The Pentagon War game

by Roger M. Wilcox
Originally begun on 27-December-1983

This webpage was last modified on 9-April-2002


MOVEMENT AND GAME SCALE

The Pentagon War is played on a map of hexagons (abbreviated "hexes"), where each hex represents an area of space about 1,500 kilometers across.  To simplify the complex variety of movement a space battle can entail, each playing piece (or "counter") must be centered in a hex and facing one of the hex's sides at all times.

DIRECTIONS

If you look down at the upper-right corner of the hex map, you will see a diagram labelled with the letters A through F, like so:

Absolute Directions
These six letters are called the six direction vectors, or simply directions; all facings and velocities in this game are represented in terms of these six directions.  For example, a spacecraft in hex 1015 that is facing hex 1014 is said to have a facing of A; if it were facing hex 0915, it would have a facing of F.

Directions with letter names are absolute directions, relative to the map itself.  Relative to the facing of the craft, however, directions with number names can be used, like this:

Relative Directions
The lower-left corner of the map has a diagram showing these numbers as they would relate to a spacecraft facing direction A.  As a spacecraft rotates, the letter-name directions stay fixed, but the numeric directions turn with the craft.  Whatever facing a craft has, then, is considered direction 1 for that craft.  Direction 3 relative to a craft facing C would be the same as direction E; direction 5 relative to a craft facing D would be the same as direction B.

Any spacecraft (but not any non-mobile base) may change its facing to any facing desired at the start of each impulse, although it doesn't have to.  This is done in that impulse's Rotation Segment, and represents the tactic of "tumbling" to bring your toughest armor and most powerful weapons to bear against your opponent.

VELOCITY

On the Acceleration Record form, there are two "Velocity Component" lines at the top labelled A and C.  Each line represents how fast your spacecraft is travelling in that direction only.  For instance, if the entry for the A line was 0 and the C line was +6, the spacecraft would be heading straight in direction C at a speed of 6.  If the entries were A = -5 and C = +3, your spacecraft would be travelling with a velocity of -5 in direction A and at the same time with a velocity of 3 in direction C.  Note that since direction A points exactly opposite of direction D, a velocity of -5 in direction A is the same thing as a velocity of +5 in direction D.

(Spacecraft may also have fractional velocities; that is, a spacecraft's A-component might be, say, 10 and 3/4.  The way to handle these special cases will be dealt with shortly.)

At the beginning of a scenario, each spacecraft will be given a pair of "starting velocity components." These are its A and C velocity components in hexes per turn, the maximum speed in the game being + or - 12.  The turn is subdivided into 12 "impulses," during which some spacecraft may or may not have to move according to their speed.  For each velocity component, cross-reference that velocity on the Impulse Chart with the current impulse.  If a number is indicated, it moves one hex in the direction of that component (A or C).  In the case of a negative velocity component, it moves one hex in the opposite direction (a spacecraft with a C component of -3 would move one hex in direction F on impulses 4, 8, and 12).

There are certain impulses — most notably impulse 12 — during which both of a spacecraft's components may be scheduled to move.  If a spacecraft has both a positive (+) A-component and a positive C-component, or if both its components are negative, these moves will look like jolts in one direction followed by awkward jumps 120° away.  Needless to say, the spacecraft does not not actually "jog" first in one direction, then the other.  The hex it careens into is not actually crossed; and in practice, the player controlling the spacecraft does not even have to move it into that hex.  A spacecraft moving in both +A and +C directions on one impulse can be moved smoothly one hex in direction B.  Likewise, a spacecraft moving in both -A and -C directions on the same impulse may be moved straight into the adjoining hex in direction E.  The components are there just to minimize the calculations you have to make during play.

ACCELERATING

Spacecraft may change the values of their velocity components.  This is called accelerating, but may be referred to as decelerating when you accelerate opposite to your general direction of movement.  To do this with maximum efficacy, the spacecraft must have engines equal to or greater than its Size Class (q.v.).  If it does not have enough engines, it will not be able to change its velocity components as quickly as it might otherwise be able to.

