Thursday, 31 December 2015

Weapons: Mk-7 Mine


            The Mk-7 Anti-track mine resembles a square plastic carrying case or flattened jerry can, 4 inches deep and 10 inches to a side. It has a moulded carrying handle and weighs around 11 pounds. The basic mine contains virtually no detectable metal although optional fusing systems may change this. The design has been widely copied. Outer casing is typically a mud-brown colour although grey, green and pale-sand colours are also produced. The pale-sand model also works well in snowfields.

            The Mk-7 Anti-track mine is a pressure-activated and can be scattered from ground vehicles, helicopters and low-flying aircraft, or can be manually buried. The mine is non-buoyant, waterproof and can be operated to a depth of 1 yard underwater. The mine is either surface-laid or buried down to 70 mm below the ground surface.

            The Mk-7 Anti-track mine is provided with a double anti-shock device operating mechanically and pneumatically. This device prevents the mine from being triggered when an impulsive load is applied onto the pressure plate, caused either by an accidental drop, when scattered by a helicopter dispenser, by the detonation of a nearby or suspended explosive charge, or by the action of fuel-air explosive mine-clearing systems.

            The hinged pressure plate on one face of the mine has glass shear pins and the sensitivity of the mine can be varied by changing these pins for ones of a different diameter or wall thickness. The plastic casing also has several auxiliary fuse wells. The mine can also be fitted with optional anti-handling devices, electronic proximity fuses or a tilt-rod fuse kit.

            The Mk-7 is of limited effectiveness against modern fighting vehicles but can disable them by cutting a track or destroying a wheel. It is effective against soft-skinned vehicles and many military cybershells.

            Somewhat obsolescent, the Mk-7 remains in wide use due to its low-cost, simplicity and versatility. Many organisations use the Mk-7 as a convenient demolition and satchel charge. Typically one fuse well will be fitted with a pull-igniter and a ten-second length of fuse in addition to any more sophisticated detonation systems.

            A Mk-7 does damage of 6d x 13 cr ex. Dismantling the mine yields 8lbs of useable advanced TS explosive, each pound doing 6d x 4 cr ex.

 

Useful Conversion Formulae


            GURPS source material generally uses the US version of the imperial system. If you are more comfortable with metric measurements this is generally not a problem.
  • One hex can be considered to be either a yard or a metre with little actual effect on game mechanics unless large numbers are involved. For metres into yards divide by 0.914.
  • An item weight in kilograms can be converted to pounds by multiplying by 2.2.
  • Speeds in kilometres per hour can be converted to miles per hour by dividing by 1.6. The mph result can then be halved to get the more game useful yards/sec equivalent:- 4 mph=2 yd/s.  
            Other imperial units such as cubic feet can usually be treated as arbitrary game units.  

            Temperature can be a problem. Many rules are written referring to 10˚(F) increments, for example.
            p.B9 tells us one Fahrenheit degree is 5/9 the size of a degree Celsius” and “To convert actual thermometer readings, subtract 32 from the Fahrenheit temperature and multiply the result by 5/9”. More convenient is to remember the approximation that:-

1˚F = 0.55˚C
1˚C = 1.8˚F

more easily remembered as:-

10˚F = 5.5˚C
18˚F = 10˚C

            Hence when a rule talks of “for every 10˚ change in temperature” it can be read as “for every 5˚C change...”. The comfort zone defined in Temperature Tolerance on p.B93 can be read as being For ordinary humans, this zone is 30°C wide and falls between 1°C and 32°C”.


Space Travel.
            While on the subject of useful formulae and conversions a useful one for Transhuman Space  and other space-based campaigns is:-

Delta-V (mps) ÷ 1100 = AU/day.
or
Days of Travel  = Distance in AU/(delta-V (mps) ÷ 1100)

 
            To convert Delta-V (mps) to a top speed in yards per sec multiply by 1,800.
            To convert Acceleration in G to a move of yards per second per second multiply by 10.


Falling Distances and Velocity.

Page 431 of the basic rules gives a table of velocities for falling objects. Alternately the formulae below can be used using a value of 10.73 for “g” on Earth. For other planets multiply this value by the relevant scaling factor (eg: 0.38 for Mars, 0.9 for Venus, 0.17 for Luna). Increasing density of atmosphere or fluid the object is falling through will reduce velocity.

