Sensors in starship combat

[paltrysum]

I've run starship combat sequences a few times, but I have a few questions to confirm whether I've been doing it correctly:

• Based on the Starship Combat rules, it doesn't appear that you need a sensor lock to hit a starship with your weapons. That seems counter-intuitive to me, but are the rules attempting to indicate that you can always detect another starship (merely based on its physical presence) but the use of things like stealth, an emissions absorption grid, countermeasures, etc. make it difficult to get a sensor lock on an opposing ship? It would therefore be harder to hit, but you can still hit, even without a lock, right?
• If the above is the case, what does that imply for ships that use things like stealth, stealth jump, etc., that make detection difficult? If you don't need sensors to hit an opposing ship, are you really ever impossible to detect, or are you just difficult to get a lock on?

The primary sensors are radar and lidar, so the detection method is physical, meaning it doesn't matter whether or not you're running your fusion power plant to be detected. Typical sensor arrays are just detecting your physical presence by bouncing radio waves or light off your hull. However, at long range with your power plant turned off, you might be indistinguishable from a random asteroid, I suppose.

Any clarification would be helpful. Now that we're embarking upon "Pirates of Drinax," and starship combat will be common, I want to make sure I'm doing it right.

 

[AnotherDilbert]

You still need to detect a spacecraft to fire at it:

Under normal circumstances, an Electronics (sensors) check is all that is required to detect and identify a target that has moved into range of sensors.

The detecting ships sensor DM and skill are positive DMs, and the targets stealth DM is a negative DM, just as with the Sensor Lock roll.

If the target's transponder is active the target should be detected automatically, unless there is a planet in the way. Transponders are mandatory in Imperial space, but perhaps not around Drinax?

Then you can attempt to Sensor Lock a target with a separate roll, and the target can attempt break the lock (Electronic Warfare).


Note that in general Visual and Thermal sensors have the best range and will pick up the target first, not Radar (p150). If a spacecraft is using active Radar it's easier to detect it, DM+2 (p151). There is no advantage with turning on your Radar, it only makes you easier to spot.

 

[paltrysum]

Do you need to detect it once and then the ship is effectively one you can attack for the duration of combat? Or can you lose track of it and need to reacquire it on a round-by-round basis? I want to make sure I fully understand how stealth and other negative DMs affect your ability to hit a ship with your weapons during combat.

 

[AnotherDilbert]

The sensor rules are very simple, there is no mechanism to lose track or reacquire a target.

"has moved into range of sensors" hints at that you can't track at longer range than you can detect, so if a ship moves out of range and then reengages you have to detect it again.


Houserules:
If a stealthed ship is sneaking up on someone I allow a sensor roll for each range band it comes closer, with a DM equal to half the range DM to attack on p156 (Short +1 to Distant +3). If you know that someone is out there, e.g. because they talk to you or shoot at you, I allow one roll per round. Once you have seen them, you continue to see them.

 

[baithammer]

MB 2ed page 150.

Under normal circumstances, an Electronics (sensors)
check is all that is required to detect and identify a
target that has moved into range of sensors

So, yes there is still a requirement to detect and identify ships.

Further, there are two skill checks at play.

Sensors: The use and interpretation of data from
electronic sensor devices, from observation
satellites and remote probes to thermal imaging and
densitometers.
Making a Detailed Sensor Scan: Routine (6+)
Electronics (sensors) check (1D x 10 minutes, INT
or EDU).
Analysing Sensor Data: Average (8+) Electronics
(sensors) check (1D hours, INT).

Sensor locks do have an effect.

Sensor Lock (Sensor Operator)
An improved target lock may be obtained on an enemy
spacecraft with a successful Electronics (sensors) check.
Attacks made by the spacecraft against this target gain a
Boon until the sensor lock is broken (see Electronic Warfare).

 

[paltrysum]

So then the answer is: Once you have detected a ship, you can fire on it. Having a sensor lock improves your chances of hitting. You can still fire on a ship without a lock, but using AnotherDilbert's (very reasonable) house rule, you can lose track of an opponent if they get out of sensor range.

 

[Condottiere]

At visual range you could probably hit something without a sensor lock.

 

[baithammer]

That is what targeting computers are for.

Also, if the target is no longer in range it can't be tracked or locked by definition. ( This is where pickets and stealth ships come in handy.)

 

[Condottiere]

Some (expensive) missiles could home in on targets on their own.

Energy weapons at distance would need onboard guidance.

 

[baithammer]

Missiles can be launched at a target area instead of a specific target and if a target presents itself the terminal guidance can then conduct the attack.

 

[arcador]

A question I have is, do all ships have EM sensors?

 

[AnotherDilbert]

A question I have is, do all ships have EM sensors?

Sensor Types
The following are the types of sensor commonly found on spacecraft across Tech Levels.

Visual (all): Electronically-enhanced telescopes.
Thermal (all): Picking up heat emissions.
Radar/Lidar (all): Detects physical objects. Active use bounces beams off a target and thus makes it easier to be seen (DM+2 to Electronics (sensors) checks to be detected in return).

Yes, all sensors have Visual, Thermal, and Radar/Lidar.

Advanced Sensors add Densitometer, Very Advanced Sensors add NAS.

 

[paltrysum]

Here's something to consider: the Harrier is extremely hard to detect. Could it be possible that an opposing ship repeatedly fails in its attempts to locate the Harrier with its sensors, all the while the Harrier is perforating it with particle beam shots? That -6 DM from stealth might make it appear to the opposing ship as if it is just being attacked by a phantom in the dark.

 

[AnotherDilbert]

There is no automatic detection when you attack, so yes you can attack without being detected.

I would give a bonus to detecting the attacking ship, but that is another house-rule.


Lest the players become to cocky, remind them that ships with good sensors and sensor operators (warships) have a good chance of detecting them...

 

[PsiTraveller]

The stealth attacks and stealth ability of ships reminds me of submarine warfare where shots are from a general heading and cause chaos and destruction on the defending ship. If the stealth effect holds the defenders will indeed be shooting into the dark and hoping to hit.

 

[CaladanGuard]

Yeah. I might give my group the chance to take potshots from the dark out at long ranges with only a bonus to the victims sensor rolls.

I do have them automatically detected when they come up to Medium...or Short range then open fire though (Unless they can come up with some reasonable way to convince me they shouldn't be). Mainly, so it isn't too hard on their poor targets. I figure at those ranges, the vector they get from the weapons, plus the fact that the Harrier goes to active sensors for weapon solutions means they can pretty quickly figure out what's happening. Not that it helps some poor Far Trader when they've just been blindsided.

 

[Condottiere]

What's the engagement distance, one sixth of a light second?

Energy weapons will be actively emitting a lot on the electromagnetic scale.

I would assume that missiles launching will be lighting off their rocket motors.

A stealthed ship would retain surprise and initiative.

Not quite that stealthy once it starts actively pinging and firing off it's weapons.

 

[baithammer]

Energy weapons need dwell time and focus in order to do damage, so the range is much shorter than merely casting light.

 

[Linwood]

A stealth vessel launching missiles could change course and speed after launch to try to break sensor contact. This would work even better if you allow the existence of missiles with a delay before engaging thrust so that the initial launch has a very low signature. And if those missiles themselves had stealth....

 

[Reynard]

Remember even the visual aspect is being electronically enhanced in order to find a speck of several hundred tons in all of space. EAG and Stealth Coat both remove EM emissions which can blur visual light as well. This is why all sensors are affected.

Think too that a person in good cammo firing at you doesn't mean you automatically spot. You might have a general location but that doesn't hit a target.