#RPG Rulings – Understanding Gravity in #TheExpanse Using #CepheusEngine #TravellerRPG

Season 5 of The Expanse TV series is streaming now, which means its that time of the TV season that I look once again at how I can take the hard-ish science fiction of James S.A. Corey and depict it in a roleplaying game campaign. This time I am focused on one foundational aspect of the setting that I took for granted before – gravity.

Getting Down with Gravity in The Expanse

Gravity in The Expanse is kept fairly realistic. The sources of gravity are what we expect from our current understanding of physics. Gravity is created by mass (planets, moons, planetoids, asteroids), spin habitats, or along the thrust vector of ships. Gravity is also a vital part of the cultures in The Expanse. From Belters who are tall and lanky from growing up in low-g but weak in normal gravity to Martian Marines who train at 1-g to be ready to fight on Earth, gravity is an important descriptor (discriminator?) between different factions. Gravity also has important impacts to space travel and combat; look no further than the need for “the juice” to withstand high-g acceleration or maneuvers or how it acts to limit human activities if one’s body is subjected to high-g stress for long durations (not to mention the catastrophic consequences of decelerating too quickly, yuck).

Courtesy pintrest.com

Rules of Gravity

I don’t presently own The Expanse Roleplaying Game from Green Ronin so I do not know the details of how they handle gravity in that setting. However, I am a long-time Traveller RPG player. These days I enjoy the modern incarnation of the Original 2d6 Science Fiction Roleplaying Game by using the Cepheus Engine rules set.

For my exploration of of gravity and The Expanse, I focused on five RPG rule sets or settings:

I really appreciate how all these various rule sets can work together to create an internally consistent, plausible setting. Although I use all these different rules sets and settings for reference, I will describe my rules interpretations primarily in Cepheus Engine terms for ease of integration across the various rules incarnations. My goal here is not to “science the sh*t” out of gravity in my RPG campaign, but to lean on a reasonable set of rules to provide good setting “flavor.”

Characters and Gravity

Characters in Cepheus Engine are described using three physical characteristics; Strength, Dexterity, and Endurance. The usual character generation method is to roll 2d6 for each characteristic. Each characteristic can range from 1 to 15 with 7 being a human average. Interestingly, when creating the physical characteristics of a character, there is no adjustment in the rules based on a low-gravity homeworld. Instead, an (assumed) low gravity homeworld grants certain default skills. Specifically, a homeworld with a Trade Code of “Asteroid” or “Vacuum” earn the Zero-G-0 skill (CESRD, p. 26)

The CESRD also has rules for alien species that are not specifically intended for human characters but I note them here as they may prove useful:

  • Notable (Characteristic): Some species are notably dexterous, intelligent, tough or strong. Characters from such races have a positive Dice Modifier when rolling for that characteristic (+2 unless otherwise specified), and their racial maximum for that characteristic is increased by the same amount. (CESRD, p. 44)
  • Weak (Characteristic): The opposite of Notable (Characteristic), some species are weaker, less resilient or less well educated than others. Characters from such races have a negative Dice Modifier when rolling for that characteristic (-2 unless otherwise specified), and their racial maximum for that characteristic is decreased by the same amount. (CESRD, p. 45)

The Clement Sector setting supplement Tree of Life: Altrants in Clement Sector defines an altrant as, “groups of humans which, from birth, have been altered thanks to advanced genetic manipulation, to have abilities different than a baseline human. These changes were most often made to allow humans to be able to perform tasks and live in environments which would be difficult or impossible for baseline humans.” If one ignores the “genetic manipulation” and instead views the change as “naturally evolved” then two Body Alterations found in this supplement may be useful:

  • Muscle Increase Package: Often referred to as the “Hercules” alteration, this procedure alters the body to make it as strong as it can possibly be. This alteration is the equivalent of years of strength training and will give the body the appearance of a successful bodybuilder. Taking this alteration gives the character +3 to their STR and -3 to their DEX immediately after the full alteration time period has passed. (Tree of Life, p. 45)
  • Vestibular System (Improved): This alteration improves the sensory system which provides the user with their sense of balance, spacial orientation, and balance. This gives the character a +2 DM to any physical task performed in gravity of less than 0.50 standard. However, the character will suffer a -2 DM to any physical task attempted in gravity of more than 1.25 standard (Tree of Life, p. 49)
Courtesy geekwire.com

The CESRD is also limited in what affect gravity has on characters. The skill “Zero-G” provides some guidance for actions in zero-gravity environments:

Zero G: The Character is acclimated to working and living in micro-gravity environments and freefall. The character is trained and familiar with the use of weapons and combat in such environments. In addition, the individual has been trained in the wearing, care, and maintenance of all types of Vacuum Suits and Combat Armor commonly used in these conditions.

CESRD, p. 57

[As an aside, looking back over the history of Traveller, the Zero-G skill, seemingly so foundational to a science fiction setting, has evolved in interesting ways. In Classic Traveller Little Black Book 1: Characters and Combat, one finds the skill Vacc Suit but not Zero-G. The CESRD has Zero-G but not Vacc Suit. T5 has both Vacc Suit (which it names as a Default Skill that all characters start with) AND Zero-G.]

Rules for “High and Low Gravity Worlds” are found in Chapter 12: Worlds of the CESRD:

High and Low Gravity Worlds: Worlds where the gravity is 0.75 or less are low-gravity worlds….Humans tend to find life on low-gravity worlds to be initially pleasant, but regular exercise regimes and medicinal supplements are required to prevent bone and muscle degradation. Those who spent too long on low-gravity worlds cannot tolerate higher gravities. Characters on low-gravity worlds suffer a -1 DM to all skill checks until they acclimatize, a process which takes 1D6 weeks. Characters with Zero-G skill at level 0 or better acclimatize instantly.

High-gravity worlds have a gravity 1.25 times or more than of Earth….Humans find high-gravity worlds unpleasant. Especially high-gravity worlds require the use of pressured or powered suits to support the human frame. Characters on high-gravity worlds suffer a -1 DM to all skill checks until they acclimatize, a process that takes 1D6 weeks.

CESRD, p. 168

Going back deep into the Classic Traveller lore, Module 2: Beltstrike includes rules for activities in zero and low gravity. Basically put, anytime the characters attempted to move or otherwise act in zero-g they had to make a saving throw of 10+ (on 2d6), applying modifiers as found on the Zero-G Activities Chart:

Classic Traveller Module 2: Beltstrike, p. 11

The more recent Orbital 2100 also provides rules for activities in zero-g environment. The task roll in Orbital 2100 is the spiritual successor of Beltstrike but greatly simplified:

Every crewman on DSV [Deep Space Vehicle] or orbital vehicle will have Zero-G skill-0 as standard. Higher levels of the skill are indicative of much greater experience of working in zero gravity. A crucial task, whether it is aligning and antenna or an EVA, shooting someone with a revolver or trying to shut an airlock door quickly to prevent an intruder forcing their way in, requires a skill check. For regular activities, skip the rolls entirely.

Avoid Losing Control in Zero-Gravity: Zero-G, Dexterity, Instant, Average (+0)

Apply the following DMs: Using a tool to repair/construct -2, Firing a gun -3, striking with tool, weapon, fist etc., or pushing/pulling -4, using a handhold +2

Losing control means that the task has failed until control reestablished, the character is tumbling! Roll again to regain control, but this time there are no DM’s, either positive or negative, except for those derived from Zero-G skill and Dexterity characteristic.

