Doomsought
Well-known member
I can't think of any excuse for a gun launched missile where a two stage rocket would not avoid potentially lethal stress, except for the "We already have this tube, we want to have a missile as variant ammo".
The Role of Ground Forces in Interstellar Warfare
- Thread starter Zyobot
- Start date
It depends on how serious the stress issue actually is. WWI-II shells only had roughly 10% fill weight due to steel weight limits, while by the 1960s we had reached 25% fill weight, which is apparently the sweet spot for shrapnel production.
Non-shrapnel based rounds are harder to find definite info on. The W-82 nuclear 155 mm shell suggests you can fit a 2 kt nuclear bomb and a rocket assist into a 43 kg package. If its like the older rocket assist you have about 10 kg for the rocket motor+fuel, a 25 kg nuke, leaving roughly 8 kg for everything else. 10 kg of stuff in a 40 kg package is a mass ratio of 4, higher than what I assumed.
I could be overstating component weights, but I also could be understating them, and needed shell thickness to survive gun fire might be even less. There may still be a fair bit of room to engineer better weight ratios. The penalty weight does not necessarily seem particularly high for being fired out of a gun. The W-82 seemed to have experimented with a titanium body, rather than steel. Titanium might be excessive in 2020 for an artillery round shot at some random infantry in a hole, but might not be excessive in 2300 to the job of killing cube sats and harassing enemy spaceplanes.
I'm not sure its nearly as crippling an issue for a space force to deal with, and assuming conventional guns aren't completely obsolete, giving your AA and artillery some counter orbit weaponry seems useful.
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Spare me the mistaken sarcasm. Equating RAPs to rockets with space capable dV is like implying that any third world country with terrorists putting together shoddy Grads can also build a Falcon 9 too because both are rockets.
These shells have tiny sustainer motors that add mere tens to low hundred m/s over a relatively long time at the price of considerable payload reduction, with some of the boost being shared with the base bleed effect, not the kind of massive, high performance optimized motors you are talking about here. There is an insanely massive performance gap between that and space capable rockets.
Why would it suffer all that drag and gravity loss before reaching max speed rather than at the end of its range?
Also you forgot the speed of launching aircraft being part of the maximum speed.
Again, you forget the design mass tax plus engineering headaches added by cannon adaptation. For starters the rocket no longer can have super thin, barely sufficient to keep the rocket intact standing walls. Now it needs artillery shell walls. And similar issues apply to many other design elements. You save fuel for the first stage, at the price of making everything else lower performance and\or more expensive.
My argument is that if your supposed cheap, spammable weapons requires a whole bunch of bleeding edge tech of the future to be even remotely feasible, it's probably no longer cheap and spammable, and if you have that tech available at all, there are better applications for it anyway.
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Okay, sorry, turns out I was wrong and these were partially solved problems in 1960s tech. I dramatically overassumed how novel the problems were.
Project HARP - Wikipedia
So, propellant grain and casing survivable to beyond what I needed the systems to do was a partially resolved problem in a relatively shoe string project in the 1960s.
Here, you can find diagrams of solid and liquid fueled rockets. Here's one with links to diagrams of the more common rockets launched in the program.
Martlet 3A
So, the big question this poses: is it possible to produce a lower performance gun in the future than was achieved in the 1960s? Mated with modern day tech used regularly by the military? Is 1960s engineering mated with modern day electronics a conceivable thing for the future to achieve? Could the future maybe even . . . exceed the accomplishments of a Canadian research program built on WWII surplus? Is such a thing conceivable?
Your treating comparatively trivial problems that involve the refinement of 1960s capable tech as massive problems. Same as with the liquid fuel argument where you were also treating problems mostly resolved with 1960s-70s tech as grave problems that would make such a project in the future impossible.
Because for some weird reason the people with starships waging interplanetary war are less tech savvy than the 1970s.
So, my cheap, spammable weapons likely are actually going to be comparatively cheap and spamable, because the underlying technology isn't even 1990s tech as I was assuming with the W-82 example, but 1960s tech, refined! Apparently you you can actually reach the needed performance with sheet metal, no titanium or other exotics required!
