“Inertia-less” Revised Rules For Phase World Starships
(Also includes Mutants in Orbit, Macross, and Robotech Starships)
Index:
Star Ship F.T.L. Modifications
How to Treat speeds and ranges
The author is a heavy reader of science fiction writing and am very choosy about what I read. Compared to most Science fiction including Star Trek Novels, Babylon 5, and David Weber’s “Honor Harrington” series, the “non” F.T.L. (Faster than Light) speeds of Starships in Phase World are far to slow. A good example of this is how long a Phase World starship would take to travel from the Earth to Mars on normal drives. Based on how long it takes our probes to get there and how fast they are, it would take years for Phase World starships to go from the Earth to Mars. In addition, in combat a Robotech RPG starship could accelerate to .01% to .02% of light, attack a Phase World starship with its weapons that dwarf the range of Phase World weaponry and be undefeatable by any starships from Phase World. C.J. Carella wrote that the starships in Phase World are suppose to be more advanced that Robotech and Macross Star Ships and this simply is not the case if you use the ranges and speeds in the Phase World books.
The problem with the author’s original starship rules is that due to the calculations involved, the system is daunting to both players and game masters alike. In order to resolve this system, the author has created an alternate set of starship rules designed to be simpler to use yet still give the high pace feel of science fiction. This is done through an inertia-less system similar to what is used in the “Starfire” game system. In this, starships (fighters, power armors, and missiles as well) create a special field which removes inertial and allows ships to travel at incredible speeds. This system has a weakness in that when the field is shut off, the starship or other vehicle comes to virtually a complete stop. This drive in effect creates artificial rules on the propulsion. As much as possible is written so the “Inertia” based and “Inertia-Less” system work identically as far as ranges.
The special inertia-less fields have limitations on their top speed based which is derived from their top speed. Use the starships top speed in Mach speed and simply convert that into percentage of light. Starships on the author’s website would simply be converted by using their acceleration in percentage of light per turn and multiplying that by 10. That becomes the top speed of the starship. Optionally, speeds can become 1/10 of what their mach speed in terms of their top speed. In those cases, the acceleration of the authors should be converted directly into the top speed.
First Example: A Black Eagle has a maximum speed of Mach 16 in the Phase World Source Book. This means that the starfighter would have a top speed of 16% of light in the inertia-less system.
Second Example: A Warshield cruiser has a listed speed of Mach 8.5 in the Phase World Source Book. This means that the starship would have a top speed of 8.5% of light in the inertia-less system.
Third Example: On the authors website, the Human Alliance Osprey class starfighter is listed as having an acceleration of 1.2% of light per melee. When converting over to the inertia-less system, the fighter would have a top speed of 12% of light.
To convert the speed of starships to miles / kilometers per second, simply multiply that speed by the percentage of light of their speed (for example: Warshield cruiser has a top speed of 8.5% of light. This breaks down to 15,834.0 miles per second or 25,482.3 kilometers per second.) For comparative purposes, the best thing is to calculate the distance traveled per melee round (15 seconds) and simply multiply by 15 to calculate this. (For the Warshield, this would be 237,510 miles or 382,234.5 kilometers.) On the web, there is a shareware program available called master converter which makes conversions easier.
Running starships at maximum sub-light speed for extended periods can be extremely hard on the systems. For every eight hours of operation at maximum speed, the ship’s engineers have to make an engineering roll (starship engineering in most cases), If the roll fails then the ship is limited to half of maximum speed. This then becomes the maximum speed and if the crew attempts to maintain that speed for over eight hours, they must roll an engineering roll with similar results if roll is failed. If three rolls are failed then the drive is assumed to have failed completely and will take several days to repair. In order to repair a damaged drive, the ship’s crew will require 2 to 8 days (2D4) to repair and may require additional parts.
As long as a ship travels at half of maximum or less, engineering rolls are not required.
Robotech Starships follow a similar set of rules with the auxiliary engines speed in “Mach” simply converted into the ship’s top speed in percentage of light. Example: Ikazuchi Command Carriers have a top speed on its auxiliary engines of Mach 7. The starships top speed would be 7% of the speed of Light. This rule does not effect most small ships such as star fighters. They use a different set of rules. Unless upgraded with Phase World style engines, the fighters acceleration in G should be equal to the fighters top atmospheric speed in Mach. If they are dropped by a starship traveling at high sub-light speed, they will immediately drop into normal space and normally be unable to be effective. See Inertia based system for more details on them.