Orbital 2100 v3, p. 125

Before we get into making a character for The Expanse, let’s also consider what the spacecraft in book and TV series show us.

Ships and Gravity

The Expanse Canon

Way back in October 2016 and February 2017 I did two posts on how I viewed the depiction of spacecraft in The Expanse in Cepheus Engine-terms. To recap, there are three basic forms of Maneuvering Drive (M-Drive) shown in The Expanse; the “Teakettle,” the fusion torch, and the Epstein Drive:

Flying teakettle was naval slang for flying on the maneuvering thrusters that used superheated steam for reaction mass. The Knight‘s fusion torch would be dangerous to use this close to the Canterbury and wasteful on such a short trip. Torches were pre-Epstein fusion drives and far less efficient.

Leviathan Wakes, Chapter 3

By doing some backwards math I worked out that the “Teakettle” tops out at 2-G acceleration. Based on the upper limits of the instruments in Solomon Epstein’s ship, the fusion torch appears to have a limit of 7-G acceleration. In the novella The Drive, Epstein’s new drive pushes him at something like 12-Gs and in Season One of The Expanse the Rochinante pushes upwards of 17-G acceleration. As fast and exciting a high-speed run is, the mundane reality of travel in The Expanse is that ships usually plod along at a much slower cruising rate. Judging from the book Leviathan Wakes and the novella The Drive it appears that “cruising speed” is somewhere around 0.3-G acceleration. This ‘minimal acceleration provides just enough g-force to avoid the penalties of zero-g activities. This low-G acceleration is also important to note because it plays into the design of the ships.

Courtesy Syfy.com

Ship Gravity Using Cepheus Engine

One of the major “handwavium” technologies in Classic Traveller and now Cepheus Engine is that with the advent of the gravity-based maneuver drives you also get artificial gravity, known in the Traveller setting as “Compensators”:

  • Compensators. Integral to Maneuver Drives, Gravitic Drives, and Lifters is an inertial compensation component which counteracts the effects on acceleration on occupants of the ship. (T5 v5.10, Book 2: Starships, “How Maneuver Works,” p. 101)

In The Expanse there is no artificial gravity device for spacecraft so we need to find some rules to help us depict what happens with too much, or too little, gravity and what design decisions can be made to compensate.

Gel-y Juice

In The Expanse, there are two technologies for dealing with the crushing force of high-g acceleration. The first is acceleration gel; “Thirty minutes later, the engines kicked on, pressing him into the acceleration gel at a joint-crushing high-g burn for thirteen days, with one-g breaks for biological function every four hours.” (Leviathan Wakes, Chapter 46)

The second acceleration compensating technology is “The Juice:”

Going on the juice was pilot-speak for a high-g burn that would knock an unmedicated human unconscious. The juice was a cocktail of drugs the pilot’s chair would inject into him to keep him conscious, alert, and hopefully stroke-free when his body weighed five hundred kilos. Holden had used the juice on multiple occasions in the navy, and coming down afterward was unpleasant. 

Leviathan Wakes, Chapter 5

Standing Up In Space

The design of ships in The Expanse is also driven by the lack of an artificial gravity device. Fortunately, the setting of Orbital 2100 is in our near future and leans heavily into pre-gravitic spacecraft design similar to The Expanse and therefore can be used as a guide:

The biggest difference in space technology is the absence of anti-gravity….Not only are the drives different but the lack of on-board gravity means the crew must operate in zero-G throughout the mission. The only way to mitigate this is the installation of spin habitats, or rotating sections of the spacecraft, that ‘simulate’ gravity.

Orbital 2100, Chapter 5: Spacecraft Design, p. 37

For The Clement Sector setting, ship design is found in the Anderson & Felix Guide to Naval Architecture. Included in A&F is a module for designing Pre-Gravitic Drive Spacecraft. Here we actually get rules for continuous micro-gravity exposure as well as alternate methods of producing artificial gravity, both of which are also featured in The Expanse:

For every four week period of continuous micro gravity exposure there will be a one point strength and endurance characteristic loss that will require 1d6 weeks of recover in a one standard gravity environment.

The two main methods of producing artificial gravity are:

Thrust

Producing “rear is down” gravity

A ship under acceleration will produce thrust gravity. In this instance the ship’s internal layout will need to be perpendicular to the axis of the ship or ninety degrees to the line of flight.

Centrifugal Rotation

Producing “out is down” gravity

For any type of method using centrifugal rotation to produce gravity, the internal layout must be aligned so that decks face inward towards the center of the rotation arc.

Anderson & Felix Guide to Naval Architecture, “Artificial Gravity,” p. 106
Courtesy syfy.com

Expanse-ive Characters

Having looked at many rules of Traveller and Cepheus Engine, how do I think characters from The Expanse could be portrayed?

Building a Better Belter

For Belter characters, at character generation I give each the Weak (Strength) and Weak (Endurance) trait from the CESRD alien species listing. I also give Belters the Vestibular System (Improved) alteration found in The Clement Sector supplement Tree of Life. Note that Belters grow up with the Zero-G skill so they instantly acclimatize when moving between different gravity world unless they cannot exercise or medicinal supplements are not available. To simulate the absence of such I ruled that they suffer loss of strength and endurance the same as if they were exposed to micro gravity for long periods.

I’ll point out here that the Belter career in the CESRD is perfectly adequate for generating a Belter character. However, if you have access to the Cepheus Engine supplement Uranium Fever: Asteroid Mining Rules for the Cepheus Engine from Stellagama Publishing (2018) the Independent Belter, Company Belter, and Planetary Miner careers are well worth the small cost of the product.

For Mars – Hu-ah!

I tend to generate and play Martian characters pretty much as a standard human. Being born, raised or living on Mars for any extended length of time automatically earns the Zero-G skill. Martian Marines, of course, are generated using the CESRD Marine career although I also draw upon materials found in The Clement Sector, in particular the sourcebook Hub Federation Ground Forces.

Acceleration

There are no specific rules in Cepheus Engine or Orbital 2100 for acceleration effects on characters. Looking at “Falling and Gravity “in CESRD (p. 164), we see that on a 1g world, a character suffers 1d6 damage per 2m of fall. The rules further specify that for higher g worlds, multiple the 1d6 by the planet’s gravity number. The Epstein Drive accelerates at 11-G which we can compute as 11d6 damage. The question is the time period in which this damage takes place. Falling is assumed to be instantaneous, but declaring 11d6 damage per combat round (every 6 seconds) does not seem to fit the events of The Drive. This seems excessive because an average character in Orbital 2100 (7 Strength/7 Dexterity/ 7 Endurance) only has 21 damage points until death. The “average” damage from 11d6 is 44, meaning an average character is dead twice over!

Perhaps we should assume the 11d6 damage takes place every space combat round  (1,000 seconds/16.6 minutes) instead? This better reflects the painful, but non-instantaneous death like Solomon Epstein experiences in The Drive. It still seems like an excessive amount of damage guaranteeing a quick character death.

Looking around for a solution, and not finding one in the rules, I suggest a “house rule” that acceleration couches (built with that acceleration gel) absorb some of the damaging g forces. In This New Ocean: A History of Project Mercury, acceleration couches in the Mercury spacecraft were designed to absorb 9G (assumed to be the maximum G at reentry). If we use couches to absorb, say, 10 of 11G, the character will have only 1g of damage (1d6) per space combat round. This means an average human may  last as long as six space combat rounds, or about 100 minutes, before succumbing to the strangling G forces. We could also say that prolonged exposure to high-g, defined as more than 1-G acceleration but less than the 9-G acceleration gel couch rating, will subtract one from the strength and endurance characteristic every 16 space combat rounds (around 4 hours) unless there is a four-round (1 hour) break in acceleration at 1-G or less. This fits with the time period in Leviathan Wakes when talking about acceleration gel.

