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Imperial Squadrons Bombardment Factor Question

There's really only 3 ship bound weapons that are viable for ortillery, at least in a generic sense.

Specifically deadfall ordnance (which are not "factored" in ship designs at all), missiles, more specifically nuclear missiles, and meson guns.

Lasers deterioate greatly in atmosphere, and PA pretty much don't work at all.

Regular missiles are possible, but, frankly, very inefficient in terms of bang/buck per missile deployed.

I truly think for a determined bombardment effort, deadfall would be the most efficient mechanism of wide scale bombardment, just in terms of cost and effectiveness.

Cheap, gravity powered "JDAM" systems make these particularly effective. The hard part is simply getting through planet based point defenses. Those need to be reduced in both the missile and deadfall case.

Of course, the mega weapon is the meson gun, which is a spectacularly over powered piece of kit in the Traveller universe. You don't need spinals for this, the bay weapons are very effective. We don't really have a maintenance interval for meson guns, so we don't know their ROF and how long they can go. Since they just require power, of which is effectively infinite in the TU, they may well have long runtimes. Since invading fleets have a week plus of free reign, this makes the meson guns extremely dangerous. 8, 16, 24 dedicated bombardment cruisers with several meson tubes, going 24x7, methodically turning the planet surface in to resembling a golf ball.
 
There is also the use of mass drivers as a weapon system for bombardment.

In MWM's novel ships do indeed use mass drivers for planetary bombardment; they are no use at ship combat scale IMHO because you can not fire the projectile fast enough to stand a chance of hitting anything at ship combat ranges.
 
Guys, these are all good thoughts.

I do think though, that BF factors are a bit more on the tactical side of ortillery. whartung, what you talk about would be strategic bombing, no?. The BF in all three games is used for fighting individual units or ships/boats, not the whole planet. Actually, a lot of pinpoint targets instead of "turning the planet into molten rock".

So in a way we need to differentiate between strategic and tactical ortillery? I get the feeling that the design choices in the BF derivation include both, though.

Mass Driver and Kinetic solutions seem not to be modelled by any of the three games.
 
Rules of engagement can effect type of weapon systems and targets.

Deadfall ordnance is basically Stratofortresses dropping their loads from orbit, which unless the planetary defences are blinded, distracted, suppressed or destroyed, would tend to make them sitting ducks, especially open to meson or ion cannons, and if damaged enough, they'll perform a catastrophic re-entry.
 
whartung said:
There's really only 3 ship bound weapons that are viable for ortillery, at least in a generic sense.

Specifically deadfall ordnance (which are not "factored" in ship designs at all), missiles, more specifically nuclear missiles, and meson guns.
Click to expand...

If you think about it, deadfall ordnance is just a specialised missile. It will need engines (even just a small rocket) to slow down enough to get it into the upper atmosphere where it can do an atmospheric braking manoeuvre (probably about 1-2km/sec1 from orbital velocity to give it a reasonable footprint that it can be aimed at). Then it would need a heat shield and some sort of guidance system once it got through the upper atmosphere.

The minimum useful payload for this type of weapon would probably be about the equivalent of an artillery shell, maybe a 50-100kg warhead plus guidance systems and heat shielding. You would also probably have to launch a load of decoys with your fire mission to saturate ground-based point defence. The heat shielding would also be a somewhat effective defence against energy weapons fire such as lasers,2 so you might not want to ditch it until the last minute.

Variants with larger warheads might be interesting but you would have to trade this off against the numbers needed to saturate ground-based point defence fire. This might also depend on the effectiveness of the decoys, so YMMV.

If you view a missile bay as something like a vertical launch system that can take a variety of different missiles, this type of weapon could just be fired from a missile bay.

As an alternative, something similar could be launched from a mass driver, which might save the weight of the rocket engine. However the payload would be much the same - except the mass driver shell version would have to be tougher to handle the acceleration. This might negate the weight advantage of not having to carry an engine to do the de-orbit burn.

As a corollary, for much the same reason you need about 30km/sec of delta-V to drop things into the sun, which is why we don't use this method to dispose of radioactive waste. Short Youtube video about this.

1 Can you tell I've been playing way too much Kerbal Space Program?
2 The harder it is to damage the projectile with point defence fire, the fewer shells the point defence system can destroy in a given length of time, so there would be some optimal level of toughness for the shells and some optimal ratio of shells to decoys (which would be much lighter). Given that after the initial burn the re-entry is un-powered (i.e. it is using atmospheric braking to slow down) some heat shielding will be necessary, which can double to toughen the shell somewhat against incoming laser fire.
 
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Disclaimer: a I don't know IS, most of this is for FFW.

whartung said:
There's really only 3 ship bound weapons that are viable for ortillery, at least in a generic sense.

