System Tactics

[Ulsyus]

Has anyone used a diagram of a system to track movement and encounters between ships or squadrons? Something that allows a ref to plot movement between planets, belts, L-N’s, standard routes, jump points, etc.

 

[mike wightman]

I use the map from Renegade Legion Prefect - do a google search with those keywords and then click on images.

The fleet maneuver chart in MgT HG2e is similar.

 

[whartung]

Has anyone used a diagram of a system to track movement and encounters between ships or squadrons?

This is a first class concept in Starfire. Their system hex map is a 15 Light-Minute hex. That kind of places Mercury, Venus, Earth, and the Sun all in the same hex in the center, and Pluto 21 hexes from the Sun, just to give you a scale. They combined two standard play maps, and map the system out as a 60 map hexes in diameter. (With the sun in the center, Pluto is 9 hexes from the edge of the map).

Just to give you a sense of scale.

Star Systems are Space, and Space is big.

If you accelerate at 1G for 24 hours, and travel at that velocity, you move a bit more than 4 light-minutes per day.

If you make that a hex size, 4 light-minutes per hex, 1 day per turn, Pluto ends up about 85 hexes from the Sun. Earth ends up 2 hexes from the Sun. Mars, 3 hexes, Jupiter 11, Saturn 20.

The problem is that the outer system planets are WAY out there, and inner system is "tiny" in comparison. Get a map large enough to show the entire system, and your inner system gets squished.

Fifth Frontier War, of course, does not use a tactical map. The issue there is that 99.9999999% of system space is spectacularly uninteresting. So, you just abstract it all away. "Nothing matters until the fleet gets to the main planet".

I've advocated that, under 5FW, there should be "destination boxes" for "the gas giants", and "the main world". If you were to travel by normal space, the gas giants are roughly a week of maneuver away anyway, so you can either "fly" or "jump". If you have your defenses on your main world, you're not going to be able to reach a refueling fleet at the gas giants in time anyway. By the time you get their, they're ready to jump out. So, you should, in theory, provision forces to defend "the gas giants", as well as the main world. And I say "the gas giants" as, it's just too much detail to track their relationships to each other. Having to defend several gas giants, boy what a mess that would be.

The other problem is that if you're using "days" of acceleration as a scale, you need "days" of deceleration to decelerate.

Imagine a 1G fleet accelerating from Jupiter to earth (8 hexes). First turn, they're 1 hex. Second turn they're 2 hexes, for a total of 3. They coast the 3rd turn (now 5 hexes), and decel to earth over the next 2. The defending fleet, "racing" to meet them, they meet in the middle. 2 turns (days) of acceleration. Mayday, in "hex" terms, a 10,000km hex. The closing speed of the fleets, in Mayday terms is 355 hexes per turn.

Anyways, I'm rambling again..."There he goes again..."

 

[kilemall]

That closing speed can be a suicidal way for a small force to sacrifice itself to gut a larger one, assuming you model kinetic damage.

 

[whartung]

That closing speed can be a suicidal way for a small force to sacrifice itself to gut a larger one

Seems unreasonable.

They're closing at ~3.5M m/s. A Tigress, is roughly 80 meters in diameter. So, any error of greater than 2 microseconds, and your aim is probably off.

However, to be fair, a grain of sand at those velocities imports about 95MJ of energy. Which is not nothing. So, as you pass by fire off all of your sandcasters.

 

[mike wightman]

That's only the equivalent of a 24kg warhead, would that get through the armour of a Tigress?

 

[kilemall]

That's only the equivalent of a 24kg warhead, would that get through the armour of a Tigress?

That’s one grain of sand. To do the reflection voodoo it do, has to be a fairly coherent cloud.

 

[kilemall]

Seems unreasonable.

They're closing at ~3.5M m/s. A Tigress, is roughly 80 meters in diameter. So, any error of greater than 2 microseconds, and your aim is probably off.

However, to be fair, a grain of sand at those velocities imports about 95MJ of energy. Which is not nothing. So, as you pass by fire off all of your sandcasters.

