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XF-309 “Pigeon” and XF-310 “Spider”

This article originally appeared in the January/February 2014 issue.


Intended target: Irregular TL6-7 infantry, who hide and maneuver in caves, urban areas, and among civilians, making it difficult to find and identify them in time to destroy them.

“Pigeons” are deployed in swarms on the order of 10-50,000, which fly around a target zone, look, network with each other and with behind-the-lines fire control; and when they’re assigned a target, go and explode themselves at it. (The “Spider” variant scurries where “Pigeons” can’t fly.)

These drones are built using GURPS 3ed. rules from GURPS Vehicles, GURPS Robots, and GURPS Ultra-Tech 1 and 2.

The warhead yields can be, and often are, downgraded significantly, in order to minimize collateral damage. Careful selection of lethal radius, and with the guidance of a skilled pilot at the forward base, can allow, for example, for one ground-car to be destroyed without harming those nearby—or even for the passenger to be killed without killing the driver.

These drones have also been made available in smaller quantities to law enforcement for use in specialized situations where direct approach by officers is contraindicated.

Design requirements

When possible, before deploying Pigeons, artillery should be used to clear the area of opposing artillery, MBTs, and radio jammers. The latter can also be located by certain sensor modules, the data communicated by lasercomms, directing Pigeons to target such jammers.

Design Details

Common chassis:


Description Mass (lbs) Volume
(cu ft)
Price ($)
Body Drive See Drive Options (one required for use)      
  Electronics Radio, short range (10 mi) 25 0.005 50
    Scrambler     500
    LLTV 0.5 0.01 1250
    GPS 0.5 0.01 100
    Computer Small, Robot, C2 2 0.005 1000
      Program: Computer Navigation, C2     500
      Tiny, Dedicated, C1 0.25 0.005 40
      Program: Datalink, C1     400
  Internal Battery: Rechargeable Power Cell, 20,000 kW 2.2 0.022 220
  Modular Socket A 3 0.06 30
  Modular Socket B 3 0.06 30
Structure Streamlining: Good; Strength: Super-light; Materials: Std; Struct: Robotic. Cheaply made. 1HP 1.46   548
Surface Armor: Metal, Advanced, DR1 0.548 0.001 11
  Blackout Paint     0.731
  Waterproof     7.31
  Liquid Crystal Skin 0.731   146
TOTALS 39.189 0.178 4833.041

The common chassis contains basic functionality, except for being able to move. There are two drive options, the “Pigeon” and the “Spider”, as shown below. One option must be selected for each drone, at the time of manufacture.

Drive Options


Description Mass (lbs) Vol (cu ft) Price ($)
“Pigeon” MMR Helicopter Drivetrain, 1.67 kW, lift 20 lbs, thrust 2.67 lbs 5.5 0.11 137
Multiple Main Rotor (MMR), folding, 1HP 0.366   110
“Spider” Legged Drivetrain, 0.1 kW (0.017 kW per leg) 6 0.12 300
Legs×6, Improved Suspension      

With either drive system, these drones have Size Modifier –2, Health 11, Body ST 2, DX 9, and IQ 5.

Performance Characteristics

“Pigeon” configuration: Stall Speed 0, Drag 1.22, Top Speed 130 mph, Accel 3 mph/s, Maneuver Rating 12g, Stability Rating 3, Decel 50 mph/s, Endurance 7h50m, Maintenance Interval 179h.

“Spider” configuration: Speed Factor 13, Top Speed 40 mph, gAccel 10 mph/s, gDecel 20 mph/s, gMR 1.75, gSR 4, ground Pressure 92.9 lbs/sf, Off Road Speed 40 mph, Operating Duration 5d16h of movement. (Nearly indefinite when standing still.)

Size comparison: Take a dozen US-standard bricks (7"×3.5"×2.25"), and stack them on top of each other. From top to bottom, that’s roughly the size of the drone, nose-to-tail.

Module Options

These modules are all 3 lbs mass, 0.06 cu ft volume, for fitting in Modular Sockets A and B. Load-outs are per drone per mission, and can, with proper support (e.g., some number of drones being equipped with the Robot Arm module), be changed during deployment.

Munitions Modules

Gas modules allow chassis recovery/reuse; explosives modules usually cause chassis destruction.


Munitions Options
HEDP Default module for Module Socket B
91mm, normal. Configured as self-destruct. Damage 6d×25(5) [6d]
ICM Damage:
0-120 yds: 4d concussive + 4d frag.
120-240 yds: 1d + 1d
Blackout Gas Radius 39 yds 1560
Tear Gas Radius 39 yds 310
Riot Gas Radius 39 yds 1060
Sleep Gas Radius 39 yds 2560
Nerve Gas Radius 39 yds 2560
Non-Weapon Modules

A wide range of modules are available for information-gathering and control.


Non-Weapons Options
Battery Default module for Module Socket A
TL8 Rechargeable Power Cell, 27,272.7 kWs
LLTV Mag ×6 1500
PESA Range 0.75 mile 12000
Thermograph Range 1.5 mile 6000
LADAR Range 0.75 mile, 0.375kW 3750
RADAR Passive, Range 1.5 mile 9000
RADAR Range 1.5 mile, 0.375kW 1500
RADAR Low-Res imaging, range 0.75 mile, 0.375kW 3750
RADAR High-Res imaging, range 53 yds, 0.375kW 3000
Sound Detect Surveillance, Level 15 15000
Laser Chemscan Range 750 yds 1500
Visual Sensor Robot, Night Vision, 360° 7100
Laser Optics Det. Range 3.75 mile 3750
Radiation Sensor Basic Sensor + RADAR/Laser Detector 100
Anti-jammer   650
Radio Dir Finder Receive-only, range 10 mile  
Laser Comm Range 20 mile  
Robot Arm ST 10, retractable, 0.05 kW. Use to change modules mid-flight in other Pigeons/Spiders. 6000