Cargo Capacity For Vehicles

[C-Note]

How does everyone handle this?  For the ships in my Star Hero campaign, I use the Encumbrance rules.  The cargo capacity is 10% of the ship's lifting STR.  The ship can carry more, but with Encumbrance penalties.  I haven't figured out cargo Volume, just Mass.

[eepjr24]

2 hours ago, C-Note said:

How does everyone handle this?  For the ships in my Star Hero campaign, I use the Encumbrance rules.  The cargo capacity is 10% of the ship's lifting STR.  The ship can carry more, but with Encumbrance penalties.  I haven't figured out cargo Volume, just Mass.

6e2 187 has both volume and mass rules for vehicles based on size (you can increase the mass lift by buying up the STR separately). 

[C-Note]

2 hours ago, eepjr24 said:

6e2 187 has both volume and mass rules for vehicles based on size (you can increase the mass lift by buying up the STR separately). 

 

Yup.  That's what I use. 6E2 187:  "Vehicle STR can lift exactly as much as character STR. Encumbrance rules apply and may slow down heavily-loaded vehicles."

What about volume of cargo space as a percentage of vehicle volume?  10%, using same rules as Encumbrance for STR (or more if vehicle is encumbered)?

[unclevlad]

If you want something closer to real...

 

http://yrc.com/trailer-dimensions/

 

A semi trailer is generally bigger than a school bus...altho they're pretty comparable.  School bus is listed as 250 cubic meters...it's not even close.  The 28' High Cube trailer has an internal volume of a touch over 2000 cubic feet...that's less than *60* cubic meters.  And I believe this kind of trailer's rated for more than 12.5 tons.  On the flip side...a 747 can't come *close* to lifting 3.2 kilotons;  the max takeoff weight is given as about 400 tons.  

 

Work out the cargo size first.  That's largely separate from the hull size, in large spacecraft because aerodynamics are meaningless.  (I'm assuming interplanetary/interstellar ships, not orbit-to-surface shuttles.)  Then figure they're designed to run 100% full, albeit not necessarily with exceptionally heavy stuff.   So...average density of 5 or so.  That's most rocks;  iron is 8, copper and silver 9.  But if it can handle 10,000 cubic meters...and that's only 100 meters by 10 by 10...density 5 says it's 50,000 tons.  

 

BTW, it's plausible there's no such thing as running light under most circumstances.  There's no economic reason to do so.

[unclevlad]

What's the purpose here?  Why do you need game stats?  Also, what kind of ship?  There's everything from a bulk freighter as mentioned above, to something like the Millenium Falcon which was never really a freighter in the first place.  (And the cargo mass on that layout is actually probably just a fraction of the overall ship mass, at least as they portrayed it.)

[C-Note]

20 minutes ago, unclevlad said:

What's the purpose here?  Why do you need game stats?  Also, what kind of ship?  There's everything from a bulk freighter as mentioned above, to something like the Millenium Falcon which was never really a freighter in the first place.  (And the cargo mass on that layout is actually probably just a fraction of the overall ship mass, at least as they portrayed it.)

 

The characters are having a ship built.  Using the Encumbrance rules, it's easy enough to figure out cargo capacity for mass.  Cargo capacity volume appears to be left to the GM, so I want to know if anyone has a method for determining that.  My suggestion above is to apply Encumbrance rules to Volume the same way it applies to STR. 10% of vehicle's total volume allocated for cargo.

 

I realize this is a rough calculation.  If the vehicle has extra STR, the cargo volume would increase.

[unclevlad]

What's the purpose of the ship?  Freight hauler, smuggler, courier/yacht (all passenger space, little dedicated cargo space)?

[C-Note]

1 minute ago, unclevlad said:

What's the purpose of the ship?

 

It doesn't matter.  I'm trying to work out a general mechanic for calculating cargo volume.  e.g. If it's a cargo ship, it would purchase extra STR with a limitation "Only for Lifting/Carrying".

[unclevlad]

It does matter.  There is no general mechanic.  A tugboat might have 5% cargo space.  A supertanker is probably 85%.

[Chris Goodwin]

The limiting factor for spaceships is mass, not volume.  I mean, you can strap all kinds of things to the outside of a ship, as long as it doesn't require air.

 

[dsatow]

1 hour ago, Chris Goodwin said:

The limiting factor for spaceships is mass, not volume.  I mean, you can strap all kinds of things to the outside of a ship, as long as it doesn't require air.

 

 

Yeah but spaceships break other vehicle reality issues in HERO too.  Technically, if you can accelerate and have enough fuel, you shouldn't have a top speed.

[eepjr24]

12 hours ago, C-Note said:

 

Yup.  That's what I use. 6E2 187:  "Vehicle STR can lift exactly as much as character STR. Encumbrance rules apply and may slow down heavily-loaded vehicles."

