely be based on achieving the minimal acceleration to achieve some baseline performance for lethal velocity.

The sources state however that the charge is timed to explode after penetration. not on impact.

You guys are crazy eheh
It's sci-fi !!! Bolters fire their rocket-bullet-shell in any fraking way the Adeptus mechanicus like....
And come on ... they can start their "travel" with an explosion and then keep their speed using rocket-like propellent... justa as melissia said
... I don't see the difficulties...

All this physics jargon makes my head sore!

punkow wrote:You guys are crazy eheh
It's sci-fi !!! Bolters fire their rocket-bullet-shell in any fraking way the Adeptus mechanicus like....
And come on ... they can start their "travel" with an explosion and then keep their speed using rocket-like propellent... justa as melissia said
... I don't see the difficulties...

That would mean the rocket motor would be incredibly small and not to mention variable over the trajectory. given the design, it points against this.... I don't see the difficulties here... you start out at some initial velocity, light the rocket motor gain kinetic energy. This is very simple physics your arguing over people.

also to all the nay sayers out there you can't count on the explosive charge as they ONLY explode after penetration because theres no fluff saying otherwise -(see I can use your logic too melissa)

This whole arguement really needs to stop croping up. I could swear we had this same exact argument a month or two ago and we came to a logical conclusion.

If your going to talk about efficancy, the amount of energy transfered to a projectile that is fired through conventional meens, i.e a gun barrel, is much greater then the amount of energy transfered to a projectile via rocket. This is why armor peircing rounds are allows fired via the first method or a verison like it. An explosive round is the only type delivered by pure rocket propulsion.

six months ago you would have been correct and still are on a technical level. but we have recently unveiled a high speed anti-ballistic missile missile that kills with pure kinetic impact. But you are right about guns being more efficient...if they're designed right. Designed wrong they are a lot less efficient. In fact if I can pull it up I'll quote the efficiency term for "perfect" firearm that I derived a while back, which assumes total powder burn in a very short time interval.

Long story short efficiency is related to the initial and final volumes of the system. and also to the specific heat of the powder/air mixture and the number of molecules. Right now I'm working on non perfect systems where the burn rate has to be integrated with respect to temprature, time and pressure. Basically the second law of thermodynamics becomes a first order non homogeneous differential equation that CAN'T be solved by method of separation of variables.

Only read the first page of this thread but my input would be: I think autoguns have equiv of contempary AP rounds but are more innacurate than lasguns (Inquisitor rulebook IIRC).
As for bolters i remember once being told they incorparate some form of mass driver Tech in the Chamber (No source).
Finally @ Melissia you mention a Negative Outcome being impossible to prove, using this logic neither can a Positive be truelly proved. Metaphysically speaking the probability of a positive outcome being proved is merely many factors more likely. As for 'Rock-Hit' (preferable to 'Miss-ile' launchers IMO) i believe the rogue trader rulebook goes into a little detail on the components of a 'Crack' missile.

Yeah but like most it just says "hollow charge warhead" which implies Gen II, that would make gen III the equivalent of str 10 when it comes to vehicles. ... and also ap 1 but thats a given with the way Gen III works. but something about a modern shaped charge blasting land raiders like they were nothing just doesn't sit well with me.

gendoikari87 wrote:six months ago you would have been correct and still are on a technical level. but we have recently unveiled a high speed anti-ballistic missile missile that kills with pure kinetic impact. But you are right about guns being more efficient...if they're designed right. Designed wrong they are a lot less efficient. In fact if I can pull it up I'll quote the efficiency term for "perfect" firearm that I derived a while back, which assumes total powder burn in a very short time interval.

Long story short efficiency is related to the initial and final volumes of the system. and also to the specific heat of the powder/air mixture and the number of molecules. Right now I'm working on non perfect systems where the burn rate has to be integrated with respect to temprature, time and pressure. Basically the second law of thermodynamics becomes a first order non homogeneous differential equation that CAN'T be solved by method of separation of variables.

long sotry short, your having a discussion with people many of who are engineers and work in the defence industry. You know not what your talking about.

And how do you know? I assume you mean you are one yourself? If you are then you would know of the test I speak of. and also what is involved in the thermodynamics behind firearms. and YES I do know what i'm talking about because I'm trying to get INTO the defense industry. I have not yet finished however and do still have a lot more left to learn.

