"High Guard" and fuel skimming

[whartung]

There's a meme about vulnerable fleets skimming fuel, a particularly dangerous operation that leaves them vulnerable, and thus necessitating the use of other ships flying overwatch, in the "High Guard" position, during the operation.

As a corollary, there's the heroic SDBs lingering, undetected, beneath the ammonia clouds of the Gas Giant and waiting to strike at invading fleets, perhaps just as they are starting to skim.

Yet I've not seen much documentation about the fuel skimming process, it difficulties, and how it makes ships vulnerable. Also, I haven't seen how SDBs (who are ostensibly in the same environmental conditions if not actually skimming themselves and perhaps even deeper in the gravity well) are I guess immune to the combat limitations of a skimming fleet, thus tilting the board in the SDBs advantage during this tricky time.

So, just curious about how this bastion of lore doesn't seem to have many mechanics tied to it.

 

[Andrew Boulton]

Skimming ships are on a predictable course, with limited manoeuvring options (due to the gravity and atmosphere).

 

[Orr]

Part of this predictable course is that ships skimming will have their flight performance envelopes greatly limited due to the fact they're in an atmosphere. The "thinness" of the atmosphere won't matter because of the hypersonic or greater speeds the ships are moving at.

The combination of great speed and an atmosphere means they will not be able to spin on their X, Y, and Z axis like they do in a vacuum without being destroyed by the atmospheric drag such a maneuver would create. When an enemy or missile is detected and unlike in a vacuum, a ship won't be able to reorient itself by any large amount and begin thrusting to produce a new vector without destroying itself in the process.

The presence of an atmosphere also means near misses can damage or destroy vessels as shock waves can now play. The explosion of warheads, meson gun bursts, and maybe even superheated columns of within the atmosphere created by energy weapons can produce shock waves which directly damage ships or, more dangerously, cause a ship to slightly tumble and then be destroyed by atmospheric drag.

 

[shadowcat20]

As for High Guard, If the fleet does have to cut and run, the skimming ships will have fuel. The High Guard will be a last stand to allow them to get away.

 

[Major B]

All the above fits the way I understand it.

The SDBs still suffer the same disadvantages of being in the gravity well as well as the vulnerabilities of being in atmosphere. Their advantage is that from this position they can hide from sensor scans until the time comes to exploit the vulnerability of those skimming.

 

[whartung]

Ok, but how are these disadvantages manifested as game mechanics?

In B5, it's easy to see how the ships that are skimming are the ships not considered as part of the front line. The "High Guard" is the front line. (And the mechanics of the front line are very fuzzy to me, as it's been quite some time since I've read those rules.)

What benefits do nuclear missiles have should they hit ships that are skimming? What disadvantages do ships have for skimming? Are there any benefits for the skimming ships, say, to avoiding sensor lock on with them being so close to the planet. As a corollary, are they perhaps somewhat blinded to ships out in cleaner space? Do ships lose their Agility bonus while skimming (seems like a good simple mechanic)?

Since SDBs suffer from likely the same effects as the skimming ships, if not more so, then what advantages do the SDBs get overall? Free first shot of surprise? Able to hit the B5 reserve line directly (since they don't have to go past the "High Guard")?

How long do the ships suffer from the skimming affects?

Seems like the mechanic of 1 Turn establishing orbit, then the next turn they can start skimming, skimming can take as long as necessary (do pilots have to make continuing task checks, or simply once), and then they can break away whenever they want, suffering only the effects of the gravity well and it potential impact on future vectors.

Gas Giant skimming, the High Guard, and SDBs are notable chunks of Traveller lore, but I just haven't seen many rule effects on the entire process.

 

[HG_B]

The SDBs still suffer the same disadvantages of being in the gravity well as well as the vulnerabilities of being in atmosphere. Their advantage is that from this position they can hide from sensor scans until the time comes to exploit the vulnerability of those skimming.

Except, SDBs generally have a much higher power M-drive and are heavily armoured. Their ability to maneuver will be much greater than a ship skimming at hypersonic speed in atmosphere.

 

[Major B]

Except, SDBs generally have a much higher power M-drive and are heavily armoured. Their ability to maneuver will be much greater than a ship skimming at hypersonic speed in atmosphere.

To be effective in their mission they should be, but in this particular example (using the gas giant atmosphere for concealment) firing up the power plant for greater acceleration makes them easier to detect and target.

But that is how I've interpreted them working. Whartung's point is very valid here because in MT (my preferred rule set) the mechanics of the game do not necessarily model the points I've made here without modification.

I'm less familiar with HG and even less with regard to other rule sets so I wonder if other versions better model this scenario and the advantages/disadvantages brought up in this thread.

 

[HG_B]

To be effective in their mission they should be, but in this particular example (using the gas giant atmosphere for concealment) firing up the power plant for greater acceleration makes them easier to detect and target.

If they are in a GG their PP is already 'fired up'. Or, they have plunged to their death...

 

[Orr]

Ok, but how are these disadvantages manifested as game mechanics?

They aren't. I've got every Traveller starship combat game from Mayday to Brilliant Lances and none of them answer all or even most of your questions.

