HG 2e Small Craft requiring 4 weeks of fuel

[snrdg121408]

Evening PST all,

Why does the HG 2e Light Fighter with a cockpit which has life support rated for 24 hours need four weeks of fuel?

Yes, the rules say that the minimum fuel load is four weeks regardless of hull size, this did not make sense to me in CT either.

I felt that HG 1e approach to small craft fuel requirements p. 59 was more realistic especially for hulls like the light fighter that usually operates for less than 24 hours.

 

[AnotherDilbert]

Related Q & A here:
http://forum.mongoosepublishing.com/viewtopic.php?f=89&t=119434

I allow non-jump capable spacecraft with less than 4 weeks of fuel. I also allow ships to carry less internal fuel tankage than one full jump, and make up for it with e.g. drop tanks. That is definitely a house-rule, inspired by msprange's answer in the quoted thread.

Note that the official Gazelle also use this house-rule.

 

[AndrewW]

I allow non-jump capable spacecraft with less than 4 weeks of fuel. I also allow ships to carry less internal fuel tankage than one full jump, and make up for it with e.g. drop tanks. That is definitely a house-rule, inspired by msprange's answer in the quoted thread.

Note that the official Gazelle also use this house-rule.

Not a house rule, carrying the full fuel required for a jump is not required. Only requirement is the minimum of 1 ton for the power plant, so allowing a ship to carry less then 1 ton of power plant fuel would be a house rule.

 

[Reynard]

I go on the idea just because a ship has lots of endurance it doesn't mean you must use it immediately. It means they don't have to refuel frequently. Just keep track when a ship is actually using fuel as you tour around the star systems. You might find you will need to refuel for a jump but only need a percentage used for power plant 'topping off'.

 

[AnotherDilbert]

Not a house rule, carrying the full fuel required for a jump is not required. Only requirement is the minimum of 1 ton for the power plant, so allowing a ship to carry less then 1 ton of power plant fuel would be a house rule.

Jump Drives
The fuel tankage needed for a jump drive is related to the size of the ship and the length of the jump, as follows;
10% of the total tonnage of the ship, multiplied by the maximum jump score of the drive
The result of this is the number of tons that needs to be dedicated to jump fuel.

Thanks for the clarification, I misunderstood this to be a requirement.

 

[snrdg121408]

Morning PST AndrewW,

I allow non-jump capable spacecraft with less than 4 weeks of fuel. I also allow ships to carry less internal fuel tankage than one full jump, and make up for it with e.g. drop tanks. That is definitely a house-rule, inspired by msprange's answer in the quoted thread.

Note that the official Gazelle also use this house-rule.

Not a house rule, carrying the full fuel required for a jump is not required. Only requirement is the minimum of 1 ton for the power plant, so allowing a ship to carry less then 1 ton of power plant fuel would be a house rule.

Technically, allowing a ship to carry less than one d-ton of fuel was originally part of MgT per HG 1e p. 59. Hg 2e for whatever reason decided to negate the HG 1e rule, breaking established HG 1e designs in the process.

A rule being incorporated into the current rule set from an earlier or later version is not in my opinion a house rule since they were established at some point.

Bring in a rule from a different game or ignoring requirements would be in my opinion a house rule.

For example a rule requires that a starship needs to have a jump drive in addition to a power plant and a maneuver drive. A starship is presented with only a jump or a jump drive and power plant are house rules.

 

[snrdg121408]

Hello Reynard,

I go on the idea just because a ship has lots of endurance it doesn't mean you must use it immediately. It means they don't have to refuel frequently. Just keep track when a ship is actually using fuel as you tour around the star systems. You might find you will need to refuel for a jump but only need a percentage used for power plant 'topping off'.

The requirement for all spacecraft, hulls >= 10 d-tons, requiring a minimum of 1 d-ton or 4 weeks of fuel using maximum thrust is an item that has never made sense to me especially when life support or the expected duration of operations is less than 4 weeks.

The endurance of the >= 100 d-ton Star Ship mentioned above or a >= 100 d-ton System Ship is totally different than the Small Craft example of the 10 d-ton Light Fighter with a cockpit life support system rated for a maximum of 24 hours plus the duration provided by a pilot's vacc suit life support system.

Breaking down the fuel requirement:
1 week of power plant operation appears to be 0.25 d-tons of fuel at the spacecraft's maximum thrust
1 day of power plant operation appears to be about 0.03 d-tons of fuel at the spacecraft's maximum thrust
1 hour of power plant operation appears to be about 0.001 d-tons of fuel at the spacecraft's maximum thrust

Without the requirement of 1 d-ton/four weeks of fuel the light fighter's fuel requirement using a 1 d-ton TL 12 fusion power plant is 1 d-ton x 0.1 = 0.1 d-tons which is just a bit over three days of operation. That would allow a bigger cargo hold or a touch more armor.

