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Author Topic: Where do aerospace battles occur?  (Read 1498 times)

Challenger

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Where do aerospace battles occur?
« on: 21 May 2021, 10:17:13 »
As a thought experiment I tried to sit down and work out how a ship captain would have to manoeuvre if they wanted to engage an enemy vessel, as in achieve a low enough relative velocity that a 'typical' aerospace battle would occur rather than merely a high speed pass.

In short, my conclusion was that this was almost impossible unless both sides wanted a stand up fight and 'cooperated' in bringing about the engagement. The high speeds, the massive distances and the relatively slow accelerations involved all conspire to make it very difficult to actually match velocities with an enemy manoeuvring in system vs one in orbit round a planet.

Which got me to thinking, where do space battles typically take place in the BT universe? Do they take place in the open space between planets, or does practical concerns limit them to the space near planets and other fixed objectives?

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AlphaMirage

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Re: Where do aerospace battles occur?
« Reply #1 on: 21 May 2021, 10:36:44 »
I wrote a whole essay about this (2nd Star League Guide to Warships in Fan Fic, linked below.) In the fiction it is typically a mutually agreed engagement often occurring in planetary orbit or near moons, aka 'fixed' areas. At this speed the velocities could be low enough to vector toward one another. The second most common place seems to be at the standard jump points as the KF drive neutralizes velocity. You can intercept an intrusion there if you are waiting at the right jump point or have a charged jump drive to reach it. Also jumpships are effectively motionless to anything other than space stations so they are easy prey there for any spacecraft practicularly small craft.

Alan Grant

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Re: Where do aerospace battles occur?
« Reply #2 on: 21 May 2021, 12:35:40 »
A guy I was talking to about this once made a joke I'll never forget. He said space combat is like the movie gunfights where the actors are in a gun battle on one floor of a multi story building. The heroes suddenly reach an elevator and the doors close, they leave the gunfight behind them. The elevator goes up or down. Elevator music plays, and it's a weird goofy moment because amid the crazy battle they are just awkwardly standing there listening to elevator music. Cue some funny dialogue, then the elevator reaches a new floor, the doors open, there's a gunfight on this floor too and the characters rush forward guns blazing.

The elevator is the transit between orbital bodies like planets and space stations to a jump zone and back. From orbit or from your jumpship you begin a 1-2 G burn (typically 1 G) over the course of the multi day journey to your destination. You build up incredible speed. Halfway to your destination you flip over and begin the deceleration burn to cancel out the speed so that once you arrive at the jump zone or planet you are at a reasonable maneuvering speed much closer to zero.

In transit you are moving too fast to fight. Moving at massive velocities where even the slightest changes in course can send you hundreds of kilometers in a different direction in a matter of seconds and minutes. Engagements would last in a blink of an eye and then you'd be out of range again. It's a waste of fuel, it's a drain on your crew and probably a waste of ammo. At those sort of speeds, you'd flash past your opponent, get a split second to fire, then you'd instantly be out of range again and it could take hours or days to intercept again and do it all again.

So you are right in that there's a certain mutually understanding that attempting that kind of fight is just somewhere between rare and never done. Not due to any kind of human behavior or code or ethics or even tactics, but due to physics. The same physics that say standing on the roof of a moving car with no restraints or protection while it's moving at high speed might be a bad idea. You can't argue with that.
« Last Edit: 21 May 2021, 12:45:04 by Alan Grant »

Bedwyr

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Re: Where do aerospace battles occur?
« Reply #3 on: 21 May 2021, 13:22:23 »
The same physics that say standing on the roof of a moving car with no restraints or protection while it's moving at high speed might be a bad idea. You can't argue with that.

And that makes for a really good analogy for why we have the fantasy of orbital combat: it's the rule of cool and that's all there is to it. No sane opposing combatants would actually execute a fight on the roof of a train or a car, but we've seen it since the near beginning of cinema. So the existence of the rules and the aerotech box set is a testament to pure "that's badass!" combined with verisimilitude.

I think Cray wrote that sidebar in SO saying basically if you want to simulate real space combat, take your record sheets of each side and insert them into a shredder.
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AlphaMirage

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Re: Where do aerospace battles occur?
« Reply #4 on: 21 May 2021, 14:32:41 »
I think Cray wrote that sidebar in SO saying basically if you want to simulate real space combat, take your record sheets of each side and insert them into a shredder.

That is a hidden gem in that rule book. First time I actually looked at the rules to write my tract on space combat and found that I had to reread it several times to ensure that it was in fact in the book.