For starters there is a disproportiunate ammount of scientists and engineers that play minature wargames and post on this site(I think thats why the spelling is so bad most times).

As for what I do, I'm an engineer with the Army.

As for your the weapon system that your describing... Its launched like a missle, whether its launched from a ground based platform or mounted on an aircraft, its self propelled up until it reaches a certain distance from its target. The penatrator itself is then fired useing a shaped charge.

Now....guess what a shaped charge is.....Its the same principle as a gun or a cannon.

Even a poorly designed gun transfers energy more efficiantly then something self powered, there is much less energy lost to the enviroment in a gun or a cannon. The only thing that a missle has going for it, is its range.

Efficancy is a broad term, if your going to use it for anything you need to describe it. For example; with a missle system I could measure the efficancy of the propulsion system over its entire flight , and even then I could go deeper.

If you for some reason need to know what a bolt translates to in modern equivilant look up the US military HEAT round.

gendoikari87 wrote:The sources state however that the charge is timed to explode after penetration. not on impact.

Doesn't rule out what I was saying about an expulsion charge to boost its initial muzzle velocity. I actually design munitions for the government and while I wouldn't go too far in hypothesizing how a fictional weapon works, realize there are degrees of penetration and many different ways of achieving it. For example one non-balistic means of penetration is a small plasma jet that is ignited to preceade the projectile, thus allowing the projectile to rely less on balistic velocity. There are other means and bolter could even use some crazy thing yet to be imagined.

Point is "timed to explode after penetration" is so vague from a design stand point it says very little about the actual functionality. Penetration can describe just the fracturing of the surface material of a target, the indention and deformation into, or the partial or complete passage into the target. All are degrees of penetration, that from a stand point we'd have reason to initiate an explosive for different reasons at these different degrees of penetration to get different results.

Another problem with your concept of a bolter is that you treat it as though there is a single "type" of bolter ammo. That they'd all function identically up unto the point of the warhead. Both by fluff and rules there have been shown to be different types and the main advantage of a weapon like a bolter would be the ability to select the right shell and warhead for the right job.

For example... (I'm making this up)... the silenced bolter shells for example might have no expulsion charge at all only the quiet hiss of the miniature rocket, while an armor piercing shell might be more like a conventional bullet where all the power is transfered in the initial acceleration. The mechanics of the warhead could also vary. With so many ways to defeat armor the warhead could be a tandum warhead if its trying to rip completely through armor before detonating the primary charge, or if its trying to cause a failure of the armor itself it could detonate as it enters, or it could attempt to cause blunt force trauma by detonating on impact to the armored enemy.

Aka, mind telling me where you work out of?

As for your the weapon system that your describing... Its launched like a missle, whether its launched from a ground based platform or mounted on an aircraft, its self propelled up until it reaches a certain distance from its target. The penatrator itself is then fired useing a shaped charge.

That's not the one I was talking about. I think that's a recent american anti-ballsitic missile I'll have to look it up but I think the one I was looking at was israeli. It might have had a charge but it wasn't a shaped charge.

Now....guess what a shaped charge is.....Its the same principle as a gun or a cannon.

In the same way that bullets operate on the same principal of bullets. hell WE don't even full understand the interactions of the copper liner with the target. There are models that do a good approximation but recently me and one of my professors have been looking into unruh radiation as a source of part of the effects. Personally I just think it's go to do with surpassing the flow rate of the material.

Even a poorly designed gun transfers energy more efficiantly then something self powered, there is much less energy lost to the enviroment in a gun or a cannon. The only thing that a missle has going for it, is its range.

This is just not true. if you make the barrel of the gun something ridiculously short, it's going have a VERY small amount of energy transfered to it. A rocket will generally have about 50% (more with toroidal aerospikes under the right conditions).

Efficancy is a broad term, if your going to use it for anything you need to describe it. For example; with a missle system I could measure the efficancy of the propulsion system over its entire flight , and even then I could go deeper.

I suppose you are right, and in this case I mean Efficiency = energy transferred to the projectile/Total energy in the powder or rocket fule.

If you for some reason need to know what a bolt translates to in modern equivilant look up the US military HEAT round.

