House Rules - Fixing Ship Fuel Operational Times

[Solomani666]

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IMTU A ship during jump utilizes the part of the power supplied to the jump engines to operate the ships systems, thus extending the operational endurance of all starships by one week.

This rule helps to alleviate the horrendously low operational endurances of free traders and far traders.

Note: Without this rule a far trader will be unable to make 2 sucessive jump 1's.


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[Galadrion]

Er... horrendously low operational endurances? Most of the ships listed in the main book have endurances ranging from two to four weeks... of which, jump will take up one. By my reckoning, that leaves one to three weeks for in-system operations. In ships designed for single- or multi-g constant boost. (The Type S will have thirteen weeks of fuel after a jump - if it makes a full, two-parsec jump! It'll have even more endurance if it only jumped a single parsec, and thus has half its jump fuel left.)

Just how far are you planning on traveling in-system that you need more than a week's constant boost? Come to think of it, if you're looking at a normal-space jaunt that will take more than a week, why aren't you micro-jumping it?

 

[Solomani666]

Er... horrendously low operational endurances? Most of the ships listed in the main book have endurances ranging from two to four weeks... of which, jump will take up one. By my reckoning, that leaves one to three weeks for in-system operations. In ships designed for single- or multi-g constant boost. (The Type S will have thirteen weeks of fuel after a jump - if it makes a full, two-parsec jump! It'll have even more endurance if it only jumped a single parsec, and thus has half its jump fuel left.)

Just how far are you planning on traveling in-system that you need more than a week's constant boost? Come to think of it, if you're looking at a normal-space jaunt that will take more than a week, why aren't you micro-jumping it?

When a free trader enters a system after a jump it might only have 4-6 days of fuel left.

A inaccurate jump into a system with the only gas giant on the other side of the star would leave the ship stranded.

If you calculate the odds, inaccurate jumps are an everyday occurrence.

Besides, these are player characters we are talking about. When does anything not unexpected ever happen?


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[phavoc]

The fuel supply of a ship is outrageously low, at least for warships. Today a warship is expected to be able to cruise for for weeks, if not months with its fuel supply.

Most warships have a range of about 6,000 miles @ 2/3rds speed (~20 knots), about half that at full speed. Traveller fusion reactors (by the rules at least) consume fuel as if they were constantly powered at full capabilities. While in jumpspace power consumption is at its lowest since all you need to power is life support and onboard systems. No drive or weapons capabilities are present.

We don't really know anything about the power requirements of the drives, though it is understandable that your beam weaponry would consume a great deal of power (which potentially makes missile-armed warships advantageous since their power requirements would be far less).

From a military standpoint, if you consume 70% of your fuel just getting to your area of operations, you are already at a tactical disadvantage. I don't think the fuel aspect was ever thoroughly thought out and compared to reality. Plus the nuclear reactors they have seem rather silly, since you need to fuel them annually when today a nuclear reactor goes for a decade or more before it requires servicing (Nimitz class carriers go about 25yrs between refueling).

 

[alex_greene]

The energy efficiency of fusion is, next to antimatter, the highest available - and it is an absurdly high figure.

On a per mass, or per nucleon basis one gram of deuterium in a fusion reaction yields 10^12 J (275 million kcal). Fission yields 20 million kcal per gram of U235, about 7% the power of fusion.

Operational times for power plant hydrogen fuel on the order of two hundred years before refuelling would not be amiss.

I also thought of an alternative house rule for Jump fuel consumption. I'll outline that in a separate post.

 

[CosmicGamer]

The game mechanics do not get into the micro managing of fuel usage. This is, to me, for making the game more playable to a wider group of people. Just like other portions of the game mechanics that are simplified, it allows one to spend more time role playing and less time looking up more complex rules and doing the record keeping.

What if the ship is using thrust 1 instead of thrust 2? What if we only use thrust to get up to speed then "drift" to save the fuel for decelerating and maneuvering when we reach the destination? Time for the GM to step in and be a GM.

The rules do not specify what a "week of operation" is. So there is plenty of room to come up with your own concepts and do the micro managing if you want or there is a special case need for such.

For normal day to day operations, the general rules have worked well enough in my games so far.

 

[phavoc]

The game mechanics do not get into the micro managing of fuel usage. This is, to me, for making the game more playable to a wider group of people. Just like other portions of the game mechanics that are simplified, it allows one to spend more time role playing and less time looking up more complex rules and doing the record keeping.

What if the ship is using thrust 1 instead of thrust 2? What if we only use thrust to get up to speed then "drift" to save the fuel for decelerating and maneuvering when we reach the destination? Time for the GM to step in and be a GM.