Key to the whole thing is trailing scouts providing final targeting. The missiles and beams need to be firing before they can even detect directly.

 

[Tobias]

Seems unreasonable.

They're closing at ~3.5M m/s. A Tigress, is roughly 80 meters in diameter.

I don't think that's correct. A sphere of 500 kdtons would be 234 meters in diameter. Tigress, while not being a perfect sphere, should be in that general ballpark.

 

[Ulsyus]

This is a first class concept in Starfire. Their system hex map is a 15 Light-Minute hex. That kind of places Mercury, Venus, Earth, and the Sun all in the same hex in the center, and Pluto 21 hexes from the Sun, just to give you a scale. They combined two standard play maps, and map the system out as a 60 map hexes in diameter. (With the sun in the center, Pluto is 9 hexes from the edge of the map).

Yeah, I have Starfire (old and newer versions) and while this is a nice simple way to represent things, as you mentioned it has a lot of empty space. Plus, I don't have the skills to write script to show where the locations of planets are in their orbits at any particular points in time (AND that'd be going OTT for my game), so things would be rather static

I've advocated that, under 5FW, there should be "destination boxes" for "the gas giants", and "the main world". If you were to travel by normal space, the gas giants are roughly a week of maneuver away anyway, so you can either "fly" or "jump". If you have your defenses on your main world, you're not going to be able to reach a refueling fleet at the gas giants in time anyway. By the time you get their, they're ready to jump out. So, you should, in theory, provision forces to defend "the gas giants", as well as the main world. And I say "the gas giants" as, it's just too much detail to track their relationships to each other. Having to defend several gas giants, boy what a mess that would be.

That's the option that I was leaning in favour of, but wanted to see what else people had thought of. Given this is all in aid of getting miniatures onto a tabletop, I'm fine with abstracting some of this process out in order to make pushing miniatures around happen more easily.

The other advantage of using this method is that it still allows for meeting engagements as you've described, but they're short and potentially brutal, so would need some mechanics around the idea to both enable and constrain them.

 

[whartung]

I don't have the skills to write script to show where the locations of planets are in their orbits at any particular points in time

That's not that hard.

The orbital period for a planet is calculated by:

T = 2 * pi * sqrt(r / G * M)

T is the orbital period in seconds.
G = Gravitational Constant (6.673e-11)
m = mass of the thing you're orbiting around (the sun, for example)
r = orbital radius (just assume a circle)

The suns mass = 1 solar mass = 1.9891e30 kg

The earths orbit = 1au = 149.6 Mkm, 1.496e11 m

T = 2 * pi * sqrt(1.496e11^3 / 6.673e-11 * 1.9891e30)
T = 31556467 s. Divide by 3600 for hours, 24 for days and you get 365.24.

Once you have the orbital period, take your date, say Imperial 100-1105. Imperial years are 365 days (365 * 24 * 3600 seconds).

So, this is (year * 365 + day) * 86400 seconds. Divide that by 31556467 (our orbital period) and we get: 1104.557.

That .557 means that we're "55.7% through the annual orbit". So, multiply that by 360 = 200.52 degrees.

That's where the planet is.

In a single formula, given a year, day, primary mass, and planetary orbit:

orbital position = ((Y * 365 + D) * 86400) / 2 * pi * sqrt(r / G * M), take the fractional part of that (=MOD(x, 1) in Excel) * 360.

And you're absolutely right, 99.99% of the time, it does not matter. But if it did, the math isn't that hard.

 

[Ulsyus]

And you're absolutely right, 99.99% of the time, it does not matter. But if it did, the math isn't that hard.

You're right, and thanks for all of that!!

 

[Enoki]

Given how big space is, and the likely very short range of sand--after all it's for the ship firing its protection--that it'd be more of a threat to other friendly ships in formation than any hostile vessel a gazillion (highly technical term there) kilometers away.