Um... no. Heat rounds are linear shaped charges that detonate away from the surface creating a jet of ... "molten" metal. I say it like that becuase it's NOT molten but the high speed shock wave rapidly deforms the copper (or steel) liner so that it acts like a liquid... and the metal it hits can also be modeled like a liquid. After penetration the jet dispurses into what my friend calls the Liquid metal shotgun. a horrible description of what's really going on but hey he's a pure physicist working on nano technology, I don't expect him to be up on all the latest military tech and how it works.

bolts on the other hand have a hardend adamantium tip to penetrate and explode AFTER penetration. In n way do they work like H.E.A.T.

Doesn't rule out what I was saying about an expulsion charge to boost its initial muzzle velocity

I wasn't, or at least didn't mean to I tend to come off as confrontational when I don't want to or mean to be. All I am saying is this. IF and yes that's an IF bolts rely on getting into the body cavity before explosion then they work for the most part on kinetic energy. If they are given some initial velocity by a main charge, yes they are lethal, but they are more lethal at longer ranges after they have accelerated to higher speeds. That's all. There are other factors that could change this but based PURELY on what the fluff says directly it indicates that they have a higher penetration at longer ranges depending on the ratio of rocket to initial charge. I mean we could spend days theorizing what ifs but we have so little to work on based on what GW says.

Catyrpelius wrote:If you for some reason need to know what a bolt translates to in modern equivilant look up the US military HEAT round.

I think a "bolt" weapon has a lot more going for it than that. A HEAT round is a decent enough example of the warhead, but propulsion and guidance not as much.

I think a bolter system is more of a cross between an XM25, M203's grenades, and some yet to be invented micro rocket system.

Some guided rocket or missle systems as they near their target can increase the rate their fuel burn to boost there velocity from a cruising speed to a less effiecent balistic speed. The main determinate for whether a rocket is designed to do that is what its intended target is and whether the fuel exploding will contribute better than the speed.

Catyrpelius wrote:Aka, mind telling me where you work out of?

Philadelphia metropolitan area, as a sub-contractor. Worked on everything from TOW, to XM25, to that modified Aegis used to shoot down a satelite.

Heres another though... bolts are large and explosively filled... think what a micro ARENA system would do to halt marines advance... granted against such small rockets ARENA isnt going to be as effective but it's 40k years in the future. I'm sure the tau could build something... and the idea of marines getting frustrated that they cant hit anything amuses me.

Im going to answer your post in numbers as I hate multi-quotes.

1 - If the Israeli's are useing it, it usually meens that it was a joint venture with the USA. Either way this is a moot point, anti missel laser systems are the way of the very very near future.

2 - Where are you getting a copper liner from?

3 - Any one that doesnt work for the defense industry always makes this mistake/generlization. Your assumeing that we only have one type of energetic, when in actuality we have many that suit different roles, and thats all that I can say...

Skipping 4 and 5 because they dont matter, but as for number 4, actual research supports my conclusion.

6 - I messed up alittle here, I got inturupted and lost my train of though.

gendoikari87 wrote:Heres another though... bolts are large and explosively filled... think what a micro ARENA system would do to halt marines advance... granted against such small rockets ARENA isnt going to be as effective but it's 40k years in the future. I'm sure the tau could build something... and the idea of marines getting frustrated that they cant hit anything amuses me.

Thats kinda what the XM25's airburst grenade does.

Aka, I'm out of Piccatinny doing large caliber munitions work atm.


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To exapand on my HEAT argument, I've always thought that bolt is a cross between a HEAT and a Sabot round. Make the Sabot mass reactive and there you go, it satisfies all of the arguments about bolt rounds.

Philadelphia metropolitan area, as a sub-contractor. Worked on everything from TOW, to XM25, to that modified Aegis used to shoot down a satelite.

You are my god.

and to respond to yours.

1. Amen. we do need to work on battery technology though.

2. Modern Shaped charges use a copper or steel liner for the hollow cavity. Basically they make use of the neumann (spelling) effect instead of the munroe effect.

3. huh? more forms of energies?

4. which is 4 your are referring to?

To exapand on my HEAT argument, I've always thought that bolt is a cross between a HEAT and a Sabot round. Make the Sabot mass reactive and there you go, it satisfies all of the arguments about bolt rounds.

That would make them quite beefy. also anybody every thought of making a shaped charge for the M203 for light vehicle work?