The rules do not specify what a "week of operation" is. So there is plenty of room to come up with your own concepts and do the micro managing if you want or there is a special case need for such.

For normal day to day operations, the general rules have worked well enough in my games so far.

That's the point. According to the rules, if you are drifting lying in wait you are burning 100% of your fuel. If you are accelerating at 6Gs and firing 1,000 lasers, bay weaponry and a spinal mount you are burning exactly the same amount of fuel.

The rules say you burn a weeks fuel in a week's time - no more, no less. And that is the entire point of the thread. It doesn't really jive at all with what we know is possible, and it doesn't fit into the extrapolated model of technology. in 1970 it made sense for a model/9 computer to displace 13 tons (26 if you were using fib). Now nobody disagrees that computers essentially take up no tonnage.

 

[dragoner]

Now nobody disagrees that computers essentially take up no tonnage.

Electronics take up a huge amount of space on aircraft, warships, tanks, etc.; and given that the meanest Traveller spacecraft does a 1000 times more than those (such as the duties of the entire NASA ground control), I don't think anyone thinks that wouldn't take up some space.

 

[Condottiere]

1. As I interpret the rules, possibly the intent, during jump transition the power plant is energizing the jump drive; if it stops or hiccups (ie the power plant), you fall out of hyperspace.

2. During this period, the power plants burns it's normal fuel consumption.

3. In normal space, there are a number of options to power down or shut off the primary power plant. I suppose you could sprint for a turn, possibly on overdrive, then switch to solar power and batteries, until you need to dock at the starport.

 

[phavoc]

Now nobody disagrees that computers essentially take up no tonnage.

Electronics take up a huge amount of space on aircraft, warships, tanks, etc.; and given that the meanest Traveller spacecraft does a 1000 times more than those (such as the duties of the entire NASA ground control), I don't think anyone thinks that wouldn't take up some space.

I would disagree with that evaluation. The functions of a spacecraft are not inherently different than what goes on with an aircraft. Passenger airliners today, or fighters, have a large amount of electronics installed. A passenger aircraft typically has 3-5 independent pitots in place to just measure airspeed. A spacecraft will have just as many systems, and a few more to handle space-only systems.

Ground control didn't actually manage anything on the spacecraft. They monitored systems for safety and to alert the crew to things that were happening. The Space Shuttle had 1970's style computers that could have been replaced with a single iPad (or perhaps even an iPhone - they had bubble memory!). Electronics make things both more simple and more complex. Assuming a continued scaling up of capabilities, the TL12 hand computer would most likely be as capable as the most powerful computer system we have today. Though at some point Moore's law will fail, but thus far it's been holding more or less true.

1. As I interpret the rules, possibly the intent, during jump transition the power plant is energizing the jump drive; if it stops or hiccups (ie the power plant), you fall out of hyperspace.

No, that's not what would happen, at least under MGT hyperspace rules. The jump bubble, once created, naturally wears down while you are in jump space, and when it gets to a certain level your pocket universe fails and you return to realspace. The jump drive is only necessary to create the bubble.

2. During this period, the power plants burns it's normal fuel consumption.

Yes, it does. It runs at full power when the only systems that can use that power are life support and ship board power (lights, computers, etc). Sensors are useless, weapons are useless, and the drive is useless. So they should not be consuming any power, thus the output of your powerplant should be a tiny fraction of what normal usage would be.

3. In normal space, there are a number of options to power down or shut off the primary power plant. I suppose you could sprint for a turn, possibly on overdrive, then switch to solar power and batteries, until you need to dock at the starport.

As long as you draw power from your fusion power plant, every erg of power consumes the same amount of fuel as would be consumed as if it were running at 100% of power. The rules don't allow for reactors to run at 120% power (ala The Hunt for Red October).

 

[dragoner]

Ground control didn't actually manage anything on the spacecraft. They monitored systems for safety and to alert the crew to things that were happening.

Exactly what a traveller ship does on its own, as well as jumping, diving into gas giants, battle, sensors, gravitics, inertial compensation, ad nauseum. Which is a lot more, and more systems than aircraft have.

 

[phavoc]

Ground control didn't actually manage anything on the spacecraft. They monitored systems for safety and to alert the crew to things that were happening.

Exactly what a traveller ship does on its own, as well as jumping, diving into gas giants, battle, sensors, gravitics, inertial compensation, ad nauseum. Which is a lot more, and more systems than aircraft have.

Virtually all of that would be automated, like it is on aircraft or ships today. Sure, there's more systems to automate, but you have more computing power to take care of the little stuff and only require the crew within certain parameters. And the computer power takes up less space. All those things really would cancel each other out. So with the increase needed in electronics to take care of things you'd probably have an overall net decrease in absolute tonnage due to the vast increase in capabilities of the systems. To simplify, you can do more with less.

