Chapter 4: The Cold Hard Facts

Space travel isn’t as easy as many science fiction books and movies make it appear. In the classic space opera, ships perform maneuvers that are frankly impossible in any kind of realistic sense. Diving fighters somehow create screaming shrieks in vacuum. Massive cruisers roll and bank like stunt planes at a county fair. And no one worries about things like how much acceleration a human body can tolerate, relativistic effects, and other intrusions of real science into the fiction at hand. In this chapter we’ll take a look at a few “real-world” issues that affect spacegoing craft and warfare in the future. You don’t have to pay attention to any of this; there’s a lot of outstanding science fiction that chooses not to pay attention to the cold hard grasp of reality. But if you prefer a game where the impossible is simply ruled out, read on.

Fight Or Flight

Speed may be a ship’s best defense. A spaceship traveling at extremely high speed is almost impossible to engage in combat. The faster a ship goes, the more difficult it is for enemy vessels to interfere with its passage—and the harder it is for the fast-moving ship to successfully employ its own weapons against targets at much slower speeds. The difference in velocity (or delta-v, as it’s sometimes called) becomes a gulf or barrier nearly impossible to cross from either direction. Imagine a patrol ship traveling at a speed of 10. It covers ten 1,000-kilometer hexes in 30 seconds, or 1.2 million kilometers per hour. It can travel from the Earth to the Moon in about ten minutes, from the Earth to the Sun in about 150 minutes, and from the Sun to Pluto in about 100 hours. That’s pretty fast. Now imagine that the patrol ship has orders to intercept an enemy raider entering the inner system at a speed of 100. In terms of the round sequence, the best the patrol ship can hope for is one shot at the raider as it passes. Assuming the patrol craft has an acceleration of 3, it will take 30 rounds of maximum acceleration just to reach the same speed as the raider—and then the patrol craft will have to add even more speed to have a chance of overhauling the raider in a tail chase. The raider isn’t in a great position if it’s imperative that it destroys the patrol craft. At a speed of 100, the raider is suffering a penalty of –24 to its maneuvering class (remember, each four points of speed is a –1 penalty). Assuming that the raider was MC 3 to begin with, its current MC is –21 . . . which means that it can perform a maneuver once every 22 rounds. If the raider spots the patrol craft at a range of 1,000 hexes (that’s one million kilometers), it couldn’t perform a maneuver to adjust its course accordingly until it was ten full rounds (1,000 hexes) past the patrol ship!

Table 4–1: Speeds Speed*

KPH 120,000 240,000 360,000 480,000 600,000 1.2 million 2.4 million 6 million million 50 million 100 million 150 million 300 million 450 million 600 million 750 million 900 million 1.08 billion

Au/Hr 0.0008 0.0016 0.0024 0.0032 0.004 0.008 0.016 0.04 0.08 0.33 0.67 1.0 2.0 3.0 4.0 5.0 6.0 7.2

%c 0.01% 0.02% 0.03% 0.04% 0.05% 0.1% 0.2% 0.5% 1.1% 5% 9% 14% 28% 42% 56% 70% 83% 100%

At PL 7+ scale; for PL 6 scale, multiply by 200. For example, a speed of 4 at PL 7 is the same as 800 on the PL 6 scale. Take a look at TABLE 4–1. If a ship has an acceleration of 4, it’s pretty fast for the Gravity Age. But it needs to increase its speed to 1,250 to reach a cruising speed of 1 AU per hour. That’s three hundred game rounds of acceleration, or about two and a half hours.

High Speed Combat Clearly, there are logistical difficulties in playing out a battle between ships with a delta-v of 50 or 100 points of speed, let alone 500. Most shipboard weapons have a maximum range of ten to twenty thousand kilometers; most shipboard sensors, forty to sixty thousand kilometers. A ship moving at a speed of 50 may begin the round outside of weapon range, move right past an enemy vessel, and wind up outside of weapon range again. For this reason, delta-v acts as a barrier to combat. If one ship’s traveling at speed 100 and the other one’s going at speed 10, there’s nothing they can do to each other until one slows down or the other speeds up. By the time that happens, the fast-moving ship will be many millions of kilometers away from the point of initial contact. For this reason, most space combat actually takes place in the vicinity of planets or stations where a commander can expect to find his enemy traveling at a few thousand KPH. It’s simply impossible to intercept a fast-moving target in open space. For every 10 points of delta-v between the attacker and the target, the Gamemaster may assign a 1-step penalty to attack rolls. A ship at speed 0 suffers a +5 step penalty to

hit a ship traveling at speed 50, and vice versa. That assumes, of course, that the ships somehow get within weapons range of each other in the first place.

