A Couple Missile Opinions

[kilemall]

A few other notes.....


I decided that the bay missiles are 15x the size of the traditional CT missile, so 50kg is the usual missile rack version, the bay missiles are 750 kg.
This multiplier aligns with the bay missile attacks being roughly at the 15 and 30 standard missile counts, makes for a nice big missile that fits into that bay cell. So make that 1 bay missile per 50-ton attack, and 2 bay missiles for a 100-ton attack, 50 shots each type.

Going all in on the 'miniship' metaphor, I decided to design the missiles using the HG small craft/ship rules, building them out as though 1 dton = 1kg. So a regular 50kg missile would be built as a 50 ton small craft with 10 'tons' devoted to the warhead, and the bay missiles as 750 ton 'boats' with a 150 ton warhead.
Then, simply divide the cost by 1000.

Working backwards through the missile supplement, saw that the bay missiles would be horribly hard to get through as is. I would work up a penetration aid package that would never fit in a standard missile, but does easily fit into a bay missile and which causes point defenses fits to intercept successfully (TL being a major variable as to success).

Speaking of penetration, that's a large part of why I had to work out this material in detail, as a major difference of my CT/HG hybrid is armor has to be penetrated to do damage. That means a LOT of shots that would be taken in either CT or HG minor surface damage would do nothing, and don't even need to be rolled.

Had to figure out how to work in kinetic effects in missiles to overcome armor as in high velocity passes to overcome TL armor advantage, what effects closing would have on play, work that in with how the lightspeed weapons function (basically farther they are less ability to pen/do damage, close in suicide range maybe major ships can be penetrated with greater damage).

 

[Proneutron]

With missiles, if you can't outrun them, you have to be agile enough to dodge them; they could, of course, reacquire the target.

With Newtonian movement you are less agile if you have less acceleration measured in G's. For anything that counts vs. a small missile that Trav uses.

 

[whartung]

Been away for awhile, I appreciate the responses.

WB kilemall.

 

[Straybow]

The biggest problem with all this is that power is not linear with acceleration. Power demand increases as the SQUARE of acceleration. So if the tables are linear (and they are roughly so with relation to ship size), then the actual performance would be square root of the table value, topping out at 2.45G.

The second problem is that missiles have to maneuver. An aerial missile uses fins to accomplish this. In hard vacuum a rocket-like missile has to flip around and add vectors, which makes tracking a target a bit more complicated. M drive is not rocketry but gravtech that can add a vector by gimballing effectors or emitters of some sort, which will be far less limiting.

Thirdly, Traveller's use of volume-based mechanics instead of mass-based mechanics means that everything inside the volume is being accelerated equally, or very nearly so. The old 6G limit was not based on what the crew comprised of ugly bags of mostly water can withstand, but some other inherent practical limit on gravtech.

We still have the power demand problem to overcome to get up to 6G if that is allowed. I don't think you can build a fusion power plant small enough to fit in a missile. Batteries are even more limited in energy density. Nevermind reality, close your eyes and think of England.

So, given all that, how do missiles work? Add physical rocketry in for the initial boost phase (with an expendable stage), and then again at kill phase. If you are using 1000 sec turns, I don't think you can carry enough fuel in a missile for anything except guidance burns.

By comparison, the space shuttle with a gigantic external fuel tank would reach LEO in a bit over 500 sec using 2.5G thrust. So even a mere +1G would require too much fuel for a 1000 sec burn.


Darn it, reality! Stop harshing my Traveller buzz! I cast Magic Missile!

 

[vegascat]

Air to air missiles used today may be able to shed a bit of light on the discussion. Today 2 basic types of missiles are used, the difference being guidance and size. Radar guided missiles are 8 inch diameter by 12 feet long and look for the radar reflection it locks in on. It does take a radar transmitter blasting at the target. Heat seeking missiles are 5 inches diameter and 10 feet long looking for a heat profile without any other input. Radar guided missiles were able to destroy their target 8 to 13 percent of the time depending on training and rules of engagement. Take a look at the wiki at https://en.wikipedia.org/wiki/AIM-9_Sidewinder and https://en.wikipedia.org/wiki/AIM-7_Sparrow.
The warheads were 80 and 20 pounds including the fusing, explosives and fragmentation casing. The missile does not have to contact the target, a side looking radar of a type in use since WWII can detonate the warhead if it gets close. The design of the warheads and the way the casing is constructed will cause massive damage to an aircraft if it detonates anywhere close by.