These Boots Are Made For Walking

One important piece of equipment is The Expanse is Magnetic Boots. Characters with the Zero-G skill automatically can use Mag Boots; other need 1d6 hours to acclimatize. (I’m so tempted here to say that, based on canonical events in the TV series, female characters get an automatic -2 DM on the time roll, but that would be gender biased, eh?)

“Now you just walk around like you’re in pumps.”

Working In Space

When the player characters are in low-G or micro-G environments, I makes sure to use the Orbital 2100 working in space task check unless they are wearing Mag Boots (count as a handhold for the +2 DM) or the ship is moving with at least 0.3-G acceleration. I also enforce the A&F prolonged micro-gravity exposure rule.

Rochinante, Meet Broadsword and Azhanti High Lightning

Ships in The Expanse are built using what I call a “tower-ship” or “tail-sitter” design where the decks are arranged like floors in a building perpendicular to the axis of thrust. Classic Traveller and Cepheus Engine don’t have many designs to reference, but I will point out that the Azhanti High Lightning-class of cruisers (Classic Traveller Game 3 – Azhanti High Lightning) or the Broadsword Mercenary Cruiser (Classic Traveller Adventure 7: Broadsword) are built using a tower-ship/tail sitter design like the Rochinante. If you want to see a Cepheus Engine ship design that uses the tower-ship configuration I recommend you get Ship Files: Atticus Class Freelancer from Moon Toad Publishing (2017). This 100dTon ship is a tail-sitter not that much smaller than the Rochinante….

Courtesy Moon Toad Publishing

RPG Thursday – Soaring into battle with #TravellerRPG

“What’s that?”

Strom turned his attention from his mapping instruments and looked over at the panels that Ga’de, his co-pilot and fellow Scout, was now studying intently. The optical array had picked up something and flashed an alert. Whatever it was, it was unidentified for the moment.

“It’s small and cool,” Ga’de reported. “Maybe 5 dTons in size. Why is it in a retrograde orbit?”

“Yeah,” Strom thought out loud. “It’s coming straight at us.”

Ga’de glanced away from his instruments and over at Strom. His brow was furrowed. “They’re attacking?”

Strom was thinking out loud. “Since we got here, the western continent has not liked our presence. They’re the most vocal about the ‘danger’ of ‘outer space aliens’. They’ve made announcements that they are willing to fight to keep us out.”

Ga’de harrumphed. “What imbeciles. They just can’t accept that they’re not alone in the universe and somebody else made it to the stars before them. We offer them technology and they reject us because we threaten their ”culture’. Why can’t they see that we offer them the future?”

Inwardly, Strom agreed but talking about it was not the solution right now. “Can we get any sort of ID on it?” he asked.

Ga’de turned back at his instruments. “Hard to tell, optics seem to show something winged. Do they have manned small craft?”

Courtesy astronautic.com

On a small screen next to his station Strom consulted the few files they had on the planet so far. In a previous expedition they had raided what passed for a library on this planet and acquired an “Encyclopedia” but it was a physical paper document. It had taken a while to scan it into the computer and the cross-references were poor. Imagine that; a planet so backwards they didn’t even have the SmartNet yet!

“Yes, they are working on a crewed launch capability using capsules. But the only thing shown here is crude ballistic missiles, nothing more than TL5 at the best. Wings…that’s different,” Strom trailed off.

“Do we maneuver?” There was a nervous edge in Ga’de’s voice.

Strom considered. “We’re higher tech. And we have to finish this mapping mission. Besides, we can’t let them think they can push us around.” He paused for just a moment. “No. We maintain course.”

Optics continued tracking the black winged object. A bit nervous now, Strom nudged the thrusters a bit to slightly change their vector; a few moments later the black winged object adjusted too.

“That’s not right,” Strom thought. “It means it’s guided…by a hu-man?

The range was closing rapidly. The approach looked like it was going to be close.

Somewhat belatedly, Strom stirred into action. “Ga’de, get to the turret, fast.”

Ga’de got up and raced from the control cabin. The winged craft kept closing.

Strom watched his panel as the turret indicator light came on. His heart sank when Gade made his first call.

“Damn systems rebooting! Something about an urgent update!”

Strom strapped himself in as he started throwing switches. “Strap in, we’re gonna burn!”

Time seemed to slow to a crawl. Strom saw on the optics the winged beast release a smaller object that flared briefly and accelerated quickly towards his saucer. He saw out of the corner of his eye a warning from the radiation detector. He heard Ga’de cursing the Gods in the turret.

These Stars Are Ours, Stellagama Publishing, 2017

He reoriented the ship and punched the M-Drive. As Strom was slammed back in his chair by the acceleration he thought about his mission. The Quorum had sent them here to expand the frontiers of their small empire. Surely, this lesser-developed planet, just at the cusp of spaceflight, would welcome them. After all, they were a highly compatible species as secretive missions before had shown. Some of the specimens captured were still alive and helping the Quorum even now. Sure, some had resisted, but they were the exception, right?

The small missile flared again but brightly this time. It changed course to intercept Strom’s saucer. Before he could manuever again the small object exploded with a blinding flash of light. As the expanding atomic fireball rapidly washed over his saucer, Strom thought that, surely, their superior technology would save them. Surely….



Deep inside a bunker buried under a mountain, the General watched intently as the stream of information from SIDS, the Space Intruder Detection System, reported the nuclear detonation in orbit above. The Eastern Pact would be upset by the large EMP event above their continent, but setting them back while destroying the alien intruders was but a small price to pay for saving the planet.

The General watches (Courtesy Wargames)

The General glanced to his right at the two ‘Agents’ dressed in identical black suits. They kinda looked like that a-hole J. Edgar’s men, but something was not quite right. The older one had never smiled. The younger one kinda fidgeted until the older one glared at him then he too stood by emotionless. They didn’t even laugh at his spark plug joke. Shaking his head ever so slightly, the General swore under his breath that he would never understand why they wore sunglasses this deep inside the mountain.

Sighing, the General spoke up, “Control, take us to DEFCON 5. Ops, make sure all reports are are captured for Project Blue Book. Comms, get me a channel.”

“Ground Control to Major Tom….”

Courtesy collectorsweekly.com

This mini Traveller RPG adventure was inspired by a tweet by @pilliarscreatio showing a Boeing Dyna-Soar hot-staging into orbit.

Key materials referenced include:

#Coronapocalypse #TravellerRPG #Wargame – Math lessons with Squadron Strike: Traveller (@AdAstraGames, 2018)

I HAVE BEEN A TRAVELLER RPG PLAYER SINCE 1979 when I got my Classic Traveller Little Black Books set. Over the years I also played many wargames based on the Traveller setting. Of those, I always had a soft spot for tactical starship combat. This week my #coronapocalypse wargame was Squadron Strike: Traveller (Ad Astra Games, 2018). What sets Squadron Strike: Traveller (SST) apart is its fully 3D model which uses Newtonian movement in space. Be warned – the back of the box rates the game as Moderate complexity and notes, “Players need to do addition and subtraction.” The last time I played SST was January 2019. At that time I was working my way through the tutorial booklet and was not past the 2D scenarios. Well, this weekend I worked my way through all four scenarios of the Tutorial and discovered SST is not for the faint of heart; there is a steep learning curve that will challenge (and burnout) your brain cells. You WILL need to do more than just addition and subtraction! However, if you persevere the payoff is a very good, playable-albeit-complex model of ship-to-ship combat in the Traveller RPG universe.

