Orbital bombardments, planetary defenses, Death Stars, etc.

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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Elfdart »

tezunegari wrote: 2019-02-03 04:58pmIIRC that beam weapon in RotS was a SPHA-T according to one of the EU novels. Placed in the fighter hangar by Anakin to give the Venator a surprise attack during an Assault that then got adopted by the fleet.
It wouldn't be the first time something that started off as a "field expedient" became popular because it worked. With this contraption I'm guessing it's not easy to aim except at targets that are so big, close or slow-moving that it's hard to miss them.
Or has that been retconned into a dedicated weapon already? (beam details and sound of the weapons differ from the SPHA-T though that could be attributed to being fired in space vs in-atmo)
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

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EA: SW BF2 on the Kamino map A VSD has a dedicated cannon inside the ventral hanger
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Sea Skimmer »

Elfdart wrote: 2019-02-03 05:49pm It wouldn't be the first time something that started off as a "field expedient" became popular because it worked. With this contraption I'm guessing it's not easy to aim except at targets that are so big, close or slow-moving that it's hard to miss them.
My biggest question is how is it even getting the depression to fire out this way? Unless they reversed the gravity plating, put it on the ceiling, and then are actually elevating the gun.

Cause otherwise you'd need a pretty big ramp, as the normal SPHA-T didn't appear to even be able to fire horizontally, it had to point the gun up at least slightly.

But hey if you gotta aim the whole ship for the traverse axis, that's not exactly a deal breaker if its an extra heavy gun and everything else is in a conventional mount. It's not worse then the situation cannon armed galleys were in, and Star Wars fighting resembles a 16th century galley melee in more ways then one.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Elfdart »

It's hard to tell, since you don't see up into the bay, but it could be mounted at that angle. It's not any goofier than straight down. Unless there's some kind of huge swivel mount, the ship will have to move to bring it to bear anyway -kinda like the Wave Motion Gun from Yamato.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Elheru Aran »

IIRC there's some kind of overhead crane in Star Destroyer bays. Would almost be a necessity anyway. I don't see any reason why they couldn't have simply picked up a SPHA-T with that and held it against the roof of the landing bay to give it a better, though still somewhat limited, field of fire.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Esquire »

Do we have any idea what kind of firepower a SPHA-T puts out?
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by KraytKing »

A dozen of them brought down a Core Ship. That's a pretty powerful battleship brought down very quickly by a small number of guns, so I would say they are competitive with other turbolasers the ship would mount.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Lord Revan »

KraytKing wrote: 2019-02-06 10:00am A dozen of them brought down a Core Ship. That's a pretty powerful battleship brought down very quickly by a small number of guns, so I would say they are competitive with other turbolasers the ship would mount.
Also while some did target the open landing gear hatches others simply cut thru the armor so it's not a case of bringing down the core ship thru bypassing the armor either.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Esquire »

I thought the core ships were missing most of the power and shielding of the assembled ship, plus obviously nearly all the weapons - not so?
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Batman »

Would make sense as the bulk of the volume is in the ring and the only 'offensive' armament the ICS states is point defense TL but the shielding is almost 10 times that of an Acclamator. Of course that assumes shields were up in that sequence.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Mange »

KraytKing wrote: 2019-02-06 10:00am A dozen of them brought down a Core Ship. That's a pretty powerful battleship brought down very quickly by a small number of guns, so I would say they are competitive with other turbolasers the ship would mount.
In the opening space battle of ROTS, a Munificent-class frigate was destroyed by a single turbolaser blast fired from the ventral hangar of a Venator-class Star Destroyer. I don't know if it's canon anymore, but the ICS said it was a SPHA-T.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Crazedwraith »

Mange wrote: 2019-02-07 12:57pm
KraytKing wrote: 2019-02-06 10:00am A dozen of them brought down a Core Ship. That's a pretty powerful battleship brought down very quickly by a small number of guns, so I would say they are competitive with other turbolasers the ship would mount.
In the opening space battle of ROTS, a Munificent-class frigate was destroyed by a single turbolaser blast fired from the ventral hangar of a Venator-class Star Destroyer. I don't know if it's canon anymore, but the ICS said it was a SPHA-T.
That was where the conversation started, mate.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

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Crazedwraith wrote: 2019-02-07 01:22pm
Mange wrote: 2019-02-07 12:57pm
KraytKing wrote: 2019-02-06 10:00am A dozen of them brought down a Core Ship. That's a pretty powerful battleship brought down very quickly by a small number of guns, so I would say they are competitive with other turbolasers the ship would mount.
In the opening space battle of ROTS, a Munificent-class frigate was destroyed by a single turbolaser blast fired from the ventral hangar of a Venator-class Star Destroyer. I don't know if it's canon anymore, but the ICS said it was a SPHA-T.
That was where the conversation started, mate.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Elheru Aran »

Here's a thought: if radiation concerns and such are an issue, perhaps ground-level SPHA-T fire is dialed down, but in space, they can go full bore?