Although to be fair the best way to protect yourself from an invasion or hurt the enemy in the BT universe is to blow up those dropships and capture jumpships. Thus warships and aerospace in some capacity make sense

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Re: Where do aerospace battles occur?
« Reply #5 on: 21 May 2021, 15:09:53 »
And that makes for a really good analogy for why we have the fantasy of orbital combat: it's the rule of cool and that's all there is to it. No sane opposing combatants would actually execute a fight on the roof of a train or a car, but we've seen it since the near beginning of cinema. So the existence of the rules and the aerotech box set is a testament to pure "that's badass!" combined with verisimilitude.

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Re: Where do aerospace battles occur?
« Reply #6 on: 21 May 2021, 17:58:25 »
Yeah, the dual "Oh shit!" remarks really get to the "reality" of high speed intercepts...  ;D

Charistoph

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Re: Where do aerospace battles occur?
« Reply #7 on: 21 May 2021, 19:05:09 »
A guy I was talking to about this once made a joke I'll never forget. He said space combat is like the movie gunfights where the actors are in a gun battle on one floor of a multi story building. The heroes suddenly reach an elevator and the doors close, they leave the gunfight behind them. The elevator goes up or down. Elevator music plays, and it's a weird goofy moment because amid the crazy battle they are just awkwardly standing there listening to elevator music. Cue some funny dialogue, then the elevator reaches a new floor, the doors open, there's a gunfight on this floor too and the characters rush forward guns blazing.

The elevator is the transit between orbital bodies like planets and space stations to a jump zone and back. From orbit or from your jumpship you begin a 1-2 G burn (typically 1 G) over the course of the multi day journey to your destination. You build up incredible speed. Halfway to your destination you flip over and begin the deceleration burn to cancel out the speed so that once you arrive at the jump zone or planet you are at a reasonable maneuvering speed much closer to zero.

In transit you are moving too fast to fight. Moving at massive velocities where even the slightest changes in course can send you hundreds of kilometers in a different direction in a matter of seconds and minutes. Engagements would last in a blink of an eye and then you'd be out of range again. It's a waste of fuel, it's a drain on your crew and probably a waste of ammo. At those sort of speeds, you'd flash past your opponent, get a split second to fire, then you'd instantly be out of range again and it could take hours or days to intercept again and do it all again.

So you are right in that there's a certain mutually understanding that attempting that kind of fight is just somewhere between rare and never done. Not due to any kind of human behavior or code or ethics or even tactics, but due to physics. The same physics that say standing on the roof of a moving car with no restraints or protection while it's moving at high speed might be a bad idea. You can't argue with that.

Weber goes over this numerous times in his Harrington series.  However, the Harrington series has some huge advantages in that they don't use fuel for propulsion and their accelerations are many orders higher than anything producible in Battletech (a merchant ship usually runs at around 120-150 Gs, for example, while a Super Dreadnought can pull 400 Gs, to say nothing about the Destroyers pulling 500, easy).

Still, it IS possible, but very annoying and very expensive if you require fuel for propulsion.  While small changes in course can alter your destination wildly, those course changes still take time to develop something that could avoid an incoming force.

There is also the advantage that BT has in that they don't have to guard against ships tossing the equivalent of world-ending meteors traveling at near light-speed at your planet.  At most, you might get some Jihadists wanting to make some cities glow, but they like to be a bit closer when they fire like most orbital bombardments.  This makes setting up interception solutions relatively easy on a planet or when they are escaping, because you have a good idea where their JumpShip is.

So one generally doesn't have to deal with "deep space" intercepts, nor should one generally be concerned with trying.  At least until they develop grav wedge and inertial dampener tech going at any rate.
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Re: Where do aerospace battles occur?
« Reply #8 on: 25 May 2021, 21:29:47 »
in the novels, the naval battles (including fighter/dropship stuff) seems to mostly occur in two places..

at the jump point, usually after one force arrives via jump.
or in orbit over a planet, usually as an invading force is attempting to do an orbital insertion or a landing.

jump points tend to see more warship battles (once warships show up), while dropships and fighters usually show up more in the stuff in planet orbit.