You guys are lucky I don't have the facilities to even do modelling at my school. I'd love to get into muntions design but I'm a bit better at internal mechanisms so I'll probably end up working for some small arms company.


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Thats kinda what the XM25's airburst grenade does.

Isn't the XM25 hand held?

Aka, I'm out of Piccatinny doing large caliber munitions work atm.

Hiring by any chance?

1 - ATM you need a relativly low wattage laser to bring down a missle, you just need to explode the onboard fuel stoarge. I'm not sure that we have a battery powered laser yet, due to the size of modern lasers most of them are contained on some type of vehicle and just draw from their power.

2 - Gotcha, didnt understand where you were comeing from originally.

3 - An energetic is what we call a propellant, there are alot of them and each of them has differend burn characteristics, some burn much much faster then others. A faster burning energetic will allow you to empart the same velocity on a shell with a shorter barrell however it will lower efficancy of the overall system.

4 - Was in referance to the efficancy of a rocket. Rockets expend more energy, they have more forces to overcome then a balisstic projectile.


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Piccatinny is always hiring, however its generally easier to get in as an engineer.

An energetic is what we call a propellant, there are alot of them and each of them has differend burn characteristics, some burn much much faster then others. A faster burning energetic will allow you to empart the same velocity on a shell with a shorter barrell however it will lower efficancy of the overall system.

Oh I know what you were talking about, Projectile size and propellant burn rate and all that goes in with the efficiency based on that. I was meaning that if you have a ridiculously short barrel it doesnt matter what kind of powder your using, it's going to be less efficient. ... like less than a half inch.. or better yet, no barrel just the cartridge open to air. with no cylinder to contain the energy at all you loose a lot.

Piccatinny is always hiring, however its generally easier to get in as an engineer.

But WILL they hire a physicist... at least if he writes a few papers on ballistics. I've got one almost done.

The burning propellant has to be contained, if it isnt contained then it isnt a gun.

The same could be said about a rocket if the bruning propellant isnt focused and directed.

Laser are the future for interception, mostly because of the inevitable developement of hypersonic missiles that will make alot of other interception methods too difficult to be worthwhile.

A cheap mans anti-missile system is just to try and blanket an area with high powered radio waves potenitally frying the circuits... obviously more and more we're forced to more robustly grounding the electronics to shield and protect them for that reason. Directed forms of this is how many aricraft protect themselves. It just always comes down to power.

The XM25 is a new squad level grenade launcher designed to shoot around and over walls. It has a sensor that reads its rotations through the Earths magnetic field to determine how far its traveled, it detonates itself once its traveled the distance the triple redundant laser and infared range finders communicate to it as it leaves the barrel. Upon detonating it directs flachettes and shrapnel unidirectionally towards the target on the opposite side of the imposing terrain.

Something like... Str 4 AP6 Rapid Fire, Ignore Cover

It has other modes and other grenade types, thats just kinda the primary selling point. Its a steal at a cost of about $15 a grenade.

Catyrpelius wrote:Aka, I'm out of Piccatinny doing large caliber munitions work atm.

Great, maybe you can yell at some ARDEC people for me...

Catyrpelius wrote:The burning propellant has to be contained, if it isnt contained then it isnt a gun.

The same could be said about a rocket if the bruning propellant isnt focused and directed.

Snub nose revolvers?... I hate those things.

A cheap mans anti-missile system is just to try and blanket an area with high powered radio waves potenitally frying the circuits... obviously more and more we're forced to more robustly grounding the electronics to shield and protect them for that reason. Directed forms of this is how many aricraft protect themselves. It just always comes down to power.

Doesn't TOW get around this by being wire guided or is the computer still in the warhead. I'm sorry I'm not an expert on electronics. most of my area of study is in shaped charges and firearms.

I can't really say, I'd have to wait for the next job announcment email. 90% of the people I work with are Engineers though.

Damn physics professors! they lied to me, told me I could get any job an engineer could with a physics degree.

aka_mythos wrote:

Catyrpelius wrote:Aka, I'm out of Piccatinny doing large caliber munitions work atm.

Great, maybe you can yell at some ARDEC people for me...

Just as long as I'm not yelling at myself.

I'd be interested to know how you guys solved the self destruct fuse problem so cheaply.

Comparisons cannot be made...at least not logically or accurately.