"Inertia Based" Revised Rules for Phase World Starships:
(Also includes Mutants in Orbit, Macross, and Robotech Starships)
Star Ship Speeds:
Star Ship Acceleration
Star Ship FTL Modifications
Energy Weapon Ranges
Missile Ranges, Top Speeds, and Accelerations:
How to Treat speeds and ranges:
Methods to Streamline Combat:
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. 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 go 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
All Phase World Starships are theoretically capable of reaching .99 of the speed of light; However, Starships carry radiation and particle shields and they limit how fast that Phase Starships can actually reach. Because Larger ships can mount heavier and more effective radiation and particle shields, Large ships can reach a higher top speed than smaller starships. This is equaled out the fact smaller ships normally have a higher top end acceleration. Normally Runners will have military grade shielding but other than them most civilian ships have a lower top speed because ship designers were unwilling to invest as much space for shielding as military ships. These figures are meant for an average Sol type solar system. Systems with higher particle densities would slow down the ships top speeds.
- Capital Ships: 60% of light (6,000 tons and greater)
Runners, Bombers, and Heavy Fighters: 50% of light (250 tons and greater)
Star Fighters: 40% of light (Normally 5 tons and greater)
Space Combat Power Armors & Robots: 20% of light (Includes Avenger, Silverhawk, and Battleram
Civilian Ships: 20% of light
These rules can be revised and all ships can be allowed to reach 99% of the speed of light depending on the opinion of the players and the game master.
Robotech Starships are also reduced for the same reason. Their particle and radiation shielding are not at Phase World standards which only allows the starships to reach the listed book ranges. If their radiation and particle shields were raised up to the standards for Phase World then they to would have the same top end speeds. This does not include Robotech and Macross Star Fighters because they are basically short range craft, They could get engine upgrades as well and would then be able to take advantage of the higher speeds. In the Robotech: Sentinels® the speed of fighters is listed as increased 75% over listed speed in space. These speeds are much slower that what could be expected in space. Instead of 75% increase, revise the speed of the fighters as an acceleration in G when the fighters are operating in space. This means that fighters can reach up to 20% of the speed of light before they exceed what the fighters shielding can protect the crew from. Fighters and shuttles also have limited reaction mass when they are operating in space, consider fighters to have four to eight days of reaction mass when operating in space and consider shuttles to have two to four weeks of reaction mass for operating in space.
Mutants in Orbit starships are similarly effected by the same rules. A starships top speed is limited by the ability of its radiation and particle shielding. Ships with enough fuel can reach up to 20% of the speed of light (equal to Phase World civilian shields). In research, I have found no systems like the traction drive in Mutants in Orbit and the system should be replaced by the fusion and ion engines in mutants in orbit. These rules also includes Rifts Earth vehicles if they can break atmosphere.
Acceleration also includes deceleration because all it is acceleration in the opposite direction. All starship acceleration is effected by two factors. First is the capability of the drive and second is the ability of the artificial gravity system to compensate for the starships acceleration. If the artificial gravity system fails and a starship is accelerating, S.D.C. beings would be turned into jelly, M.D.C. creatures such as the Kreeghor would be killed by every bone in their body being destroyed, and completely solid organisms such I assume machine people are would survive but be unable to move. Starships acceleration is in many ways more important that its top speed. The way that acceleration is calculated is that you use the starships Mach speed and divide it by ten. This becomes the ships acceleration in percentage of light per turn.
Some groups may consider the acceleration to be too great, if that is the case take the Mach speed and divide the number by 100 and use that for the acceleration of the ship in percentage of light per turn.
First Example: A Black Eagle has a maximum speed of Mach 16. This means that the starships acceleration is 1.6% of the speed of light per turn.
Second Example: A Warshield cruiser has a listed speed of Mach 8.5. This means that the starship can accelerate at up to .85% of the speed of light in a turn. This means that small starships will usually be able to catch larger ones unless the Large starship is already traveling much faster that the small ship.
