HG: Subcraft hangars

[GypsyComet]

MGT HG states that these are 130% of carried craft size and allow for full maintenance.

Sorry, but that's really silly, and not nearly enough space.

The simplest case would be the Modular Cutter or any of the "pure cylinder" subcraft in that family. An additional 30% around the cutter is *just* enough to square up the spot on the deckplan. If you assumed that one side of the cutter bay was kept form-fitting you would get maybe *two feet* of flat bay space beyond the hull on the other side.

If the Cutter has taken any damage that compromises its shape, that "hangar" is useless, as it still has no room for anything beyond the normal shape of the cutter.

And that's just the Cutter. Go to the winged forms and 30% won't let you have full access to the wings. Even a 100% increase will have trouble, and a 200% or 300% increase (so a 3x or 4x bay) will still feel cramped.

I honestly don't see the problem with encouraging designers to spent lots and lots of volume on stuff like subcraft. It's firmly present in visual SF, silly or otherwise. The boarding bay in the Star Destroyer from Episode IV is thousands of tons, as is the Death Star bay the Falcon gets parked in, and even the shuttle bay on the TOS Enterprise is hundreds of tons (for little 10-ton shuttles), not to mention the maintenance garage on the next deck down. Don't even ask about the big docking bay on the nose of Babylon-5, or the landing bays on the Galactica (either version).

 

[andrew boulton]

T4 used:

Minimum: 200%
Spacious: 400%

 

[SSWarlock]

Yeah, I'd go with at least 150% as the minimum. And that's from my experience of working on my car in my two-car garage, with two cars in the garage. My sub-vehicles bays allow at least another 1.5 meters clearance around the entire sub-craft silhouette.

T4's standard isn't unreasonable, IMO.

 

[rust]

Hmmm ... :?

Let us take a look at some real world data:

The hangar deck of the aircraft carrier Nimitz is 208 meters long, 33 me-
ters wide and 7.6 meters high, and it is designed to serve up to 60 air-
craft. With a volume of about 52,166 cubic meters this leaves a minimum
of about 870 cubic meters per aircraft.
An F-18 Super Hornet is 18.32 meters long, has a wingspan of 13.63 me-
ters and is 4.88 meters high. It requires a volume of about 1,218 cubic
meters "with wings", and probably about 432 cubic meters "without wings".

Of course this is just a very rough estimate, but I think that 200 % for
a small craft hangar seems reasonable, provided one defines the hangar
as a location where small craft are not only stored, but also maintained
and - if necessary - repaired.

 

[GypsyComet]

Aircraft carriers benefit from large common decks, however, and also have, under some circumstances, the entire flight deck for overflow. The raw volume per plane is thus a bit misleading. Since there are no inner walls, a crew can "borrow" the excess volume of the planes around the one they are working on even when they are all crowded into the service deck.

If an aeroform can fold up various bits, then a single bay of 200% might work. Once you have to provide a hangar *shape* that can handle the fully deployed aeroform, 200% gets tiny mighty quick.

Fortunately, we (Traveller designers, that is) can also benefit from large common hangars, as long as those hangars are not *also* the landing bays. Again, look at the aircraft carrier. Planes land on the roof, not in the hangar. While SOME ATUs assume that gravitic drives are capable of Star Wars-like control, not all people or settings do, so you really need somewhere big and open if you are designing for hot landings, and somewhere ELSE for storage and maintenance.

 

[rust]

While SOME ATUs assume that gravitic drives are capable of Star Wars-like control, not all people or settings do, so you really need somewhere big and open if you are designing for hot landings, and somewhere ELSE for storage and maintenance.

Yep, I assumed that small craft could land on the hull surface of their car-
rier if necessary, and from there be moved into the hangar, which should
not be too difficult under zero G, I thought.

 

[PFVA63]

An F-18 Super Hornet is 18.32 meters long, has a wingspan of 13.63 meters and is 4.88 meters high. It requires a volume of about 1,218 cubic meters "with wings", and probably about 432 cubic meters "without wings".

Hi,

If I understand it correctly 1,218 cubic meters is about 87 dtons which seems hight for an airplane but I guess alot depends on how much of that space is actually part of the airplane and how much is the space around it. Unfortunately I do not yet have a copy of High Guard, but in past versions of Traveller I had always assumed that the displacement of a ship or craft in Traveller actually refered to the volume in the ship and not the volume of the bounding box around its hull including all the fins and appendages etc.

If you look at this figure from GlobalSecurity.org it indicates that the actual volume of an F-18 appears to takes up only a part of the bounding volume of its Length x Width x Height. as such I would have assumed that empty space under the wings and fuselage (not taken up by the landing gear) would be a part of the extra space needed to stow the craft.

Regards

PF

Maybe if I get a chance later I might try and make a better estimateof the actual enclosed volume of a plane like the F-18 and compare it to how much actual space you might need to stow it aboard a ship.