In B5, it's easy to see how the ships that are skimming are the ships not considered as part of the front line. The "High Guard" is the front line. (And the mechanics of the front line are very fuzzy to me, as it's been quite some time since I've read those rules.)

I found a file in the file section here about a B5 battle that explains some of those things.

What benefits do nuclear missiles have should they hit ships that are skimming?

I already wrote about shock waves upsetting flight profiles and producing catastrophic drag effects.

What disadvantages do ships have for skimming?

We've all mentioned many disadvantages.

Are there any benefits for the skimming ships, say, to avoiding sensor lock on with them being so close to the planet.

Most of the ship combat rules ignore sensors and those that do mention them don't mention much about sensors in a gas giant.

Do ships lose their Agility bonus while skimming (seems like a good simple mechanic)?

Yes. because of the limited flight profiles I posted before.

Since SDBs suffer from likely the same effects as the skimming ships, if not more so, then what advantages do the SDBs get overall?

They know where they are and where their targets likely are.

Free first shot of surprise? Able to hit the B5 reserve line directly (since they don't have to go past the "High Guard")?

I'd say yes to both.

Gas Giant skimming, the High Guard, and SDBs are notable chunks of Traveller lore, but I just haven't seen many rule effects on the entire process.

Well we don't know exactly what tactics grav tanks employ either and people still use them. :rofl:

 

[shadowcat20]

Keep in mind, SDB's tend to have M6 and heavy armor. I would assume this means they could go deeper into the planet without crushing and still be able to climb out of the gravity well. They could pop up and hit skimmers without being chased back down. Any damage at all would be a ship killer though.

 

[Major B]

If they are in a GG their PP is already 'fired up'. Or, they have plunged to their death...

The power plant only needs to be putting out enough power to the thrusters to maintain station. If they want to accelerate "upward" to attack then they need to increase power plant output which makes the SDB easier to detect with neutrino sensors.

But again, this is how I interpret the functioning of a power plant, a slight modification of the MT rule set. Others could interpret the rules differently by assuming the power plant is always functioning at full output so there will be no difference generated by the actions of the SDB.

 

[HG_B]

The power plant only needs to be putting out enough power to the thrusters to maintain station. If they want to accelerate "upward" to attack then they need to increase power plant output which makes the SDB easier to detect with neutrino sensors.

Hmm, which rule set is that in?

 

[Major B]

Hmm, which rule set is that in?

I pointed out the rule set in my post. Here it is again, and I'll underline it.

The power plant only needs to be putting out enough power to the thrusters to maintain station. If they want to accelerate "upward" to attack then they need to increase power plant output which makes the SDB easier to detect with neutrino sensors.


But again, this is how I interpret the functioning of a power plant, a slight modification of the MT rule set. Others could interpret the rules differently by assuming the power plant is always functioning at full output so there will be no difference generated by the actions of the SDB.

 

[Andrew Boulton]

This would make a good subject for an article for Challenge...

 

[HG_B]

I pointed out the rule set in my post. Here it is again, and I'll underline it.

The MT Fusion PP rules don't cover variable fuel usage based on how much you use your M drive. You pointed out a house rule you made. So, my point (from a rules perspective) stands as written. I'm not saying that it is a good or, bad house rule. Simply that it is one.

 

[E.D.Quibell]

The MT Fusion PP rules don't cover variable fuel usage based on how much you use your M drive. You pointed out a house rule you made. So, my point (from a rules perspective) stands as written. I'm not saying that it is a good or, bad house rule. Simply that it is one.

That's incorect.

There is no mention in the rules as to how the power plant is used, only "All craft need some source of energy to supply power to the installed components" RM Page 58. And the way to denote your duration at full power output. There is nothing in the rules that advocates for or against variable fuel usage based on the use of the M drive.

The rules govern the amount of power per unit of PP (down to fractions), and the fuel usage per unit of PP (down to fractions).

There is, however, a way to calculate the power required per G of Manueuver drive, given the number of Manuever drive units required against the hull displacment, and thus the fuel usage required per G of maneuver/hours (depending on the G output (It's non linear)).

So while I havn't looked into the particular details of this case there is nothing in the MT rules that disallows this, and if you wish to do the maths to work out the amount of fuel per g/day, g/hour or even g/minute there is a mechanisum for you to do so.

So while it may not be the most generaly accepted interpritation of the rules it certainly can be a valid and provable one.

Best regards,

Ewan

 

[HG_B]

That's incorect.

There is no mention in the rules as to how the power plant is used, only "All craft need some source of energy to supply power to the installed

Yep, as I stated, only a rule for full power usage. ANY other rule is a house rule.

 

[E.D.Quibell]

Yep, as I stated, only a rule for full power usage. ANY other rule is a house rule.

It doesn't say that.

Your interpretation seems to be for full power usage. However that is _your_ interpritation. It's not the rule.

Best regards,

Ewan

 

[HG_B]

It doesn't say that.

Your interpretation seems to be for full power usage. However that is _your_ interpritation. It's not the rule.

Best regards,

Ewan

Then, show me the rule for partial power usage, where are the tables or rules? Well?