BattleTech - The Board Game of Armored Combat
BattleTech Game Systems => Aerospace Combat => Topic started by: Colt Ward on 29 April 2019, 15:41:16
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One of the original BT books, the 2nd GDL novel IIRC, has a moon base where the DC Navy places their patrol small craft/DS, defending ASF and I believe they had some weapons . . .
Does the weapon ranges of intro weapons really support a moon providing a defensive shield for a planet? or at least most of one?
Does the introduction of subcap or the re-introduction of capital scale weapons make it more feasible/desirable?
Would it matter if it was a moon like Luna or Phobos/Deimos?
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One of the original BT books, the 2nd GDL novel IIRC, has a moon base where the DC Navy places their patrol small craft/DS, defending ASF and I believe they had some weapons . . .
Does the weapon ranges of intro weapons really support a moon providing a defensive shield for a planet? or at least most of one?
Does the introduction of subcap or the re-introduction of capital scale weapons make it more feasible/desirable?
Would it matter if it was a moon like Luna or Phobos/Deimos?
Maybe. Naval weapon ranges won't reach from Earth's moon to Earth, although a Capital Missile might be able to cross the distance and hit a target. Might take more than a few turns, though, even with magic Battletech fusion drives.
Technically, if you are on the dark side of Earth's moon, and a spaceship is in geostationary orbit above you, Earth's moon could be said to be 'shielding' the Earth from the spaceship.
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I think the "defensive shield" is more the fighters and other craft (and possibly any active sensors), rather than the weapons intended to protect the refueling and repair bays.
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Was it really a base for SDS weaponry though?
Well, I guess it could be a left over SLDF era base that did have some.
But mostly I thought it was just an air field for early interdiction
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Under current rules, capital hexes are 18km across, and the longest-ranged weapons (aside from missiles) are 56 hexes at extreme, if you use the variable range optional rule. 18*56 = 1008 km max range. So for most practical moons, there isn't nearly enough range to defend the planet with ballistic/energy weapons. Units capable of independent maneuvering(ASF, capital missiles in bearings-only mode, etc.) can guide themselves to a target, so they're not limited by that range cap, but any direct-fire weapons are. Even a moon like Phobos is not nearly close enough - it's got an orbital radius of over 9000 km, and even if you measure surface-to-surface (instead of center-to-center), it's still about 6000 km.
My impression is that the first batch of rules, back in the 80s, used much larger hexes - big enough that moons or maybe even planets could fit into a single hex. Under those rules, the ranges ought to be sufficient to use moons to protect planets. But under StratOps, no. That said, using capital weapons to protect the moon base itself would still be a thing.
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There have been cases when a faction on a moon used mass drivers to bombard the planet into submission.
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There have been cases when a faction on a moon used mass drivers to bombard the planet into submission.
Not talking about Adam Selene's efforts.
BUT . . . does that range given include mass drivers? Then you also get into using the gravity well your sitting above to slingshot projectiles at oncoming fleets . . .
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Not talking about Adam Selene's efforts.
BUT . . . does that range given include mass drivers? Then you also get into using the gravity well your sitting above to slingshot projectiles at oncoming fleets . . .
Mass drivers have ranges of 32-40 hexes at extreme, so yes, they're included. (Nobody said that the rules needed to make any sense)
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Well, there is a difference between maximum and effective ranges- so it makes some sense.
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Well, there is a difference between maximum and effective ranges- so it makes some sense.
They already get a +2 to hit as-is, and with another +6 to hit they're already beyond their effective range even at extreme. It'd be pretty rare for them to hit even at long range, unless they're shooting a city that can't dodge.
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Bearing only launched naval missiles can cover a pretty huge distance.
Absent of those, however, I'd say it would be the ships you base out of it that would be the outpost's real value.
And I suppose if you want to be technical, other naval projectiles don't just stop when they reach their maximum range, but I'd say you wouldn't have any luck targeting a ship accurately. At best they'd be useful for indiscriminate (effectively unaimed) bombardment of a planet. Maybe... maybe they could be used in a surprise attack against an unsuspecting target.