Achieving Orbit Sitting at the bottom of Earth’s gravity well, we spend a lot of time thinking about ways to gain enough velocity to achieve orbit or escape Earth’s gravitational influence altogether. It’s just as tricky and takes just as much energy to lose enough velocity to fall into orbit for a spaceship approaching a planet from interplanetary space.

Table 4–2: Orbital Windows Outbound Achieve Orbit Escape Orbit Inbound Enter Orbit De-orbit

PL 7

1.5

PL 7

1–3 0–1

PL 6

30–60 0–30

This means that a ship must slow down to a reasonable speed before entering orbit or attempting a landing. Reaching the vicinity of the planet you’re heading toward with a speed of 300 or 400 is useless; the ship will simply sail past without a chance of making orbit, or impact the planet like a big steel meteor. Therefore, a ship has to start decelerating a long way out so that it’s traveling at a manageable speed when it reaches its destination. For example, a ship traveling at 2 AU per hour is moving at a speed of 2500. If it has an acceleration of 2, it will take that ship 1,249 rounds (about ten hours) to slow down to a speed of 2, which is pretty good for entering orbit. The end result: any ship trying to reach a particular planet is traveling at a speed of 10 to 20 when it’s within 50 to 100 hexes of its destination, and it’s still slowing down.

Table 4–3: Stopping Distance (Spd 10) Acc

Hexes 45 hexes 21 hexes 12 hexes 9 hexes 6 hexes 5 hexes

Rounds

TABLE 4–3 shows how many hexes a ship traveling at a speed of 10 needs to perform a straight deceleration to a speed of 1, and how many rounds it takes. In other words, a ship with an acceleration of 2 slowing down from interplanetary travel must be at least 21 hexes from its destination when it slows to speed 10, and it will take three more rounds of deceleration to reach a speed of 1. For most battle or encounter scenarios, you can say that the arriving ship begins at speed 10 at the appropriate distance from the planet (although more cautious approaches are certainly possible).

Acceleration

The force of gravity at the surface of the Earth is a continuous acceleration of about 10 meters per second per second straight down. This equates to an increase of roughly 100 KPH per phase, in the standard ALTERNITY round structure. In 30-second Warships rounds, 1 G represents an increase in speed of roughly 1,000 kilometers per hour over 30 seconds of continuous acceleration. In other words, if you started the round flying at a speed of 120,000 kilometers per hour and accelerated at 1 G for the whole round, you’re traveling at 121,000 kilometers per hour at the end of the round. Humans can tolerate 1 G forever; we spend our entire lives pinned to the surface of the planet by this force. Unfortunately, 1G of acceleration won’t get you very far in space travel unless you accelerate for a long, long time. Most spaceship engines at PL 6, 7, and 8 are capable of accelerations of dozens, hundreds, or thousands of Gs. It’s remotely conceivable that fluid tanks, anticoagulants, and artificial respiration might allow a human to endure 30 or 40 Gs for a short time, but an unprotected human would die pretty quickly under such forces. Higher accelerations would leave nothing but raspberry jam on the bulkheads—if there were bulkheads left. Most ships would tear themselves to pieces under acceleration strong enough to instantly kill a human.

Fusion Age Travel Engine systems of Progress Level 6 create accelerations of up to 60 or 70 G, give or take. For routine travel, a Fusion Age ship does not use all of its acceleration capacity—it’s much more comfortable and convenient to use a steady acceleration of 1 G or a little less, which also provides the accelerating ship with a reasonable simulation of gravity for most of the trip. In combat, however, a ship must employ accelerations that strain human and machine to their limits.