“t” is the time in seconds. “d” is the distance fallen in yards in “t” seconds. “vi” is velocity in yards per second after “t” seconds of falling.




vais the average velocity in yards per second for an object that has been falling “t” seconds.


Wednesday, 30 December 2015

LLW: Water Cannon and Brine Throwers.


            The only GURPS stats for a water cannon that I can find are in GURPS Vehicles  (p.118) and these omit certain criteria that one might wish to know. The table below attempts to adapt those rules to TS 4e. It is assumed that the water cannon is mounted on a suitable vehicle. Being intended for TS this system is a little lighter than those of earlier TLs. Total weight of a system is dependent on the reservoir capacity, maximum number of shots being represented by “S”. Volume of the reservoir tank can be taken to be S x 0.08 cf. Each shot of liquid weighs 4.25lbs. A single, totally filled, 100 shot small water cannon therefore weighs 20+25+425 = 470 lbs and has an 8cf tank. A reservoir tank may supply more than one projector. Each additional projector weighs 20lbs if small, 40lbs if medium and 80lbs if large.

LIQUID PROJECTOR (Water Cannon) (DX-4 or other Liquid Projector-4)
Weapon
Damage
Acc
Range
Empty Weight
RoF
Shots
WPS
Small Water Cannon
4d Special
-
40/60
20+0.25S
Jet
S
4.25
Medium Water Cannon
4d Special
-
55/80
40+0.25S
Jet
S
4.25
Large Water Cannon
4d Special
-
80/120
80+0.25S
Jet
S
4.25
 
            A water cannon is treated as a jet (4e p.B106) but using the 1/2D and Max ranges given on the table. It does no damage and instead has a knockback effect. It does the equivalent of up to 4d damage for calculating knockback.

            Knockback rules are for every full multiple of the target’s ST-2 rolled, move the target one hex away from the water cannon. A target that has no ST or is not resisting uses HP instead (4e p.B378).
            Knockback into something hard may cause actual damage. (GURPS Vehicles suggests 1d per 2.5 hex of knockback).

            Potentially a water cannon can have dyes, irritants or malodorants added to the water. Some versions have a separate reservoir allowing the operator to only use additives when desired. In practice such additives are seldom used since their use in a water cannon can result in a major clean-up problem!

Brine-Thrower.
            The availability of compact, efficient refrigeration units allowed the development of a variant known as a brine-thrower. The addition of additives such as salt to the water allows it to remain liquid when chilled to below normal freezing point. Treat as a normal water cannon but with a follow-on effect similar to being immersed in arctic seawater. Every minute roll against health or lose 1 FP. Normal clothing, including winter clothing provides no defence. A diver’s drysuit, high levels of cold tolerance or something water-tight such as a battle-suit may provide some protection.

 

 

Tuesday, 29 December 2015

Weapons: TS Derringers.


            Originally derringers were designed to use a large-calibre bullet in a small weapon. During the twentieth century derringers were manufactured in a wider variety of calibres. In 2100 the most common models of derringer fire standard 10mm and 4mm caseless pistol rounds. The short barrels of these weapons reduce the effectiveness of these high-velocity rounds. Recoil makes follow-up shots slow and muzzle flash and noise is noticeable!

            Four-barrelled versions with a passing resemblance to the COP inc pistol are also available.

Guns (Pistol) (DX-4 or most other Guns at -2)
Weapon
Damage
Acc
Range
Weight
RoF
Shots
ST
Bulk
Rcl
Derringer
10mm
 
2 pi
 
 
0
50/300
0.4/0.053
1
2(3i)
6
-1
3
Quad Derringer
10mm
2 pi
 
 
0
50/300
0.55/0.11
1
4(3i)
6
-1
3
Derringer
4mm
 
1+2 pi-
 
 
0
50/300
0.4/0.o11
1
2(3i)
6
-1
3
Quad Derringer
4mm
1+2 pi-
 
 
0
50/300
0.55/0.o22
1
4(3i)
6
-1
3