This is why earlier i said "go straight to battleship calibers". That's the only way to get required mass and size budgets to play around with militarily useful projectiles.Okay, sorry, turns out I was wrong and these were partially solved problems in 1960s tech. I dramatically overassumed how novel the problems were.
Project HARP - Wikipedia
en.wikipedia.org
And it still demonstrates some of the problems, and reasons why such ideas are not being pursued further.
Also note how absolutely, way beyond any military standards massively long were the barrels used in those experiments, which with proper adjustment of powder charges and their burn rates allows significant reduction to the peak acceleration the projectile undergoes, compared to being fired out of a more compact, military standard weapon. That in turn provides massive reduction in the acceleration related problems to begin with.
Yes, but not with the limitations of a 155mm caliber, those barely got to high atmosphere with tiny payload. At minimum we are talking a stationary facility, cruiser, or giant SPG with something along the lines of a crazy long 8 inch gun.So, propellant grain and casing survivable to beyond what I needed the systems to do was a partially resolved problem in a relatively shoe string project in the 1960s.
Here, you can find diagrams of solid and liquid fueled rockets. Here's one with links to diagrams of the more common rockets launched in the program.
Martlet 3A
So, the big question this poses: is it possible to produce a lower performance gun in the future than was achieved in the 1960s? Mated with modern day tech used regularly by the military? Is 1960s engineering mated with modern day electronics a conceivable thing for the future to achieve? Could the future maybe even . . . exceed the accomplishments of a Canadian research program built on WWII surplus? Is such a thing conceivable?
But as you can see, the kind of performance we really need here was provided only by saboted projectiles fired out of the battleship gun (the smaller guns barely reaching the required altitudes only firing straight up, which means low military utility, nevermind payload budget to deal with some minimal countermeasures and maneuvering).
By sheer required size alone, i don't think weapons with this kind of size are that cheap or spammable. We're essentially talking of something along the lines of a heavy to superheavy railroad gun, except with high elevation mechanism, put either on a stationary mount, but for purposes of not getting ganked easily, preferably put on some kind of rail system that goes into a tunnel underground or under a mountain for concealment and some degree of bombardment resistance.
At the same time, this system is an alternative to putting the same expensive interceptor stage, minus designing and reinforcing it for the stresses of cannon firing, on a ballistic missile. Not necessarily a particularly huge one that's expensive to build and handle due to its size, even something like Pershing 2 was getting apogees of 360 km (while being 7 or so tons, fitting in the footprint of a 40ft container), and i'm not sure if those tests were even going straight up.
@Marduk
I'm not sure it does show that: for example, they also had 7 inch guns which also were able to achieve good mass ratios.
One can have stronger rounds, or more advanced rocket fuel to get away with lower muzzle velocity, lower payload needed through more advanced electronics, ecetera. The fact that the 7 inch projectile of the 70s only really needs marginal improvements to deliver needed effects strikes me as very reasonable.
The really large guns seem necessary for what HARP was working towards, namely payload delivery, with the end goal of a 3 stage orbital satellite delivery system.
This is a comparatively much less demanding mission, of delivering military payloads (which have to be designed to withstand being fired from artillery anyways) to a suborbital location.
Massively lower acceleration also doesn't seem to be the case with most of the HARP design: the long guns were used to achieve higher muzzle velocities, not lower accelerations.
As comparison, the artillery shell electronic ratings are for 15,500gs.
Assuming artillery exists, Archer systems being fairly standard equipment with forces seems quite reasonable, and based on all this having anti -orbit rounds available also seems quite doable: in military aerospace terms its fairly minor add ons to already existing systems: you already have the targeting computer, data links, artillery hardened electronics, control surfaces (to gimbal the thrust or veins, depending on what's optimal).
It doesn't actually have reason to all that much more expensive than existing guided shells, which are in the $80,000 to $40,000 range, especially when its an old, developed technology: an Excalibur round right now is still cutting edge in development limited run production. After a 100 years of development and refinement and million+ production run, costs can be pretty low relatively.
Missiles also have their place as more capable weapon systems, but something fairly small and low individual capacity seems like it could be quite useful too, while mostly using the future equivalent of off the shelf components.
