General You Turn off Gravity on the Ship: How Long Before Hilarity Ensues?

[Hairy Jim DeGriz]

I ran a homebrew scenario where the PC Pilot was being forcefully relieved of command by the Security Officer (SO). The ship was depressurized to retrieve orbiting objects, and the Security Officer’s stunner failed to penetrate the vacc suit or disable the pilot. The pilot then turned off the gravity on the next turn and started to roll the ship on the third turn.

Since a personal combat round is 6 seconds and a starship combat round is 6 minutes (60 personal combat rounds), I house ruled that shutting down the artificial gravity was 1) was not an instantaneous change and 2) would cause a general alarm to be sounded on the ship, before the gravity was switched to zero. The pilot made a routine electronics check (6+) and I house ruled that if he succeeded with an effect of 4+ he could shorten the shutdown time.

This gave everyone a chance to make at least one saving throw to grab something (a significant action) when the alarm sounded. The SO missed her DEX throw to grab hold of something.

Q 1. Are there any written rules official or unofficial that cover the operation of ships systems and how long actions take?

Q 2. Any thoughts on how long it would take to turn off all of the circuits running the anti-gravity? I think it might be related to the size of the ship?

The pilot succeeded, and the artificial gravity was shut down in 1 personal round (6 sec.), which in retrospect seems too short. The SO failed her next saving throw and was thrown into the wall, as the ship began to roll. Here I thought maneuver thrust in 0-gee would affect the ship in 6 seconds, but welcome anyone with a greater understanding of physics to please comment.

Later on, one of the PCs got into a turret, which had not been powered up. In space combat rounds it takes 6 minutes to make one attack, which I would guess largely consists of targeting and building up power in the weapon (or powering the launch system for missiles and sand).

I did not allow the PC to fire the weapon “while it was powering up” - for the duration of personal combat, which was over in less than 6 minutes. However, I did allow them to use the sensors and targeting, which enabled them to “attract the attention” of another spacecraft.

Q 3. If a boarding action is raging around a turret gunner, when would you expect the turret to attack, in the sequence of personal combat? After D6 x n personal rounds? During the second personal combat round? (sensors check, then trigger)? After 30 personal combat rounds (3 minutes)?

The final question revolves around opening an Iris valve when one side is pressurized and the other is not pressurized. Once the PC succeeded on their electronics check to override the door’s opening mechanism, I ruled that there would be a 30 second warning before the door opened, which now seems to short. But 5 combat rounds worked well for dramatic effect. I considered making it one personal combat round if they rolled a 12 or effect +6.

Q 4. How long does it take to open an Iris valve if the sensors detect atmosphere on one side but not the other? Can it be opened or does it need to be breached?

The main lesson I learned is that combat in space is very complex, you have to account for numerous other variables including artificial gravity, the movement of the ship, unsecured cargo that shifts, change in atmosphere, and creative PCs.

 

[Grav_Moped]

You're talking MgT, which affects things a bit.

IMTU (CT with later stuff dragged in for ambiance or detail), there'd be a difference between setting artificial gravity to zero, disabling the inertial compensation, and simply shutting the whole grav-comp system off entirely.

A complete shutdown would be quick (pull the breaker, even if it's virtual).
Setting gravity to zero would take a few seconds because of safety interlocks.
Similar interlocks on the inertial compensation would have a longer delay.
Invoking anti-hijack gravity control games would be very quick.

 

[Hairy Jim DeGriz]

You're talking MgT, which affects things a bit.

IMTU (CT with later stuff dragged in for ambiance or detail), there'd be a difference between setting artificial gravity to zero, disabling the inertial compensation, and simply shutting the whole grav-comp system off entirely.

A complete shutdown would be quick (pull the breaker, even if it's virtual).
Setting gravity to zero would take a few seconds because of safety interlocks.
Similar interlocks on the inertial compensation would have a longer delay.
Invoking anti-hijack gravity control games would be very quick.

I'm looking for anyone's thoughts on these processes, regardless of system. define "very quick" in game terms: 6 seconds? 1D6 x 6 seconds? Lives are at stake here!