 

[GypsyComet]

So the bounding box on an F/A-18 is, in Traveller grid, roughly 12 squares long, 9 squares wide, and 3 squares high. That's 81 dtons. Examining the dimensions of the major parts of the fusilage, adding the relatively small real volume present in the wings and vertical stabilizers, and waving my arms around a lot comes up with a real displacement of *maybe* 6 dtons.

That's close to 15 times, and that's to be able to stuff it into a box with landing gear and wings deployed.

1.3 times is nowhere close, unless you apply that multiple to the 81 tons of bounding box. I would use the bounding box for all other calculations as well, so a launch tube system (launched craft x 25 dtons) for such a fighter would take up just over 2000 dtons.

We begin to see why space carriers are so big.

Heck, even the smallest "carrier" I've seen in anime (the Bebop) is a 12kton monster, and that carries just three subcraft AND has external launch.

The problem, of course, is that ships and small craft are designed as enclosed volume, not bounding volume.

I'm willing to forgive Traveller quite a bit for its lapses with regard to the laws of physics, but as a deckplan wonk I find it much harder to forgive lapses in simple solid geometry.

 

[simonh]

I'm willing to forgive Traveller quite a bit for its lapses with regard to the laws of physics, but as a deckplan wonk I find it much harder to forgive lapses in simple solid geometry.

IMHO this is due to Traveller saying that a dton is purely a measure of volume, when in fact it's actualy used as a measure of 'Size', where 'Size' is a poorly defined combination of volume and mass. Think of it as a quantum value that is both mass and size at the same time, in the same way that a photon is both a particle and a wave simultaneously.

In some circumstances it makes sense to consider it to be a measure of mass (e.g. when using the drive table to determine thrust based on the Dton size of a spacecraft), and in others it makes sense to consider it to be a measure of volume (when working out some but not all aspects of a deck plan layout).

Clearly the 130% rule for hangers doesn't work well for volume, but if you consider it to be the mass of fixtures and fittings required to convert a bare hull space into a hangar bay it sort of almost makes sense, if you squint hard enough when you look at it.... And don't think about it too hard.... Or at all, actualy.

From a practical point of view, the 130% rule imposes some overhead for small craft without beign punitive, and is close enough to past design systems to make alow them to be squeezed into the new design system. All of which are IMHO more desirable attributes than perfect realism.

Simon Hibbs

 

[GypsyComet]

Since MT and TNE I've made the assumption that dtons are NOT mass, but can be an indicator of mass. With CT and MT M-Drives and all J-Drives being "magic", their being volume-based doesn't bother me in the slightest. TNE made a volume-to-mass relationship assumption *that it stated openly*, allowing for the mass-based drives prevalent in that edition to work with relatively little in-game silliness.

The first constraint on Traveller ship design has always been displacement. As such, it should also *always* be the one constraint treated with the most care and attention. Power, surface area, and mass are pulled out a random donkey for every edition, to greater or lesser effect on what the system can and cannot do.

Volume defines the environment of RPG play in ways the other parameters do not, and thus it needs to make real world sense even where the others do or may not.

 

[Patron Zero]

Number crunching aside, I see the small craft bays aboard a naval vessel utilizing every possible (cubic) inch available.

If one thinks modern day aircraft carriers jam up the fighter bays, imagine what such would be like were anti-grav capable tractors and other TU tools available.

That conceptual image should fully illustrate the atypical carrier vessel of the Imperium and other military forces.

 

[AKAramis]

I've always presumed that 130% rate is not bays, but custom berths, much as are shown on the CT Merc Cruiser.

CT-HG says bays can only hold 50% of their own volume in small craft. While this is in the section on empty Weapons Bays, it seems as good a rule as any.

 

[simonh]

I've always presumed that 130% rate is not bays, but custom berths, much as are shown on the CT Merc Cruiser.

CT-HG says bays can only hold 50% of their own volume in small craft. While this is in the section on empty Weapons Bays, it seems as good a rule as any.

So a Subsidised Merchant could use it's cargo bay to carry half the rated tonnage in small craft as well. It works for me.

Simon

 

[Patron Zero]

Might be helpful to see something regarding vehicle bays for small craft and starships that ferry ATVs, AFVs and other conveyances utilized while planetside.

I think the formulas might be more 'generous' concerning the space available-space usable ratio though, that opinion based on my real world experiences on-offloading vehicles in military transport aircraft.

 

[AKAramis]

I've always presumed that 130% rate is not bays, but custom berths, much as are shown on the CT Merc Cruiser.

CT-HG says bays can only hold 50% of their own volume in small craft. While this is in the section on empty Weapons Bays, it seems as good a rule as any.

So a Subsidised Merchant could use it's cargo bay to carry half the rated tonnage in small craft as well. It works for me.

Simon

for reference, the cube root of 2 is approximately 1.2599... so for small craft, that's about 13% to either direction....

so clearance around in such bays would average 13% of the dimension.

 

[Leo Knight]

This thread makes me smile, since these are the same arguments I've been having with myself and others since 1977. The first edition of Traveller didn't link tonnage with anything. It was just an abstract number, and several interpretations came up.

