Robot: TL 8 Sentry Gun

[Reisender]

Wiki: Sentry Gun

TL 8 Sentry Gun

Disclaimer:
A more complex test of the robot construction rules. I guess some form of a Sentry Gun has already been published in other publications, so this might be redundant.

Just gathering up some ideas.

Cost
Cost should be kept as low as possible as a Sentry Gun is just a tool that should be affordable.

Weapon
Preferable some form of machine gun or at least an assault rifle.

Tech Level(TL)
TL 8.

Chassis
The size of a big suit case for easy carry by two people. => Size 4

Locomotion
Stationary, has to be set up. => None

Chassis Option
Some reinforcement. => Armour upgrade.

Locomotion Modification
None

Manipulators
Just the gun on a gun mount. => Remove both standard manipulators
Note: Though we remove the standard manipulators we still need a DEX value for the gun handling, so we use the standard DEX for a standard manipulator of that Tech Level. Since a TL 8 manipulator has DEX 5(-1) we will increase this to DEX 6(+0) to avoid the negative DM. The cost for upgrading a single manipulator will be used for that.

Default Suite

We do not need the Voder Speaker so we replace it with a Drone Interface.

• Visual Spectrum Sensors to avoid obstacles in its path.
• A Wireless Data Link to connect the remote control.
• A Drone Interface
• A Auditory Sensor
• A Transceiver 5km

Zero-Slot Options
Things that might improve the visual sensors and that help with targeting.
An Encryption module to prevent anyone from hacking the Sentry Gun.
Maybe some camouflage as well.

Slot Cost Option
At least the gun mount and something to increase ammo capacity.
Fire Control is quite expensive, but somehow I feel that a Sentry Gun should have one though
we keep it Basic.

• Weapon Mount
• A Weapon Mount(Heavy) or Weapon Mount(Medium)
• A Weapon Mount Autoloader
• A Fire Control(Basic)

Brain
Just aiming and firing. => Primitive

 

[Reisender]

Stats using the Robot Handbook

Name: TL 8 Sentry Gun
Description:
The size of a big suit case it comes disassembled in a large box or crate and has to set up manually. Assembled it has a height of about 1 meter giving its mounted Assault Rifle some clearance.
Once set up it is stationary and has to be configured and programmed for the situation at hand. This includes the definition of the firing modes of the mounted Assault Rifle, the survailance and firing arcs and the targets, though it does not have a true friend-or-foe algorithm. For example the firing mode can be defined depending on the number of targets though the Sentry Gun can only engage one target at a time.
With all those sensors installed it can opperate under most circumstances. It has an effective range of about 100 meter.
It can be programmed, controled and monitored with a computer through its Drone Interface, the Wireless Data Link and the 5km Transceiver. Data received includes live video from its Auditory and Visual Spectrum Sensors including thermal and light intensifier vision, ammo count, barrel temperature and other relevant status and error messages.
But once configured correctly it does not need supervision and can opperate autonoumously, surveiling the designated area and opening firing according to its setting.

Robot	Hits	Locomotion	Speed	TL	Cost
TL 8 Sentry Gun	12	None	Stationary	8	Cr19'000

Skills	Gun Combat(Slug) 2 (includes DM from Fire Control System(Basic) ), Recon 1 (from Recon Sensor)
Attacks	Weapon Range Damage Magazine Magazine Cost Traits Sentry Gun 200 3D 330 Cr165 Auto 2
Manipulators	none; DEX 6(+0) for Laser Designator and gun handling
Endurance	216 hours
Traits	Armour(+6), Small(-1), Scope(only for single shot firing mode)
Programming	Primitive(homing)(INT 1)
Options	Auditory Sensor, Drone Interface, Encryption Module, Fire Control System(Basic) #1, Improved Camouflage #2, Laser Designator #3, Light Intensifier Sensor, Thermal Sensor, Recon Sensor, Transceiver 5km, Visual Spectrum Sensors, Weapon Mount(Medium), Weapon Mount Autoloader #4, Wireless Data Link

#1 Adds DM+1 to weapon(Already included in Gun Combbat(Slug) skill of Sentry Gun).
#2 Infrared and thermal; DM-2 to detection
#3 Laser effective range 100m; Roll DEX(8+) check with range DMs as Minor Action each round; successfully designated target is hit with DM+2 or DM+4 in subsequent round if stationary.
#4 Adds 10 more magazines for a total of 330 rounds.