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Re: Where do aerospace battles occur?
« Reply #9 on: 03 June 2021, 18:08:38 »
Does it make sense for any planet to have aerospace forces in this regard?  I'm thinking ground-based surface-to-orbit weapons and conventional aircraft would be an effective defense for a lower cost than space-going ships and fighters.  You'd just have to make sure the weapons cover any orbital blind spots that may occur.
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Re: Where do aerospace battles occur?
« Reply #10 on: 03 June 2021, 19:26:03 »
That depends on your tolerance for debris falling from the sky on random communities.  If your population density is low enough, sure, that tactic totally works...  ^-^

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Re: Where do aerospace battles occur?
« Reply #11 on: 03 June 2021, 21:21:45 »
Does it make sense for any planet to have aerospace forces in this regard?  I'm thinking ground-based surface-to-orbit weapons and conventional aircraft would be an effective defense for a lower cost than space-going ships and fighters.  You'd just have to make sure the weapons cover any orbital blind spots that may occur.
Surface weapons don't provide enough coverage. Honestly surface based military airfields don't make sense. A squadron based in an orbiting Leopard can be anywhere on world in minutes with minimal fuel burn. No chance of the pesky ground pounders overrunning your base. And you can run intercepts out to luna orbits without difficulty.

If you are shooting something in orbit it is too late. They have already dropped those 'Mechs, nukes, whatever. Castle Brian's exist on the assumption you can't make an intercept and are going to have to wear the hit. It is always better to at least try before then.

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Re: Where do aerospace battles occur?
« Reply #12 on: 04 June 2021, 06:14:41 »
Good points, especially the one about chunks of dropship and warship falling from orbit  xp
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Re: Where do aerospace battles occur?
« Reply #13 on: 04 June 2021, 16:11:44 »
Does it make sense for any planet to have aerospace forces in this regard?  I'm thinking ground-based surface-to-orbit weapons and conventional aircraft would be an effective defense for a lower cost than space-going ships and fighters.  You'd just have to make sure the weapons cover any orbital blind spots that may occur.

The problem is BT space-based weapons have very short range.  Assuming 60 hex maximum range for capital weapons, the problem is that each hex is only 18 km from face to face, so the mounting platform's diameter of coverage is 121 hexes (60*2 + the hex it is in), or ~2,178 km.  As a comparison, Earth's circumference is 40,075 km, so putting stations in LEO at the tip of each other's range means you would still need 19 of them.  They will not be able to support each other, so any attacker can overwhelm them one at a time.  That is even if the attacker chooses to engage them, instead of just going over them.  These combat stations will not be able to maneuver compared to an attacker's forces, so are effectively stationary targets.  Putting the weapons on a planet's surface has other issues, such as limited firing arcs (60 degrees, iirc), and atmosphere further reduces their range.

ASF and Small craft though (and combat Dropships) can maneuver, giving a carrier-style space station or ground base the ability to engage targets attacking anywhere around the planet.  You also have the issue that a heavy Naval PPC masses 3000 tons, while Aerospace Fighter Bays mass 150 tons (I add another 50 tons for spare fuel/supplies).  So if you could mount a single HNPPC or 15 ASF bays, the ASF bays would give you better coverage for dealing with enemy attacks.  Also, the HNPPC will do a total of 150 standard damage when it hits, so as long as each of the ASF can do at least 10 pts of standard damage they will equal the HNPPC in raw damage.

Space-going ships and fighters are be more expensive, but they also provide more coverage vs enemy forces.  Otherwise if you have an attacker in orbit (or even just their supply ship), your conventional fighters can never engage it, and it can avoid your ground to space weaponry (unless your ground to space weaponry can maneuver).  A small/concentrated enough population can still defend themselves with conventional aircraft, as the attacker only has one region they can profitably raid.  As the planetary population expands though (in numbers/area) there will soon be a need for fast response forces that are at least sub-orbital-capable.

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Re: Where do aerospace battles occur?
« Reply #14 on: 04 June 2021, 19:07:20 »
I think Cray wrote that sidebar in SO saying basically if you want to simulate real space combat, take your record sheets of each side and insert them into a shredder.

I did, but it was in the context of high speed closing engagements that might occur at thousands of hexes per turn. The StratOps rules for high speed closing engagements only multiply kinetic damage by small factors rather than a more realistic exponential increase.

Engagements headed in the same direction, like co-orbital battles to secure space dominance, aren't quite as lethal.

« Last Edit: 06 June 2021, 18:12:35 by cray »
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Bedwyr

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Re: Where do aerospace battles occur?
« Reply #15 on: 04 June 2021, 19:23:46 »
Engagements headed in the same direction, like co-orbital battles to secure space dominance, aren't quite as lethal.