What about volume of cargo space as a percentage of vehicle volume?  10%, using same rules as Encumbrance for STR (or more if vehicle is encumbered)?

I am going to stay out of the accuracy arguments, as people are trying to take an example and extrapolate it to a maximum. But if you look at the chart on 187, it gives the maximum volume in cubic meters for a given size value. So a Size 10 vehicle could hold up to 2000 cubic meters of cargo internally. If you want more exact rules on this, check out The Ultimate Vehicle. It's for 5e, but it was written by Bob and Steve and has some very good examples.

 

[C-Note]

1 hour ago, eepjr24 said:

I am going to stay out of the accuracy arguments, as people are trying to take an example and extrapolate it to a maximum. But if you look at the chart on 187, it gives the maximum volume in cubic meters for a given size value. So a Size 10 vehicle could hold up to 2000 cubic meters of cargo internally. If you want more exact rules on this, check out The Ultimate Vehicle. It's for 5e, but it was written by Bob and Steve and has some very good examples.

 

 

Thanks.  I have a old hard copy of this in a box somewhere.  HERO never released the 6th Edition version of Ultimate Vehicle, although it was referenced in 6E Star Hero.  I think it should be the next Kickstarter project.

[eepjr24]

8 hours ago, dsatow said:

 

Yeah but spaceships break other vehicle reality issues in HERO too.  Technically, if you can accelerate and have enough fuel, you shouldn't have a top speed.

I think technically (if your universe follows the special theory of relativity) you could not get above ~1,079,252,000 kph. Also, there is the small matter of deceleration, which if your acceleration and deceleration ratio is 1 would be at the half way point. I think Hero takes the justifiable stance that this implies a maximum top speed based on acceleration and distance and averages it for folks who really don't care to work out light year distances between points. Otherwise, just buy FTL and call it a day.

 

- E

[dsatow]

36 minutes ago, eepjr24 said:

I think technically (if your universe follows the special theory of relativity) you could not get above ~1,079,252,000 kph. Also, there is the small matter of deceleration, which if your acceleration and deceleration ratio is 1 would be at the half way point. I think Hero takes the justifiable stance that this implies a maximum top speed based on acceleration and distance and averages it for folks who really don't care to work out light year distances between points. Otherwise, just buy FTL and call it a day.

 

- E

 

True.  The speed of light isn't just a good idea, its the law (of physics).  Even accelerating at 1 km/sec, it would take over 34 years to reach that speed and 34 years back.  Given the human body can only survive sustained g-force of ~3G(30m/sec) over a prolonged period, it would take over 1100 years to reach the speed of light.  Interestingly enough, a web comic I'm reading(grrlpower), a character is just encountering this problem.  http://grrlpowercomic.com/archives/2918

 

The thing is, all forms of movement in HERO, except maybe teleportation and FTL, take into account friction/drag.   This isn't as big a problem in space than in an atmosphere and since most adventures take place planet side.  I personally chalk a vehicle's speed limit up to the same physics as hearing an explosion in space in movies.

 

 

 

[unclevlad]

The vehicle table has more issues than that, but yeah, you don't have drag to speak of, and you don't have gravity issues.

 

You either have FTL, or peta-scale teleport (jump gates).  You don't have a space game without one or the other.  

 

If you want costing, yeah, you may want to go in reverse.  The vehicle size rules are somewhat meaningless because you can piggyback 100% cargo space, or build a mildly larger hull to increase cargo space.  It's all about mass, and that's all about STR.  100 cubic meters of cargo space can represent 1.5 kilotons of cargo *real* fast...high density ship parts.  And 100 meters is nothing, on the ship size table.

 

So the approach looks to be:

a)  decide the ship's basic size, based on crew and mission.  For *interior* cargo storage alone...figure anything from 5 to 25% of the hull volume might be cargo space.  How many weapons?  How much passenger space...and are we talking berths or suites.  So you can assign anything in that range sanely enough.  

b)  Figure out how much more STR you want to sink in.  Figure each cubic meter of cargo space is 10 tons, for an average.  It can be more, cuz that's only density 10 stuff.  Tungsten, osmium, and iridium are all 18+, IIRC.  Figure the density 10 is a reasonable design rule.  

c)  That tells you how much STR you need to buy.  You do need big engines to move lots of mass.

 

A common approach to FTL is that gravity is the enemy.  Going FTL requires space to be sufficiently flat...which means, the more mass you're carrying, the further away from the star you have to get.  It's not a matter of slower or faster based on load, it's yes/no.  The slower/faster comes in when dealing with in-system movement, if that's at sublight speeds. '

 

But as was pointed out too...velocity has to to with drag.  Higher mass would lower acceleration, but in space, it doesn't change the max speed.  Fundamentally, the basis for the 6E2 vehicle table...which is seriously flawed IMO to begin with...relies on assumptions that just don't hold.  So abstract the concepts you need, which pretty much is baseline BODY, STR, and OCV+.