The Tutorial book in SST uses a programmed learning approach. If you are a player that just wants to read the rulebook and play you will fail. The 3D concepts used in SST almost defy writing – they really must be experienced in a structured manner to be understood. As designer Ken Burnside writes in the sidebar Don’t Just Read, Play:

The first tutorial is highly scripted – you pretty much follow along and mark boxes. Get in the habit of playing the tutorials; the verbiage is intended to be read while you’re doing things. If you just read the tutorial, there’s a non-zero chance you’ll find it tedious and overwhelming. If you play the tutorial as you read it, you’ll see how it all the pieces and parts fit together.

Tutorial 1 introduces the Sequence of Play and the 2D version of the Altitude Vector Information Display – AVID. The AVID is the heart of SST and to understand the game one has to master how to use the AVID. The tutorial walks the players though the 2D version of the Ship System Display, the SSD, as well as basic 2D movement and combat. At the end of Tutorial 1 the player is familiar with the basics of Plotting, Movement, and Combat.

avid+example
AVID. This ship starts facing hexsides B/C and is rolled 30 degrees right. The plot calls for pivoting 60 degrees to the right and pitching the nose up 30 degrees. Easy to read, yes? (Courtesy Ad Astra Games)

Tutorial 2 is another 2D scenario, but this time new concepts like Sandcasters (defenses in the Traveller universe), ECM (used to show technological advantages), Profile Numbers (harder to hit when a narrow profile is presented), missile combat and defense, Crew Rate (just how good are your redshirts?), Damage Control (Where’s Scotty?), and different damage allocation. The concept of Action Points (a combination of power allocation and command and control) is also introduced. For real Traveller RPG fans, there is a sidebar note about integrating character RPG skills into a portion of the game here.

At the end of Tutorial 2, Squadron Strike: Traveller looks to be a moderately-more-complex version of Mayday (GDW, 1978) or Power Projection: Fleet (BITS: 2003). Tutorial 3 changes all that with the introduction of 3D movement.

The first concept that one has to wrap their head around is the 3D AVID. One has to take the 2D graphic shown on the Movement Card (shown above) and imagine it as a sphere.

Avid+Ball
3D AVID imagined (Courtesy Ad Astra Games)

The tutorial makes it clear that there are a few skills are needed; skills that wargamers may not have:

There are three skills you’ll need to master with the the AVID. Unless you’ve been an astronomer, pilot, or driven a submarine for a living, none of them match things you’ve done in gaming or in real life before. It will take some repetition before things “click” The first skill, which we’ll go into now, is orientation. We’ll cover the other two (shooting bearings and mapping them to firing arcs) in the Combat Phase.

If you cannot handle this you will make it no further in learning the game. To help your imagination visualization, the game uses Tilt Blocks to show your ship’s altitude and orientation on the mapboard.

Box+Mini+Roll+and+Pitch
Left – Ship facing A, no pitch or roll, altitude 0. Right – Ship facing A, pitched up 60 degrees, rolled right 30 degrees, altitude +2

weapon+bear+2
Target is visible in red box so Mounts S & U bear but Mount T does not (Courtesy Ad Astra Games)

If you have not given up yet (and you shouldn’t because the Tutorial steps you through everything – although you may need more than one pass to grok it all) you now need to Shoot Bearings to see which weapons bear and can fire. This again requires some imagination math because you have to figure out which window the enemy is in and then see what weapons bear and can fire. Fortunately, the tutorial steps you through the process and there are many helpful tables on the Reference Card.

As “complex” movement is, I really appreciate the “simplicity” of combat resolution. For each attack you ALWAYS roll 4x d10 (1x red, 2x black, and 1x blue). The red die is your Accuracy– roll Accuracy or greater to hit (very few die mods). The two black are “2d10-” which means you subtract the smaller from the larger for a difference which is additional Damage added to the Base Damage number. The blue die is the Hit Location. I really like this streamlined combat approach – roll one die pool and you immediately have hit, damage, and hit location!

The end result of all that math work is a VERY good game of Traveller. Ken Burnside writes of the differences between generic Squadron Strike and Squadron Strike: Traveller:

  • The Traveller universe, set 3,500 years in the future, uses Mode 2 (Newtonian) movement and doesn’t use tactical fuel
  • ECM is turned on, but ECCM is deliberately not used; only the Imperials have ECM in this product, and it shows a Traveller tech-level advantage
  • The Traveller setting uses sand, hull armor, and component armor as the primary defenses of warships
  • Sandcasters, which are “burst mode” shielding with a name change, throw sand in the path of incoming fire
  • In a break from normal Squadron Strike usage, but consistent with Traveller, the “meson” weapon trait makes the weapon vulnerable to meson screens, but lets the weapon ignore sand and the surface armor of the ship
  • Traveller uses two SuperScience Defenses: The meson screen works against weapons with the Meson trait….Nuclear dampers work against missiles.

After I got thru all four tutorials I had several ships and SSDs ready, so I just played around with the system. Once you learn the game it plays fast. The tutorial mentions The Hockey Puck Analogy which is very appropriate:

One of the best explanations of Squadron Strike tactics came from a player named Patrick Doyle. Momentum movement games are about where the hockey puck will be; not where it is now. Always keep an eye on both the target’s ship and how far out their EoT (End of Turn) tent is from their current location.

Squadron Strike: Traveller is a game that will require regular play to maintain proficiency. As tough as the game is to learn, once learned it plays pretty quickly. Fortunately, the game support small engagements as well as larger squadron-level battles. That said, Ship Book 1 has 15 different ships (although many have variants) and there are a few extra ships available online. Like most every Traveller RPG player, I like to design my own ships and I would like to put them into this game. There is supposedly a ship design spreadsheet available for registered users (so…where is that login?). I guess this is also a good place to mention that there is an AVID app available for web/Android/iOS devices. I looked at it but it was not immediately intuitive to me so I just kept plodding along (and learning) the manual way.

Given the abundance of extra time from the Coronapocalypse I think a few battles may be shortly in order!

#Retro #TravellerRPG #Wargame #AAR – Invasion: Earth – The Final Battle of the Solomani Rim War (Game Designers’ Workshop, 1981)

BLUF – Game mechanics are deceptively simple but through play one discovers it’s not necessarily combat that is important but executing an invasion plan that requires proper logistical planning and bringing the right forces to bear at the right time and place versus a stubborn defense that must know when to ‘hide’ and fight another day.

NOW THAT I ACQUIRED A GRAIL WARGAME IN THE TRAVELLER RPG UNIVERSE, it was time to play it. Invasion: Earth – The Final Battle of the Solomani Rim War (GDW, 1981) takes place in the Third Imperium setting of the Classic Traveller RPG. The game depicts the invasion of Earth (Sol) by the Third Imperium in the year 1002 (the 55th or 56th Century compared to today). Interestingly, Invasion: Earth (IE) is a ‘historical’ game in the Traveller RPG line as the invasion takes place just over 100 years in the past of the default setting (years 1105-1107).