Protection from Acceleration Accelerations of more than 2 G or so require special protective measures for a ship’s passengers and crew. Characters in normal seats or positions are unprotect ed. They may be injured or killed by extreme acceleration, but aren’t at risk for damage from routine maneuvers. Characters sealed into acceleration tanks and prepared with various drugs and mechanical devices are protected against acceleration. All crew stations and passenger quarters are fitted to protect their occupants; donning Gsuits and preparing for extreme acceleration takes about 10 minutes (or 2 game rounds for PL 6 combat).

Effects of Acceleration The exact effects of acceleration naturally depend on just how much acceleration you’re talking about. 3 G or less (Acc 0 to 0.2): No ill effects. 3 to 9 G (Acc 0.2 to 0.5): Protected characters suffer no penalties; unprotected characters suffer a +2 step penalty to all actions. Any character attempting to move around the ship at an acceleration of 3 G or more must attempt a Strength check. On a failure, the character suffers a short fall and sustains damage accordingly (see TABLE P15 in the ALTERNITY Play er’s Handbook). 10 to 25 G (Acc 1): Protected characters suffer no penalties. Unprotected characters can take no actions at all and must attempt an Stamina—endurance check each round, suffering 0, 1, 2, 3, or 4 points of stun damage for an Amazing, Good, Ordinary, or Marginal success. 26 to 40 G (Acc 2): Protected characters suffer a +2 step penalty to all actions (including all crew checks). Unprotected characters can take no actions at all and must attempt an Stamina—endurance check as described above at a +3 step penalty. 41 to 60 G (Acc 3): Protected characters can take no actions at all and must attempt an Stamina—endurance check as previously described. crew checks are still possible at a +3 step penalty (the ship’s computers take over). Unprotected characters die. 61 to 90 G (Acc 4 or 5): Protected characters can take no actions at all and must attempt Stamina—endurance check at a +3 step penalty. crew checks are still possible at a +5 step penalty. Unprotected characters die. 91 G or more: No character survives, regardless of protection.

Starting and Stopping Not all acceleration injuries are slow, crushing deaths. Crewmembers walking about the ship when the captain suddenly decides to begin an unannounced 20-G deceleration are liable to break arms, legs, spines, and bulkheads as they’re dashed against the nearest hard surface. Characters with no warning of the impeding change are subject to falling damage for a short fall (3 to 9 G), medium fall (10 to 25 G), long fall (26 to 40 G), or terminal fall (41 G or more). For this reason, most captains make a point of announcing maneuvers before they cut in the rockets.

Gravity Age Travel In the Gravity, Energy, and Matter Ages, most engine systems provide compensation for acceleration or ignore acceleration altogether. These engines are hundreds of times more powerful than the fusion torches and ion engines of the Fusion Age, and there is simply no way that ordinary hulls—let alone unprotected humans—could stand up to this

kind of punishment without changing the rules altogether. At PL 7, acceleration compensators are part of basic engine design; the particle impulse and gravity induction drives are capable of thousands of gravities, but as long as the engine generates thrust, it also generates a protective field that counteracts the tremendous acceleration of the engine. The gravitic redirector of PL 8 works in much the same way. At PL 8, the inertial flux engine functions by instantaneously altering the inertial state of all matter on board the ship at the same instant. Relative to the rest of the ship, the passengers experience no acceleration at all. At PL 9, the spatial compressor simply annihilates distance around the ship, so that very modest accelerations produce enormous results. An outside observer might record an acceleration of ten thousand G, but inside the ship the same motion is experienced as a mild tug.

Relativity

Ships moving at extremely high speeds begin to experience significant relativistic effects—time dilation, elongation, increase in mass, and other phenomena that become apparent as a ship nears the speed of light. Most of the time, these effects are simply immeasurably small. (Heck, if you go for a walk and come back to your house, there would be some infinitesimal difference between your perfectly accurate wristwatch and your perfectly accurate wall clock.) However, spaceships are capable of traveling at speeds so high that relativistic effects can really matter.