Either that or a Munificient is much lighter than a Core Ship; I haven't followed Star Wars discussion in much depth for a long time...
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

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Dial-a-yield solves so many other problems, why not this ine too? :D
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Marko Dash »

or maybe it's power supply limited (capacitor fed?) by the reacter of the SPHA-T and when they hooked it up the a warship grade reactor they were able to simply pump much more power through it.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Sea Skimmer »

Elheru Aran wrote: 2019-02-05 12:00pm IIRC there's some kind of overhead crane in Star Destroyer bays. Would almost be a necessity anyway. I don't see any reason why they couldn't have simply picked up a SPHA-T with that and held it against the roof of the landing bay to give it a better, though still somewhat limited, field of fire.
Recoil would probably not like the idea of firing while attached to a crane.
Esquire wrote: 2019-02-06 04:43pm I thought the core ships were missing most of the power and shielding of the assembled ship, plus obviously nearly all the weapons - not so?
They were supposed to be loading troops not under construction. But it is unlikely that they would have shields up in that situation all things considered. Doesn't strictly matter, just melting a bunch of steel like was happening would indicate a pretty high level of firepower for how big they actually are.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Lord Revan »

There's also the possibility that the SPHA-T cannon hit something sensitive when firing at battle of Corusant. Though turning SPHA-T (or just their cannon) into a dedicated bombardment cannon either for orbitital bombardment or clearing an LZ doesn't that stupid.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Elheru Aran »

Sea Skimmer wrote: 2019-02-08 03:48am
Elheru Aran wrote: 2019-02-05 12:00pm IIRC there's some kind of overhead crane in Star Destroyer bays. Would almost be a necessity anyway. I don't see any reason why they couldn't have simply picked up a SPHA-T with that and held it against the roof of the landing bay to give it a better, though still somewhat limited, field of fire.
Recoil would probably not like the idea of firing while attached to a crane.
SPHA-Ts have recoil?

That said I wasn't thinking about the crane holding it that much, more like it'd pick up the SPHA-T, turn it upside down and maybe act as an anchor point of some kind while its feet clamp onto the hangar bay roof. *shrugs* I know the walkers can magnetize their feet because they operate in space a couple times, no reason the SPHA-T couldn't do so too.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Lord Revan »

Elheru Aran wrote: 2019-02-08 04:15pm
Sea Skimmer wrote: 2019-02-08 03:48am
Elheru Aran wrote: 2019-02-05 12:00pm IIRC there's some kind of overhead crane in Star Destroyer bays. Would almost be a necessity anyway. I don't see any reason why they couldn't have simply picked up a SPHA-T with that and held it against the roof of the landing bay to give it a better, though still somewhat limited, field of fire.
Recoil would probably not like the idea of firing while attached to a crane.
SPHA-Ts have recoil?
They seemed to have it in AOTC when they fired at the coreship.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Batman »

They did when initiating fire certainly. What should recoil look like for a constant beam weapon?
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Elheru Aran »

Batman wrote: 2019-02-08 05:18pm They did when initiating fire certainly. What should recoil look like for a constant beam weapon?
Yeah, I just looked up a YT clip of Geonosis and while the SPHA-Ts do exhibit a recoil along the barrel when they fire and rock back very slightly, there's nothing after that, just maintaining the beam while elevating to keep fire on the core-ships.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Lord Revan »

Batman wrote: 2019-02-08 05:18pm They did when initiating fire certainly. What should recoil look like for a constant beam weapon?
Recoil is just the opposite vector force to the main force, so for a constant beam the recoil should be a constant force pushing back so it should at furthest reach of travel until the beam is terminated when return to "rest" position.


In essence think the way modern artillery peices are pushed back, then instead of the weapon resetting it would stay in the "max recoil" position until the weapon fire is terminated.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Ender »

A few miscellaneous points for issues raised throughout the thread

1) In comparing weapons it's not just how big the boom is at the end point because directed energy weapons function differently. You want to figure out the equivalent of the overpressure wave, heat, and radiation to get an approximation of equivalent energy. I'll explain more below

2) "Energy bleed" doesn't help solve anything. Dumping the energy into the air around it doesn't make it not damaging, i means you end up with a very large line source for the heat and radiation (that heavily ionized air will be shedding particulate and energy radiation). This is less consistent with the visuals than we see

3) Blast size at the end point should be nothing close to the appearance the blast of an energetic equivalent bomb. Mike explained this about a decade ago HERE, but basically an explosion is the function of the mols of gaseous material and their overpressure (a function of detonation velocity or how rapidly the material is made gaseous). With TNT or RDX, the light elements provide their own energy and gas as they drop to a lower state (translation: "go boom"). With a direct energy weapon however, they need to apply a great deal of energy making the target a gas and then exciting it to that level. Particularly when you are shooting a planet and you are hitting mainly silicon dioxide or iron.