 

[Spinward Flow]

Actually, anyone paying attention beyond the "immediacy" of a combat situation would pretty quickly recognize that ANY DEBRIS (and both sandcasters and missile launchers "chuck debris") from a combat engagement in space will result in long term navigation hazards.

Expended "sand" from sandcasters doesn't ... despawn ... when the combat is over.
It stays in orbit ... until it hits something.

Here is what this kind of thing looks like with debris thrown off by comets in the Terra system (including Haley's Comet):

Are those debris fields going to be a hazard to navigation?
Technically, yes. It's why Terra gets "regularly scheduled meteor showers" every single year.

Now, obviously a sandcaster is going to expend A LOT LESS debris than a comet can ... but the principle is the same. The only meaningful difference is in terms of scale (and location and velocity).

So although the BENEFITS of use of sandcasters is relatively short lived, the navigation hazards that they can produce can potentially last a very long time indeed.

 

[Baroun Tardis]

Actually, anyone paying attention beyond the "immediacy" of a combat situation would pretty quickly recognize that ANY DEBRIS (and both sandcasters and missile launchers "chuck debris") from a combat engagement in space will result in long term navigation hazards.

Expended "sand" from sandcasters doesn't ... despawn ... when the combat is over.
It stays in orbit ... until it hits something.

Here is what this kind of thing looks like with debris thrown off by comets in the Terra system (including Haley's Comet):

Are those debris fields going to be a hazard to navigation?
Technically, yes. It's why Terra gets "regularly scheduled meteor showers" every single year.

Now, obviously a sandcaster is going to expend A LOT LESS debris than a comet can ... but the principle is the same. The only meaningful difference is in terms of scale (and location and velocity).

So although the BENEFITS of use of sandcasters is relatively short lived, the navigation hazards that they can produce can potentially last a very long time indeed.

I would think, though, that at the TL's we're talking about, it would be a trivial excersize to take a bunch of parachute size pieces of plastic, weighted and spinning so they spread out nicely, and dump them in the path of the sand such that the relative impact speed is low enough to scoop up the debris without destroying the scoop.
It'd be relatively expensive, and probably only done on approach paths to high usage ports where it would make a meaningful difference.

 

[whartung]

Are those debris fields going to be a hazard to navigation?

That's a valid point, and I think it should put a "rule of thumb" limit to how fast someone should pilot a ship.

Specifically, there is a limit to how much your armor can withstand a micro meteorite impact.

At 1G, a grain of sand starts reaching .50 Caliber bullet energy (20KJoules) between 1.5 and 2 days of acceleration.

At 1G to 100D of Earth, we're looking at 187J of impact energy, a 9mm is about 480, as comparison. I wouldn't want to be hit by it, but the simplest of armor should handle that readily.

At 6G to 100D of Earth, you're looking at 1115J of energy.

So, the task is what's a reasonable amount armor for a civilian trade craft. And, to be fair, perhaps the nose is doubly armored just for this use case, and also, the nose shape affects this as well. But, still, there will be some limit -- and that will limit the speed a craft can safely travel, regardless of their acceleration. And, obviously with the hope that they don't get hit in the same spot twice. You can certainly travel at higher speeds, but the likelihood of a penetrating impact becomes higher.

It's an interesting maintenance problem as well. As part of the annual maintenance, the front armor of a ship may need to be replaced as it can just be ablated over time by micro meteor impacts. That said, at a certain level, for the primary use case (i.e. 100D travel to jump), there's some level that's just "enough" and, effectively immortal. But it still must be inspected.

So. Simply, largest particle that's reasonably worth protecting against, and how fast can you travel given your armor where that particle is no- to low-risk of penetration. Those should just be standard design guidelines for civilian craft.

And, to the overall point, it may not be a hazard to navigation. Rather, it's simply an accepted aspect of space travel and designed around.

 

[kilemall]

One of the things that makes our ships different then RL current craft is lack of concern for weight and corresponding effectively armored hulls relatively speaking.