The rules that originally applied to the exceeding the top speed is now applied to the ships acceleration. A ship can exceed its top acceleration by up to three times but when top acceleration is exceeded the engine has an 18% chance of burning out checked every turn. If the engine burns out, emergency systems will allow the ship to accelerate up to .2% of the speed of light. This means that starships that have their engines burnt out will take a long time to stop. In addition to the engines failing, there is a 1% chance per turn that when a ship is accelerating above maximum that the artificial gravity will fail and kill most of the crew as described above.
There is one final area that needs to be described. That is that the inertial mass of an object increases as the speed of light is approached. This is calculated by using this Formula
- Gamma = 1 / square root(1 - (v/c)*(v/c))
v - velocity, c - speed of light,
This is a table of how these figures come out
The apparent length of the object is divided by the gamma factor, apparent time is slowed by this factor. The momentum and kinetic energy of the object is increased by the factor, so it's apparent inertial mass (not gravitational mass) is also increased by this factor.
In game terms, this all means that a Starship acceleration is divided by the Gamma factor to calculate the ships new acceleration. In practical terms, this does not need to be worried about until 40% of light has been achieved.
With time dilation, the dilation does not have enough effect on the crew at .60 of light to have the crew start losing attacks
Robotech and Macross starship accelerations use the auxiliary engines speed divide it by ten and that is the starships acceleration in percentage of light. Example: Ikazuchi Command Carriers have a top speed on its auxiliary engines of Mach 7. The starships acceleration 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. This can be rounded up to the nearest 0.5 or whole number or can be left as the original number.
These formulas are used to calculate the ships velocity and top speed for both fighters and shuttles:
- Velocity = Acceleration x Time + Initial Velocity
Distance Traveled = Acceleration x ½ x Time ² + Initial Velocity x Time
1 G = 32 feet (9.8 m) per second ²
Unless a ship is propelled by gravity based systems, the amount of reaction mass a starship has become important. Most ships and fighters use hydrogen, helium, or a mixture of both for reaction mass. Most larger Robotech and Macross ships propulsion systems are at least partial based on gravitic systems and reaction mass is not a problem but for must shuttles and fighters, the amount of reaction mass is relatively important. Assume that fighters to have four to eight days of reaction mass depending on the size of the fighter and assume that shuttles have from two to four weeks or reaction mass depending on the size of the shuttle. This is how many days the fighter or shuttle can travel at .5 G of acceleration. The consumption of reaction mass doubles for 1 G of acceleration and then doubles for every G of acceleration up to maximum acceleration. If a ship burns over half of its fuel accelerating, the ship will be unable do decelerate fully and needs to either be recovered by a ship moving faster or be lost. Fighters and shuttles will often accelerate for a period of time and then cruise using the speed already built up.
With the Elimination of the traction drive, all Mutants in Orbit ships use acceleration in G and the amount of fuel. Like Robotech and Macross fighters and shuttles, the top atmospheric speed of the ship in Mach is converted to the maximum acceleration of the ship in G. This can be rounded up to the nearest 0.5 or whole number or can be left as the original number.
These formulas are used to calculate the ships velocity and top speed for all Muntants In Orbit ships:
- Velocity = Acceleration x Time + Initial Velocity
Distance Traveled = Acceleration x ½ x Time ² + Initial Velocity x Time
1 G = 32 feet (9.8 m) per second ²
The amount of reaction mass for all Mutants In Orbit. Most Mutants in orbit ships use hydrogen, helium, or a mixture of both for reaction mass. Assume that fighters have enough reaction mass for four to eight days of acceleration at .5 G and assume that shuttles have two to four weeks of reaction mass at the same acceleration. Large ships are assumed to have two to four months of reaction mass at .3 to .4 G of acceleration. For shuttles and fighters, double the consumption for 1 G or acceleration and double the consumption for every 1 G of acceleration beyond 1 G up to the ships to speed. For large ships, double the consumption of fuel at double the base acceleration and for each increase of twice the base acceleration of the ship. A large ship with a base acceleration of .3 G would burn twice as much fuels at .6 G and the ships fuel consumption would double for every .6 G beyond the initial .6 G of aceleration. If a ship burns over half of its fuel accelerating, the ship will be unable do decelerate fully and needs to either be recovered by a ship moving faster or be lost. Ships will often accelerate for a period of time and then cruise using the speed already built up.