Dilation The amount of time dilation, increase in apparent mass, or elongation observed aboard a ship traveling near light speed is proportional to just how close it is to light speed. While a tiny but measurable amount of dilation occurs at any velocity, we’ll sum up the notable breakpoints. Dilation is expressed as a ratio or multiplier, known as gamma.

Table 4–4: Gamma Speed

AU/hour 0.18 1.0 2.0 3.0 4.0 5.0 6.0 6.5 7.0 7.1 7.239 7.24

%C 1.1% 14% 28% 42% 56% 70% 83% 90% 97% 98.1% 99.99% 100%

g 1.0003 1.01 1.04 1.1 1.2 1.4 1.8 2.3 3.9 5.1 60.2 inf

For example, gamma is 1.4 for a ship moving at 70 per-

cent lightspeed (or 5 AU per hour). If the ship travels for 10 hours at that rate, only 7.1 hours pass on board the ship (10 divided by 1.4 is 7.1). At 97 percent lightspeed (7 AU per hour) passengers on board the ship experience only 2.6 hours compared to the 10 hours that pass outside. It’s theoretically possible for a ship to approach the speed of light so closely that millions of years would pass outside, while only hours passed inside. Gamma also affects a ship’s acceleration value. Since acceleration represents how much thrust the engines produce compared to the mass of the ship, you could reduce the ship’s acceleration by the ratio. For example, a ship with an acceleration of 3 is traveling at a speed of 8,100 megameters per round (90 percent lightspeed). Normally the ship could increase its speed by 3 per round, but its current velocity reduces its acceleration to 1.3 (3 divided by 2.3 is 1.3). If the ship hits 97 percent lightspeed (gamma 3.9), its acceleration of 3 would be reduced to 0.76. Eventually, its acceleration becomes infinitesimal.

Time and Space The dilation effect of extreme velocity poses some interesting questions for space travelers, especially in a game universe where true faster-than-light travel is not possible but highgamma relativistic travel is possible. Imagine a ship whose power plant and engines are powerful enough to accelerate to 99.99 percent lightspeed within a few hours of launch. It doesn’t have an FTL drive and can’t break the lightspeed barrier—but travelers on board that ship will feel like they did! Let’s say that the spaceship is traveling from Earth to Tau Ceti, a Sol-like star about twenty light years from Earth. If the ship traveled exactly at the speed of light, it would take twenty years to make the trip. But the ship can’t reach light speed; nothing in the universe can. Instead, the ship reaches a speed of 99.99 percent lightspeed. At a dilation ratio of 60.2, the twenty-year voyage would take about 120 days. At a gamma of 600 (call it 99.999 percent lightspeed), the trip would take about 12 days of shipboard time. Twenty years pass in the universal frame of reference for only 12 days inside the ship. What would this mean? If you’re talking about alien worlds with little or no contact with each other, surprisingly little. Each time the characters visit a new system, the rest of the universe gets a little older, but they’re only passing a few short weeks. Back home, friends and family live decades that their spacefaring loved ones don’t experience. Bank accounts and mutual fund accumulate years and years of interest. Society changes, grows, perhaps becomes unrecognizable to the traveler who returns after a trip of four or five decades that she experienced as less than a year. But as long as each new planet she visits isn’t home (or someplace that can affect or be affected by her homeworld) the time dilation means little to her. Even if the traveler journeys between worlds in close contact with each other, relativistic travel wouldn’t mean

What Is the Speed of Light? In case you were wondering, the speed of light is about 300,000 kilometers per second…roughly one billion kilometers per hour. If you’re maneuvering a ship on the megameter scale, a ship moving at the speed of light would travel 9 million kilometers—or 9,000 megameters—per round. Most of the PL 7 or better engine systems described in this book have enough power to quickly reach this speed through constant acceleration. A ship with an acceleration of 3 could reach lightspeed in 3,000 rounds, or about 25 hours. But it doesn’t work this way. Relativity rears its ugly head. As a ship accelerates toward lightspeed, its extreme velocity begins to cause dilation effects. In effect, as its velocity approaches the speed of light, its mass approaches infinity. This means that it’s impossible to reach the speed of light through simple acceleration, no matter how good an engine you have at your disposal. You can’t accelerate to the speed of light, but you might go faster than light by means of a drive or device that takes you from one star to another star faster than light could actually travel the same distance.