I'm not sure it does show that: for example, they also had 7 inch guns which also were able to achieve good mass ratios.
One can have stronger rounds, or more advanced rocket fuel to get away with lower muzzle velocity, lower payload needed through more advanced electronics, ecetera. The fact that the 7 inch projectile of the 70s only really needs marginal improvements to deliver needed effects strikes me as very reasonable.
The really large guns seem necessary for what HARP was working towards, namely payload delivery, with the end goal of a 3 stage orbital satellite delivery system.
This is a comparatively much less demanding mission, of delivering military payloads (which have to be designed to withstand being fired from artillery anyways) to a suborbital location.
Massively lower acceleration also doesn't seem to be the case with most of the HARP design: the long guns were used to achieve higher muzzle velocities, not lower accelerations.
As comparison, the artillery shell electronic ratings are for 15,500gs.
Assuming artillery exists, Archer systems being fairly standard equipment with forces seems quite reasonable, and based on all this having anti -orbit rounds available also seems quite doable: in military aerospace terms its fairly minor add ons to already existing systems: you already have the targeting computer, data links, artillery hardened electronics, control surfaces (to gimbal the thrust or veins, depending on what's optimal).
It doesn't actually have reason to all that much more expensive than existing guided shells, which are in the $80,000 to $40,000 range, especially when its an old, developed technology: an Excalibur round right now is still cutting edge in development limited run production. After a 100 years of development and refinement and million+ production run, costs can be pretty low relatively.
Missiles also have their place as more capable weapon systems, but something fairly small and low individual capacity seems like it could be quite useful too, while mostly using the future equivalent of off the shelf components.
In what world the military payloads meant to intercept enemy spacecraft are a less demanding mission? And no, the payloads absolutely are not designed to withstand being fired from artillery anyway if they are being launched by other means...@Marduk
I'm not sure it does show that: for example, they also had 7 inch guns which also were able to achieve good mass ratios.
One can have stronger rounds, or more advanced rocket fuel to get away with lower muzzle velocity, lower payload needed through more advanced electronics, ecetera. The fact that the 7 inch projectile of the 70s only really needs marginal improvements to deliver needed effects strikes me as very reasonable.
The really large guns seem necessary for what HARP was working towards, namely payload delivery, with the end goal of a 3 stage orbital satellite delivery system.
This is a comparatively much less demanding mission, of delivering military payloads (which have to be designed to withstand being fired from artillery anyways) to a suborbital location.
Massively lower acceleration also doesn't seem to be the case with most of the HARP design: the long guns were used to achieve higher muzzle velocities, not lower accelerations.
Also look at the acceleration figures mentioned in HARP. Intentional or not, there is a reason why the currently used guided shells have parts tested to 30,000g.
Who cares about mass ratios if your payload budget is 20kg and about 50-200 km short of typical spysat and space station orbits even if directly above the gun?
Downscaling so far with a gun based system is a terrible idea considering how it ends up with a system with minimal if any utility, pretty much no versatility, and no room for upscaling, unlike slapping boosters on rockets or scaling down payload in larger options.
Having either a meanngful reserve of potential altitude for non-vertical shots or second stage, maneuvering projectiles with separate dV reserve is necessary for these guns to have some kind of practical engagement area coverage.
Costs absolutely can skyrocket in artillery shells if you go for extreme ballistic performance. See: the cancellation of AGS... over shell costs.
As comparison, the artillery shell electronic ratings are for 15,500gs.
Assuming artillery exists, Archer systems being fairly standard equipment with forces seems quite reasonable, and based on all this having anti -orbit rounds available also seems quite doable: in military aerospace terms its fairly minor add ons to already existing systems: you already have the targeting computer, data links, artillery hardened electronics, control surfaces (to gimbal the thrust or veins, depending on what's optimal).
It doesn't actually have reason to all that much more expensive than existing guided shells, which are in the $80,000 to $40,000 range, especially when its an old, developed technology: an Excalibur round right now is still cutting edge in development limited run production. After a 100 years of development and refinement and million+ production run, costs can be pretty low relatively.