Physically, Invasion: Earth is a small game more suited to a folio than a box. The map is small, 16″x21″, which covers not only Sol but also holding boxes for different space locations as well as the terrain key. The game includes 480 counters although half are game markers leaving only 240 pieces for actual combatants. Yes, the counters are small – 1/2″ sized – and challenging to this grognard’s eyes. This is a game where a magnifying glass and tweezers to move stacks is required!

1CEAD605-6313-4973-824F-D591047C6061

The rule book is just as small – 16 pages – and I previously talked about what I like about it. Although Invasion: Earth is both a space battle and ground combat game, a scenario will see mostly ground combat. As I played my first game of Invasion: Earth I discovered the game proceeded in noticeable ‘phases’ where the players face different challenges and are forced to make sometimes painful decisions.

Phase I – The Space Battle

The Imperial player starts in the Out-System Box and has to ‘jump’ into the Sol System. The arrival area is known as Deep Space. Since the Solomani ships cannot ‘jump’ the Out-System Box effectively serves as the ‘off-map’ assembly area for the Imperial player. The Solomani player cannot set up in Deep Space but instead is limited to Far Orbit (which includes Luna) and Close Orbit – the only orbit which interfaces with the planet. In Phase I the Imperial player has to push aside the Solomani space forces to get to Close Orbit and land troops on the planet.

C9196584-FF89-4C3D-BDF1-C10F5C015B8F
Invasion begins….

The problem is those pesky Solomani ships and boats. All ships and boats (non-FTL capable ships) have three ratings – Attack Factor / Bombardment Factor / Defense Factor. However, using the right ship/boat in the right space combat is important. In combat against starships you use the Attack Factor. Combat against boats and ground units use the Bombardment Factor. Each has its own Combat Resolution Table (CRT) where losses are expressed in ‘hits’ or Defense Factors that must be eliminated. This means the first decision the Imperial player faces is how to divide his force to attack defending ships and boats because each squadron can only attack one or the other. Space Combat continues until one side is eliminated or disengages. Ships that disengage move the the Deep Space box where they go into ‘hiding.’ Additionally, if there are no Imperial ships in Close Orbit, those pesky System Defense Boats (SDB) can hide in the ocean. Hidden units have advantages later during the actual Invasion and Occupation phases of the game.

Phase II – Advance Base

For the Imperial player, movement to/from the Out-System can only happen once a turn. This means to bring reinforcements from the Out-System effectively takes two turns. However, if the Imperial player lands a Base on Luna, it becomes an advanced staging area. The challenge for the Imperial player is balancing a need to invade Sol and consolidate forces on Luna. Sounds easy until you take into account Transport.

Different space units have different transport capacities. Ground units have different strength based on their size. Generally speaking, an army is 5C (500), a corps 1C (100), a division 20, a brigade 10, and a regiment 5. Bases (supply points for the Imperial player) are the equivalent of 1C. Different ships can transport different ground units; an Assault Carrier (AR) can carry 6C, a Battle Squadron (BR) carries 20, and a Cruiser Squadron (CR) carries 5. Each ground unit must be carried by a single naval unit – there is no combining 4x CR to carry that 20-Factor division. So the Imperial player has to figure out the logistics game of what ground unit is carried by what squadron. This challenge is not only present in this Advance Base Phase but throughout the game. It becomes even more challenging after Turn 2 when two of the four AR in the game are withdrawn.

Phase III – Invasion!

The invasion of Sol can take place in parallel with the consolidation of an advance base; indeed, the Imperial player is almost forced to execute these two in tandem given the need to achieve victory in the least amount of time. In Invasion: Earth there is little differentiation between ground units but the few differences there are make a big difference.

When landing, eligible defenders roll on the Surface Bombardment Table to see what percentage of the landing attackers are destroyed. The defender totals their Bombardment Factors and rolls single d6 on the column that is closest to, but not more than, that value. The roll is modified by two qualities of the attacker – Tech Level and unit  type.

5ccd2249-eaeb-4308-9005-23c7d3959e82.jpeg

Tech Level (TL) is a key concept in the Traveller RPG setting. The higher the TL the more advanced the unit is. TL is one of the most important factors in combat (more on that later) but in an orbital assault units of a lower TL have a -1 DM to the defenders attack roll, meaning they are likely to suffer MORE casualties. Unit type also plays an important roll. Performing an orbital assault with a unit other than a Jump Troop or Marine is a -3 DM (!). The last thing an attacker from orbit wants to do is land a low-tech, non-Jump or Marine unit against a determined enemy! This means the Imperial player should try to lead the orbital assault with those (few) Jump or Marine troops – assuming they are available and loaded properly on the lead wave.

Phase IV – Occupation

Assuming the Imperial player is able to land troops, in order to win they must control, through occupation, all but 10 Urban hexes on Sol. Control of an Urban hex is through Garrisons. To Garrison a hex it must be either occupied solely by an Imperial unit or within the Zone of Control (ZoC) of an proper Imperial unit and NOT in the ZoC of a Solomani unit. In practice this means the Imperial player will have to slog through many Solomani defenders. To do so will require a thorough understanding of Supply, what makes units different from one another, and Replacements.

Supply for the Solomani player is easy – any Urban or Starport hex is a source of Supply. The Imperial player on the other hand must bring their own supply with them in the form of Bases – that cost 1C to transport – meaning only the (few) AR can deliver them to the surface. Bases also make great targets for the Solomani player. Units that start the turn out of supply may not attack and can defend with half their current value.

At first glance, the ground combat system looks rather like a Lanchester Attrition Model that Trevor Dupuy would be proud of. Combat is a simple odds roll with results expressed in Percentage Loss. The stacking rules allow up to 1000 factors (!!!) in a single hex. So why would one want to play this uninteresting attrition game?

Well, because of the few unit types and Tech Level.

There might not be many different ground units in the game, but the few differences are very important:

  • Army, Corps, and Planetary Defense units ONLY extend a ZoC
  • Armor units have their strength doubled in attack or defense
  • Elite units have their strength doubled (this can stack with the Armor bonus)
  • Tech Level differences are COLUMN SHIFTS on the CRT
  • Mercenaries with over 50% losses have their attack strength halved (they are in it only for the money)
  • Commando units ignore enemy units and ZoC during movement and are always in Supply making them the ultimate infiltrators
  • Guerrilla units are attacked with a +3 DM when hiding.

F17507A9-F876-4B9D-8E4A-5B986D0FD120
An Imperial TL14 Elite GravArmor Division takes on a Solomani TL11 Infantry Corps. 1:5 odds? Not so fast….

In keeping with a core tenet of the Traveller RPG the greater the TL difference the more the hurt! Assume a TL14 Imperial Elite Tank Division (20-14) is attacking a defending TL11 Solomani Infantry Corps (1C-11) as shown above.

  • Imperial attack 20×2 (Armor) x2 (Elite) = 80 vs 100 (1:1.5 SHIFTED UP 3 columns to 2:1) – 8 in 11 chance of 10-70% losses
  • Solomani defend 100 vs 80 (1:1 SHIFTED DOWN 3 columns to 1:3) – 3 in 11 chance of 10-20% losses.

27d00719-b560-45d4-9e14-71b09b500dd5.jpeg

At the end of each calendar quarter, a special turn is executed. This is where both sides can receive Replacements in the form of Replacement Points (RP).

  • Solomani – Accumulate 1x RP for each ungarrisoned Urban hex on the map (there are 61 Urban hexes at the start)
  • Imperial – RP comes in the form of a Wave of 100 RP.