Mutants in Orbit cannot follow the inertia-less starship rules simply because they rely on thrusters. See Inertia based system for more details on them. This also includes Rifts Earth vehicles
Even though starships are inertia-less, they still require time to accelerate. This is due to the fact that the drive field requires a bit of time to be brought up to full power. This also means that a starship completely turning around will require several minutes in some cases
Missiles accelerate to maximum speed instantly and travel at full speed from launch
Starfighters and Power Armors accelerate to maximum speed in one melee round. For the first melee round, their maximum speed is half of normal.
Small Starships (Destroyers and Frigates) accelerate to maximum speed in two melee rounds. For the first two melee rounds, their maximum speed is half of normal.
Medium Starships (Cruisers) accelerate to maximum speed in three melee rounds. For the first three melee rounds, their maximum speed is half of normal.
Large Starships (Battleships and Dreadnoughts) accelerate to maximum speed in four melee rounds. For the first four melee rounds, their maximum speed is half of normal.
Robotech and Macross starship follow the same rules although fighters still follow acceleration rules.
Starship F.T.L. (Faster than Light) Modifications:
Since starship speeds have been greatly increased, the distance away from a planet must be increased in order for the ship to not be able to jump instantly. Since the strongest gravity source in a solar system is normally the star, distances are measured from the star.
The baseline for distance from the sun is based on a star of the same size as Sol (our sun) with different stars requiring more or less distance from the star. With a Red Dwarf star, one could be relatively close to the star while White and Blue stars would require far greater distance from the star. Other objects such as large planets, Brown Dwarf Stars Neutron Stars, and Black Holes, will have their own required distances. Jupiter has a mass of approximately 0.1% that of the sun and Brown Dwarfs can have masses from 1% to 5% that of the sun. Mass of neutron stars is around 2 solar masses. Stellar Black Holes have masses of 5 to around 30 solar masses. Starships tend to avoid Black Holes whenever possible.
A table for types of drives is provided below. To put distances in perspective, the Earth is approximately 8.3 light minutes from the sun and Jupiter is approximately 43.2 light minutes from the sun.
Of note, most planets which are colonized will be of the main sequence K5 to G0 spectral types with an occasional F5 or M0 spectral type. Other stars, the planets will almost certainly be tidal locked (around smaller stars) or the stars simply burn out too fast.
Phase Drives:
Instead of Phase Drives being effected by the atmosphere of a planet, they are effected by gravity. If a ship tries to activate its P-drive too far inside the gravity of an celestial object, the drive and possibly the ship itself will be ripped apart. Using a Phase Drive, one needs to be at least 40 light minutes out from a sun like star to enable the drive to be activated safely. Note that speeds in faster than light are unchanged.
Contra-Gravitonic Drives:
As with Phase Drives, the distance is greatly expanded. Using a Contra-Gravitonic Faster than Light Drive, one needs to be at least 40 light minutes out from a sun like star to enable the drive to be activated safely. Note that speeds in faster than light are unchanged.
Rift Jump Drives:
Instead of it simply being the gravity and ley lines of the planet, it is the gravity and ley lines of the entire system which effect the ability to a ship to activate a Rifts Jump Drive.
For very high magic star systems, multiply normal distances by 2.0
For a high magic star system, multiply normal distances by 1.5.
For moderate magic star systems, multiply distances by 1.0
For low magic star systems, multiply distances by 0.75
For extremely low magic star systems, multiply distances by 0.5
Spacegate Jump Systems:
These systems are the only exception to the distances for the Faster than Light propulsion systems. This is because they work on a completely different principle. The spacegates may be near a planet without interfering with their ability to be used.