Missiles also have their place as more capable weapon systems, but something fairly small and low individual capacity seems like it could be quite useful too, while mostly using the future equivalent of off the shelf components.
Long-range projectiles for Navy’s newest ship too expensive to shoot
At $800,000 per round, the Long Range Land Attack Projectile has been priced out of business.
arstechnica.com
Shell costs are not magically mandated to be small, they are being kept small at the cost of compromising away more ambitious performance goals.
Secondly, why would any interstellar civilization maintain long production runs and expertise in them for what is essentially minimal performance defensive weapon of desperation?
If anyone would want this, it would be with their asses on fire, to be done within weeks or months.
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From the sound of it, future's penny pinchers in the defense department trying to do orbital defense cheaply at any cost.
Well, one of us presumes ground forces will be able to, at the very least, duplicate the achievements of the 1960s, and may even, just maybe, surpass those achievements.
The other seems to believe gun and missile tech peaked in the 1950s, and is offended that the far future might, maybe, be able to do a bit better.
That seems to be the current argument, whether the future might be more advanced than the 1960s.
In what world the military payloads meant to intercept enemy spacecraft are a less demanding mission? And no, the payloads absolutely are not designed to withstand being fired from artillery anyway if they are being launched by other means...
Also look at the acceleration figures mentioned in HARP. Intentional or not, there is a reason why the currently used guided shells have parts tested to 30,000g.
Who cares about mass ratios if your payload budget is 20kg and about 50-200 km short of typical spysat and space station orbits even if directly above the gun?
Downscaling so far with a gun based system is a terrible idea considering how it ends up with a system with minimal if any utility, pretty much no versatility, and no room for upscaling, unlike slapping boosters on rockets or scaling down payload in larger options.
Having either a meanngful reserve of potential altitude for non-vertical shots or second stage, maneuvering projectiles with separate dV reserve is necessary for these guns to have some kind of practical engagement area coverage.
Costs absolutely can skyrocket in artillery shells if you go for extreme ballistic performance. See: the cancellation of AGS... over shell costs.
The grand irony of this is that by that same line of thinking, it was supposed to be a relatively cheap and compact alternative to reduce the need for large and expensive Tomahawk missiles... Ending up with a cost similar to one.Long-range projectiles for Navy’s newest ship too expensive to shoot
At $800,000 per round, the Long Range Land Attack Projectile has been priced out of business.
Shell costs are not magically mandated to be small, they are being kept small at the cost of compromising away more ambitious performance goals.
Secondly, why would any interstellar civilization maintain long production runs and expertise in them for what is essentially minimal performance defensive weapon of desperation?
If anyone would want this, it would be with their asses on fire, to be done within weeks or months.
Eh, we seem to now be getting into they are possible, just not optimal, which is fair. US defense projects failing I don't think is that strong an argument.
The question there is now not its possibility, but its viability. I think this is somewhat like the argument over if there's any reason for fighters to still have gun when missiles are around.
I think it crosses with a lot of other valuable likely to exist things.
1.WH40,when IG have units using Napoleon age tactic which still work,and best are like USA from Vietnam war.
2.SW,where stormtroopers dies easilly not only to Luke or Han,but even little furries.
3.ST,when dudes could teleport anything,but still fight with guns.Well,spaceguns,but still.
That is why most people think so.
Bear Ribs
Well-known member
It does make me wonder what the technology on the invading interstellar spaceship is like. Steam? Oars?
Well,in WH40 big guns on battleships are loaded by slaves.....
And,there is good book with sailships in space - The two-space war by Dave Grossman.With space neo - british empire captain who get space elves princess.
Honestly, guns of some sort seem quite reasonable. Its hard to do better in a small package than chem guns. I could see something very much like the OTO-Melara could arm the patrol boats of the year 3,000.
Its quite hard to get better energy density than chemical fuels. As far as I'm aware, this generally requires either nuclear (which generally has handling or minimum scale issues) or some types of superconductors, which tend to be temperature finicky.
For a small boat/vehicle/spacecraft, chem guns/missiles are likely a viable contender for widespread use under quite a wide range of plausible tech.