much in a large but static galactic society. If nothing really changes over time other than the fact that your acquaintances get older and you get richer, you might not mind missing centuries of history as you journey from world to world. It’s possible that spacefarers might form a distinctive sub-culture or segment of society, rootless vagabonds admired, pitied, or even reviled by the people they serve. The most difficult scenario is the middle case—worlds in close contact that are not static, where society advances and technology increases immeasurably each time the characters get off the boat in a new place. They grow more and more antiquated as centuries and millennia spin by them, one day finding that their world is nothing like the world they knew only a few weeks or months ago in their own time.

3D C Ombat

The ship combat rules presented in the first two chapters depict combat as a two-dimensional confrontation. Frankly, this is a gross simplification made for the purpose of keeping game play fast-moving and fun. If this strikes you as too simple, read on. Adding the z-axis to your game doesn’t materially affect most of the steps in the sequence of play. The two places where three-dimensional positioning and movement matter are in the movement phase and the fire phase.

3D Position Since each hexagon on the mapsheet represents a megameter (1,000 kilometers), we’ll arbitrarily divide a ship’s altitude above or below the plane represented by the mapsheet into 1,000-kilometer increments too. Think of the bat-

tlefield as a stack of identical mapsheets set 1 hex width apart, with one mapsheet in the middle of the stack actually functioning as the reference level for all the others. The reference level or zero-level is the mapsheet you have spread out on your table to play out a ship combat, and a ship is either above or below this reference level by some number of megameters.

Indicating Elevation You might try small poker chips or tokens placed under the ship miniature or counter as a method for indicating altitude. Use white chips to indicate elevation above the reference map—a miniature with six white chips under it is actually 6 MM above the reference level. Red chips indicate a position “under” the map in the exact same way. You could also construct a clip stand scaled to your own map and miniatures. Clip stands are used for some dogfighting games—it’s a heavy hexagonal base that marks where the plane is on the map, while the plane itself is moved up or down a rod or dowel standing up from the base and marked in altitude increments.

neuvers available to a commander. (See “Maneuvers” in Chapter 1: Basic Combat .)

Climb or Dive When a ship performs a climb or dive maneuver, it allocates some of its horizontal speed into vertical movement. Although it’s not perfectly accurate, we’ll simply say that this allows the commander to split his ship’s movement into a horizontal and a vertical component. For example, a ship with a speed of 4 dives; the captain could move 3 hexes forward and 1 hex down, 2 hexes forward and 2 hexes down, or 1 hex forward and 3 hexes down. The climb or dive ends at the end of the ship’s current movement, although it could certainly climb or dive again in following rounds. Realistically, the ship could actually designate a new climb rate or dive rate as a default part of its “straight” movement. However, for the sake of ease of play, we’ll say that a ship completes its climb or dive in one round of movement, and climbs or dives again if it wants to keep gaining or losing elevation.

Roll Counting Range To determine the range between two ships at different levels, you’ll need to do a little math. First count the horizontal distance, as indicated by the hexes separating the two markers. Then, count the vertical distance indicated by their chips. For example, a ship at elevation +6 MM and a ship at +2 MM are separated by a vertical distance of 4 megameters. Now, square the horizontal distance, square the vertical distance, and add them together. The actual distance between them is the square root of the sum. You’re solving for the length of a right angle’s hypotenuse. Pythagoras put it a little better: x 2 + y2 = z2, where x is the horizontal distance, y is the vertical distance, and z is the “slant range” directly between the two points. Slant range = Square root of (x2 + y2) Let’s say that the two ships above happen to be 7 hexes away from each other horizontally, and 4 hexes away from each other vertically: Range = Square root of 72 + 42 Range = Square root of 49 + 16 Range = Square root of 65 Range = 8.06 (round down to 8) If the first ship fired on the second ship with no vertical separation at all, the range would be 7 hexes. But the 4-hex vertical difference increases the actual range of the attack to 8 hexes.