 

[Proneutron]

The design of the warheads and the way the casing is constructed will cause massive damage to an aircraft if it detonates anywhere close by.

A problem with this is that aircraft are thin paper kites compared to Trav micrometer shedding, (at incredible velocities with no added armor) ultra tough spacecraft hulls. Frag won't touch them. ONLY nuke or direct super high speed kinetic hits will damage.

 

[whartung]

Radar guided missiles were able to destroy their target 8 to 13 percent of the time depending on training and rules of engagement.

RADAR guided missile only have an 8-13% success rate? That seems kind of terrible.

Air to Air missiles are designed to disrupt very finely balanced feats of engineering magic that let the bodies fly at all. The smaller planes don't do well with chunks of the body or control surfaces being is less than perfect shape. Holes and tears developing in aircraft traveling 100's of miles per hour tends to develop in to larger holes and tears as the wind and air friction react badly with the what was once a smooth aerodynamic surface.

All told, high speed fighter jets are fragile at best.

In space, a hole is just a hole to be taped over with aluminum tape and some Great Stuff gap filler.

 

[Proneutron]

Radar guided missiles were able to destroy their target 8 to 13 percent of the time depending on training and rules of engagement.

Nope. "Since its debut during Desert Storm and through Iraqi Freedom, the AMRAAM has defeated six targets in combat for 13 shots taken at beyond visual ranges—roughly a 46 percent success rate. " nationalinterest.org

 

[Grav_Moped]

Air to air missiles used today may be able to shed a bit of light on the discussion. Today 2 basic types of missiles are used, the difference being guidance and size. Radar guided missiles are 8 inch diameter by 12 feet long and look for the radar reflection it locks in on. It does take a radar transmitter blasting at the target. Heat seeking missiles are 5 inches diameter and 10 feet long looking for a heat profile without any other input. Radar guided missiles were able to destroy their target 8 to 13 percent of the time depending on training and rules of engagement. Take a look at the wiki at https://en.wikipedia.org/wiki/AIM-9_Sidewinder and https://en.wikipedia.org/wiki/AIM-7_Sparrow.
The warheads were 80 and 20 pounds including the fusing, explosives and fragmentation casing. The missile does not have to contact the target, a side looking radar of a type in use since WWII can detonate the warhead if it gets close. The design of the warheads and the way the casing is constructed will cause massive damage to an aircraft if it detonates anywhere close by.

The launch platform's radar does not have to be "blasting at the target", missiles can carry their own transmitter (active radar homing)*. It used to be necessary (semi-active radar homing, where the missile tracks the signal bounced from the target while using the launch vehicle's own signal for reference)**. It was also necessary for beam-riding missiles (point the radar beam at the target, and have the missile keep itself inside the beam)†, but that technology was obsolete by 1960.


*AMRAAM
**Sparrow
†RIM-2 Terrier, Nike Hercules (the latter also had Command Guidance in addition to being a beam-rider).

 

[kilemall]

The biggest problem with all this is that power is not linear with acceleration. Power demand increases as the SQUARE of acceleration. So if the tables are linear (and they are roughly so with relation to ship size), then the actual performance would be square root of the table value, topping out at 2.45G.

The second problem is that missiles have to maneuver. An aerial missile uses fins to accomplish this. In hard vacuum a rocket-like missile has to flip around and add vectors, which makes tracking a target a bit more complicated. M drive is not rocketry but gravtech that can add a vector by gimballing effectors or emitters of some sort, which will be far less limiting.

Thirdly, Traveller's use of volume-based mechanics instead of mass-based mechanics means that everything inside the volume is being accelerated equally, or very nearly so. The old 6G limit was not based on what the crew comprised of ugly bags of mostly water can withstand, but some other inherent practical limit on gravtech.

We still have the power demand problem to overcome to get up to 6G if that is allowed. I don't think you can build a fusion power plant small enough to fit in a missile. Batteries are even more limited in energy density. Nevermind reality, close your eyes and think of England.

So, given all that, how do missiles work? Add physical rocketry in for the initial boost phase (with an expendable stage), and then again at kill phase. If you are using 1000 sec turns, I don't think you can carry enough fuel in a missile for anything except guidance burns.