 

[Lurking Grue]

Cool, well done!

Maybe it's just semantics, but the sentry gun should have a mounted machine gun, not an assault rifle. Machine guns are better suited for longer autofire, area defense and stopping frontal charges (by aliens or boring old humans) than assault rifles. Don't have the Robot Handbook so I don't know if it has any difference rules-wise, though. Also, the Aliens version has a 500 round drum magazine on it, why not up the ammo loadout of your design from 330 to 500 as well (not using stacked 30 round magazines but a belt or drum instead, if available in the book)? Just a thought.

 

[Reisender]

Cool, well done!

Maybe it's just semantics, but the sentry gun should have a mounted machine gun, not an assault rifle. Machine guns are better suited for longer autofire, area defense and stopping frontal charges (by aliens or boring old humans) than assault rifles. Don't have the Robot Handbook so I don't know if it has any difference rules-wise, though. Also, the Aliens version has a 500 round drum magazine on it, why not up the ammo loadout of your design from 330 to 500 as well (not using stacked 30 round magazines but a belt or drum instead, if available in the book)? Just a thought.

Yes, I wanted to install a machine gun, unfortunately the machine gun listed in the Core Rulebook or Central Supply Catalogue counts as a Heavy Weapon, requiring a Weapon Mount(Heavy), which is too big for a robot this size.
So the Assault Rifle was a compromise. It has more range than a submachine gun, which would have had the higher rate of fire.

 

[Lurking Grue]

Okay, fair enough. I thought it might have something to do with how the rules are in the Robot book and is thus a compromise. No worries, we'll just call it a very beefy assault rifle then (reinforced barrel and all).

 

[Arkathan]

Modify the MG mount to accept a robotic controller, include one "manipulator" to allow the robot to aim, and you don't have to worry about the weapon fitting into the robot. Just the Robot ONTO the weapon.

 

[AnotherDilbert]

Brain
Just aiming and firing. => Primitive

Is it supposed to fire at everything that moves, or is it supposed to discriminate?

 

[CordwainerFish]

Is it supposed to fire at everything that moves, or is it supposed to discriminate?

The sentry guns in the film seemed to be strictly motion activated. They didn't even aim, just hosed down their arc of motion.

 

[Reisender]

Is it supposed to fire at everything that moves, or is it supposed to discriminate?

I would assume that it is able to discriminate between a rat sized or a human sized target if configured that way. But it would not be able to distunguish between a friendly human or an enemy human sized target.

 

[Reisender]

The sentry guns in the film seemed to be strictly motion activated. They didn't even aim, just hosed down their arc of motion.

Yes, that would probably the simpliest form of a smart gun and the one presented here is certainly capable of it. Anything above that is up to the referee I would say. The rules just state that it does not have the capabilities of a hunter/killer brain, which seems to have a more sophisticated friend-or-foe algorithm.

 

[Reisender]

Modify the MG mount to accept a robotic controller, include one "manipulator" to allow the robot to aim, and you don't have to worry about the weapon fitting into the robot. Just the Robot ONTO the weapon.

I guess there is more than one way to skin a cat.

 

[CthulhuStig]

Nice. I absolutely love that movie and those sentry guns. I never understood why they would have cut the sentry gun scene from the original version.

@Reisender Your example is also really interesting to me as I'm currently in the process of adding robot construction to Auto-Jimmy. Is your use of the DEX value for the default manipulator of a robot at that TL your own house rule, or is that something you found in the rule book somewhere?

