Switching the maneuver drive for the jump drive

[Straybow]

Personally the way I can reconcile the performance of Traveller ships with their fuel use is to postulate that the magic of null-grav technology can reduce inertial mass as well as gravitic mass.

Heh heh, RAW is almost always impossible to implement without the crutch of something that is clearly not As Written.


In Revising the science of Traveller I calculated the need for exhaust velocity in the 0.05c-0.1c+ range. Reducing the inertial mass of the ship will also reduce the inertial mass of the reaction mass. I suppose the inertial mass of the exhaust will regain its "natural" mass as it passes outside the grav field, but there's no way to transmit the impulse back to the reduced-mass ship.


The necessity of some sort of "reactionless" drive emerges.

 

[boomslang]

In Revising the science of Traveller I calculated the need for exhaust velocity in the 0.05c-0.1c+ range.

I crunched it a few decades ago in college and came up with something in the neighborhood of 0.17c (and around 1 million Kelvins), so your calculation back in 2003 has always seemed to me to be, if anything, slightly on the conservative side.

:alpha:

 

[Werner]

I crunched it a few decades ago in college and came up with something in the neighborhood of 0.17c (and around 1 million Kelvins), so your calculation back in 2003 has always seemed to me to be, if anything, slightly on the conservative side.

:alpha:

So if we assume each maneuver drive can operate for 4 weeks, with 2 weeks of acceleration and 2 weeks to decelerate we get the following maximum velocities:
Maneuver 1 = 2% of the speed of light
Maneuver 2 = 4% of the speed of light
Maneuver 3 = 6% of the speed of light
Maneuver 4 = 8% of the speed of light
Maneuver 5 = 10% of the speed of light
Maneuver 6 = 12% of the speed of light

Where in order to operate for 4 weeks
Maneuver 1 requires 10% of the hull volume to be fuel
Maneuver 2 requires 20% of the hull volume to be fuel
Maneuver 3 requires 30% of the hull volume to be fuel
Maneuver 4 requires 40% of the hull volume to be fuel
Maneuver 5 requires 50% of the hull volume to be fuel
Maneuver 6 requires 60% of the hull volume to be fuel

Under this system there is only one kind of jump drive, you charge its capacitor for 2 weeks, and the highest speed your Starship attains determines what kind of jump your Starship makes, if you get to 2% of the speed of light you can do a Jump-1, if you get to 4% of the speed of light you can do a jump-2. To put it another way, every percentage point of the speed of light that you can reach, you can jump half a parsec, this doesn't cap out at jump-6 either, the limiting factor is how fast your Starship can go. If you are desperate to send a message, you can accelerate a maneuver-6 starship to 24%, by using all of its fuel of the speed of light and do a jump-12. If the ship is manned, you can use staging to achieve this, essentially have a larger starship carry a smaller Starship, and you lose the larger Starship, and use the fully fueled smaller Starship to save the crew, they decelerate for 4 weeks to go from 24% of the speed of light to 0% of the speed of light.

 

[Straybow]

I crunched it a few decades ago in college and came up with something in the neighborhood of 0.17c (and around 1 million Kelvins), so your calculation back in 2003 has always seemed to me to be, if anything, slightly on the conservative side.

:alpha:

Yeah, as stated it assumed 100% fusion output efficiency and 100% efficiency of conversion to thrust. Neither would be likely to exceed a small fraction, and it would take handwavium tech to make that.

 

[Straybow]

So if we assume each maneuver drive can operate for 4 weeks, with 2 weeks of acceleration and 2 weeks to decelerate we get the following maximum velocities:
Maneuver 1 = 2% of the speed of light
Maneuver 2 = 4% of the speed of light
Maneuver 3 = 6% of the speed of light
Maneuver 4 = 8% of the speed of light
Maneuver 5 = 10% of the speed of light
Maneuver 6 = 12% of the speed of light

Where in order to operate for 4 weeks
Maneuver 1 requires 10% of the hull volume to be fuel
Maneuver 2 requires 20% of the hull volume to be fuel
Maneuver 3 requires 30% of the hull volume to be fuel
Maneuver 4 requires 40% of the hull volume to be fuel
Maneuver 5 requires 50% of the hull volume to be fuel
Maneuver 6 requires 60% of the hull volume to be fuel

Under this system there is only one kind of jump drive, you charge its capacitor for 2 weeks, and the highest speed your Starship attains determines what kind of jump your Starship makes, if you get to 2% of the speed of light you can do a Jump-1, if you get to 4% of the speed of light you can do a jump-2. To put it another way, every percentage point of the speed of light that you can reach, you can jump half a parsec, this doesn't cap out at jump-6 either, the limiting factor is how fast your Starship can go. If you are desperate to send a message, you can accelerate a maneuver-6 starship to 24%, by using all of its fuel of the speed of light and do a jump-12. If the ship is manned, you can use staging to achieve this, essentially have a larger starship carry a smaller Starship, and you lose the larger Starship, and use the fully fueled smaller Starship to save the crew, they decelerate for 4 weeks to go from 24% of the speed of light to 0% of the speed of light.