By comparison, the space shuttle with a gigantic external fuel tank would reach LEO in a bit over 500 sec using 2.5G thrust. So even a mere +1G would require too much fuel for a 1000 sec burn.


Darn it, reality! Stop harshing my Traveller buzz! I cast Magic Missile!

For these reasons I'm not even 'looking back' at chemical-based reaction missiles, except anti-missile terminal approach PD ones where cranking up to 50-100Gs accel in a few seconds is a desirable characteristic. Note I am NOT saying 50G in the CT 1000-second perspective, just that accel for a few seconds like ABMs.


I suppose a polonium-based radioisotope 'battery' might have the energy density needed, but swapping out batteries every 4 months seems like a pretty expensive proposition.
https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator


Another option I considered is using the capacitor in HG associated with BG energy absorption but which is noted as available at TL9. 36 EPs per ton of capacitor. Assuming we are going with a 'handwave' of a largely gravitic M-drive, then most of the power plant and fuel that my theoretical missile build would be instead capacitor.

Assuming a 'normal' density of 1000kg per ton and civilian missiles are 50kg total/25-35 kg 'fuel' and military/bay missiles are 750kg with a 3/5 fuel 'budget' of 450 kg, that leaves us with about 1.08 EP for the small missiles and 16.2 EP for the bay missiles.

My assumption is that these are capacitors and do not have the characteristics of batteries, so no pre-charging back at the starbase or hours before the battle, maybe a turn or two before use.

So each classic turret missile would cost the same to charge then fire as a laser, and a 50-ton battery shot is one missile and 100-ton battery shot is two missiles. So 16 EP and 32 EP per salvo, respectively.

That certainly would change the nature of missiles being 'free energy' weapons and have to be built into the 'energy budget' of power plant/fuel usage for ship design.

Costing as per ammo shot would make them more expensive, dropping the power plant from each missile and substituting capacitors isn't cheaper either, as capacitors are 4 MCr per ton so the bay missiles are approaching 2Mcr each. Key part would be to go back through and see what the 'energy budget' would be for each missile size vs. M-drive usage.

Could be using all that fuel space ends up with LR missiles and the more typical capacitor-missile would use much less capacitor and leave more room for bigger warheads and penetration aids. That's a particular item I feel the bay missiles would need anyway, being a 1-2 missile target rather then 15-30 swarms. Then if you do pay up for the full capacitor 2MCr, then it has that extra range at a cost of being easier to destroy and much more expensive to buy. Just keep in mind that I'm allowing for increased DV to be increasing damage, so a LR missile becomes a stationbuster and that's a game effect you want to think twice about introducing.

OTOH the energy budget may explain why ships fire just one missile per rack or one bay missile attack per turn rather then ripple off all rack/bay salvos.

I may go check out that rabbit hole anyway as an interesting difference in some opponents being equipped differently then 'the standard', but I don't have an overwhelming need to kick microfusion to the curb. Most of the material has them, including robots and presumably air/rafts and other personal level vehicles, so pretty well established it's a 'thing' and I like the game value of missiles staying energy-low systems.




If I wanted to go long-term battery power, guess I would figure out scaling up Striker batteries, that would be a 'charge at base or during quiet times' activity, and I think it would mean not much of an option except at higher TLs.


As for all my commentary on meatbag Gs, that's me working backwards from 'player choices' and stuffing the agility potential genie in a bottle that won't break the game, then assuming the missiles have similar limits due to grav field tech. Whatever advantages missiles have being 'not human' and not subject to stresses of the flesh would be countered by the demands of miniaturization of the M-drive to the smaller form factor.

Yes hard maneuver would lessen optimal impacts as the missiles have to 'burn accel' on different vectors just to achieve an intercept and thus have less kinetic damage potential. That's part of the point of reintroducing the mechanic, for players to have tactical maneuver choices to make that affect their survival.

 

[Proneutron]

Does T5 say what the propulsion system is for standard ship missiles?

 

[AnotherDilbert]

Another option I considered is using the capacitor in HG associated with BG energy absorption but which is noted as available at TL9. 36 EPs per ton of capacitor. Assuming we are going with a 'handwave' of a largely gravitic M-drive, then most of the power plant and fuel that my theoretical missile build would be instead capacitor.

Ok...

Assuming a 'normal' density of 1000kg per ton and ...

Way off base. A Displacement ton is ~14 m³. 14 m³ of water is about 14 tonnes and 14 m³ of steel is about 140 tonnes.