Especially with the tech pyramid and power rules (80/20). If your space empire has a 1,000 inhabited worlds and 100 billion citizens, 1 planet (likely the capital) will have 25 billion, next closest 15 billion, 10 will have over a billion, 40 worlds with 300 million ish, 150 with 100 million pops, and 800 with sub 10 mil, many even sub mil, populations.
So, you might have your super advanced Clark tech, but only 5% of your planets have the scale and tech level to play the cutting edge game, and really its only the top 1% of planets are actual contenders providing 80% of the cutting edge tech, like FTL or advanced weapon systems.
Meanwhile, 200 worlds should be quite capable of trivially producing a 76 mm cannon, and another 600 could produce it either in its entirely, or at least some parts of it, like basic shells and support structures, and only needing to import the guidance packages and precise lightweight motors, or such.
And the final 200 worlds too marginal to even produce 76 mm parts still likely need some level of protection, at least to the level where 30 rebels/commandos can't conquer the planet with a space bus. Super death beams may be more valuable than the entire colony, or at least cripplingly expensive to maintain on local economy/shipping needs.
76 mm tanks/boats gives the local government enough firepower they can't be easily taken over by IRA/Al Qaeda type organizations, while adding a bit more friction to enemy actions.
There is a reason why tanks are armed with cannons, not hypertech ballistae firing tungsten bolts at 1500 m/s. There are limits to what certain technologies can do no matter what.
With chemical guns, the limit is gas expansion rate. You either go to some truly exotic chemicals or gun technologies with their own issues, or switch to something completely different.
And... energy density is not everything. A railgun using the chemical energy stored in fuel powering some super-capacitors may be worse in energy density as a total system, but can fire slugs at mach 10 or more. Chemical guns won't do that, period, no matter what.
Tech proliferation however can be quite funny with that stuff, including in military matters. For example, IRL most third world countries have supersonic fighter jets, even though very few are even close to being able to make those. It gets even more ridiculous with stuff like cellphones.
These 76mm guns that barely reach orbit will be utterly useless against space commandos with a stealth bus, because actually detecting the bus in a timely manner allowing effective fire against it with such slow weapons will be something way beyond the capability of a C3I and sensor network of a planet desperate enough to rely on such crappy weapons.
Those would be *far* more useful against the commandos once they get to the ground, or at least below 20 kilometers.
Bear Ribs
Well-known member
Sounds like Ground Forces still have a role in interstellar warfare then.
For a lot of roles though, such as a vehicle mobile weapon system, energy density counts for quite a bit. A 3,000 m/s muzzle velocity would also likely be quite worse for this job anyways. Its already a compromise vs missiles, a railgun takes all the problems of a gun system and makes them worse.
Sure, there are planes in Africa. There are very few planes built in Africa. The ability to import stuff doesn't really counteract my point any. When we are on one planet and nothing is more than a 24 hour plane ride away, importing stuffs a non issue (and even in that situation, maintaining a mechanized force there is difficult). If it takes some time to import things, that becomes a more pressing issue.
Especially if space is particularly big travel time wise: it might take a week to get to the nearest system with a comparative hub of a 100 million, 6 months to the actual big planets. Relaying on things only made in the big two systems is increasingly questionable.
Of course, that bring in issues of how sustainable low tech colonies are. Somewhere with short sleave planets you can make do with pretty low tech. An asteroid its still an open question what tech level you can survive with that. Theoretically you get get by fairly low tech once you have a sealed habitat built and some source of light and heat to keep a biosphere going, but it seems somewhat pushing things.
Open question though.
Sure, a 76 mm is a point defense weapon after all. The extended range is there mostly to, well, extend its threat range. Its primarily an anti-missile anti air weapon, with some anti orbit squeezed in so its not totally helpless.
Mostly self defense. You need the 2-3 stages in the 130 to 250 mm guns to get serious firepower, and even there its still primarily a harassment weapon. Though on smaller planets you can get quite a bit of range: 800 m/s puts you 40% to orbital velocity on the moon. An 88 Flak can apparently shoot roughly 180 km in such conditions.
No, energy density counts only as much as volume is a constraint.