Like you could potshot a station from the other side of the system, if you knew the gravity wells of the system well enough and the station didn't know it was coming (the station's got enough thrust that it can move around enough to spoil your aim if it has warning). This could apply for any other stationary target in space, probably with very little chance of deflection by errant particles or objects. Targets on ground I'm not so sure of. Atmospheric effects might not be sufficiently well understood to plot an accurate shot.
Personal headcannon notes, I assume the range bands exist because ships in combat are constantly making small adjustments to their course to throw off their opponents. Something like full evasive movement, but not quite as extreme.
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My impression is that the first batch of rules, back in the 80s, used much larger hexes - big enough that moons or maybe even planets could fit into a single hex. Under those rules, the ranges ought to be sufficient to use moons to protect planets. But under StratOps, no. That said, using capital weapons to protect the moon base itself would still be a thing.
AT1 has 6500km (seriously...) hexes. The required accelerations for the math to work turn crews into jelly.
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AT1 has 6500km (seriously...) hexes. The required accelerations for the math to work turn crews into jelly.
It works well enough if you have half-hour turns. (Using the 0.5g = 1 thrust rule, a ship exerting 1 thrust will move 7,938 km in one turn, and be moving at 15,876 km/turn thereafter. But we can round that off.) But of course, half an hour per turn seems really low for weapon rate of fire, as well as being strongly out of step with ASF-scale combat.
I might want to make turns 2-3 minutes long(and expand hexes by a factor of 4-9 as a result), but any more would start to get silly.
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It works well enough if you have half-hour turns. (Using the 0.5g = 1 thrust rule, a ship exerting 1 thrust will move 7,938 km in one turn, and be moving at 15,876 km/turn thereafter. But we can round that off.) But of course, half an hour per turn seems really low for weapon rate of fire, as well as being strongly out of step with ASF-scale combat.
I might want to make turns 2-3 minutes long(and expand hexes by a factor of 4-9 as a result), but any more would start to get silly.
Yeah, but they're explicitly 60-second turns. AT1 is silly.
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IIRC turns in AT1 were 10 seconds? Battlespace might have changed that?
Anyway yeah, AT1 movement rules were beyond silly... :D
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And the AT1 mechanics were used by the authors to inform character dialogue in the early novels (Decision at Thunder Rift and The Sword and the Dagger in particular), leading to claims that sound wildly hyperbolic under later rule sets, such as Renfred Tor's claim that his JumpShip's laser array could burn a DropShip out of space from 10,000 kilometers away.
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If you want to Defend w/o capital and sub capital weapons . Environmentally sealed Gun Emplacemets . Light Gauss for something in the Extented Range Bracket . Silver Bullet Gauss Firing in Flack mode with anti air Fire control like a Rifle Man and Arrow IV Standard rounds in flack mode until you get ADA arrow IV . Use Fortress Construction rules for the actual moon base facilities and you want to use Capital Missiles and sub capital weapons .
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I would think a Moon base would be utilized as a quick response force with inbound intruders.
Base's defenses itself would i think, be regulated by era. Would Arrow Missiles be usable as space defense system? In 3060s, the anti-ship missiles become a thing, but their poorman's capital weapon. However, it's kinda limited in Succession Wars Era.
Its more useful than having no space station since Succession Wars didn't allow for many space stations, so your stuck with a DropShip in orbit providing platform for fights.
Bases be also a nice way launch reinforcements, a unsuspecting raider wouldn't be expecting too.
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Moons are basically indestructible fighter carriers. Even a moderately long-legged fighter can cycle between low planetary orbit and cislunar orbit in a couple hours, which gives a defender with a moonbase a huge advantage in maintaining control over the airspace. You can start harassing incoming invaders earlier and keep doing it longer than point-intercept sorties from the surface will allow. And to shut down the launching facilities an attacker has to divert precious ground troops away from the main invasion, opening up a vulnerable second front.
Direct-fire weapons on moonbases are pretty pointless except for protecting the "airfield" itself.
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Airless moons may be a good place for damaged craft to recover, as it avoids problems with re-entry. A fighter carrier DropShip would be ideal for fighters and small craft, but those may not be available, and there's the DropShips themselves.
If they are buried that could also provide some defense against kinetic ballistic attack.