3D Movement Obviously, moving in a three-dimensional battlefield requires rules for gaining or losing elevation. We’ll handle this in the simplest manner possible, by expanding the ma-

The roll maneuver allows a ship to “sideslip” one hex as it moves forward. In the 3D movement system, a ship may use a roll to either gain or lose 1 megameter of elevation. It’s really the same thing as a 1-hex climb or dive, but the cinematics are a little different.

Turn and Loop When a ship performs this maneuver, it must gain or lose one megameter of elevation.

3D Fire The major consideration for weapons fire in a 3D combat system is how elevation affects arcs of fire. The principal arcs of fire defined in Chapter 1: Basic Combat gain a new component in 3D combat—target aspect. (The zero arc ignores attitude rules.)

Target Aspect A potential target may be in one of three possible aspects toward the attacking ship: high, flat, or low. Flat: The horizontal separation between the firing ship and the target is greater than or equal to the vertical separation. For example, a ship 5 hexes away on the mapsheet and only 3 hexes lower than the firing ship is a flat shot. A ship may fire normally on a target with a flat aspect. High: The vertical separation exceeds the horizontal separation, and the target has a higher elevation than the firing ship. The firing ship can’t attack the target unless it has weapons that can fire into the high arc or it maneuvers to change its own attitude.

Low: The vertical separation exceeds the horizontal separation, and the target ship has a lower elevation than the firing ship. The firing ship can’t attack unless it has weapons that can fire into the low arc or it maneuvers to change its own attitude.

Attitude This term describes the general orientation of the firing ship to its target. Is it level, climbing, or diving? A climbing ship can shoot flat and still hit an enemy target that would otherwise be in the high arc; the target isn’t really over the firing ship if the firing ship is heading toward it straight-on. It should be difficult but possible for a ship to perform minor attitude adjustments or spins to freely face in any orientation for a shot. However, for the purposes of game play we’ll say that a ship must spend most of the game round pointing in the right direction to shoot. In other words, a ship can’t ignore firing arcs by simply spinning left, right, up, and down as it moves. Level: The firing ship did not make a maneuver that changed its elevation during the most recent movement phase. Weapons firing into all standard arcs may only fire on targets with a flat aspect. Climbing: The firing ship gained elevation in the last movement phase. In its forward arc of fire, a climbing ship may fire on targets with a flat or high aspect, and in its aft arc of fire, the ship may fire on ships with a flat or low aspect. Weapons firing into other arcs can only fire on flat-aspect targets. Diving: The firing ship lost elevation in the last movement phase. In its forward arc of fire, a diving ship may fire on targets with a flat or low aspect. In its aft arc of fire, the ship may fire on targets with a flat or high aspect. Weapons firing into other arcs may only fire on flat-aspect targets.

High and Low Arcs In 3D combat, two new firing arcs are added to the six standard arcs (forward, aft, starboard, port, zero-starboard, and zero-port): the high and low arcs. The high arc is defined as any hex whose vertical separation is at least one hex more than its horizontal separation. For example, an External cruiser that is exactly one hex higher than a Concord battleship but occupies the same horizontal hex would be in the battleship’s high firing arc. Similarly, if the enemy ship was located in a hex five megameters higher and only two hexes distant horizontally, it would also be in the high arc. The low arc is exactly like the high arc, but in reverse. In the example above, the Concord battleship would be located in the External cruiser’s low arc. Weapon Firing Arcs: The high and low firing arcs are treated exactly like the other standard arcs for purposes of ship construction and designating arcs of fire for weapons. For example, a turret normally permits three firing arcs, so a ship designer could designate those as the forward, port, and high arcs (a wing turret portside), or maybe the port, starboard, and low arcs (a belly turret midships). Universal Turrets: A weapon turret can fire into four arcs if it’s designated as a universal turret. One of the arcs must be high or low; the costs is an additional 25% cost and space above and beyond a standard turret. In other words, a standard turret requires an additional 25% cost and space, and a universal turret requires an additional 50% cost and space beyond that of a standard mount for the same weapon. See Chapter 5: Ship Construction.