So orbital velocity sand for ships orbit/entering and leaving atmo is probably no big deal, maybe sensitive sensors or exposed EVA at worst. OTOH, they also get some velocity going prior to those mid course flips, so may be more dangerous in flight.

 

[Spinward Flow]

I would think, though, that at the TL's we're talking about, it would be a trivial excersize to take a bunch of parachute size pieces of plastic, weighted and spinning so they spread out nicely, and dump them in the path of the sand such that the relative impact speed is low enough to scoop up the debris without destroying the scoop.

Actually what you would want to use is a Repulsor Bay or other "gravity field projector" type of device to "gather up" any ... litter ... that might be clogging the space lanes. Not exactly a street sweeper, but you get the idea.

If your craft can match velocities with a debris field, you can use a projected gravity field to "scoop" that debris up and remove it from orbit.



Obligatory shout out to the anime Planetes and the criminally underpaid crew of the Technora Debris Section ...

 

[Condottiere]

You have to use those cargo scoops and nets on something.

 

[kilemall]

That's a valid point, and I think it should put a "rule of thumb" limit to how fast someone should pilot a ship.

Specifically, there is a limit to how much your armor can withstand a micro meteorite impact.

At 1G, a grain of sand starts reaching .50 Caliber bullet energy (20KJoules) between 1.5 and 2 days of acceleration.

At 1G to 100D of Earth, we're looking at 187J of impact energy, a 9mm is about 480, as comparison. I wouldn't want to be hit by it, but the simplest of armor should handle that readily.

At 6G to 100D of Earth, you're looking at 1115J of energy.

So, the task is what's a reasonable amount armor for a civilian trade craft. And, to be fair, perhaps the nose is doubly armored just for this use case, and also, the nose shape affects this as well. But, still, there will be some limit -- and that will limit the speed a craft can safely travel, regardless of their acceleration. And, obviously with the hope that they don't get hit in the same spot twice. You can certainly travel at higher speeds, but the likelihood of a penetrating impact becomes higher.

It's an interesting maintenance problem as well. As part of the annual maintenance, the front armor of a ship may need to be replaced as it can just be ablated over time by micro meteor impacts. That said, at a certain level, for the primary use case (i.e. 100D travel to jump), there's some level that's just "enough" and, effectively immortal. But it still must be inspected.

So. Simply, largest particle that's reasonably worth protecting against, and how fast can you travel given your armor where that particle is no- to low-risk of penetration. Those should just be standard design guidelines for civilian craft.

And, to the overall point, it may not be a hazard to navigation. Rather, it's simply an accepted aspect of space travel and designed around.

I have a thread on this. The parameters I came up with are a combination of the detectable range of the objects, size of objects affecting both detection and amount of vee needed to avoid, vee of objects and ship, and of course the g rating of the ship to put on a quick accel to avoid.

If the object is say 1km wide, at most that is a minute to clear it and any associated debris. Something that big should give plenty of warning.

The problem would come with multi kilometer wide meteor swarms, especially if somehow they are made up of low detectable material (what is the detection range of ice?). Or with a sufficiently small object that makes detection a close range affair, but with a corresponding low level of impact.

Most objects should be time neutral, but head on encounters of both object and ship on can cut down reaction time.

The other quantification is damage if impact occurs. I would think basing on missiles would do, with vee increases/decreases like the missile supplement. Armor should be a factor that may lessen or eliminate lower impact hits.

I envision normal routine to be using the Evade program during maneuver to automate the reaction avoiding debris. You don’t want a pilot stim break to threaten your ship.

A similar issue comes with space weather such as star flares and CMEs that are to be avoided. Many of those phenomena are going to be easier to detect, but more of a long maneuver to avoid, since they can be huge. Similar issues re detection/G but on the scale of hours. In that case your vee limit would be about risky areas closer into stars.

Damage quantification should probably be plasma/PA weapon-like. Armor and/or rad shielding should help- no idea if nuclear dampers can be set wide enough to mitigate a flare that is several times wider than the ship. I would probably rule that it’s a unique separate version of ND that typically only goes to inner planet specialized ships.