Minimum fuel in boats

[Matt123]

Hmmm, I run the risk of sidetracking Hals 8tn Zhodani Fighter thread, I'll be good...

Many players often underestimate the mission-required flight durations of even 'short-range' small craft. ...snip...

You make very valid points in your post, points that should be taken into account by boat architects and procurers to ensure thier purchases can do the job expected.

The fuel rules for boats however is still arbitrary. It removes the decision from the architect and actively penalises boats intended to act on short trips only. You made some good examples that well illustrate your points. Here are some examples of the need for the other extreme of minimal carried fuel (plus a safety margin),
-commercial interface boats - minimum 1tn fuel occupies potential passenger/cargo/income earning space,
-fighters optimised due to budget constraints - the smaller the fighter the cheaper the hull MD & PP. Saving close to 1tn in a sub 10tn fighter makes a huge differance.
-assault landers - 28 days fuel carried for a 4-6 hour operation & occupying potential armour space.

I can go on. I'm not attempting to invalidate your examples or points, they are very valid. and your examples are well served by the existing boat fuel rules. The point I am making is that my examples are forced to also comply, creating design inefficiences in a range of commercial & military craft.

In reality, unless the 28 day & 1tn minimum fuel requirement for boats was legislated Imperium wide (placing it up there with no piracy & no nukes), competition in the boat building industry would have done away with these minimums centuries ago. Commercially it doesn't make sense to outlay business capital for the capacity to lift 28 days of fuel into orbit 3 times a day, rather a smaller cheaper boat or one with a larger payload capacity. And a fuel storage tank at the landing pad.

One can argue of course "thats the way its done in Traveller". To that arguement I suggest the canon examples of boats being relied on to form that opinion are all designed to be as general purpose and customisable as possible. General purpose is the arch enemy of specialised boats, which one would expect to be more efficient.

Thinking on it a little more, I'm really questioning how big the fuel safety margin should be.

Where am I going with this? I dunno but I thought it deserved its own thread.

IMTU, I use a minimum of 1 day fuel endurance for boats, no minimum tn. As a guide to fuel capacity I use 3x designed maximum flight duration. Most of my specialised boats however only need an endurance of 8 or so hours, the same endurance as a pilot using a small craft couch.

 

[Hal]

It is possible, that this was one of the many reasons people moved on, or attempted to move onto the newer MegaTraveller Ship design system. There, one could keep track of individual fuel usage in smaller lots because of the actual design rules themselves. In fact, I recall reading a long time ago, that it was a "Novel" idea to include a fuel reserve just for powering up the ship laser power generator - instead of having to keep track of running a power plant at full power for everything. Having enough fuel for 12 hours worth of laser firing was a good idea <g>.

The easiest way to handle the issue for CT's HG, is to just do away with the minimum fuel volume requirements for fuel itself, and allow one to include 1/4 the fuel requirements for a one week's duration. Funny how that works actually - because if your ship was in jump space for a week, and has been operational for 2 weeks, you only have one week's fuel left. So, play loose with the rules regarding a minimum fuel volume and see where it gets you.

 

[atpollard]

I liked the MegaTraveller/Striker solution of designing 'small craft' in 1 cubic meter base units (1/14 dTon) with a 1 cubic meter limit.
A good simplification for a more HG like rules set would be 0.1 dTons as the smallest unit.

Personally, I always found the 4 decimal place calculations in MegaTraveller to be a waste of time and effort.

As a time specification, I suggest 2x the typical mission as a good typical duration.
2 weeks between jumps suggests 4 weeks of fuel.
10 min surface to orbit shuttle might be good with 20 minute minimum (or 1 hour to allow for loitering in orbit).

 

[boomslang]

Commercially it doesn't make sense to outlay business capital for the capacity to lift 28 days of fuel into orbit 3 times a day, rather a smaller cheaper boat or one with a larger payload capacity. And a fuel storage tank at the landing pad.

There are many things which do not make sense commercially in the OTU [cough, cough]for example, per-Jump cargo and passage rates rather than per-parsec ones[/cough, cough], and yet they are presented as hard & fast rules.

I figure it is a combination of legacy Vilani cultural OCD and blanket megacorporate control of anything-but-free market forces, resulting in some completely absurd regulations which appear arbitrary and even counter-productive to the critical observer.

I am always wary of House Rules; they always seem to unlevel the playing field and invite unintended consequences.

For example, you could just omit fuel entirely and run your small craft off of capacitor banks plugged into a modified Drive unit (in something as small as a Fighter, 1 dton of capacitors ought to buy you that 36 turns' endurance easily) -- then you can ignore Fuel hits in combat!