If the spacecraft has enough engines, it may accelerate either or both of its velocity components by one-quarter (1/4) of a hex per turn each impulse.  On any impulse that the player wishes for his spacecraft to accelerate, he or she merely says so during the acceleration segment.  The player then writes down the component(s) of this acceleration (see below) on the appropriate impulse line of the Acceleration Record.  The component(s) that the acceleration changes is determined by the spacecraft's facing at the time it accelerates, as follows:
FacingA-ComponentC-componentwrite down
AIncreaseNO CHANGEA+
BIncreaseIncreaseA+C+
CNO CHANGEIncreaseC+
DDecreaseNO CHANGEA-
EDecreaseDecreaseA-C-
FNO CHANGEDecreaseC-

At the end of the turn, the player adds up all the + and - indications for the A-component, counting each such indication as a velocity change of 1/4 of a hex per turn.  He or she does the same for the C-component.  These changes are now added to the old velocity component values (lines 1 and 2 of the same turn) to arrive at the new values for the next turn.  And finally, at the beginning of the next turn (velocity determination phase), the player writes down the spacecraft's new velocity in that turn's "Velocity Component" column lines on the Acceleration Record.  (If this all sounds confusing to you at this point, see the Movement Example below.)  Given 12 impulses in a turn and a maximum acceleration of 1/4 of a hex per impulse, the most either velocity component may change by since the previous turn is 3.

(NOTE: An acceleration of three hexes per turn per turn along either or both vectors is called the "standard" acceleration in The Pentagon War.  It represents a physical acceleration of nearly 125 times Earth's gravity.  This is why most "fighter" spacecraft in the game are unmanned.  The spacecraft which carry and maintain these fighters are manned, however, and therefore use much more limited speed-change rules.)

Either or both of the velocity components of a spacecraft may be changed for the next turn.  You will discover as you use this system that smooth acceleration toward one component and against another will allow a spacecraft to "turn" in flight.  However, a neophyte may find this system of turning awkward, since spacecraft do not maneuver like airplanes or automobiles.

If the spacecraft does not have as many engines available for thrust as its size class, or if it elects not to accelerate at the full rate, the owning player must write things down a bit differently.  Instead of just noting the component(s) and sign of the acceleration, this whole mess is preceded by the fraction of a standard acceleration that the spacecraft undergoes this impulse.  So if a size class III spacecraft only uses 2 engines for thrust on the seventh impulse while facing in direction E, its owner would write down "2/3A-C-" on his acceleration record's "Impulse 7" line, indicating that during that impulse it was only accelerating at two-thirds standard.  If the spacecraft performed two more identical maneuvers over the course of the turn, the three of them combined would all count as an A-velocity-component and C-velocity-component change of -2/4 (-1/2) of a hex per turn at the turn's end.

MOVING WITH FRACTIONAL VELOCITY COMPONENTS

You will probably end up with velocity components ending in odd fourths on several turns.  If you don't want to muck around with the advanced rules, use a simple "round down" rule — that is, a component value anywhere from 1 up to 1 and 3/4 counts as a component value of 1, a component anywhere from 3 to 3 and 3/4 counts as 3, et cetera.  This makes it more difficult to accelerate at the beginning of a scenario than it is to decelerate, since starting components are usually whole integers.

MOVEMENT EXAMPLE

At the start of turn 3, the Alpha-Centaurian fighter "Aklinon" has velocity components of A = +6 2/4 and C = -2 3/4.  It rotates so that it is facing direction E on impulse 4, and declares it is accelerating.  The player now writes down "A-C-" in the "Impulse 4" line of the Accelerations space (line 7) under turn 3 to indicate that on impulse 4, it decelerated both components.  This is the same as saying that on impulse 4, it accelerated in direction E.  The velocity components are now A = +6 1/4 and C = -3 0/4.  This acceleration will not actually take effect until the velocity determination phase of the next turn, however, so for the rest of the current turn the Aklinon's C-component is still considered -2 for movement purposes.

Since this is impulse 4 and the Aklinon's A-Component rounds down to +6, it must move one hex in direction A during the Movement Segment of this impulse.  If Aklinon had been facing direction C, it could have accelerated in direction C (which would have increased its C-Component only), but it could not have accelerated in any other direction.  On impulse 5, the Aklinon will not move, although it may rotate to some other facing and/or accelerate if it so chooses.  On impulse 6, however, both its A-component (integer value +6) and its C-component (integer value -2) have a move indicated on the impulse chart.  Thus, the Aklinon will move one hex in direction A and one hex in direction F (because F is opposite of C).