 

[Grav_Moped]

I'm looking for anyone's thoughts on these processes, regardless of system. define "very quick" in game terms: 6 seconds? 1D6 x 6 seconds? Lives are at stake here!

"Very Quick": How fast can you type or vocalize the command to do so -- including whatever security/safety override command you're using? The lag time isn't in the controls or system. (Has to be -- inertial comp reacts quickly enough that it can't have significant lag.) Once it has confirmed that it's really authorized and directed to shut it off, it's off.

The RPG delay on this is whether the rest of the personnel present recognize the command to shut it down in time to take individual action.

 

[kilemall]

I’d say the authorization chain for such a shutdown would be a key part of time implemented, along with safety protocols based on what type of ship.

In general, the smaller the ship the shorter the authorization and time (say pilot or engineer instantly on a scout, any two of pilot/engineer/troop commander/captain in 30s on a Type C or SDB, 1-2 officer plus captain on bigger boat 1m or less).

In addition, the function of the boat may up the time involved or people to okay. In particular passenger or troopships may require the chief steward or troop commander time to secure their charges.

 

[Grav_Moped]

I’d say the authorization chain for such a shutdown would be a key part of time implemented, along with safety protocols based on what type of ship.

Agreed if using normal protocols. There may be a contingency safety-override capability. It may or may not be documented.

 

[Spinward Flow]

Q 1. Are there any written rules official or unofficial that cover the operation of ships systems and how long actions take?

Rarely. It's mostly left up to Referee discretion.

Q 2. Any thoughts on how long it would take to turn off all of the circuits running the anti-gravity? I think it might be related to the size of the ship?

As long as it takes to enter the command into the computer and execute it.
Once the command is given and authenticated, the "Gravity OFF Switch" is as fast as flicking off a light switch.
So the only real time consuming part of the action is the user interface.

Q 3. If a boarding action is raging around a turret gunner, when would you expect the turret to attack, in the sequence of personal combat? After D6 x n personal rounds? During the second personal combat round? (sensors check, then trigger)? After 30 personal combat rounds (3 minutes)?

The turret would need to be powered up in order to "do" anything at all.
"Booting up" a turret from a shut down condition should not be instantaneous. To give you a classical TV example, there's a delay between a ship's captain calling battle stations/general quarters and when the bridge officer reports to the captain that all weapon systems (phaser banks?) are manned and ready.

There's also the question of whether the use of the turret is intended to actually hit (and damage) anything else. If the weapons in the turret are being used to signal distress (firing wild, basically) then that would take a lot less time. If you're talking about a target acquisition/lock on sequence intended to trigger warning sirens in another craft (to get their attention), that would take a lot longer.

Q 4. How long does it take to open an Iris valve if the sensors detect atmosphere on one side but not the other? Can it be opened or does it need to be breached?

An iris valve opening and closing (the motion) should take about ~6 seconds if the pressure is equalized on both sides.

If there is a pressure differential, it's not just a matter of "open up anyway!" manual override because the pressure differential could be jamming the operation of the iris valve causing friction to lock the iris sections together against each other (safety precaution engineering). If you DO manage to force the valve open with a pressure differential on the two sides, you're going to get a "decompression event" through the valve (if it opens). If that pressure differential is 1 bar (standard atmosphere) vs 0 bar (vacuum), you're looking at a "blowout" condition due to the pressure differential (NOT recommended). At that point, you're more into the realm of breaching (and all the hazards that implies) rather than just simply opening.

 

[Enoki]

I would add, that as the ship gets larger, the grav system isn't one thing, but broken into various areas. This would be done to prevent total loss of the system from some sort of equipment failure. Thus, on a larger ship, you would have to shut down multiple areas, and it is very possible that all areas are not controlled from the bridge. I'd think that was particularly true on a ship intended for combat / military use. You don't want total centralized control to avoid some system being taken out in a single hit.

As for atmosphere versus vacuum in hatch opening, I'd say this depends. For something like an airlock, I'd think there were several (multiple) interlocks between the inner hatch and outer one that require specific conditions to be met to open or close them. If it were me devising such a system, I'd make up a 'ladder logic' chart like are used in industrial controls.