Each RP can rebuild a single ground unit combat factor. It takes 100 RP for the Imperial player to build a Base. The Imperial player can also use a Wave to replace any three eliminated naval units. The Solomani player can start to rebuild an SDB unit at a Starport for no RP but it will not be completed until the next quarter’s special turn (assuming it was not destroyed by being overrun or bombarded). There are additional rules for Emergency Replacements which can be called upon outside of the special turns but are not as plentiful.

End State – Victory

Victory in Invasion: Earth is not based on playing a set number of turns. Instead, in each end of quarter special turn Victory is checked. The Imperial player always has the option of abandoning the invasion which awards the Solomani player a Major Victory. If not, play continues every quarter until the Solomani have 10 or fewer Urban hexes ungarrisoned by the Imperial player. At this point, the Imperial player is awarded 10 VP. Modifiers are then applied:

  • -1 VP for each quarter of the invasion
  • -1 for each Replacement Wave taken by the Imperial player
  • +1 if all Solomani surface units eliminated
  • +1 if all Solomani naval units eliminated.

The Level of Victory Table is then consulted:

  • VP 7+ > Imperial Decisive Victory
  • VP 4-6 > Imperial Major Victory
  • VP 1-3 > Imperial Marginal Victory
  • VP 0 or -1 > Draw
  • VP -2 or -3 > Solomani Marginal Victory
  • VP -4 or less > Solomani Major Victory

In order to win, the Imperial player must be both quick AND efficient with their resources; making as much as they can with the assets they have on hand. The Solomani player benefits from a long, drawn out war of attrition and hiding some units to prevent their destruction (a Fleet-in-Being?).

In my game, the Imperial player did not achieve the Standard Victory (10 VP) until the fifth quarter of play (-5 VP). The Imperial player also took 3x Wave of RP (-3 VP). Not all Solomani ground forces were eliminated and there was a lone Solomani CR that hid in Deep Space the entire game . This was enough for an Imperial Marginal Victory – and boy did it feel marginal!

AAR – or – After Action Reaction

Invasion: Earth turns out to not be the game I was expecting. Looking at the box and the first pass through the rules thought I saw a somewhat staid game with a very old-fashioned combat model that didn’t look like a vision of the future but rather a rehash of the past. Instead, what IE delivers is a master-class lesson on opposed landings and shows a vision of the future where timeless lessons of amphibious landings are applied to orbital assaults. The rules drive the players to carefully husbanding their resources and allocating forces with thought. Indeed, I had not expected a game that appears this simple to be this deep in the decisions it forces upon players.

864C7DA1-A60A-45DC-927B-B2BA4C5BEE16

I note that Invasion: Earth was published in 1981, a year before the 1982 Falklands War where the Royal Navy and British ground forces were challenged to figure out how to carefully load troops and logistics on few amphibious ships and execute an amphibious landing far away from their bases. The British also faced a narrow timeline for action being called upon to invade and retake the islands before the winter.* Invasion: Earth and the Falklands War are eerily similar, and even more eery when one considers IE came before the Falklands War. Then again, maybe designers Marc Miller and Frank Chadwick were just expressing age-old, never-changing lessons of amphibious warfare in this paper time machine.

If so they did a very good job.


*For a good modern wargame on the Falklands War that is soloable, I recommend Mrs. Thatchers War from White Dog Games.

#TravellerRPG Tech – Beams & Missiles & Casters, oh my!

In Classic Traveller RPG and the more recent Cepheus Engine implementation of the rules spacecraft weapons generally are either Missile or Beam (lasers, particle beams, fusion beams). In Traveller 5 another class of weapons, Data Broadcasts or Beamcasts, is introduced. As advanced as Traveller technology is, it appears that Humaniti is too inventive.

190211-d-me312-001
dia.mil

In February 2019, the Defense Intelligence Agency published Challenges to Security in Space. This volume is part of their Military Power Publications. As befits an intelligence agency, the focus is on, well, the threat:

Space-based capabilities provide integral support to military, commercial, and civilian applications. Longstanding technological and cost barriers to space are falling, enabling more countries and commercial firms to participate in satellite construction, space launch, space exploration, and human spaceflight. Although these advancements are creating new opportunities, new risks for space-enabled services have emerged. Having seen the benefits of space-enabled operations, some foreign governments are developing capabilities that threaten others’ ability to use space. (Executive Summary)

One graphic in particular stood out to me; it concerns Kinetic Energy and Orbital Threats:

fullsizeoutput_6e2
Challenges to Security in Space, DIA, p. 10

In Traveller RPG terms, Kinetic Energy Threats are covered by Missiles. However, several of the Orbital Threats shown are not immediately represented in Traveller or Cepheus Engine.

Lasers, KKVs, and Robotic Mechanisms are easily portrayed using the existing Traveller or Cepheus Engine rule set. Using Traveller 5 one can get to Radiofrequency Jammers using Datacasters.

High-power Microwaves is not easily found in the rules. This weapon is maybe a form of an EMP device:

The electromagnetic pulse (EMP) weapon, also called the e-bomb, or the radio flash weapon, is capable of disrupting or damaging the circuitry of most electronic devices.

The weapon accomplishes this by sending either a single pulse or a series of fast, high-powered pulses of electromagnetic energy in the range of 100 MHz to 20 GHz. These pulses are similar to a lightening strike or a nuclear blast. The power level of these pulses can be several hundred megawatts (MW). The EMP weapon has a range of at least several hundred meters, but reportedly can be transmitted up to 15 Km.

The specific method by which the pulse attaches to the circuitry is called coupling. Coupling is simply the binding of an energy wave onto a conductor. There are two types of coupling. The first is called front door coupling and it happens when the energy wave binds to the antenna of a device. The other type is called back door coupling. It occurs when the wave binds to external components such telephone lines, network cables and power lines.

It can also occur with ports on the back of a computer, such as serial ports. After the energy binds, it then moves through the circuitry, frying or disrupting sensitive internal components, such as crystal diodes, ICs, mixers, logic circuits, etc.

The precise targeting of electronic devices can be accomplished in the following way: First the EMP weapon can be aimed in a specific area. The primary factor is not the power of the pulse, but the ability to focus the output. The energy must be accurately deposited at a certain range to be effective.

Next, it can be configured to send a single pulse consisting of a specific frequency, which will only destroy the circuitry of a device that functions on that frequency. In this manner, if an operator has the frequency signature of a target device, then only that single device will be affected, while others in the area remain unharmed.

Furthermore, a series of fast pulses consisting of multiple frequencies can be sent to an area, which will affect the circuitry of all devices operating on those frequencies. This type of delivery is referred to as an ultra wideband pulse (UWBP). It can be adjusted to cover large areas, even an entire city. (newworldwar.org)

In Traveller/Cepheus Engine terms this sounds like a weapon that can be used to destroy sensors or otherwise fry circuits. At higher Tech Levels, the EMP pulse could even be tailored to attack specific components of a ship.

Chemical Sprayers looks interesting. Even spraying something as simple as water in space may create ice that could be lethal at high velocities. Or maybe its chemicals to coat optics or smear solar cells? Other sci-fi ideas may be a chemical that eats at door seals (depressurization?). Maybe what we have here is an early form of the Sandcaster?

Of course, the lowest-tech solutions are also effective. Where in Traveller was there ever harpoons in space?