Most small craft in my opinion function like modern day aircraft shuttling cargo and passengers between different locations. The various sizes of aircraft do not have the same fuel requirement. Fuel requirements are determined individually that include some reserve as a space cushion for the unexpected events.

MgT HG 1e Small Craft design sequence made the distinction between the endurance of spacecraft >= 10 d-tons and small craft. The removal of the rules in HG 2e is a minor disappoint which also reminds me of the material that was omitted when CT LBB 5 HG 1979 was revised in 1980.

Unfortunately the MgT Gazelle is not the CT or MT Gazelle anymore than the TNE Gazelle either for different reasons.

Of course I'll try to follow the current rules even if I feel they do not make sense, especially when an earlier rule set had them. Heck, limiting the amount of fuel on small craft would I think balance out having a small craft capable of mounting downgraded range and power to weapons from being able to use maximum acceleration on an M-Drive and High-Thrust Reaction Drives to close with a target.

Not to mention that the target's side has probably launched small craft of their own to counter the other sides incoming fighters and an attempt to sneak there own into the enemies hulls >= 100 d-tons.

 

[Condottiere]

The one tonne fuel rule is irrelevant for starships, and I suspect an attempt to clean up accounting.

It is relevant when you're min maxing lightcraft.

If it was a requirement to act as a heatsink, there can be no argument as to it's inclusion; but there's explanation.

 

[snrdg121408]

Afternoon PST Condottiere

The one tonne fuel rule is irrelevant for starships, and I suspect an attempt to clean up accounting.

It is relevant when you're min maxing lightcraft.

If it was a requirement to act as a heatsink, there can be no argument as to it's inclusion; but there's explanation.

A starship requires at least 168 +/-16.8 hours or one week of power plant fuel to run the basic ship systems and apparently the jump drive traveling between star systems. The M-Drive Power requirement is an energy reserve in my opinion.

On CRB 2e p. 153 the Transit Times Chart and he Common Distances for Traders Chart hints that a starship might have to transit 7.3 days which is another one week the power plant has to provide power for basic ship systems, M-Drive, Senors, and other energy using systems. In normal space the power required by the jump drive is becomes the portion of the power planet output used by the sensors and other systems requiring energy.

Taking the time in jump space and accounting for worst case of transit time from the jump exit point and to the outbound jump point a starship probably should have at least three weeks of fuel. Bumping the requirement to 4 weeks and 1 d-ton for safety is okay, besides the 1 d-ton of space use is not a significant amount of space.

Using the standard 1 d-ton and the standard Imperial mouth of 4 weeks a starship power plant consumes 0.25 d-tons of fuel in one week, approximately 0.036 d-tons a day, or approximately 0.002 d-tons per hour. (I hope my math is right.)

The 10 d-ton Light Fighter cockpit life support is limited to 24 hours of operation is wasting 0.998 d-tons of space for fuel.

That brings up the issue of were does the fuel come from for a stars ships and system ship's carrying small craft and other systems requiring fuel?

 

[Reynard]

You're not really 'wasting' space for fuel on small craft any more than your air/raft is wasting fuel when parked in its bay. It's on standby until used and doesn't need a refill until it begins to run out. In most game instances, such small craft don't need to keep track of refueling over long periods unless it becomes a plot device.

Space craft and star ships are way different burning up fuel at horrendous rates so they need to be tracked for refueling and endurance.

I always assumed, and I remember references to, power and fuel ports being part of docking bays and hangars. I vaguely remember mention about refueling fuel cells within a ship.

 

[snrdg121408]

Hello Reynard,

You're not really 'wasting' space for fuel on small craft any more than your air/raft is wasting fuel when parked in its bay. It's on standby until used and doesn't need a refill until it begins to run out. In most game instances, such small craft don't need to keep track of refueling over long periods unless it becomes a plot device.

Space craft and star ships are way different burning up fuel at horrendous rates so they need to be tracked for refueling and endurance.

I always assumed, and I remember references to, power and fuel ports being part of docking bays and hangars. I vaguely remember mention about refueling fuel cells within a ship.

There is a significant difference in my opinion between a 10 d-ton small craft and an air/raft since in MgT CRB 2e and HG 2e there are no fuel requirements for vehicles light the air/raft that I have found in the two books.