Two jumps a month is already a tough limit. I dunno who would want to have 5-6 weeks each jump cycle.

 

[Grav_Moped]

Two jumps a month is already a tough limit. I dunno who would want to have 5-6 weeks each jump cycle.

Plus it makes something like an XBoat network ludicrously expensive.

To get a pace of one per day, you need 14 ships accelerating outbound, 7 in Jumpspace, and 14 decelerating inbound. And, though it's relatively minor, you're looking at 13.4 hours message lag (radio/laser at 1.0c across 48,400 light-seconds) each way from the world to the Jump point.

Compare with standard Traveller which uses 7 ships per week and has only minutes of lightspeed message lag.


I'm not sure of the math, but it might be easier (maybe quicker too) to leave the XBoats coasting at fractional-c and meet them with refueling tenders.

Also, if the maneuver drive ratings are volume-based rather than mass-based, drop tanks would really help here.

 

[Werner]

Plus it makes something like an XBoat network ludicrously expensive.

To get a pace of one per day, you need 14 ships accelerating outbound, 7 in Jumpspace, and 14 decelerating inbound. And, though it's relatively minor, you're looking at 13.4 hours message lag (radio/laser at 1.0c across 48,400 light-seconds) each way from the world to the Jump point.

Compare with standard Traveller which uses 7 ships per week and has only minutes of lightspeed message lag.


I'm not sure of the math, but it might be easier (maybe quicker too) to leave the XBoats coasting at fractional-c and meet them with refueling tenders.

Also, if the maneuver drive ratings are volume-based rather than mass-based, drop tanks would really help here.

What if the jump drives are instantaneous? Basically there is no jump space, the Starship quantum tunnels in the direction it is moving, basically if it is traveling 2.6% of the speed of light it quantum jumps 1.3 parsecs to Alpha Centauri traveling in the same direction and speed it was traveling when it left the Solar System. This makes messages travel faster. Starships receive information packets prior to jumping and then transmit those information packets when they arrive, it would take about 5.376 hours for a signal to reach a Starship about to depart the Solar System, and another 5.376 hours for the message to travel from the Starship to a planet in the habitable zone.

 

[Grav_Moped]

What if the jump drives are instantaneous? Basically there is no jump space, the Starship quantum tunnels in the direction it is moving, basically if it is traveling 2.6% of the speed of light it quantum jumps 1.3 parsecs to Alpha Centauri traveling in the same direction and speed it was traveling when it left the Solar System. This makes messages travel faster. Starships receive information packets prior to jumping and then transmit those information packets when they arrive, it would take about 5.376 hours for a signal to reach a Starship about to depart the Solar System, and another 5.376 hours for the message to travel from the Starship to a planet in the habitable zone.

That eliminates the 1-week lag, so interstellar communication takes 2 days round trip rather than 2 weeks.

This changes the civilization built up in the universe significantly from that of Traveller.

 

[Werner]

For high traffic systems the communication is fast, takes about ten hours and change, as you want to allow the ship room to decelerate, you should also allow a random factor, to avoid jump missiles, a 100 ton spaceship moving at 2% of the speed of light has a lot of kinetic energy. 100 tons is 100000 kg moving at 2% of the speed of light is 6,000,000 meters per second. Kinetic energy is (1/2)×100,000 kg × (6,000,000 m/s)^2 = 1.8 × 10^18 joules of energy. If you add some random factor, you reduce the probability of a ship appearing right in front of a planet and impacting it releasing all that energy.

 

[kilemall]

I look at maximum speed as being how quickly a ship can dodge a rock or meteor group vs. running into it. Higher G drives allow for more avoidance in a given time frame.

 

[Condottiere]

Unless it's chasing you, I'd go for long range sensors.

 

[Werner]

I look at maximum speed as being how quickly a ship can dodge a rock or meteor group vs. running into it. Higher G drives allow for more avoidance in a given time frame.

The maneuver drive tops out at 12% of the speed of light with 60% of the ship's volume taken up by fuel, assuming you save enough fuel to slow down again, 12% gives you Jump 6. This is irrespective of the maneuver drive you use, if you use a Jump-1, you will still need 60% of the hull volume as fuel, but it will take 12 weeks at 1g acceleration to reach 12% of the speed of light and another 12 weeks to slow down again.

 

[Straybow]

What if the jump drives are instantaneous? Basically there is no jump space, the Starship quantum tunnels in the direction it is moving, basically if it is traveling 2.6% of the speed of light it quantum jumps 1.3 parsecs to Alpha Centauri traveling in the same direction and speed it was traveling when it left the Solar System. This makes messages travel faster. Starships receive information packets prior to jumping and then transmit those information packets when they arrive, it would take about 5.376 hours for a signal to reach a Starship about to depart the Solar System, and another 5.376 hours for the message to travel from the Starship to a planet in the habitable zone.