While coding up the rules, I noticed that they weren't very clear around what the DEX of a robot with no manipulators would be, especially if the robot also has no locomotion. As I couldn't find anything explicit, I had been thinking of using the base DEX for a manipulator at the robot's TL in the same way you did. It just feels a little strange as (I think) it would effectively make manipulators pointless as you could just take them off and the robot would still have the same DEX, this would be especially weird for a robot with no locomotion so no way to move under its own power.

I was just wondering if I've missed some important piece of info hidden away somewhere. I swear, it feels like I spend more time playing hunt the rule in the source books than I spend coding stuff.

 

[Reisender]

@Reisender Your example is also really interesting to me as I'm currently in the process of adding robot construction to Auto-Jimmy. Is your use of the DEX value for the default manipulator of a robot at that TL your own house rule, or is that something you found in the rule book somewhere?

While coding up the rules, I noticed that they weren't very clear around what the DEX of a robot with no manipulators would be, especially if the robot also has no locomotion. As I couldn't find anything explicit, I had been thinking of using the base DEX for a manipulator at the robot's TL in the same way you did. It just feels a little strange as (I think) it would effectively make manipulators pointless as you could just take them off and the robot would still have the same DEX, this would be especially weird for a robot with no locomotion so no way to move under its own power.

I think that it was not considered in the rules that you remove both standard manipulators and still need a DEX value for something, e.g. a weapon. So yes, it was some form of house rule. My thinking was that the same technology that would move a manipulator would also be used to move a gun.

 

[MasterGwydion]

I think that it was not considered in the rules that you remove both standard manipulators and still need a DEX value for something, e.g. a weapon. So yes, it was some form of house rule. My thinking was that the same technology that would move a manipulator would also be used to move a gun.

Hopefully, MongooseMatt will have someone fix the lack of a DEX score if you remove the manipulators in a future update or errata.

 

[ottarrus]

OK, let me ask the awkward question.

Why does every single technological item in Traveller have to have a stat block and a design form filled out?

I just tell my players that the the item exists and its general capabilities.
In this case,
"The site is covered by automated MG turrets. They appear to be TL 8, but that's just from observation."
Should a PC be able to hack the sight computers, they'd get more detail...
"The turrets use Instellarms Model 8 Machine Guns on a free-gimble mount. Each turret is equipped with 500 rounds and a mix of AP and ball ammunition. They're capable of engaging targets in a 160 degree vertical arc, from 90 degrees up to nearly the base of the wall. They can be fired from the Central Security post but are usually set to automatic engagement mode. Their sensors are LI /IR with an IFF keyed to an employee badge."

To me this is just simpler than having to have every nut, bolt, and wire accounted for.

 

[Geir]

The assumption with no DEX is that you ignore the value (don't treat it as zero, but just no DEX DM) and use Fire Control options (or an explicit software Gun Combat skill) to get your DM to hit. Or at least that was my intent. Don't think I spelled it out, though.

In fact, that should be an assumption for any weapon not mounted on, or held by a manipulator. I suppose an Agility bonus could count, but can't think that hard through the migraine this morning....

 

[CthulhuStig]

Thanks @Geir . I wasn't expecting to get the official answer from the author

If it's not to much to ask, could you clarify a couple of other things relating to the Fire Control System rules?

I'm trying to work out exactly what this line means

For finalisation purposes, Weapon Skill DM is treated as the weapon skill of the robot with the integrated weapon

And how it relates to this section

A dedicated fire control system for a manipulator held weapon or any fire control system for a weapon mounted in a robot’s manipulator provides a bonus to that weapon in addition to the robot’s weapon skill, if any, but this bonus does not stack with any DEX modifier for that manipulator; instead, the larger of the DEX or the dedicated fire control system modifier applies

Am I correct in thinking that the first line applies to all mounted weapons (manipulator and non-manipulator) and it's basically saying that the Weapon Skill DM for the Fire Control System is used as the relevant combat skill when using the weapon? For example, with an Improved Fire Control System connected to a mounted assault rifle, it would mean the robot would in effect have a Gun Combat (slug) skill of 2 when using that weapon?