Right. Which I suppose isn't a big ask for orbital inclination changes for magical fusion engines.

Also, tossing the paper into a shredder is it's own rule of cool.
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Re: Where do aerospace battles occur?
« Reply #16 on: 04 June 2021, 19:40:03 »
Shredders are cool right up until you have to do maintenance on them.  Some idiot in Baghdad didn't realize they'd dropped a nickel in the pile of papers they were trying to shred (when I fished it out of the machine, I taped it up next to the partially mangled blood chit some OTHER idiot had tried to shred... plastic is ALSO something you shouldn't feed them).  It was all the more infuriating because we didn't use coins there.  All the MWR facilities used these cardboard markers (called "pogs" by the younger troops) for small change (actual coins were too expensive to fly in).

marcussmythe

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Re: Where do aerospace battles occur?
« Reply #17 on: 08 June 2021, 16:04:18 »
Some years back I did a write-up on interception and forcing/denying engagement in Battletech Warship Engagements.. its from when I was helping run that Warship Arms Race....

Hmm - this is over a year old, and was based on some assumptions about average rolls, etc, but it may be a decent jumping off place for the question of 'where does the warship fight happen'.  For what its worth, way too much thought went into the engagements in the 'Warship Arms Race Redux' game, so it may have some decent examples of Btech space combat that was reasoned out rather than purely moving at the speed of plot - at least I think so!


A very simple Model of Space Combat

1.    Someone jumps in.  Defender probably knows.   Emergence Pulse will tell you where it is and how ‘noisy’ each thing coming in is… (in terms of size class and collar count, collectively).  Only way around this is to jump far enough out that noone picks you up.
     a.   Jump in at Apex/Nadir Point - Someone will see you and scream.  You probably get to blow them up.  Unless something nasty is waiting for you.  Youll get to the planet in a while, they will have warning.
     b.   Jump in outside limit, outside detection range.  No-one knows your here, stealth approach all the way to planet based on ballistic trajectory and desired time to reignite drives (zero-zero?  Overrun?  How much warning do you want to give them?  How much of a hurry are you in?)
     c.   Jump to a Lagrange or Pirate Point:  Depends on the point, but people likely know your here.  OTOH, you are closer to your target, less warning.

2.   Once you see an unknown jump in, defender's asset's drunkwalk and go quiet.  Once you jump in as a hostile, you probably drunkwalk and go quiet and look around at least a little.
     a.   Defender now likely knows someone is here, and has some idea what they have.
     b.   Attacker probably knows NOTHING, unless it has had scouting assets in the system (Tramp Dropship?  Bug-Eye?  Jumpship with LNCSS floating in the deep black?)

3.   Attacker is here to:
     a.   Invade - this implies a zero-zero on a planet. 
     b.   Attack Fixed Location Assets - zero-zero or high speed pass on the planet or infrastructure or common jump points. 
                Zero-Zero lets you wreck it all, but you face more defenders and response time.  High speed pass lets you raid it and
                get out and have some surprise hopefully.  How you approach this depends on target, and your assets.
     c.   Attack Mobile Assets - Good luck, unless you managed to hide your emergence wave and they weren't moving much.
     d.   Scout - Look around, avoid fights, maybe take targets of opportunity.


4.   Defender is here to:
     a.   Tripwire - see and report.  Probably stays quiet and listens to fixed sensors (Planets, Bases) screaming.
     b.   Protect Assets - probably was hanging out near those assets.
     c.   Protect Commerce - probably where commerce hangs out (Apex, Nadir, Lagrange Points, Planet


5.   Attacker may go ballistic (cut drive outside drive detection range)
     a.   Ballistic only works on targets of very fixed location - yards, planets, etc.
     b.   Ballistic probably gives you surprise, less if your emergence wave was detected.
     c.   Your more likely to miss your target/not have a good intercept - remember, you can’t manuver, and you don’t detect
                the target till your almost on top of it.  Hope it didnt move!


6.   Attacker may go Zero-zero
     a.   Attacker will be detected first, unless defender was also maneuvering (running back to planet in response to
                emergence wave, etc)
     b.   If both are under power, larger sensors and better crews help you detect first.
     c.   First detector may decline or try to force engagement.
     d.   If the first detector tries to force the engagement, it may do so if its thrust is equal or better the second detectors.
     e.   Fuel supply may matter

7.   Based on the above you can work out what sort of engagement if any is likely, based on situation and doctrine and target,
         as well as who detects first and what they can do with that information.