That would tell me whether it is possible or not to do what the players want to do.

 

[mike wightman]

The artificial gravity can be varied from stateroom to stateroom. Acceleration compensation would have to be for the whole ship though.

Standard passenger comfort demands a certain level of amenity in the stateroom...
Grav plats can be adjusted to provide a range from 0.0 to 1.5 G for personal
comfort.

Also if you switch off main power the artificial gravity defaults to 0g

The Annic Nova has this to say:

A prominent power-on switch is situated on the bridge; and another is on the cantilever platform at the rear which will turn power on (but cannot turn power off ). Power-on puts all interior lights on and activates the grav plates.
When the grav plates go on, any individual not specifically stating that he or she is standing with feet on the floor, or sitting in a chair, is subject to a fall.
Each must make either a Dexterity + Vacc Suit or Athletics (coordination) or fall. If the fall occurs, the individual takes 2D damage.

Implies it is pretty quick to come on so I would assume it is just as quick when you switch it off.

 

[Hairy Jim DeGriz]

Thanks all, additional input welcome.

1. Sounds like there's no rules in one place, but some questions may be addressed in adventures.
2. One combat round under emergency circumstances is not unreasonable. Maybe like a bank teller's silent alarm button? I'm thinking when the bridge officer initiates the process, they get a [Routine] or [Emergency] > [Emergency: Are you SURE?] prompt? [Routine] could be up to six minutes, for everyone to get in position, and [Emergency] could be at the end of the personal combat round. But as @Enoki points out bigger ships would have more compartmentalization. On ships under 2k tons?
3. Would you ever fly with 0 power in turrets? @Spinward Flow brings me back to the question what happens in those 6 space combat minutes between each attack? I'm thinking turrets are always in low power mode, especially coming out of jump space, and as soon as you "Turn on the lights" they start powering up, creating a power surge which is detectable by other spacecraft sensors? "Sir, they're powering up their phasers!" At the same time, how much power does an active (or passive) sensor array need to start identifying targets?
4. The Iris Valve, I seem to recall that in some LBB, the difference in pressure caused them to lock tighter, thus requiring a breach. Whereas, correct me if I'm wrong, a hatch would blow open (creating a depressurization event) if it were unlocked, and opened into an unpressurized area. Or is it the other way around?

 

[Grav_Moped]

Would you ever fly with 0 power in turrets?

It's probably the default for liability reasons.

Boot-up time should be (should -- rules may say otherwise) under one personal combat turn. On the other hand, going from "will fire in the direction it's currently pointed" to "bogies 1-n are in the immediate field of fire" to "that particular bogie is a hostile" and then "target locked, fire" would take a bit longer. 6 seconds for each step?

 

[Spinward Flow]

3. Would you ever fly with 0 power in turrets?

Emergency Agility means the only "weapons" that you can fire are Sandcasters (because they're defensive only). Missiles and Lasers are powered down and inoperable under Emergency Agility conditions.

In terms of non-combat, turrets are very likely to remain powered down until needed. Since the CT combat systems (LBB2 and LBB5) orient around ship-to-ship combat, they don't really go into detail concerning what's going on with turrets (and the powering thereof) when a craft is not at battle stations. For later versions of Traveller where Pop-up Turrets become a thing, it's even easier to assume that turrets which are "stowed" (to surprise/deceive an adversary scanning your ship) are powered down until needed.

Obviously, a "warm boot" of a turret would be faster than a "cold boot" from a shutdown condition (so 3-5x longer to make ready from a powered off condition).

4. The Iris Valve, I seem to recall that in some LBB, the difference in pressure caused them to lock tighter, thus requiring a breach.

LBB S7, p7:

Valves are very difficult to force open once fully closed. Throw 9+ to force open a closed iris valve; DM +1 if strength 10+, +2 if dexterity 10+, -3 if the person is in vacc suit, +2 if ship power is off, -8 if locked. Gunfire and explosions will simply block the valve tighter. lris valves close automatically when a pressure difference is sensed between the two sides of the bulkhead.