(ABSOLUTE) SPEED

There will be occasions, such as ramming and flying through an atmosphere, when the individual velocity components are less important than their vector sum — when you want to know just how fast you're really moving.  While complicated vector addition would produce exact results, the following method gives reasonably accurate answers without having to use any trigonometry:

If the two components have opposite signs — i.e. one is positive and the other is negative — take the absolute value of the negative one (in other words, drop the minus sign) and add this to the positive one.

It the two components have the same sign (they're both positive or negative), just take the larger absolute value of the two.

Thus, if you had A = 5 and C = -3, your speed would be 5 + 3 = 8.  If you had A = -7 and C = -4, your speed would be 7 since -7 has a larger absolute value than -4.

SPACECRAFT UNION AND SEPARATION

When a group of spacecraft are built, they may be designed to attach themselves to one another and later detach themselves.  The most common use of this feature was with fighter groups.  Since only unmanned spacecraft can withstand the tremendous accelerations required in space combat, but only manned spacecraft can carry out repairs, manned "mobile bases" (also called "carriers" or "fighter deployers") designed to attach with three to six unmanned fighters became the staple of each star system by the time of the War.

To attach, the two spacecraft must be in the same hex and have both velocity components identical.  Magnetic beams may be used by either spacecraft to expedite this "speed matching." The facings of the two spacecraft may be either the same or 180° apart, but the choice as to which of these two facing configurations must be used had to have been made when both spacecraft were built.

When two spacecraft attach themselves to one another, the size class of the new "combined spacecraft" must be recalculated.  Since the new "combined spacecraft" is considered a single spacecraft for game purposes, repair boxes belonging to one of the pair may be used to repair the other between scenarios, and supplies may be exchanged between cargo holds; but no other facilities may be shared between the spacecraft.  Also, weapons on the linking sides of the spacecraft will be blocked.

Two attached spacecraft may detach on any launch segment of any impulse.  They begin with the same velocity components but otherwise function as completely separate units.

DISENGAGEMENT

What do you do when your single fusion-powered light fighter confronts a fleet of ion-transfer dreadnoughts emerging from a hyper hole? That's right, you leave.  Leaving a battle is known as disengagement.  It usually involves accelerating to speeds far in excess of those allowed in this game (and also far more relativistic), where combat is at best impossible.  There are two ways to disengage:

  1. Accelerate until your Speed (see above) is 12.  Then, during the current turn, declare an acceleration which would put your speed beyond 12, even if only by a small fraction.  On the next turn, if your were able to accelerate and have at least one filled fuel tank, you automatically disengage.  This consumes one fuel tank box worth of fuel (mark the box used with a dot, to indicate that it is empty).  If your spacecraft has no filled fuel tanks you may not disengage by acceleration, and the acceleration you made to get you beyond speed 12 is ignored; otherwise, your spacecraft is now out for the remainder of the scenario.
  2. Be out of range of all weapons on the map, and have a higher Speed than any other spacecraft.  "Out of range" means that no combination of weapons the enemy could possibly throw at you could hit you and do enough damage to exceed your screens.  To determine the range of seeking weapons, subtract the spacecraft's current speed from the weapon's speed, and if the weapon is farther away than this, the spacecraft is out of range and may disengage.

ACCELERATION FOR MANNED SPACECRAFT

Manned spacecraft accelerate thirty (30) times more slowly than unmanned spacecraft.  They must keep track of all their velocity component changes in increments of 1/120.  For instance, if a manned spacecraft has an A-component of +4, and it faces D on impulse 9 and declares it is accelerating, the player still writes down "A-" in the Impulse 9 line on his Acceleration Record; however, the spacecraft's A-component on the next turn will be +3 and 119/120, not +3 3/4.

RAMMING

Occasionally, the best defense against incoming invaders is to run into them.  This is not a practice recommended by any high command (except maybe the Sirians'), as it tends to waste spacecraft (and life if the spacecraft are manned).

During the movement segment of any impulse where one spacecraft has entered the hex of another, and no later, it may declare that it is trying to ram.  Then, during the ramming segment of that impulse, roll two 6-sided dice, and if their sum is equal to or less than 3 + the size class of the target spacecraft, the ram is successful.  The number needed to hit is decreased by 3 if the target is using evasive maneuvering but is automatically successful if the target is a non-mobile base or chooses not to evade the rammer.