Underlying Assumptions for This Game:
(Numbers below assume average crew and rolls.  For purposes of this game I’m treating all rolls as 7 and all crews as average unless I’ve got a reason to do otherwise)


Incoming Infrared Jump Signature:
40 Kilometer Range, +10 per NCSS Level
450 Second Warning (20 Collars, 30 LY)
150 Seconds Warning (10 Collars, 30 LY)
15 Seconds (0-1 Collar, 30 LY)
2 Seconds (0-1 Collar, 4LY)
0 Seconds (in system)

Emergence Pulse  (1au=150m km, Sol Jump Point is about 12 au out)
Typically Detect a minimum target at 5 au
+2au per NCSS Level
+1au per size class
+1au per 5 collars

Drive Plumes:
20m km, +5m km per NCSS Level, check 1/hr.

Tracking Radar (active) vs passive target
40,000km vs Large Craft, +10,000km per NCSS Lvl.  10,000KM=555 Space Hexes
4,000 km vs Small Craft, +400km per NCSS lvl

Tracking Radar (passive or active) vs active target:  1m KM, x2 or 3 for NCSS

Targeting Radar (active only) targeting data and autodetect to 10k km for large and 1k km for small craft
x2/3 for NCSS

Thermal Optical Tracking (passive)
25,000km vs LC, +2,500 k km per NCSS Lvl
2,500 km vs SC, +250km per NCSS Lvl

Thermal Optical Targeting (passive)
targeting data and autodetect to 2.5k km for LC and 250km for SC

Targeting Needed for all Weapons Fire EXCEPT Bearings Only Missiles
« Last Edit: 08 June 2021, 16:28:57 by marcussmythe »

Daryk

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Re: Where do aerospace battles occur?
« Reply #18 on: 08 June 2021, 17:07:15 »
*snip*
1.    Someone jumps in.  Defender probably knows.
*snip*
I was in another thread where one of TPTB exploded that notion.  That's true at the "normal" jump points (and the most likely pirate points), but that leaves a truly huge volume of space where it's not true at all.

marcussmythe

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Re: Where do aerospace battles occur?
« Reply #19 on: 08 June 2021, 19:42:37 »
I was in another thread where one of TPTB exploded that notion.  That's true at the "normal" jump points (and the most likely pirate points), but that leaves a truly huge volume of space where it's not true at all.

I.. could have sworn I discussed it right after that?  Most typical points, (Nadir, etc.) your caught.  Pirates maybe.  Deep Space almost certainly not.  I didnt detail the 'jump limit but not at typical points' condition, but that's going to depend on a LOT of things.  How crowded is the system?  How spread out is development?  How big is my incoming footprint (we were mostly concerned with major naval actions - 10+ warships on a side, with further jump-ship consorts... driving the range of the Emergence Pulse far beyond the 'Scout Jumpship with a Leopard on the Side' 5AU condition).

In retrospect, I think its likely that we dismissed the 'jump limit at non-standard point' for an attacker because our forces were so large (and systems of interest so well defended) that the pulse at the jump limit would be detectable, so why not just land at the standard jump point and pick up the free enemy jumpships.


Charistoph

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Re: Where do aerospace battles occur?
« Reply #20 on: 10 June 2021, 11:57:27 »
I.. could have sworn I discussed it right after that?  Most typical points, (Nadir, etc.) your caught.  Pirates maybe.  Deep Space almost certainly not.  I didnt detail the 'jump limit but not at typical points' condition, but that's going to depend on a LOT of things.  How crowded is the system?  How spread out is development?  How big is my incoming footprint (we were mostly concerned with major naval actions - 10+ warships on a side, with further jump-ship consorts... driving the range of the Emergence Pulse far beyond the 'Scout Jumpship with a Leopard on the Side' 5AU condition).

In retrospect, I think its likely that we dismissed the 'jump limit at non-standard point' for an attacker because our forces were so large (and systems of interest so well defended) that the pulse at the jump limit would be detectable, so why not just land at the standard jump point and pick up the free enemy jumpships.

Indeed.  It is far easier to jump in at nadir/zenith because flight times are known and catalogued and all you need to know is the star's type.  For any other point, those things require almost intimate knowledge of the solar system itself, including "deep space" which can vary from system to system.

If one wanted to get really tricky, one could pop out in such a way that the Emergence Wave is hidden by something like a gas giant (or if you really like to travel, the sun), but that would only guard against those on the planetary plane, and not by units at the zenith/nadir points.
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