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The airless moon also makes it hard for people to sneak up on the base. The local planet kinda didn't like the Draconis troops, so as long as the DCMS troops control access to the moonbase, you have a location where the troops can relax knowing that nobody will try to stab them while they are sleeping.
Add in very large and sensitive instruments (that won't get destroyed by a home-made mortar) to watch the planet and the jump points, and it would be a decent location. You just have to pay attention to air flow, keep the emergency doors clear of obstructions, etc. But that is all part of any vacuum-located facility.
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Airless moons aren't necessarily barren rock, either. There should be plenty of Europa-style iceballs with subsurface oceans which could provide limitless supplies of water, oxygen, and even food. With fusion power it'd be an easy matter to melt giant caves kilometers deep into the ice and fill them with inflatable habitat structures capable of supporting large base populations and big hangars airlocked to the surface through tunnels.
That would be a difficult nut even for a WarShip to crack, let alone Succession Wars-era space fleets.
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after the rules change, references to weapons on the Verthandi Alpha moon base probably would retcon to refer to standard scale defensive gun emplacements meant to protect the base from ASF attack. which in context of the dialog would basically just be a way to establish it is a proper military base, not some improvised field base.
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Don't know, if you can orbit a golf ball on our moon with a swing, I assume the escape velocity of a Naval Gauss rifle is sufficient to at least hit the earth, through not in any particular place.
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Don't know, if you can orbit a golf ball on our moon with a swing, I assume the escape velocity of a Naval Gauss rifle is sufficient to at least hit the earth, through not in any particular place.
The muzzle velocity of a naval gauss is probably sufficient to beat escape velocity for Earth, never mind the moon. ;D
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Don't know, if you can orbit a golf ball on our moon with a swing, I assume the escape velocity of a Naval Gauss rifle is sufficient to at least hit the earth, through not in any particular place.
Point of fact, the golf ball only probably flew a few hundred yards. It's still there in the same crater. A perfect swing might have gotten it to travel a couple of miles, but the odds of making such a shot one-handed while wearing spacesuit gloves are remote to say the least.
But basically any capital projectile weapon fired within a system is a long-term navigation hazard. I figure NAC shells and maybe even NGauss projectiles have a self-destruct mechanism keyed to their effective range.
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Point of fact, the golf ball only probably flew a few hundred yards. It's still there in the same crater. A perfect swing might have gotten it to travel a couple of miles, but the odds of making such a shot one-handed while wearing spacesuit gloves are remote to say the least.
But basically any capital projectile weapon fired within a system is a long-term navigation hazard. I figure NAC shells and maybe even NGauss projectiles have a self-destruct mechanism keyed to their effective range.
Probably not - self-destructing just turns one fragment into many, which is even worse.
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Probably not - self-destructing just turns one fragment into many, which is even worse.
But crucially, tiny fragments that ships' existing anti-meteoroid defenses can deal with and which will quickly de-orbit if trapped around a planet with an atmosphere.
While the chance of being hit by a single Volkswagen-sized shell is low, the consequences are dire.
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Guns fired in orbit aren't going to stay in orbit. They'll either head on their merry way out of the system (seriously, the muzzle velocity of any naval gun grossly exceeds escape velocity, it has to for any projectile but a missile with its own guidance system to have any chance of hitting another target at the range naval battles can take place at) or they'll hit the planet where the fighting is taking place.
If it flies out of orbit, space is simply too big for it to be a navigational hazard. It will hit something eventually, but the odds of that being another spacecraft are probably about as close to zero as you can achieve. If it hits the ground, well, that is a problem, but not a navigational hazard.
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I could see those bases using old school smallcraft used for Escort from the surface like the Aquarius and the Lioness or even the Intrepid ships be used chase down would be attackers when Aerospace fighters aren't available.
I guess Battletech never intended to have Surface to Orbit weaponry or satellite defense systems due to the original setting for the Succession Wars Era was low tech.
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Guns fired in orbit aren't going to stay in orbit.
I had to test this in Universe Sandbox 2 just to satisfy my own curiosity. It was surprising, I expected the influence of the sun's gravity to have more of an effect and produce a long-term solar capture orbit. But even firing the "projectile" (in this case a Tesla roadster) on a near-miss trajectory at the sun itself wasn't enough to curve the trajectory more than 90 degrees. It just bent around the sun and kept going off into infinity.