There are two effects of a ram which must be determined: The new velocity components of the spacecraft after the ram, and the damage done to both spacecraft by the ram.

To determine the new A-velocity-component-value of both spacecraft, do the following:

  1. Multiply the mass (size class) of the spacecraft that caused the ram by its A velocity component.
  2. Multiply the mass (size class) of the other spacecraft by its A velocity component.
  3. Add lines 1 and 2.  This is the total A-momentum.
  4. Add the masses (size classes) of both spacecraft together.
  5. Divide the A-momentum found in line 3 by the total mass found in line 4.  The result is the A velocity component of both spacecraft after the ram.

To get the new C-velocity-component-value of both spacecraft, follow this same procedure, excpet substitute "C" wherever you see an "A".  NOTE: If the unit being rammed is a base or planet (or anything else with "infinite mass"), both units involved will have A and C velocity components of ZERO (0) after the ram.

Ramming damage depends on total change in kinetic energy of both craft.  Determine this as follows:

  1. Find the absolute speed of the ramming craft before the ram, using the absoulte speed rules from the movement section or from the more complex optional-rules section.
  2. Multiply line 1 by itself; that is, square it.
  3. Multiply line 2 by the mass (size class) of the ramming craft.  This is its initial kinetic energy.
  4. Find the absolute speed of the other unit before the ram, square that, and multiply it by that unit's mass (size class).  This is its initial kinetic energy.  If the unit is immobile, its initial kinetic energy is 0.
  5. Add lines 3 and 4.  This is the total initial kinetic energy of both units.
  6. Find the absolute speed of either unit after the ram, and square that.  As stated above, both units will have the same velocity components after the ram, so it doesn't matter which craft you use for this purpose.
  7. Add the masses (size classes) of both units together, as per step 4 of the velocity determination process given above.
  8. Multiply line 6 by line 7.  This is the total kinetic energy after the ram.  If neither craft is moving afterwards, this line should be zero (0).
  9. Subtract line 8 from line 5.  This kinetic energy difference is the amount of energy that went into damaging both units involved in the ram.
  10. Finally, convert line 9 into actual damage points by dividing it by four (4).

This damage is applied to both the rammer and the rammee.  Ramming weights may be purchased for 10 points a throw (used on suicide spacecraft) and are destroyed on forward hull hits.  Ramming weights act as one-fifth of a size class each for purposes of determining ramming damage.

If one of the spacecraft is destroyed in the ram, the force of its explosion is applied as a separate attack that impulse.  [This distinction only matters if the target spacecraft has directional screens (q.v.).]  Since ramming damage is incurred right after the movement segment of an impulse, a spacecraft may attempt a "suicide ram" and synchronize its ram with a self-destruct order (q.v.).

RAMMING WITH A SIZE CLASS 0 VEHICLE

Spacecraft may not ram size class 0 objects (such as drones or missiles), but size class 0 vehicles may ram spacecraft or even other size class 0 objects.  To determine if the ram was successful, use the same die roll procedure as for ramming, i.e. the "hit number" with two dice is (3 + target's size class 2 if target is using evasive maneuvering) or less.  Unlike with size class I or larger vehicles ramming spacecraft, the target of a size class 0 ram may use point defense against the object when it enters its hex.

Size class 0 vehicles that successfully ram are destroyed.  Drones that ram do a base damage of one (1) point times the relative speed (absolute speed of the relative velocity) to their target, reduced by 1 if they carry no weapon, increased by 2 if they've bought a ramming weight.  Missiles that successfully ram do their full warhead strength in damage but no more than this; the extra half of their warhead strength missiles inflict upon their target when they hit is mostly due to point-blank proximity but partly due to ramming damage as well, and is already factored in.  Any time a size class 0 vehicle successfully rams another size class 0 object, both are destroyed.

Since drones are more expensive than missiles (and do less damage), ramming with drones is wasteful, but it can be of use in unusual circumstances.  Human-Centaurians never use this procedure unless absolutely necessary; Sirians, being both heavy drone users and generally nasty, use this procedure about 15% of the time.


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