 

[dragoner]

Exactly what a traveller ship does on its own, as well as jumping, diving into gas giants, battle, sensors, gravitics, inertial compensation, ad nauseum. Which is a lot more, and more systems than aircraft have.

... like it is on aircraft or ships today.

Huh? Not even close.

No, electronics will still take up tonnage.

 

[phavoc]

Huh? Not even close.

No, electronics will still take up tonnage.

I never said they didn't. I specifically called out computers used to take up tonnage. Electronics have never, to the best of my recollection, taken up tonnage in Traveller ships. They've always been included as part of the bridge tonnage allocations.

 

[dragoner]

Huh? Not even close.

No, electronics will still take up tonnage.

I never said they didn't. I specifically called out computers used to take up tonnage. Electronics have never, to the best of my recollection, taken up tonnage in Traveller ships. They've always been included as part of the bridge tonnage allocations.

In mongoose, computers are included in bridge tonnage and electronics tonnage is separate; but the difference is the same.

 

[Condottiere]

Processing shouldn't take up a significant amount of power; sensors, and possibly communications, probably will.

 

[Reynard]

I was under the impression you navigate your jump destination point as close to a target as possible with room for any gravitational limits. One reason not everyone wastes time getting 'free' fuel at a gas giant and just jumps in near the main world to refuel.

I know some think you have to reenter real space in the middle of nowhere then take a week or more reaching a final destination. That sounds like the S.O.P. of a scout survey starting at the outer reach of a new system and working their way in. If any ship needs extra fuel, it's a scout ship.

The book states interplanetary travel assumes a week for commercial vessels to reach their target, perform business and reach their next Jump point. Even an inaccurate Jump means you will spend extra time, and a little more fuel, travelling to the destination and thus more time in system than planned but not running out of fuel. Traveller isn't a killer game. Heck, your crew may be the ones performing a rescue for fellow Travellers who really somehow messed up their fuel management!

If you fear your GM plans to strand your ship in cold, deep space maybe you need to negotiate a ship with an extra few days fuel capacity similar to the legendary 'spare fuel tank' we believe automobiles supposedly have.

"We're stranded out here! The fuel gauge says Empty!"

"Nah! Don't worry, there's always a few hundred liters in the spare fuel tank. We're fine!"

 

[CosmicGamer]

According to the rules, if you are drifting lying in wait you are burning 100% of your fuel. If you are accelerating at 6Gs and firing 1,000 lasers, bay weaponry and a spinal mount you are burning exactly the same amount of fuel.

The rules say you burn a weeks fuel in a week's time - no more, no less.

That is one valid interpretation.

Perhaps in some peoples TU the power plant is either on or off and can't "throttle back"?

I find it strange when there are many ways of interpreting something, there are some people that chose to stick with the one that counters their logic instead of coming up with an interpretation that fits their needs. So be it. It's your interpretation.

To me, the more important question is game playability. There could be a game where every weapon, piece of electronics, recharging the vacc suit batteries, the coffee maker, lighting at full vs half, and so on has a power consumption rating and the players need to calculate exactly how much is consumed every week, every day, every hour, every moment of "operation"? Some people do love that nitty gritty stuff. "Captain, someone left the sensors powered up while we were in Jump. Were going to be cutting it close on fuel."

When the rules say "Fuel 44 tons One Jump–2 and two weeks of operation" I don't take this to mean the ship can only do Jump 2 and Jump 1 is impossible.

Nor do I take a generic "week of operation" to mean any and all ship activity. I don't have the capability to memorize all the rules. Please point me to any rules that are more specific on this.

The following:

IMTU A ship during jump utilizes the part of the power supplied to the jump engines to operate the ships systems, thus extending the operational endurance of all starships by one week.

off the top of my head is what the rules imply.

Using: "Fuel 44 tons One Jump–2 and two weeks of operation"
I think if a ship has the fuel and can do Jump 2, it could even do two Jump ones back to back and have two weeks of operation.

 

[alex_greene]

Perhaps in some peoples TU the power plant is either on or off and can't "throttle back".

If they're playing EVE Online or Elite or some other video game, sure.

 

[Reynard]

Simplification of game mechanics. Can you imagine accounting for every liter of power plant fuel used to see if you only need to 'top off' the tank before your next Jump? Players wanting detailed accounts of every power consumer on board so they can turn off the lights and life support in the store room and any unused state room need to find Fire, Fusion and Steel otherwise remember the week in system is a simple way to say in general you get from here to there in a timely manner unless something is in the script.

"Who was in the store room and left the lights on! We're not made of money!! I don't care if you're cold, leave the life support off and dress warmer!"