Probably the worst-case scenario would be firing something like a NAC/40 on a trajectory retrograde to an inner planet's orbit. Then you could actually get the shell into solar orbit in the opposite direction of the planet.
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I had to test this in Universe Sandbox 2 just to satisfy my own curiosity. It was surprising, I expected the influence of the sun's gravity to have more of an effect and produce a long-term solar capture orbit. But even firing the "projectile" (in this case a Tesla roadster) on a near-miss trajectory at the sun itself wasn't enough to curve the trajectory more than 90 degrees. It just bent around the sun and kept going off into infinity.
Probably the worst-case scenario would be firing something like a NAC/40 on a trajectory retrograde to an inner planet's orbit. Then you could actually get the shell into solar orbit in the opposite direction of the planet.
Escape velocity is a scalar, not a vector. As long as you don't hit anything, direction is totally irrelevant. (Surprising, and a bit counterintuitive, but it's actually true). And for a bit of quick math, escape velocity from altitude X is always exactly equal to [the orbital velocity for a circular orbit of height X] multiplied by [the square root of 2]. For something leaving Earth, the escape velocity from Earth's gravity well is 11.2 km/s (which will leave it in the solar system).
Escaping from a satellite is more complex, because you need to escape both gravity wells, but you have the satellite's orbital velocity to help you. That means it does depend on direction. If you fire it in the optimal direction, the total escape velocity to get you out of the Sun's gravity well is 16.6 km/s. So if you fire your Tesla at 15 km/s, it'll leave Earth orbit but stay within the solar system. But if you fire it at 20 km/s, it can go bye-bye. And if you go in the opposite direction, you could fire it as fast as [11.2 km/s to escape Earth] + [29.8 km/s to counter the Earth's orbital velocity] + [42.1 km/s to escape solar gravity] = 83.1 km/s. Or at least I think that's how the math works out. For comparison, it seems like capital weapons go at a minimum of [56 hexes max range] * [18 km/hex] / [60 seconds/round] = 16.8 km/s, since they hit the round that they're fired, and I suspect that most will go faster.
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This is an interesting thread. We haven't had a good, crunchy aerospace discussion in a while.
Technically, if you are on the dark side of Earth's moon
The dark side moves around the moon once a month. Do you mean the far side, which gets 2 weeks of light like the near side?
The ever-mobile dark side (http://bestanimations.com/Earth&Space/Moon/moon-animation50.gif)
, and a spaceship is in geostationary orbit above you, Earth's moon could be said to be 'shielding' the Earth from the spaceship.
Geostationary orbit is 40,000km from Earth. The moon is 400,000km. The moon would never get between the ship and Earth.
Airless moons may be a good place for damaged craft to recover, as it avoids problems with re-entry.
If they have working engines, then they could avoid high speed reentry on a planet with an atmosphere, too. With fusion rockets you don't have to hit atmosphere like a bat out of hell.
Still, an airless, low G moon is very convenient for WarShips, JumpShips, and vacuum-only DropShips, or fighters with barely more than maneuvering thrusters.
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I guess Battletech never intended to have Surface to Orbit weaponry or satellite defense systems due to the original setting for the Succession Wars Era was low tech.
I used to think that too, but I've come across enough old references to castles with (what seems to be) anti-ship weaponry that I've reconsidered the point.
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I used to think that too, but I've come across enough old references to castles with (what seems to be) anti-ship weaponry that I've reconsidered the point.
There are rule provisions for capital weapons firing into orbit, but they have the same problem as capital weapons bombarding from orbit: very short range.
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There are rule provisions for capital weapons firing into orbit, but they have the same problem as capital weapons bombarding from orbit: very short range.
Though given it's the same range as weapons mounted on a WarShip, it does let you cover a given patch of land against orbital bombardment, or against most DropShip attacks. Mount some capital missiles and you can even do anti-fighter work pretty well too. A small-ish island(which, given BT capital weapons ranges, could easily be "small" like Cyprus or something) with a Castle Brian on it is a genuinely tough nut to crack.