One of my few still existing posessions from those days is a copy of "Starships and Spacecraft", by Dave Sering, published by Judges' Guild in 1979. Their Type S Scout was the familiar wedge shape, 26m long, 18m wide, and 4.5m high. This makes its volume 351 cubic meters, for about 3.5 cubic meters per ton. Their Type M Subsidised Merchant is a series of boxes with chamfered corners, 57m long, 8m high and wide. Its volume is 3648 cubic meters, for about 6 cubic meters per ton.

IIRC, it wasn't until "Traders and Gunboats" that GDW fixed a ton as 14 cubic meters displacement, the volume of a ton of liquid hydrogen. The whole "Russian nesting dolls" problem, of how much room to leave around carried vehicles, seemed to start then. I can still remember the first time I heard somone poo-pooh a commercial set of plans, saying, "It's a terrible design. I counted the squares, and it doesn't add up to 400 tons!"

Personally, I like variety, and fun. If a design provokes my imagination, I'm willing to forgive an error in arithmetic.

 

[Beastttt]

all the cylinder space craft can have all the extra space to one side and you just roll the craft to the side you wish to work on
space for modules would be located nearby

as for other subcraft if you add each crafts +30% and have the 100% as a berth that only hold the space craft after 5 craft you get a work area that is the size of the craft plus 50%
also cargo bays can be nearby to off load cargo and some of that can be used on a temporary basis as wiggle room

MGT HG states that these are 130% of carried craft size and allow for full maintenance.

Sorry, but that's really silly, and not nearly enough space.

The simplest case would be the Modular Cutter or any of the "pure cylinder" subcraft in that family. An additional 30% around the cutter is *just* enough to square up the spot on the deckplan. If you assumed that one side of the cutter bay was kept form-fitting you would get maybe *two feet* of flat bay space beyond the hull on the other side.

If the Cutter has taken any damage that compromises its shape, that "hangar" is useless, as it still has no room for anything beyond the normal shape of the cutter.

And that's just the Cutter. Go to the winged forms and 30% won't let you have full access to the wings. Even a 100% increase will have trouble, and a 200% or 300% increase (so a 3x or 4x bay) will still feel cramped.

I honestly don't see the problem with encouraging designers to spent lots and lots of volume on stuff like subcraft. It's firmly present in visual SF, silly or otherwise. The boarding bay in the Star Destroyer from Episode IV is thousands of tons, as is the Death Star bay the Falcon gets parked in, and even the shuttle bay on the TOS Enterprise is hundreds of tons (for little 10-ton shuttles), not to mention the maintenance garage on the next deck down. Don't even ask about the big docking bay on the nose of Babylon-5, or the landing bays on the Galactica (either version).

 

[GypsyComet]

all the cylinder space craft can have all the extra space to one side and you just roll the craft to the side you wish to work on
space for modules would be located nearby

Roll it across the bay? You do realize a Modular Cutter is 20 feet tall and 100+ feet long, right? The MGT standard Cutter has an oval cross-section, and isn't rolling anywhere.

And again, 30% gives no roll room even if the hull has a circular cross-section. For a 20 foot diameter cylinder with all of the 30% surrounding half of it, the amount of space next to the hull is a smidge over 2 feet 6 inches.

The only way to rotate the hull for external repairs is to build rollers into the walls and rotate the hull in place. That's fine as long as the damage hasn't either caused bits of the hull to stick out OR to warp the length of the hull off of plumb. 100+ feet long, remember.

as for other subcraft if you add each crafts +30% and have the 100% as a berth that only hold the space craft after 5 craft you get a work area that is the size of the craft plus 50%
also cargo bays can be nearby to off load cargo and some of that can be used on a temporary basis as wiggle room

If you keep adding 30% to each carried craft the bay will always be 30% larger than its carried craft until you lose one or more of them. This is volume, not compound interest.

"Borrowing" space from one craft to work on another *can* work, and I think that's what you are suggesting, but to get that space in a useful shape the craft all have to be boxy and parked skin-on-skin. Otherwise that extra volume is always going to be tied up immediately around each craft. Go ask the Flight Commander what he thinks about piling his fighters in a corner like sardines and see what reaction you get...

 

[starfleet]

the other thing i think a lot of people forget is that your in space, set it to zero-G and you actually end up being able to work a lot easier.. all in all though does it really matter? I mean technically your talking tonnage, now I know the arguments 1 ton = xcubic meters.. yeah yeah.. but say you have a 10ton craft your using 130% of that to store it so your using 13tons of space.. using the standard 14 cubic meters that 'fighter' is gonna be a 140m cube.. with 42 cubic meters of free space around it. and lets Face reality people Your fighter is not a 140m CUBE!.. the fighter at 10tons is likely to be 50m x 40m x 10-20m if that.. I mean hell a modern fighter displaces around 10 tons and it certianly isn't a 140m Cube!

I say take into account what your doing take the 140m Cubic space as the 'MAXIMUM' area that something docked for a 10ton small craft can occuipy and then use some common sense.

 

[rust]

Ah ... 140 cubic meters is a 5.19 meter cube.

The fighter could be, for example, 10 meters long, 4 meters wide and
3.5 meters high.