Machinery is generally several times heavier than water, but of course lighter than a sold block of steel.

Let's call it about 50 tonnes per Dton capacitor?

... civilian missiles are 50kg total/25-35 kg 'fuel' and military/bay missiles are 750kg with a 3/5 fuel 'budget' of 450 kg, that leaves us with about 1.08 EP for the small missiles and 16.2 EP for the bay missiles.

That would make 30 kg about 30/50000×36 = 0.02 EP, and that is of course completely insignificant...

450 kg capacitor in the "bay missile" would be about 0.3 EP and still insignificant.





Note that 1 EP = 250 MW × 20 min × 60 s/min = 300 000 MWs = 300 GWs = 300 GJ.

0.02 EP is 6 GJ, enough to accelerate a 50 kg missile to v = √( 2 × 6 GJ / 50 kg ) ≈ 15.5 km/s at 100% efficiency.

A ship can reach 12 km/s by accelerating at 1 G for 1 turn (20 min [HG]).

A missile with a max velocity of 15.5 km/s would be overtaken by the launching ship in the second round, and never catch up to a fleeing ship.

OK, Traveller grav drives don't work that way, but the morale of the story is that even Traveller energy densities and capacitors are not magic wands conjuring infinite acceleration...

 

[BackworldTraveller]

This may be a stupid question, but where did the 50kg per missile standard come from?

I can see (per Mongoose) that you can store 20 missiles per dTon volume...so 1/20th of a dTon=625kg at density of 1. So probably nearer 1500kg to 2000kg

TNE missiles were 7 tonnes each.

 

[kilemall]

On the bit about the 50kg missile, I'm just working within the confines of the missile design sequence as written and trying to make it consistent with the Striker widths and the 1 bay missile per dTon bit of the bay weapons.

As such it's more like the liter/volume design aspects of the robots, which are also highly dense mobile pieces of tech.

I don't worry about the weight bits too much on the ships of heavy equipment vs. volume, figuring there is a lot of open access space surrounding fhe gravitic/fusiony/maneuver things. I'm well aware that Traveller dTons are relatively light densities, and I handwave the 1000kg/1dTon thing as being more about not having excessive shifting weight in flight or exceeding lift capacities even for the magic M-drives.


Bit odd pillorying missiles for unrealistic power profiles when you're quoting a ship blowing past them using 'ship-magic'. Might as well be consistent and say the missiles are on the same tech with limitations for game purposes and a reason for limited accel that sounds good.


Speaking of jacked-up conversions, there is that whole business about what does an EP mean.

Yes Striker says 250MW, but 250MW WHAT? 250MW constant generation and constant use? 250MW-seconds constant, power backed up into batteries per second of use so 1000 seconds of 250MW power needs 250GW of capacitor/battery?

Depending on how you slice it, a scout ship charging capacitors for a jump requires two turns of full juice, 2EP x 2= 4EP. Which works out to a minuscule bit of capacitor readily subsumed into the Jump drive tonnage.

But if it means 2EP x 2000 seconds, that's 4000 EP, which requires 223 tons of capacitor, not possible unless Jump drives come with an extra-dimensional bag of holding capacitor.



This isn't casual for crazy people like me who wants to get a power allocation thing going, or really figure out what that ortillery fire rate is integrated into Striker time/phasing.

Speaking of ortillery, wait until we go over those. It's hair-raising being a fire support ship against an unsuppressed planet with hidden PD/starship weapons, because they have to come in REAL CLOSE to drop those little eggs in fast enough to only have a few seconds of fire against missiles or blaze away with laser/fusion, cause atmo. But you don't get the full flavor of it unless you vector move everything around.

 

[kilemall]

This may be a stupid question, but where did the 50kg per missile standard come from?

I can see (per Mongoose) that you can store 20 missiles per dTon volume...so 1/20th of a dTon=625kg at density of 1. So probably nearer 1500kg to 2000kg

TNE missiles were 7 tonnes each.

Not stupid, just obscure.


I'm talking about the standards from the Missiles In Traveller supplement, which got published as an add-on to a JTAS issue.

https://wiki.travellerrpg.com/Missiles_in_Traveller

This tacked on a design sequence in the manner of Striker vehicles except for our little turret missiles.