If the MgT HG 2e Light Fighter was designed to operate for the same duration as system ships, star ships, and space stations then 1 d-ton of fuel fits.

In CT Striker, MT, TNE, T4, GURPS Traveller, and Traveller the amount of fuel in an air/rafts tank is determined by how much is consumed by the power plant and how long the vehicle operates before needing to refuel. In TNE a TL 10 air/raft carries 2.6 m^3 of fuel allowing the vehicle to operate for 13.9 hours.

A 10 d-ton small craft's cockpit life support has an endurance of 24 hours yet requires 672 hours of fuel while a TNE 2 d-ton carries the amount of needed for an endurance of 13.9 hours. To me the amount of space the extra 648 hours of fuel is a waste space since the 10 d-ton small craft is designed to operate for only 24 hours.

Based on a large enough hanger there will be everything needed to maintain whatever is inside. The smaller the hanger the less one will be able to do.

The other issue is that Mongoose, like CT, introduced material that was used in the first edition for designs and then cut them for the second edition.

I disagree with the rewritten small craft fuel requirements based on HG 1e rules and what occurs in the real world. A Cessna does not have the same fuel requirement as a 777. The Captain's gig does not have the same fuel requirement as a destroyer.
The small craft in MgT all require 1 d-ton of fuel does not make sense.

Thank you for the reply.

 

[Condottiere]

It's not a question of wasting fuel, more of opportunity cost, that space could be used more productively.

 

[Reynard]

A fraction of a cargo space will make or break a small craft's efficiency?

On the other hand, be brave and actually have a fractional fuel capacity. It's called Traveller Rule Zero. It's that simple. I have fractional cargo holds when there's a decimal dton left over and even have built ships with decimal dton fuel loads when the design does a fraction somewhere else and I just think they now have the legendary automobile fuel reserve. The Traveller Universe won't collapse if you fudge.

 

[phavoc]

Endurance should be based on the human occupants, not the machinery. We already have craft that be aloft/afloat far longer than their human crew.

A crewmember who has spent the last 24hrs in a spacesuit in the cockpit of a small craft is going to be difficult for most crew to endure. You wouldn't be deploying crew for more than 12-14hrs at a stretch. Small craft that have full flight decks can be deployed for longer periods (24hrs would not be too hard for the crew, though perhaps not daily).

So the fuel requirements should match the expected crew capabilities. Craft with cockpits only would not have a need for more than 24-36hrs of fuel (to cover emergencies), and craft with flight decks wouldn't need more than 72hrs (or 120hrs for extended deployments). Anything additional could be added via external tankage, though you'd pay a penalty in crew capabilities.

 

[snrdg121408]

Morning PST Condottiere, Reynard, and phavoc,

It's not a question of wasting fuel, more of opportunity cost, that space could be used more productively.

I agree that the amount of space required to store the fuel is wasting space that could be used to carry more passengers, cargo, reloads for missile racks/sandcasters, or something else.

A fraction of a cargo space will make or break a small craft's efficiency?

On the other hand, be brave and actually have a fractional fuel capacity. It's called Traveller Rule Zero. It's that simple. I have fractional cargo holds when there's a decimal d-ton left over and even have built ships with decimal dton fuel loads when the design does a fraction somewhere else and I just think they now have the legendary automobile fuel reserve. The Traveller Universe won't collapse if you fudge.

An extra 0.5 d-ton a space can hold 6 missiles, 10 sand canisters, or one torpedo for combat. That 0.5 d-tons of space could be used to add a little bit more armor.

Any space not assigned to a specific purpose is cargo space and there are no rules saying a spacecraft must have 1 d-ton of cargo space or that fractional amounts above or below 1 d-ton are rounded.

The rules in HG 2e p. 17 clearly state that "Other power plants require fuel tankage equal to 10% of their size (rounding up, minimum of 1 ton). This provides enough fuel for the power plant for a month (four weeks)."

Any fuel calculations below 1 d-ton are rounded to one d-ton and there does not appear to be any rounding requirements for fuel tonnage > one d-ton.

Per AndrewW in the post in this thread from Fri Nov 11, 2016 11:48 am referring that the Gazelle's internal fuel tankage is not enough to use her jump drive to full potential without using drop tanks. "Not a house rule, carrying the full fuel required for a jump is not required. Only requirement is the minimum of 1 ton for the power plant, so allowing a ship to carry less then 1 ton of power plant fuel would be a house rule."