Specifically deadfall ordnance (which are not "factored" in ship designs at all), missiles, more specifically nuclear missiles, and meson guns.
Click to expand...

You forgot HiEnergy weapons. At least in MT (and I guess in Striker, as MT developed from it) fusion guns make a nice precision ortillery support, and they require no ammo (so having no cost pr round and freeing volumen in your ship)

whartung said:
Of course, the mega weapon is the meson gun, which is a spectacularly over powered piece of kit in the Traveller universe. You don't need spinals for this, the bay weapons are very effective. We don't really have a maintenance interval for meson guns, so we don't know their ROF and how long they can go. Since they just require power, of which is effectively infinite in the TU, they may well have long runtimes. Since invading fleets have a week plus of free reign, this makes the meson guns extremely dangerous. 8, 16, 24 dedicated bombardment cruisers with several meson tubes, going 24x7, methodically turning the planet surface in to resembling a golf ball.
Click to expand...

I don't believe Meson guns are featured in the BF, but mostly in AF, as the main big ship killers. See that in CT:HG meson bays are of litle use, as (due to a game design glitch) they cannot be used if you have spinal MG, and you'd prefer a spinal tan several bays (at least for capital ships).

Able Baker said:
Guys, these are all good thoughts.

I do think though, that BF factors are a bit more on the tactical side of ortillery. whartung, what you talk about would be strategic bombing, no?. The BF in all three games is used for fighting individual units or ships/boats, not the whole planet. Actually, a lot of pinpoint targets instead of "turning the planet into molten rock".

So in a way we need to differentiate between strategic and tactical ortillery? I get the feeling that the design choices in the BF derivation include both, though.

Mass Driver and Kinetic solutions seem not to be modelled by any of the three games.
Click to expand...

In FFW (and I guess in IS), BF is used to fight the planetary defenses and troops, not for strategic bombing.

See that there is no instance in FFW where such Strategic Bombing is used (in fact, there are just a few such cases in the whole 3I history before Rebellion Black War). Any such action would be likely to affect UWP (as in MT:HT), so I guess most BF represents "tactical" use of orbilat bombing, mostly directed to troop concentrations.
 
In CT:HG meson bays are of little use.
In CT:Striker meson bays make for excellent ortillery.

The Imperium even has a canonical light carrier design in S:9 that has meson bays and heavy fighters...
 
mike wightman said:
In CT:HG meson bays are of little use.
In CT:Striker meson bays make for excellent ortillery.

The Imperium even has a canonical light carrier design in S:9 that has meson bays and heavy fighters...
Click to expand...

Meson bays make for very powerful ortillery, but that doesn't always mean excellent one. The collateral damages are too high, so they are seldom (if at all) used. IMHO this is like saying that nukes make for excellent artillery; while they are quite powerful, they are also too damaging for being excellent, and so they are not used.

Again, how many instances of their use (with the consequences it would have) are told in OTU history (again, before the Rebellion)?

We've already had this discussion several times, and I guess your TU is more "brutal" (if I'm allowed this word, be sure no ofense is intended) that mine.

Of course, Mesons (bays and spinals alike) make for very powerful strategical bombardment weapons, but they are too so for being used, probably due to treaties or fear of retaliation (that usually are the same thing). The BF represents, IMHO, a more tactical bombardment capacity.
 
nobby-w said:
If you think about it, deadfall ordnance is just a specialised missile. It will need engines (even just a small rocket) to slow down enough to get it into the upper atmosphere where it can do an atmospheric braking manoeuvre (probably about 1-2km/sec1 from orbital velocity to give it a reasonable footprint that it can be aimed at). Then it would need a heat shield and some sort of guidance system once it got through the upper atmosphere.

The minimum useful payload for this type of weapon would probably be about the equivalent of an artillery shell, maybe a 50-100kg warhead plus guidance systems and heat shielding. You would also probably have to launch a load of decoys with your fire mission to saturate ground-based point defence. The heat shielding would also be a somewhat effective defence against energy weapons fire such as lasers,2 so you might not want to ditch it until the last minute. ...
Click to expand...

I recall a bit from Larry Niven's book with the little elephant invaders, Footfall. Among their weapons was a missile that basically just fell. It could plummet through the atmosphere from orbit, without braking, and still be able to hit a vehicle-size target - which is really the big trick. It didn't need a warhead - any missile-shaped weapon that could survive a meteoric re-entry, and then hit a target, would hit with enough force to make a warhead look pathetic.

http://www.armaghplanet.com/blog/rods-from-god-a-terrifying-space-weapon.html

Now, the aiming part would be a heck of a trick, but I imagine a rod made of bonded superdense metal - or whatever they're using in those little high-tech fusion plants to contain everything without getting itself vaporized - could manage the re-entry.
 