It postulated an almost modular standards system, so you could fiddle with your missiles, upgrade them, have different effects so you could have generic missile or something really special and expensive on the rack waiting for a key situation. I like the fiddling modular stereo component aspect of the system, really gives the ship's gunner something to do to earn their keep other then constant sim battle gaming.

50Kg was the defined limit of the missile, but almost more like a volume design thing, although the speeds could go up a bit if you designed below 50kg with the same power package.

The way the components are described, it sounds VERY reaction-chemical fuel. But for so many reasons as described here and for decades of discussion, it doesn't work by any stretch of the imagination for pure reaction rocketry.


Which is part of the reason why you have later versions with more 'realistic' missile sizes, I suspect to 'stop the mockery'.




I'm just crossing that boundary to get a working build process so they assume their proper build costing and therefore player choice, but you really have to suss out the details to make it an alternative that is not automatically 'the way to win' or ignored as a bad weapon.

Bit nuts as I'm patching together all sorts of standards from multiple CT iterations which were designed to be separate games, with numbers that 'sounded good' to somebody at the time with 1980s publishing deadlines and less physics wonk QA or foresight to see the endless nitpicking the internet would enable.

 

[TNE2300]

"where did the 50kg per missile standard come from?"

Book 2 '81
page 17
weaponry

I'm assuming more or less arbitrarily chosen to be
a round number
light enough for a single gunner to reload in one turn
and heavy enough to seem plausible

 

[AnotherDilbert]

Yes Striker says 250MW, but 250MW WHAT? 250MW constant generation and constant use?

Yes, 250 MW is a power.

250MW-seconds constant, power backed up into batteries per second of use so 1000 seconds of 250MW power needs 250GW of capacitor/battery?

Power multiplied by time is energy.

250 MW (power) for 1000 s is 250 GWs = 250 GJ (energy). Note that the units multiply just as the numbers do.


You might think of energy as the amount of water in a swimming pool and power as the flow of water in a hose. If a hose lets 2 litres per second (think power) into the pool, after 1000 s we will have 2 l/s × 1000 s = 2000 litres (think energy) in the pool.

Depending on how you slice it, a scout ship charging capacitors for a jump requires two turns of full juice, 2EP x 2= 4EP. Which works out to a minuscule bit of capacitor readily subsumed into the Jump drive tonnage.

You forget the jump fuel that is turned into energy and buffered in the jump drive capacitors. The scout has 100 × 2 × 0.5% = 1 dTon capacitor that can contain 36 EP.

But if it means 2EP x 2000 seconds, that's 4000 EP, which requires 223 tons of capacitor, ...

No, the time is already built into the EPs. Energy = Power_constant × time. 1 EP is 250 MW for 1 turn (1200 s in HG), so 250 MW × 1200 s = 300 GJ. An EP is a measure of energy generally measured in Joule [J], not a power (flow of energy) measured in Watt [W] (=J/s).

A capacitor stores energy, power is how fast that energy flows into or out of the capacitor.

 

[BRover]

Ok...

. . .

OK, Traveller grav drives don't work that way, but the morale of the story is that even Traveller energy densities and capacitors are not magic wands conjuring infinite acceleration...

You sure about that? :rofl:
You need better handwavium. :badger:

 

[Straybow]

Assuming a 'normal' density of 1000kg per ton and civilian missiles are 50kg total/25-35 kg 'fuel' and military/bay missiles are 750kg with a 3/5 fuel 'budget' of 450 kg, that leaves us with about 1.08 EP for the small missiles and 16.2 EP for the bay missiles.

My assumption is that these are capacitors and do not have the characteristics of batteries, so no pre-charging back at the starbase or hours before the battle, maybe a turn or two before use.

No, the "ton" is the silly Traveller dTon, 14 cubic meters, which substantially filled with solid state capacitor of some sort averaging near half the density of iron would have a mass in the neighborhood of 54 tons (to make the math easy). 36 EP / 54 tons = 0.67 EP/ton. If the 50 kg were 60% capacitor, it would hold a mere 0.02 EP.

 

[mike wightman]

Ok just for giggles.

0.02EP is 250MWx0.02 = 5MW or 5MJ per second.

We know a High Guard turn is 20x60=1200 so that gives us 6GJ of energy to play with.

6GJ=0.5x50xV^2 so V=sqrt240MJ so V is in the order of 15kmps

I have no idea why I just wasted my time doing this