In case of unarmored, ground based transporters or stationary facilities, well, there's a lot of room to play with, and if you're not even nearing the engineering limits, no one cares.
They are already there, not potentially imported if needed. As fourth hand hand-me-downs if nothing else.
Yup. On the other hand, if you are going to bother making things locally, at least make them decent and with some export potential. Who wants weapons of desperation while they still have a choice as to what to import?
Would Ukraine rather have a slightly better version of a WW2 flak cannon, or a third hand early model old Patriot system?
Welp, if they can make such large scale things, they should be able to make it either somewhat up to date, or make something, anything to sell and exchange for such.
It's an extremely shitty anti missile and anti orbit system. It's only tolerable as a point defense system in a multi role setup for ships right now.
For point defense, going lower with far cheaper and more capable payloads makes sense. Considering the velocities, it won't be getting high anytime soon, so early interceptions are going to be very iffy anyway. We're talking 3-4 minutes to interception, even tiniest change in course make the shots fired useless unless they are guided, and all the way at that, not just terminally, and that's without even getting into evasive targets.
@Marduk
1) And volume and weight are going to be important constraints on anything mobile, which is critical to long term survival.
2) I'm not sure if this is a language issue, but something built somewhere else, and imported in, is imported. They are imported aircraft, unless they're a high performance aircraft built in Africa I'm unaware of.
3) Or, should a tank have zero anti air ability, or is a 50 cal on a tank still useful, if marginal? That's the relevant comparison.
4) I don't get your point here.
5) Yes. When did I say otherwise? 76 mm strikes me as the minimum scale to squeeze such a system in as a practical weapon system. At least on the anti orbital. I'm not sure its all that terrible anti-missile. But yes, 76 is a general purpose good enough round. Which is its benefit.
6) yes, the 76 mm guns primary job is like to be ground or low flying aircraft like helicopters and drones. Rocket propelled rounds lets you then squeeze in extra velocity, either for high penetration or range, either in the vertical or or horizontal.
A couple of rocket rounds thus dramatically shrinks the absolute safety range for the enemy, and keeps the enemy on their toes, imposing virtual attrition and giving local forces the ability to punish the enemy if they get lazy. If the enemy support asset does stop maneuvering and follows a very predictable standardized path, you have something to shoot at the target.
Point defense probably optimizes for a faster burn than I had for reaching orbit though: the rocket gives something like 2-3 km extra delta v. So, start with initial 800 m/s muzzle velocity, 100 g rocket burn would be 2 seconds of burn, so you've got to something like 3 km/s at roughly 3-4 km. This likely increases danger to aircraft.
1) And volume and weight are going to be important constraints on anything mobile, which is critical to long term survival.
2) I'm not sure if this is a language issue, but something built somewhere else, and imported in, is imported. They are imported aircraft, unless they're a high performance aircraft built in Africa I'm unaware of.
3) Or, should a tank have zero anti air ability, or is a 50 cal on a tank still useful, if marginal? That's the relevant comparison.
4) I don't get your point here.
5) Yes. When did I say otherwise? 76 mm strikes me as the minimum scale to squeeze such a system in as a practical weapon system. At least on the anti orbital. I'm not sure its all that terrible anti-missile. But yes, 76 is a general purpose good enough round. Which is its benefit.
6) yes, the 76 mm guns primary job is like to be ground or low flying aircraft like helicopters and drones. Rocket propelled rounds lets you then squeeze in extra velocity, either for high penetration or range, either in the vertical or or horizontal.
A couple of rocket rounds thus dramatically shrinks the absolute safety range for the enemy, and keeps the enemy on their toes, imposing virtual attrition and giving local forces the ability to punish the enemy if they get lazy. If the enemy support asset does stop maneuvering and follows a very predictable standardized path, you have something to shoot at the target.
Point defense probably optimizes for a faster burn than I had for reaching orbit though: the rocket gives something like 2-3 km extra delta v. So, start with initial 800 m/s muzzle velocity, 100 g rocket burn would be 2 seconds of burn, so you've got to something like 3 km/s at roughly 3-4 km. This likely increases danger to aircraft.