With AndrewW's reply small craft using < 1 d-ton of fuel appear to be broken designs under HG 2e which re-writes eight years of ships designed using CRB 1e and HG 1e that allowed small craft to have fractional power plant fuel tankage below 1 d-ton.

Having all spacecraft designs with a minimum of one d-ton of power plant fuel makes accounting less complicated than the rules in CRB 1e and HG 1e,

Endurance should be based on the human occupants, not the machinery. We already have craft that be aloft/afloat far longer than their human crew.

A crewmember who has spent the last 24hrs in a spacesuit in the cockpit of a small craft is going to be difficult for most crew to endure. You wouldn't be deploying crew for more than 12-14hrs at a stretch. Small craft that have full flight decks can be deployed for longer periods (24hrs would not be too hard for the crew, though perhaps not daily).

So the fuel requirements should match the expected crew capabilities. Craft with cockpits only would not have a need for more than 24-36hrs of fuel (to cover emergencies), and craft with flight decks wouldn't need more than 72hrs (or 120hrs for extended deployments). Anything additional could be added via external tankage, though you'd pay a penalty in crew capabilities.

I agree pretty much with what phovac mentioned above which what I was trying to say. A light fighter's endurance works out to be Cockpit Life Support 24 hours + Vacc Suit Life Support 8 hrs = 32 hours. Adding emergence life support to the vacc suit extends the endurance to 18 hours giving a total time of 42 hours.

I really wished HG 2e had kept HG 1e power plant fuel rules for small craft.

 

[Reynard]

"so allowing a ship to carry less then 1 ton of power plant fuel would be a house rule."

And I re-evoke Traveller Rule Zero!

 

[phavoc]

"so allowing a ship to carry less then 1 ton of power plant fuel would be a house rule."

And I re-evoke Traveller Rule Zero!

Thus spoke Reynard!

 

[snrdg121408]

Afternoon PST Reynard,

"so allowing a ship to carry less then 1 ton of power plant fuel would be a house rule."

And I re-evoke Traveller Rule Zero!

A scenario being created and gamed locally with modified ship designs can invoke your Traveller Rule Zero when everyone agrees.

In my opinion when submitting material to Mongoose Publishing any modification should be explained so that others can replicate the design along with an unmodified example.

From the examples in MgT HG 2e I've tinkered with they are much better at following the design sequence in my opinion than CT, MT, TNE, or T4 managed.

Of course I seem to inadvertently modify rules with little effort even with the help from the forum members.

 

[Condottiere]

With Warhammer you learn both the necessity of house rules, and the disdain for the necessity for most of them.

If they're fun, like needing to take a shot for each miniature lost, great; if it's to prevent over exploitative interpretation of the rules, okay.

Other than that.

 

[snrdg121408]

Morning PST all,

From MgT HG 2e Step 4 p. 17 my understanding for determining Power Plant Fuel Tank Size is:

(1) Chemical: Power Plant Size x 10 d-tons for two weeks of operation
(2) Fission, Fusion, & Antimatter: Power Plant Size x 10% with a minimum requirement of 1 d-ton that provides 4 weeks of power plant operation.

Example 1:
TL-12 1 d-ton Fusion Power requires 1 x 10% = 0.1 d-ton of fuel to operate with a power output of 15.

The minimum fuel tank size for a power plant is 1 d-ton.

An 1 d-ton power plants fuel consumption requirement is one-tenth of the minimum required 1 d-ton which suggests to me that the power plant fuel tank would not need to be refilled every 4 weeks. I think that the 1 d-ton power plant takes ten times longer to consume 1 d-ton stretching the time to refill the tanks from 4 weeks to 40 weeks.

Example 2:
TL-12 10 d-ton Fusion Power requires 10 x 10% = 1 d-ton of fuel to operate with a power output of 15.

The minimum 1 d-tons of fuel match the fuel consumption of a 10 d-ton which per the guidelines would require the tank to be refilled every 4 weeks.

Example 3:
TL-12 100 d-ton Fusion Power requires 100 x 10% = 10 d-ton of fuel to operate with a power output of 15.

An 100 d-ton power plant's 10 d-ton fuel consumption requirement is ten times the minimum 1 d-ton lasting for 4 weeks suggesting that this power plant either needs to refilled every 0.4 weeks or that 10 d-tons of lasts for 4 weeks.

I am not sure what the actual time scale the formula Power Plant Fuel Tank Size = Power Plant Size x 10% actual calculates before applying the 1 d-ton allows four weeks of operation.

I admit I may be missing something or adding something that is not in the guidelines but I think there is a bit of a problem with the guidelines on calculating power plant fuel tank size.