 


Feature image Ian Stead biomasart

#RPG #Wargaming – #TravellerRPG Tech in #Mayday (GDW, 1978)

pic4387901Mayday (GDW, 1978) won the Charles S. Roberts Award in 1978 for the Best Science-Fiction Board Game. On this snowy weekend in January I played the game as part of my 2019 CSR Wargame Challenge. As a longtime Classic Traveller RPG player and more recent fan of the Cepheus Light: Old-School Rules-Light 2D6-Based Sci-Fi Role-Playing Game it was interesting to see just how Mayday’s take on the Traveller RPG universe was different even back then. The differences in the setting means Mayday is not true to the Traveller RPG universe but makes the game challenging and fun in its own way.

Movement

pic514041Mayday uses a simple vector movement system adapted from Classic Traveller Book 2: Starships. The major setting difference in this case is in the technology used to express Small Craft. In Traveller, small craft are usually propelled by the M-Drive. As described in Traveller 5:

M-Drive: Maneuver is the standard in-system ship drive. It interacts with gravity sources to produce vector movement. It requires a separate power plant. (T5 p. 323)

Power plants in turn are usually fueled for for two weeks. For the purposes of a Mayday scenario this means a ship has unlimited maneuverability. However, in Mayday the Small Craft found on p. 13 are rated in terms of G Level; the maximum acceleration in a movement phase and the total acceleration allowed. For example, the classic Fighter is rated “4G12” which means it can burn up to a maximum 4G in a movement phase but can only make a total of 12G of vector changes before it is out of fuel. In Traveller 5 terms this looks like the Fighter is equipped with Rockets (“Chemical fuels combine in an exothermic reaction in a combustion chamber to produce thrust. Rockets are high volume fuel users”). Rockets are the lowest-Tech Level drives represented in the Traveller/Cepheus Engine rules – and even then in certain setting-specific versions (like Orbital 2100).

The implication of this technology limit for Small Craft means maneuver must be a carefully considered choice. This makes Mayday a much more interesting game with a bit of resource management.

Laser Fire

In Mayday there is only one energy weapon, the Laser. This single Mayday weapon covers all the energy weapons found in Traveller/Cepheus Engine; Pulse Laser, Beam Laser, Particle Beam, Plasma Beam, Fusion Beam. This simplification may be in part because Mayday does not use any armor on ships. In this game, ships are small and fragile.

Ordnance Launch

Surprisingly, Mayday has a complete section on building customized missiles. Players can design missiles with different guidance packages, propulsion options, warheads, and fuel. This is far more in depth than what is found in Traveller/Cepheus Engine where there are three classes of missiles; Regular Missiles, Smart Missiles, and Nuclear Missiles.

Computer Programming

beowulfii
biomassart.wordpress.com

Many people criticize the computer rules in the Traveller universe as “wrong.” After all, in this day of iPads and miniaturized computing, how come shipboard computers are rated in terms of displacement tons (13.5 to 14 cubic meters depending on the rules version used). In Mayday, like Classic Traveller, computers are rated in terms of CPU and Storage. The CPU rating is how many programs the computer can run simultaneously while Storage is the number of programs that are “loaded” in the computer. This leads to challenging game decisions. When flying my little Free Trader running a Model/1 computer (CPU 2 / Storage 4) I need make sure the right programs are in memory to be used during the turn. I may have the right program on hand, but my computer is too small to keep everything loaded and ready. Larger military ships like the Destroyer with a Model/2 bis (CPU 6 / Storage 6) don’t have as many constraints (and access to many more advanced programs too).

Although Mayday is not “true” to the commonly accepted Classic Traveller/Cepheus Engine rules the differences make for a more interesting game. Incredibly, it’s all because of the technology chosen.

#RPGThursday – Heavy Hover Tank Design for #CepheusEngine RPG

hammersslammers
By Source, Fair use, https://en.wikipedia.org/w/index.php?curid=40927431

I absolutely love David Drake’s Hammer’s Slammers series of military science fiction stories. I was so excited when Mongoose Publishing rolled out a Hammer’s Slammers supplement for Mongoose Traveller First Edition (MgT1E). Unfortunately, Mongoose did a very amateur job, demonstrating they really don’t understand the military and leaving us consumers with a poor product. Mongoose claimed that all the vehicles were created with the Traveller Vehicle Creation System and were supposed to be fully compatible with every other Traveller books. NOT SO!

The Cepheus Engine Vehicle Design System is Cepheus Engine RPG successor to The Vehicle Handbook for MgT1E. I have had the CEVDS for a while now and decided to try to recreate something close to a Slammer’s hover tank.

TL-12 Heavy Plasma Hover Tank

Using a closed 5-ton chassis (3 Hull, 3 Structure), Armor 25, the Heavy Plasma Hover Tank is a main battle tank. It has the Hostile Environmental Protections System. It carries a Fusion power plant, Code K, and a hover propulsion system, Code K, giving it a top speed of 150kph, a cruising speed of 112 kph, and an Agility DM of +1. Three kiloliters of hydrogen support the power plant for 1 week of use. This vehicle is equipped with the Advanced Vehicle Control System, Class II Laser Comms (LOS or 50 km), Basic Military Sensors (-2), and a Model 2 computer. There is a Basic Cockpit for the Driver and a Standard Seat for the Gunner/Tank Commander. The vehicle has one weapon points. A large, heavy turret carries a TL-12 Rapid Fire Plasma Gun. Cargo capacity is 7 spaces. The chassis is armored with Superdense (x5). It also mounts an Explosive Belt. The vehicle costs 690.12 KCr and takes 1,125 hours or 47 days to build.

Category

Component

Spaces

Price (Cr)

Notes

Chassis Base

60

7800

Code 9
Configuration Closed
Armor

-15

7800

Superdense (Armor x5)
Reinforced Hull

11200

Hull +2
Reinforced Structure Structure +2
Power Plant Fusion

-3

4500

Code K
Propulsion Air Cushion

-4.5

112500

Code K
Fuel Hydrogen

-3

120

Fuel Capacity = 1 Week
Controls Advanced

-2

10000

Agility +1
Communications Class II Laser

-0.04

3000

Laser LOS/Very Distant (50 km)
Sensors Basic Military

-12

20000

Comms DM 0, Very Distant (50 km)
Computer Model 2

1000

Options

500

Hardened
Accommodations Basic Cockpit

-2

1000

Driver
Standard Seat

-2

1000

Gunner/Commander
Armaments Turret (Large Heavy)

-3

93000

Rapid Pulse Plasma Cannon – TL-12

-3

90000

ROF 1/6, 12d6 Dmg
Explosive Belt

15000

Cargo

-7.1

TOTALS

0

690120

Total time to create this design was about 30 minutes. This is still a lot more time that a GM wants to take to create a vehicle at the table, but fine for a prep session. The design is not a Slammer’s blower tank – it doesn’t have a powergun nor the armor to match. But it was a good exercise of the CEVDS and an encouraging start to designing vehicles for Cepheus Engine RPG adventuring.

#TheExpanse Ships in #TravellerRPG

Watching “Home” (The Expanse, Season 2, Episode 5) with the Rocinante at high-g burns got me back to thinking about the ships of The Expanse and how they could be portrayed in tabletop RPGs. I previously looked at the Epstein Drive and how it might be translated into game terms for use in Traveller RPG or Cepheus Engine or Orbital 2100.

**WARNING – Minor Spoilers Ahead**

d70490f270d0e4985ecdeb50683f5b83
Courtesy SyFy

Going all the way back to the first book in the series, Leviathan Wakes, the small shuttle Knight gives us some insight into the technology of The Expanse:

It wasn’t long before Alex called down, “Okay, Boss. It’ll be about a four-hour trip flying’ teakettle. Total mass use at about thirty percent, but we’ve got a full tank. Total mission time: eleven hours.”