I don't think you're playing Traveller anymore.

 

[Werner]

I don't think you're playing Traveller anymore.

That's why it's called "In My Traveller Universe" is it not? You use some of the Traveller rules but not all of them, standard jump drives are only a small part of those rules. Most people don't use the OTU exactly as written, after all, why are their rules for randomly generating worlds, if you generate a world for the PCs to visit, that world is not a part of the Official OTU, it can't be found in any OTU charts, so you are creating your own universe when you do that, is it still Traveller?

When you are playing D&D and you create your own fantasy world, people don't ask that question as much, but when you do it with a science fiction RPG, there is a tendency to tie a set of rules to a setting, so people like you ask if one is playing the same game if you change the setting.

Well is playing D&D in the Dragonlance setting still D&D since in that setting magic works differently, depending on the three moons of Krynn, or is it a different game from D&D since the rules of magic are slightly different?

 

[kilemall]

The maneuver drive tops out at 12% of the speed of light with 60% of the ship's volume taken up by fuel, assuming you save enough fuel to slow down again, 12% gives you Jump 6. This is irrespective of the maneuver drive you use, if you use a Jump-1, you will still need 60% of the hull volume as fuel, but it will take 12 weeks at 1g acceleration to reach 12% of the speed of light and another 12 weeks to slow down again.

Mr. Frac-C Free Trader is gonna not be travelling anymore if the combination of sensors and 1-G accel can't avoid the uncharted meteor storm. He shoulda had a copy of Kilemall's Starship Operations on his datapad and not be doing insane speeds.


Speaking of, as part of my kinetics of missiles work there is a danger for fleets using high speed in say transiting from a gas giant refuel to a target main planet.



If the enemy can get trailing ships reporting the fleet's course, speed and location, defenders should be able to line up head on down the throat missile swarm shots and utterly devastate the invasion with minimal missile bay forces.


It follows that killing such unwanted scouts are a priority, along with possibly splitting fleets to minimize the damage possible, definitely altering course as a group to throw off any unknown or lucky passive detections.

 

[whartung]

That's why it's called "In My Traveller Universe" is it not? You use some of the Traveller rules but not all of them, standard jump drives are only a small part of those rules.

Honestly, if nothing else, jump drives are the singular core that make "Traveller", Traveller, vs "Science Fiction Game".

Shotguns are next. "We have Jump Drives, but we still rely on shotguns."

The behavior of jump is so fundamental to how the "universe" operates that it alone contributes most to the "feel" of Traveller and how the worlds interact.

Traveller is about a isolation and self reliance. All of the systems are cut off in their way, even in the core.

To paraphrase Ulysses Everett McGill from "O Brother Where Art Thou": "Astronomical oddity. 2 weeks from everywhere."

This is part and parcel to Traveller.

We've had, what, 7, 8 versions of "Traveller", all with different char gen, combat, mechanics, dice roll, etc. For example GURPs is GURPs. Jump is what makes GURPs Traveller.

If YTU has no Jump, it's not a TU, it's just a U.

 

[Proneutron]

Speaking of, as part of my kinetics of missiles work there is a danger for fleets using high speed in say transiting from a gas giant refuel to a target main planet.

Not according to the RAW. Per the rules this is a routine op entailing no special natural danger.

 

[mike wightman]

If YTU has no Jump, it's not a TU, it's just a U.

Even if I am using Traveller character generation, task resolution and combat?

So many of the sci fi settings I have used Traveller as the game engine for are not Traveller games? Then there is Thieves World the Traveller variant.

And I would argue that you have to differentiate between the original intent of the Traveller rules - which was for you to make a bespoke setting - and the OTU based setting. Oh, and GURPS Traveller is not Traveller, it should be titled GURPS The Third Imperium. GURPS + GURPS Space is closer to the original intent of the classic Traveller rules.

As time went by we got more rules iterations that were tied to the setting - MT , T4 and T5 are all tied in to the Third Imperium setting. Then there is TNE, which gave us in FF&S rules for making stuff that had absolutely no place in the OTU. MgT today still tries to offer generic stuff but often fails to define exactly what is Third Imperium specific and what is not.

 

[Proneutron]

And I would argue that you have to differentiate between the original intent of the Traveller rules - which was for you to make a bespoke setting ...

using space ships having a jump drive to get into jump space to travell to others star systems. That can be logically argued as well.

 

[Werner]

using space ships having a jump drive to get into jump space to travell to others star systems. That can be logically argued as well.

Could you use Traveller RPG rules to play Star Wars?
Could you use Traveller RPG rules to play the Star Frontiers setting?
How about Star Trek, could you do that with Traveller?
Could you do the Expanse with Traveller?
How about Larry Niven's Ringworld/Known Space setting?
Can you do Isaac Asimov's Foundation or Robots setting with Traveller?