I built a spreadsheet that calculated this a while back - it isn't optimal because I assume perfectly spherical geometries when really it should be more hemispherical/crater. But the gist is that it takes several orders of magnitude more energy to get the equivalent of a bomb. For example against a SiO2 target, to get the equivalent of a 1 kiloton detonation it takes 6 *10^19 joules released in 0.000756 seconds. That's faster than what it looks like a TL applies, so the math needs some more work, but basically it takes a 14 gigaton TL to approximate a 1 kiloton bomb. This isn't a linear relationship btw, a 100 ton bomb equivalent ("tbe" from here on out) is 6*10^17, 10 tbe is 10^15, when you get down to like 10 kg of tnt you are talking 10^9 tbe. So it isn't that far off from what we see. I should refine this more but I have a lot going on so I probably won't.

4) Big explosions are highly inefficient. The useful part of an explosion is the overpressure wave and fireball. Those scale with the cube root of the energy. If you want to wreck a country, 1000 kiloton explosions are more effective than 1 megaton explosion. You simply get more coverage and saturation for it

so now that we've covered that it takes orders of magnitude more energy to get big booms, and that big booms are less militarily useful, let's go to the final point

5) Cranking the reactor on max to fuel big booms is suicide. A starship running full power is terrible and no sensible commander wants to do it for anything but emergency manurers (eg closing the trap at Endor). The fact is that the higher your power:mass ratio is the better you can shoot and manuver, but also the faster you run out of fuel. And at peak power the operating time for star wars capital ships is low single digit hours. Physics still follow - we know the ISD masses ~10^12 kg based of its acceleration and power, we know its reactor has a peak output of 10^25 watts, which means that if every last microgram of that ship is fuel ( and it isn't) then it can at best operate like that for 10,000 seconds. Or about 2 hours, 45 minutes. An old style BDZ was basically an hour, that means it has 1 hour 45 minutes at best before it is dead in space and vulnerable. That is assuming it was fully fueled above its target - it is had been operating and deploying prior to that as expected, or if it had to fly there, going full power for an extended period may not even be possible, or if it did it would leave the ship easy pickings for much smaller craft. Something like the Invisible Hand melting a planet's surface would be a shocking act because no commander would do that, Grievous would because he can redirect the fleet and its logistics train to allow it to be done and make a point, or an Imperial commander could do it against an under developed world and expect to limp back to station without encountering a hostile. But even the bloodlust of the most moustache twirling moff would be slowed by realizing he doesn't have the gas in the tank to melt the surface and get home, so use the medium TLs to perform the equivalent of conventional bombing instead

6) Missiles don't have a delta-v advantage. The old view from the libertarian scifi authors of the 70s and 80s was about how it was easier to drop something down the gravity well than throw it up. Which is true, <i>provided you don't care what you hit</i>. But if you want to hit a specific target to achieve an objective and not just skip rocks on the ocean, you have to have your missiles do a lot of manuvering - and it unsurprisingly works out to basically the same delta-v as it would take a launch from that spot to hit your ship.

7) No cover in space, and if you can see them, they can see you

So if small booms are better, bombs are more energy efficient than TLs by several orders of magnitude, emerging to hit hard leaves you running on fumes with no cover, and any missile or missile bus you send needs a massive flight envelope to ensure they hit the target

8 ) the optimal response is atmospheric insertion capable bombers. Give them an escort and a few proton torpedoes for defense, load them up with small precision guided conventional munitions to hit your objectives, and you can effectively control a planet via targeted bombing run from a carrier in orbit much easier than you can having an ISD show up and roll out the topside HTLs. When the ISD does show up, it wants to use low level MTLs and lesser guns both by fuel constraints and destruction effectiveness. If you are going to consistently be doing insanely huge attacks on a planet's surface you might as well build a speciality platform that is huge and almost all fuel - the Death Star

Which is consistent with what we see.
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Re: Orbital bombardments, planetary defenses, Death Stars, etc.

Post by Ender »

Elheru Aran wrote: 2019-02-08 04:15pm
Sea Skimmer wrote: 2019-02-08 03:48am
Elheru Aran wrote: 2019-02-05 12:00pm IIRC there's some kind of overhead crane in Star Destroyer bays. Would almost be a necessity anyway. I don't see any reason why they couldn't have simply picked up a SPHA-T with that and held it against the roof of the landing bay to give it a better, though still somewhat limited, field of fire.
Recoil would probably not like the idea of firing while attached to a crane.
SPHA-Ts have recoil?
Not like they should have if those core ships were shielded and the SPHA-T is the equivalent of an HTL. And the "neutrino beam counterfiring" does you no good either because

1) it doubles the energy required
2) it doubles the stress on the machine itself
3) even as low as the interaction for neutrinos is, at that level at that proximity it would kill the people near by.

it is a scene with problems from a physics consistency pov.
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