Main Sequence Stars:
Spectral Type |
Mass (Sun = 1) |
Lifespan Millions of Years |
Approximate Habitability Zone |
Activate F.T.L. Drive |
O3 |
120 |
2 |
9,960 light minutes |
4,800 light minutes |
O5 |
60 |
3 |
7,367 light minutes |
2,400 light minutes |
O8 |
23 |
6 |
3,403 light minutes |
920 light minutes |
B0 |
17 |
9 |
1,826 light minutes |
680 light minutes |
B3 |
7.6 |
30 |
365.2 light minutes |
304 light minutes |
B5 |
5.9 |
50 |
240.7 light minutes |
256 light minutes |
B8 |
3.8 |
150 |
107.9 light minutes |
152 light minutes |
A0 |
2.9 |
300 |
60.6 light minutes |
116 light minutes |
A5 |
2.0 |
1,000 |
30.7 light minutes |
80 light minutes |
F0 |
1.6 |
1,900 |
20.8 light minutes |
64 light minutes |
F5 |
1.3 |
3,200 |
14.9 light minutes |
52 light minutes |
G0 |
1.05 |
8,000 |
9.6 light minutes |
42 light minutes |
G2 |
1.0 |
10,000 |
8.3 light minutes |
40 light minutes |
G5 |
0.92 |
12,000 |
7.4 light minutes |
36.8 light minutes |
K0 |
0.79 |
22,000 |
5.4 light minutes |
31.6 light minutes |
K5 |
0.67 |
45,000 |
3.2 light minutes |
31.6 light minutes |
M0 |
0.51 |
68,000 |
2.3 light minutes |
20.4 light minutes |
M5 |
0.21 |
200,000 |
0.83 light minutes |
8.4 light minutes |
M8 |
0.06 |
700,000 |
0.25 light minutes |
2.4 light minutes |
The ranges written in the Phase World are far shorter that those written for capital scale weapons for Robotech and Macross R.P.G.s. Most science fiction as well have much greater weapon ranges. While many science fiction programs show ships seeming to be very close together that is an illusion for the viewers. In a Babylon 5 episode they had a group of White Stars craft attack a group of Earth Force Destroyers. While the ranges appeared to only be a few thousand meters. The ranges that were stated were in the range of 10,000 km. To equal out Phase World Starship weapon ranges, all weapons are increased. In addition, Rail guns are assumed to fire their projectiles at incredible speeds and do not propose a problem for the ships firing them.
Capital Scale Weapons:
This includes all weapons on capital scale starships or very large runner sized starships (Stick in your eye) that do 1D4x100 M.D.C. or greater. The ranges of the weapons are changed as follows: Use the starships weapon range in atmosphere as the weapons range underwater. Use the weapons space range as the weapons range in an atmosphere. For space range, take the weapons space range, take the weapons listed space range and multiply that by 1000 to get its new space range. If the weapon has no listed space range, the underwater range is considered to be the listed range. The Atmospheric range is considered to be double the listed range and the space range is considered to be 1000 times the listed range.
First Example: A Warshield Cruiser’s main battery has a range of 10 miles in an atmosphere and 100 miles in space. The modified ranges would be that the weapon has a range of 10 miles underwater, 100 miles in an atmosphere and 100,000 miles in space.
Second Example: The secondary batteries have no listed space range. The range listed is 16 miles. This becomes the weapons underwater range, The atmospheric range becomes double listed range to 32 miles, and space range becomes 16,000 miles which is 1000 times listed range.
Star Fighter Scale Weapons:
This includes all of the lighter weapons on capital ships, all energy weapons on star fighters and other small ships, and weapons of space robots and power armors. They are treated very similarly to Capital Scale weapons. Use the starships weapon range in atmosphere as the weapons range underwater. Use the weapons space range as the weapons range in an atmosphere. For space range, take the weapons space range, take the weapons listed space range and multiply that by 100 not 1000 to get its new space range. If the weapon has no listed space range, the underwater range is considered to be the listed range. The Atmospheric range is considered to be double the listed range and the space range is considered to be 100 times the listed range.
Example: the rail gun on a SF-69 Scorpion Star Fighter has an atmospheric range of 8 mile and a space range of 16 miles. The range will become 8 miles underwater, 16 miles in an atmosphere, and 1600 miles in space.
In many cases, Robotech and Macross Capital scale weapons are not adjusted. This still gives them a small range superiority over similar Phase World weapons. The only case where capital scale weapons should be adjusted is when their ranges would be ridiculously short compared to other weapons. A good example of this is the Macross Cannon. The main gun has a range of 20,000 miles (32,000 km) and the secondary cannon has a range of 16 miles (25.6 km.) These ranges simply do not work well together. All capital scale weapons with extremely short ranges should be modified the same way as Rifts capital scale weapons. Robotech: Sentinels also states that lighter energy weapons are increased from 75% to 100% in space. Lighter weapons in Robotech and Macross are instead increases by eight times in space as compared to their listed ranges. This also applies to Rifts Earth vehicles in space and Mutants in Orbit vehicle weapons. Mutants in Orbit capital scale weapons are not modified as Phase World capital scale weapons.
Missile Ranges and Top Speeds:
In the Phase World Dimension books, you get the impression that starships lumber towards each other, not firing any weapons until rock throwing ranges (100 miles or less) and then slowly lumber together until 1 to 2 miles is reached before launching missiles. I prefer a much more dynamic starship and missile combat where missiles fly at incredible velocities and starships engage each other light second apart with missile. When a missile reaches the end of its range, it drops into normal space and most are set to self destruct. Missiles cannot be used effectively beyond their powered range.