Rifts earth ships that can reach space would also follow these modified rules.
Since starship speeds have been greatly increased, the distance away from a planet must be increased in order for the ship to no be able to jump instantly. Since the strongest gravity source in a solar system is normally the star, distances are measured from the star. These figures are based on a star that is the size of Sol (our sun). In order to modify the distance from the celestial object for the actual mass of the celestial object, you simply multiply the celestial objects mass in Sol masses by the distances. This means that White and Blue Giant class stars would have very large areas that a ship must clear before going FTL and outer gas giants would still have a relatively large distance that a ship must travel away from before entering FTL (Although less then a star). The distances are calculated by taking the largest distance that the drive requires, dividing that number by 1000 and that is the distance in light minutes. A light minute is a convenient distance to express longer distances. The distance from the Earth to Sol is approximately 8 light minutes.
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 it will be ripped apart. When using an FTL engine with a star the size of Sol, the ship must be at least 20 light minutes away from the star. The original distances listed in the Phase World book is 10 to 20 thousand miles.
The distances for a CG-Drive is increased the same way that it is for P-Drives. This means that instead of 20 thousand miles (In the Phase World book, the distance is written as 10,000 miles but it states that double is safer so I am using the larger figure) the distance is 20 light minutes.
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. The distance needed for the engine to be used is based on the magic in the system. A system that has very low magic only requires 5 light minutes and a system with a great amount of magic will require 50 light minutes before being able to activate the R-Drive.
Spacegate Jump Systems:
These systems are the only exception to the distances for the FTL 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.
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 space, 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.
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.
Missiles are not effected by a maximum speed like starships are because the missiles life span after launch is brief enough that radiation and particle damage is not a factor. About 1 % of all missile will not reach their targets because radiation or particles will either cause them to destroy themselves, become inert, or veer off course. Acceleration as per the same rules that effect starships except top speed is higher.
Extended Range Engagements:
Missiles can be used to hit targets beyond their maximum range because missiles will travel in a straight line once they run out of energy. They are of course effected by gravity wells but that can be calculated for.
- Targets that do not move are ideal for this type of strike. These include, among other things, orbital bases and cities. There is no bonuses or penalty to hit these targets.
- To hit specific targets, such as an individual building in a city, the missiles are at -8 to strike.
- To hit a large moving target such as a large Capital ship (Protector or Dreadnought for example), the missiles are at -16 to strike and unlike most attacks, the pilot can make dodges that no damage will be taken.
Missile range is 8000 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 an acceleration of 10% of light per turn (far faster than any starship)
Long Range Missiles:
Missile range is 3400 miles (5470 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 an acceleration of 8% of light per turn (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 an acceleration of 6% of light per turn (faster than any starship except a fighter exceeding it maximum safe acceleration)
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 an acceleration of 4% of light per turn (faster than any starship except if it is exceeding it maximum safe acceleration)
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 an acceleration of 2% of light per turn (slightly faster than any starship except if it is exceeding it maximum safe acceleration)
If starship Mach Speeds are divided by 100 instead of 10 when calculating the starships acceleration in percentage of light, divide al missile accelerations by 10 for missiles acceleration in percentage of light per turn.
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.
The speed of Light is 186,282.4 mile (299,729.458 kilometers) per second in vacuum. 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 and that in order for a ship to change course it must exert acceleration to make it move in the direction. For example, a Black Eagle is traveling at 10% of the speed of light it wants to turn to port. In one turn its course is now 10% of the speed of light forward and 1.6% of the speed of light to port. 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
- 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 © 1999, 2001, & 2006, 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 <email@example.com> for helping me with the effects of approaching the speed of light on acceleration and time dilation.