If my previous understanding is correct does the second section then mean, if a robot was to have a manipulator mounted weapon connected to a Fire Control System _and_ the Weapon Skill DM for the Fire Control System was higher than the DEX modifier for that maipulator, then the Weapon Skill DM is used twice when calculating the final attack roll DM? With it being used once as the weapon skill for the attack and then used again because it is also applied as "a bonus to that weapon in addition to the robot’s weapon skill"?

What makes me think that some part of my interpretation is probably incorrect is that the second section states that it provides a bonus in addition to the robots weapon skill "if any". The "if any" would suggest that there are cases where the robot doesn't have a weapon skill but, based on my interpretation of the first line, robots with a Fire Control System would always have a weapon skill as the Weapon Skill DM for the Fire Control System is used as the weapon skill.

 

[Geir]

Thanks . I wasn't expecting to get the official answer from the author

I tend to lurk more time on the forum than I should. Although posting and lurking are not the same thing, so it may be more accurate to say I loiter more than I should.

Am I correct in thinking that the first line applies to all mounted weapons (manipulator and non-manipulator) and it's basically saying that the Weapon Skill DM for the Fire Control System is used as the relevant combat skill when using the weapon? For example, with an Improved Fire Control System connected to a mounted assault rifle, it would mean the robot would in effect have a Gun Combat (slug) skill of 2 when using that weapon?

Yes, unless the robot brain was running software with a greater skill level.

If my previous understanding is correct does the second section then mean, if a robot was to have a manipulator mounted weapon connected to a Fire Control System _and_ the Weapon Skill DM for the Fire Control System was higher than the DEX modifier for that maipulator, then the Weapon Skill DM is used twice when calculating the final attack roll DM? With it being used once as the weapon skill for the attack and then used again because it is also applied as "a bonus to that weapon in addition to the robot’s weapon skill"?

What I meant to say (or write) was pick the higher of Fire Control or Gun Combat software, but not both. If the robot is, let's say picking up a gun from the ground and firing it, however, you would get both a DEX bonus (or penalty) and the higher of the Fire Control bonus or software skill level. In other words treat the robot like a biological player: you get the skill (once) and the DEX as DMs, but the skill could come from software or hardware.

What makes me think that some part of my interpretation is probably incorrect is that the second section states that it provides a bonus in addition to the robots weapon skill "if any". The "if any" would suggest that there are cases where the robot doesn't have a weapon skill but, based on my interpretation of the first line, robots with a Fire Control System would always have a weapon skill as the Weapon Skill DM for the Fire Control System is used as the weapon skill.

Um, yes, if you said what I think I said.

 

[Reisender]

OK, let me ask the awkward question.

Why does every single technological item in Traveller have to have a stat block and a design form filled out?

I just tell my players that the the item exists and its general capabilities.
In this case,
"The site is covered by automated MG turrets. They appear to be TL 8, but that's just from observation."
Should a PC be able to hack the sight computers, they'd get more detail...
"The turrets use Instellarms Model 8 Machine Guns on a free-gimble mount. Each turret is equipped with 500 rounds and a mix of AP and ball ammunition. They're capable of engaging targets in a 160 degree arc, from 90 degrees up to nearly the base of the wall. They can be fired from the Central Security post but are usually set to automatic engagement mode. Their sensors LI /IR with an IFF keyed to an employee badge."

To me this is just simpler than having to have every nut, bolt, and wire accounted for.

I see nothing wrong with your approach. Every referee is different. Some want stats and rules others prefer a more narrative style.
For me it was more like a test of the robot construction rules than that I really needed some stats for a sentry gun. If it works for the group everything is fine, isn't it?

 

[CthulhuStig]

What I meant to say (or write) was pick the higher of Fire Control or Gun Combat software, but not both. If the robot is, let's say picking up a gun from the ground and firing it, however, you would get both a DEX bonus (or penalty) and the higher of the Fire Control bonus or software skill level. In other words treat the robot like a biological player: you get the skill (once) and the DEX as DMs, but the skill could come from software or hardware.

Thanks, that makes a lot more sense