Cruise Missiles:
Missile range is 8,000 miles (12,875 km) in an atmosphere and 4,000,000 miles (6,437,376 km/ 21.5 light seconds) in space. Missile has a top speed of Mach 25 in an atmosphere and in space has top speed of 60% of the speed of light (far faster than any starship.)
Long Range Missiles:
Missile range is 3,400 miles (5,470 km) in an atmosphere and 1,800,000 miles (2,897,000 km/9.7 light seconds) in space. Missile has a top speed of Mach 20 in an atmosphere and in space has top speed of 50% of the speed of light (far faster than any starship.)
Medium Range Missiles:
Missile range is 160 miles (257.5 km) in an atmosphere and 80,000 miles (128,750 km/0.43 light seconds) in space. Missile has a top speed of Mach 15 in an atmosphere and in space has top speed of 40% of the speed of light (faster than any starship.)
Short Range Missiles:
Missile range is 10 miles (16.1 km) in an atmosphere and 500 miles (804.7 km) in space. Missile has a top speed of Mach 10 in an atmosphere and in space has top speed of 30% of the speed of light (faster than any starship.)
Mini-Missiles:
Missile range is 2 miles (3.2 km) in an atmosphere and 100 miles (161 km) in space. Missile has a top speed of Mach 10 in an atmosphere and in space has top speed of 20% of the speed of light (slightly faster than any starship.)
Robotech, Macross, Rifts Earth, and Mutants in Orbit missiles are not treated the same way although the launcher could easily be changed to the Phase World launchers. In the Robotech: Sentinels the speed and range of missiles fighters is listed as increased 75% over listed speed in space. Instead of treating it this way, treat the missiles as having eight times the range that the missiles do in an atmosphere. The missiles have the acceleration of double their Mach speed in an atmosphere in G when used in space and use the same formulas as the starships use. The missiles can also be launched beyond the missiles range and use velocity to hit the target and follows the rules listed above for extended missile ranges.
In Phase World, there is a few weapons that break from the standard rules for Phase World weapons. These are Micro missiles and grenades. These weapons have eight times the aimed range and micro-missiles travel at twice they mach speed in Gs for acceleration and are treated just like Robotech, Macross, Rifts Earth, and Mutants in Orbit missiles instead of 100 times the range and accelerations in percentages of light.
How to Treat speeds and ranges:
The speed of Light is 186,282.4 mile (299,729.458 kilometers) per second in vacuum. One way to easily remeber is consider the speed of light to be 300,000 lilometers per second. This is to allow the person to do calculations with starship speeds/accelerations and weapons ranges. Items of importance is that a starship cannot just travel in two dimensions but can travel in three dimensions. Another point to remember is that at closing courses the ranges firing can be very brief and that the best ways for extended engaging are either parallel courses or pursuit courses
There are three basic methods of doing calculations:
Keep track of speeds, ranges, altitudes, and ranges in your head. For large combats or for quick play, this and educated guesses is probably the best method.
Use Graph paper, writing down the vertical position of the starship and calculating from there. This can work with relatively small battles. Distances on the graph paper could be 100,000 miles or any appropriate distance (300,000 kilometers / 1 light second works well too.)
Using the stands for aircraft combat come up with a scale and use them. This method also works for relatively small battles.
The space combat using this system can be quite cumbersome although not much more cumbersome than the original system. Still, various methods can be used to reduce this.
Group Strikes Together: This works well for missiles but can also be used for energy weapons. Simply group strikes into groups of five or ten. Still, all strikes should not be grouped into a single roll. Relatively small numbers of attacks should be grouped into groups of five while larger numbers would be grouped into groups of ten.
Eliminate Dodge Rolls for Missiles: Instead of having rolls for missiles to dodge, have the defense roll have to roll against a base of 10 to strike the missiles. A smart missile has +4 to dodge which would increase strike roll to 14 to strike missile. A brilliant missiles has +6 to dodge which would increase strike roll to 16 to strike missile. This rule only applies to smart and brilliant missiles and normal missiles (which don’t try and dodge) would only require a 5 to strike.
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Writeup by Kitsune (E-Mail Kitsune).
Copyright © 2006 & 2015, Kitsune. All rights reserved.
I would like to recognize Chris Curtis as helping with many of the ideas listed here.
I would also like to thank Malcolm Edwards <malcolm@fedu.uec.ac.jp> for helping me with the effects of approaching the speed of light on acceleration and time dilation.