“Copy that. Thanks, Alex,” Holden said.

Flying teakettle was naval slang for flying on the maneuvering thrusters that used superheated steam for reaction mass. The Knight‘s fusion torch would be dangerous to use this close to the Canterbury and wasteful on such a short trip. Torches were pre-Epstein fusion drives and far less efficient. (Leviathan Wakes, Chapter 3)

From the book we know that the trip covers 50,000km. Working with classic space travel time equations, we can compute the Knight is traveling at about 1.0368 m/s or just over .1G acceleration.

Later in Chapter 5 we see the Knight running flat-out at 2G acceleration. At this speed the same 50,000 km trip should take only 53 minutes, which is a bit shorter than the approximately 70 minutes obliquily stated in the book. At this point it is unclear if the 2G speed is the upper limit of the teakettle or the fusion torch at low power.

The Knight does eventually clearly light it’s torch:

“Roger that, XO. Bleeding-g burn-and-flip laid in. Angled approach course so our torch won’t burn a hole in the Cant. Time to rock and roll?” Alex replied. (Leviathan Wakes, Chapter 5)

expanse20g20force
Courtesy NBC Universal

Here we have to interpolate the fusion torch acceleration based on Holden and his apparent weight. When lighting the torch Holden weighs 500 kilos. Assuming he is an average 75 kg to begin with, this works out to almost 7G. Interestingly, from the novella The Drive we know that 7G is the instrument limit on Solomon Epstein’s ship that he installed his new drive on, indicating that the fusion torch may have an upper limit of 7G.

In summary, we can say the shuttle Knight has maneuvering thrusters (teakettle) that operate efficiently at .1G. The shuttle also has a fusion drive (torch) that can accelerate it at up to 7G.

The Knight‘s torch drive could deliver a lot of thrust, but at the cost of a prodigious rule-burn rate. But if they could save the Cant, it wouldn’t matter. (Leviathan Wakes, Chapter 5)

The missiles that are fired at the Canterbury are also very impressive:

As if in answer, six new objects appeared on his radar, glowing yellow icons appearing and immediately shifting to orange as the system marked their acceleration. On the Canterbury, Becca yelled out, “Fast movers! We have six new high-speed contacts on a collision course!”

“Jesus H. Christ on a pogo stick, did that ship just fire a spread of torpedoes at us?” McDowell said. “They’re trying to slap us down?”

“Yes, sir,” Becca said.

“Time to contact.”

“Just under eight minutes, sir,” she replied. (Leviathan Wakes, Chapter 5)

For these six missiles to cover 200,000km in 8 minutes means their acceleration has to be around 150G!

In Leviathan Wakes, Chapter 51, Holden tries to remember how fast the Roci can go:

He tried to remember the Roci‘s maximum theoretical acceleration. Alex had already flown it at twelve g briefly when they’d left the Donnager. The actual limit was one of those trivial numbers, a way to brag about something your ship would never really do. Fifteen g, was it? Twenty? (Leviathan Wakes, Chapter 51)

cqb_main
Courtesy solotalkmedia.com

In the episode “Home” if I caught the screen correctly it looks like the Roci was accelerating just over 17g. This again is in line with the book; and way faster than the 6g of Classic Traveller or Cepheus Engine and far ahead of the technology in Orbital 2100 where the alternative Nuclear Pulse Fusion Drive tops out at 1.2g! Compared to the Traveller RPG or Cepheus Engine universe, the ships and weapons of The Expanse are way faster and likely far more deadly too.

As late to the game as I am, I look forward to reading more of The Expanse series and seeing what further ship secrets are hidden within.


PS: The math for figuring time and acceleration is actually easy, but to help there is an EXCELLENT site at http://www.transhuman.talktalk.net/iw/TravTime.htm that does the math for you!

 

 

 

Traveller RPG Tech – Clement Sector Zimm Drive

Many people forget that the Traveller RPG is actually a generic system. In the years since the Little Black Books came out in 1977 the Third Imperium (3I) setting has come to define the Traveller RPG to the point that many believe that the Third Imperium is Traveller. Fortunately, Gypsy Knights Games’ Clement Sector setting breaks the 3I paradigm through a few simple changes. For a taste of the Clement Sector I strongly encourage you to download the free Introduction to the Clement Sector from DriveThruRPG to see the setting differences in the Clement Sector setting.

In the Clement Sector, the FTL system is the Zimm Drive. Instead of the standard Traveller Jump Drive that moves a ship across 1-6 parsecs of space in a week, the “Z-Drive” covers 1 AU in about 1.44 seconds, one light year in 26 hours, or 1 parsec in 84 hours (3.5 days). The Zimm Drive is limited to a practical range of  2 parsecs (actually 2.44) in 168 hours or 7 standard days. Ships greater than 5000 DTons cannot be equipped with the Z-Drive, and ships between 2000-4999 DTons have a risk of the bubble collapsing. The Z-Drive uses the same space and fuel requirements as a standard Jump-2 Drive in Mongoose Traveller (MgT).

This simple technology change actually has a great impact on adventuring in the Clement Sector. In MgT, to travel in-system a distance of 1 AU using a 1G acceleration drive will take 68 hours; at 6G the best one can do is 27.6 hours (MgT Pocket Rulebook p. 145). In the Clement Sector, a ship can fire up its Z-Drive and get there in 1.44 seconds. If one is trying to get to the outer system, in MgT at 6G it will take between 55-68 hours, whereas in the Clement Sector setting it take a mere 1.85 minutes. This forces changes in how one thinks about fuel, trade, and combat.

In the Clement Sector one can use their Z-Drive instead of Maneuver Drive to travel far distances within systems, but doing so requires a change in how to think about fuel consumption. In MgT, ships can jump less than 1 parsec, but it counts as a Jump-1 event for time and fuel (Pocket Rulebook, p. 141). Z-Drive performance in the Clement Sector can literally be “dialed” to the needed range. In my games, I added a fuel tracker for the Z-Drive which gives the ship 200 hours of “Z-Time” that can be used as appropriate. Need to get to that Gas Giant to top off the tanks? That’s going to cost you 2 minutes of gas!

The Z-Drive also changes the speed of intersystem trade. The quickest way to get around in-system is no longer a Maneuver-6 Drive, but a Z-Drive. Taken together with the Z-Drive size limits, bulk freighters are uneconomical; thus the need for smaller merchant ships is greater (i.e more adventuring opportunities).

The Z-Drive changes the nature of in-system combat compared to the usual Traveller approach. In the Clement Sector, a fleet could enter the outer system, refuel at the far gas giant, organize itself, and then “micro-jump” to the 100-diameter limit. The final approach micro-jump takes less than 2 minutes compared to several days in a standard Traveller setting. In the Clement Sector there is no need for a “long approach” battle. This has an impact on planetary defense forces which must stay within 100 diameters of the target they are protecting. In effect, non-Z-Drive become “static defense” forces whereas Z-Drive defenders become the “mobile” force.

In summary, the Zimm Drive in the Clement Sector from Gypsy Knights Games is both familiar to Traveller players and just different enough to make it interesting. The changes the Zimm Drive brings to travel, trade, and combat will require players (and GMs) to think about the setting differently – one can’t automatically fall back on the “3I way.” This is yet another reason the Clement Sector is so interesting a setting to play in.