Simplest assumption to make is that if there is a pressure differential, across the bulkhead, the iris valve is "locked" automatically.
Throw 17+ on 2D if ship power is on (good luck!) ... or throw 15+ on 2D if ship power is off (good luck!).

If an iris valve is locked (due to a pressure differential), ship power is off, you have STR: A+ and DEX: A+ and are not wearing a vacc suit ... you can successfully open an iris valve with a Throw of 12 on 2D. Problem is, if you succeed, you're getting sucked through that iris valve, which will almost certainly NOT be a pleasant experience (because you aren't wearing a vacc suit!).

 

[Hairy Jim DeGriz]

I knew @Spinward Flow would have a good answer

If an iris valve is locked (due to a pressure differential), ship power is off, you have STR: A+ and DEX: A+ and are not wearing a vacc suit ... you can successfully open an iris valve with a Throw of 12 on 2D. Problem is, if you succeed, you're getting sucked through that iris valve, which will almost certainly NOT be a pleasant experience (because you aren't wearing a vacc suit!).

I think there may be an earlier, less detailed rule to this effect, but this matches my recollection:

LBB S7, p7:

Valves are very difficult to force open once fully closed. Throw 9+ to force open a closed iris valve; DM +1 if strength 10+, +2 if dexterity 10+, -3 if the person is in vacc suit, +2 if ship power is off, -8 if locked. Gunfire and explosions will simply block the valve tighter. lris valves close automatically when a pressure difference is sensed between the two sides of the bulkhead.

 

[Condottiere]

1. If weapon systems are hot and the gunner on alert, you probably could fire it off in the same round without penalty, as compared to a snapshot.

2. As regards to gravity, there are probably serious safety protocols, if you can vary between zero and ten gees; commercially, I wouldn't have thought more than two.

 

[Grav_Moped]

1. If weapon systems are hot and the gunner on alert, you probably could fire it off in the same round without penalty, as compared to a snapshot.

MgT let's you do hasty or cautiously-slow tasks. This could come into play here.

 

[Condottiere]

Could be a continuing task chain, though not quite like delayed aiming, since the target is yet to be stated.

 

[Spinward Scout]

Maybe it's in the MegaTraveller Starship Operations Manual. I'll take a look later.

But here's my take:

First Combat Round
1.) Pilot Attacked with a Stunner
2.) Stunner didn't affect the electronics of the VACC Suit?
3.) Pilot moves to engage Console

Second Combat Round
1.) Pilot turns off Ship's Gravity
A.) Selects Command Functions on Console
B.) Selects Emergency Gravity Null
C.) Pilot inputs Command Override (if they have Command Access)
D.) Screen Warning to Abort - Selects Continue
2.) Security Officer does ?
3.) Ship Intercom sounds a Warning and Warning Lights flash

Third Combat Round
1.) Gravity begins to drastically lower
2.) Security Officer does ?
3.) Pilot starts to Roll the Ship

Fourth Combat Round
1.) Gravity is now Null
2.) Security Officer does ?
3.) Anything unsecured is now affected by Inertia from the Ship rolling

Fifth Combat Round
1.) Hilarity Ensues

An Emergency option to reduce the Gravity would definitely require a Command Override or take a lot longer to Bypass.

Anyone see anything wrong with that?

 

[mike wightman]

I still think grav plates turn off as fast as lights...

 

[Grav_Moped]

I still think grav plates turn off as fast as lights...

I agree that that they can, but in practice they don't unless there is a specifically prearranged override to bypass all the safety alerts and delays.

Even then, there's probably an automated "safety interlock override confirmed" announcement just before things shut off.

Depends on how the referee wants to play it.

 

[Condottiere]

There are no variable costs in spacecraft construction, in the minor details.

If I don't need ten gee gravity plates, why should I buy them if they (probably) cost more?

We know that one to zero would at best make you nauseous, but zero to one would be dangerous, considering kinetic impact; rate of change would likely be best about rate of falling safely to the ground, or deck in this case. Or floating down.