In the 1970s and 1980s this idea was refined in science fiction novels such as Footfall by Larry Niven and Jerry Pournelle (the same Pournelle that first proposed the idea for military use in a non-fiction context), in which aliens use a Thor-type system. During the 1980s and 1990s references to such weapons became a staple of science fiction roleplaying games such as Traveller, Shadowrun and Heavy Gear (the latter game naming these weapons ortillery, a portmanteau of orbital artillery), as well as visual media including Babylon 5's "mass drivers" and the film Starship Troopers, itself an adaptation of a Heinlein novel of the same name.

From Wikipedia page mentioned: https://en.wikipedia.org/wiki/Kinetic_bombardment
 
Carlobrand said:
Among their weapons was a missile that basically just fell. It could plummet through the atmosphere from orbit, without braking, and still be able to hit a vehicle-size target - which is really the big trick. It didn't need a warhead - any missile-shaped weapon that could survive a meteoric re-entry, and then hit a target, would hit with enough force to make a warhead look pathetic.

...

Now, the aiming part would be a heck of a trick, but I imagine a rod made of bonded superdense metal - or whatever they're using in those little high-tech fusion plants to contain everything without getting itself vaporized - could manage the re-entry.
Click to expand...

The interesting part here is the "just fell" part. Simply, in order for the ordnance to "just fall", the launching platform has to be "just falling" as well. Since, by definition you can't "fall" out of orbit without braking. So, you could brake the ship and then start kicking stuff out the hatch, or you need to have the individual units (or some disposable carrier) perform a braking maneuver. Obviously, after deployment, the launch platform would maneuver back in to a stable orbit.

You don't need any spectacularly sophisticated material as a bombardment device (though, naturally, density is the go to property of such a thing). If the device has a low coefficient of drag, it will likely survive re-entry properly.

Guidance is pretty easy (for varied definitions of "easy"). We do it today with an "cheap" kit. With GPS, they have a 5m CEP. Higher tech would certainly improve on that.
 
In space it's cold,
and from the hold,
the ordnance was vented.

They drilled holes,
with telegraph poles,
'til the rebels repented.
 
Carlobrand said:
I recall a bit from Larry Niven's book with the little elephant invaders, Footfall. Among their weapons was a missile that basically just fell. It could plummet through the atmosphere from orbit, without braking, [ . . . ]
Click to expand...
With due respect to the inventor of Rods From God himself,1 there's a bit of artistic licence going on here.

If you just drop a projectile it will sit in orbit next to you (technically, whatever delta-V it got from the separation will push it into a slightly different orbit). It still has to do a braking manoeuvre to slow down enough to get out of orbit. Then it can do an unpowered re-entry, which then shaves enough velocity so that it actually hits the ground. Note that it could still be going at several km/sec when it hits.

This could be done in a few different ways:
  • Fit the projectile with a small rocket that burns enough delta-V to de-orbit it; after that it will hit the atmosphere and can re-enter and manoeuvre to hit its target. This rocket will have to provide enough delta-V to aim the projectile into the vicinity of its target, so it will need enough reaction mass to give the projectile a decent reach.

    Probably, something like 1-2km/sec of delta-V would be enough to de-orbit the projectile from orbital velocity and give it enough scope for variation in its trajectory to be able to hit somewhere within a decent footprint on the ground.

  • Fire the projectile from a mass driver, rail gun or even a big conventional gun, giving it the delta-V from firing it. Essentially, the gun would fire retrograde (backwards with respect to the ephemeris of the orbit) from the ship to shave off enough velocity to de-orbit the projectile. The round would then re-enter the atmosphere and could engage targets on the ground. Targeting different areas could be achieved by aiming the gun within the restrictions of the available muzzle velocity.

  • Manoeuvre the whole ship onto a sub-orbital trajectory and then release the ordnance, a bit like a WWII-era dive bomber. This would then require you to do another burn to get the ship back into a stable orbit. It could, however, be done at some distance from the planet - possibly on a hyperbolic orbit that will escape the planet - if the aim was accurate enough. Similar techniques are sometimes used to dispose of used stages on real space missions to prevent them from becoming space junk.

    This approach would be the closest to actually releasing deadfall ordnance but it's not just a ship sitting in orbit dropping bombs. However, given that it would need reaction mass to manoeuvre the whole ship instead of just the projectiles, it has some potential inefficiencies.
If you want to get a handle on orbital mechanics and space flight, I highly recommend taking the time to learn how to play Kerbal Space Program. I shall leave this and this little gem from XKCD.com as a starter.

1 - The concept was originally proposed by Jerry Pournelle - co-author of Footfall - while he was working for Boeing sometime in the 1950s.
 