Think of it: Fighters that can be recharged from solar panels, and that fly without fusion reactors -- and their associated heat signatures -- to give away their positions...

 

[far-trader]

...Commercially it doesn't make sense to outlay business capital for the capacity to lift 28 days of fuel into orbit 3 times a day, rather a smaller cheaper boat or one with a larger payload capacity. And a fuel storage tank at the landing pad.

Not arguing your point so much, but the canon small craft were always built on a customizable configuration. It could well be possible that the 28 day fuel supply is mandated to cover interplanetary trips.

What I'm saying is maybe the 4 week duration is a standard. Maybe not all ships need to maintain that standard but the bulk of standard designs do.

To be honest I've never seen any sense in more than a few turns worth of fuel in a fighter that wasn't intended to do long patrols and included a bunk for it. They'll get killed or kill their target long before 4 weeks.

The one ton minimum I see as a minimal size for holding, handling, and processing the fuel. It's not so much that you need that much fuel, but that you can't do it any smaller. And I'm fine with that. Or finer with it than some other issues anyway

 

[far-trader]

...For example, you could just omit fuel entirely and run your small craft off of capacitor banks plugged into a modified Drive unit (in something as small as a Fighter, 1 dton of capacitors ought to buy you that 36 turns' endurance easily) -- then you can ignore Fuel hits in combat!

But that'd be a cheat, and if I were the ref I'd simply apply any "fuel" hits to your capacitor banks (fuel by any other name). In fact I'd probably make them explode if I were cranky

...Think of it: Fighters that can be recharged from solar panels, and that fly without fusion reactors -- and their associated heat signatures -- to give away their positions...

And I quite like all those as reasons for it to be done. And I just like the ideas. But it wouldn't come without consequences imtu.

 

[boomslang]

But that'd be a cheat, and if I were the ref I'd simply apply any "fuel" hits to your capacitor banks (fuel by any other name). In fact I'd probably make them explode if I were cranky

Not necessarily; they don't blow up in HG unless they're overcharged.

OTOH, the ridiculous excessive cost to purchase and install the things should be plenty of consequences for YTU; a Fighter mounting a Laser would need 2 dtons of capacitors (72 EP) to make the 36-turn endurance minimum... that adds a cool MCr8 to the base price right there, and eats up all available displacement.

 

[Matt123]

For example, you could just omit fuel entirely and run your small craft off of capacitor banks plugged into a modified Drive unit...

I like the idea also, but its not how i see traveller ships.

The one ton minimum I see as a minimal size for holding, handling, and processing the fuel. It's not so much that you need that much fuel, but that you can't do it any smaller. And I'm fine with that. Or finer with it than some other issues anyway

The engineering solution will likely be to consider small tanks a removeable/replaceable part, rechargeable at the filling point in the same way propane is for your bbq. The example Zhodani fighter I suggested needs 0.0372tn for fuel, don't know how this relates to BBQ gas bottles tho'!

On commercial charges for cargo/passengers, I long ago adopted the standard of per parsec for cargo & per jump for passengers. I'm sure I stole the idea from somewhere. It steers J3+ transport toward cargo over passengers and/or creates a niche for very expensive high jump capable liners.

 

[mike wightman]

Hmm, perhaps this is how to explain missiles in CT.

Instead of fuel they have jump drive like capacitors that provide a certain number of g-turns of thrust.

Perhaps lifeboats could be built along these lines as well.

 

[boomslang]

Hmm, perhaps this is how to explain missiles in CT.

Instead of fuel they have jump drive like capacitors that provide a certain number of g-turns of thrust.

I have always thought in terms of ether batteries or fuel cells for missiles, but yeah, they are electric-grav IMTU instead of chemically-propelled. Pro: makes them safer and more reliable to handle; con: limits them to 6Gs maximum thrust.

Perhaps lifeboats could be built along these lines as well.

Lifeboats OTOH, need all the endurance they can get... and, being exactly the sort of thing that is subject to regulation, you are unlikely to find any short-mission-duration fuel reductions in their specs. Indeed, a few dtons of LH in a small craft's tanks might be just the thing to tap in an emergency when the mothership's fuel tanks have been shattered, then repaired, and she needs to limp to a base or a GG nearby for a fill-up...

 

[mbrinkhues]

Maybe back-porting the batteries from MT. So the fusion plant runs when the ship is using drives/guns/gravity but while coasting it can be powered down and the batteries take over.