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nobby-w said:
With due respect to the inventor of Rods From God himself,1 there's a bit of artistic licence going on here.

If you just drop a projectile it will sit in orbit next to you (technically, whatever delta-V it got from the separation will push it into a slightly different orbit). It still has to do a braking manoeuvre to slow down enough to get out of orbit. Then it can do an unpowered re-entry, which then shaves enough velocity so that it actually hits the ground. Note that it could still be going at several km/sec when it hits.

This could be done in a few different ways:
  • Fit the projectile with a small rocket that burns enough delta-V to de-orbit it; after that it will hit the atmosphere and can re-enter and manoeuvre to hit its target. This rocket will have to provide enough delta-V to aim the projectile into the vicinity of its target, so it will need enough reaction mass to give the projectile a decent reach.

    Probably, something like 1-2km/sec of delta-V would be enough to de-orbit the projectile from orbital velocity and give it enough scope for variation in its trajectory to be able to hit somewhere within a decent footprint on the ground.

  • Fire the projectile from a mass driver, rail gun or even a big conventional gun, giving it the delta-V from firing it. Essentially, the gun would fire retrograde (backwards with respect to the ephemeris of the orbit) from the ship to shave off enough velocity to de-orbit the projectile. The round would then re-enter the atmosphere and could engage targets on the ground. Targeting different areas could be achieved by aiming the gun within the restrictions of the available muzzle velocity.

  • Manoeuvre the whole ship onto a sub-orbital trajectory and then release the ordnance, a bit like a WWII-era dive bomber. This would then require you to do another burn to get the ship back into a stable orbit. It could, however, be done at some distance from the planet - possibly on a hyperbolic orbit that will escape the planet - if the aim was accurate enough.

    This approach would be the closest to actually releasing deadfall ordnance but it's not just a ship sitting in orbit dropping bombs. However, given that it would need reaction mass to manoeuvre the whole ship instead of just the projectiles, it has some potential inefficiencies.
If you want to get a handle on orbital mechanics and space flight, I highly recommend taking the time to learn how to play Kerbal Space Program. I shall leave this and this little gem from XKCD.com as a starter.

1 - The concept was originally proposed by Jerry Pournelle - co-author of Footfall - while he was working for Boeing sometime in the 1950s.
Click to expand...


Then you have as stated earlier...Mass-drivers. Or the un-rocket projectile could also be fired by cannon. Exert enough force as Nobby stated, that it has the delta-V to leave orbit and enter atmo. However this would be also tricky. Yet a rock from space could do it any way. end result below:

az-attr-crater.jpg


Meteor Crater, Winslow AZ, USA
 
Barsanuphius said:
Then you have as stated earlier...Mass-drivers. Or the un-rocket projectile could also be fired by cannon. Exert enough force as Nobby stated, that it has the delta-V to leave orbit and enter atmo. However this would be also tricky. Yet a rock from space could do it any way. end result below:

az-attr-crater.jpg


Meteor Crater, Winslow AZ, USA
Click to expand...

No mass driver needed.

  1. do the needed math.
  2. unstrap the ordinance
  3. place ordinance against back wall
  4. open bay doors & kill AG/IC
  5. point bay doors down.
  6. accelerate in direction of bay door 1 minute
  7. Accelerate opposite 1 minute. Deadfall.
  8. wait for impact.
 
Not to get too semanticky about it, but whatever process the launch platform used to de-orbit the thing, to the best of my knowledge it then just fell. I guess there might have been thrusters or something to maneuver it or start it on its way, but I don't recall mention of such. It's been some time since I read the book, so maybe I'm forgetting something.
 
If you're patient, and the bomb bay isn't amidships in all directions, you can literally just let the tidal force difference pull them out of the bay.

Keep in mind:
C/G=Center of Gravity
If you're orbiting, the portion of the ship below C/G is too slow for it's own orbit. It's very gently pulled down.
Likewise, the portion above is too fast for its orbit, and is pulled slightly up.
The moment you disconnect the clamps, the tidal force begins to treat them as nearly separate, and this also moves the CG of the ship up a bit...

If the bomb bay is in the nose of a needle config, you go nose down, and let go, and it WILL fall. Not quickly, but it will.

If you're below orbital speed, open the bomb bay, and move upward ...
 
Condottiere said:
In space it's cold,
and from the hold,
the ordnance was vented.

They drilled holes,
with telegraph poles,
'til the rebels repented.
Click to expand...

Hi, Condottiere,

Was this verse from "Footfall" by Larry Niven and Jerry Pournelle, 1985?
I am asking because I like it. I have never read "Footfall".

I did a google search and have come up short.

:coffeesip:
 
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