HG: Subcraft hangars

starfleet said:
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.

The only vehicle designs for Traveller that have ever had different volumes for actual displacement and stowage displacement were from the first edition of Striker, and the multiple for aircraft was quite large.

Striker reduced useful volume (for vehicles) due to using sloped armor, but the bounding box of the original dimensions was always used for stowing that vehicle as cargo or working subcraft.

You can't have it both ways. A subcraft designed with 10 tons of internal components cannot then be handwaved to take less than 10 tons when being stowed aboard a larger ship. Are you going to tell me that a 20-ton ship's Launch carrying 16 tons of cargo, a ton of fuel, a ton of drives, and two tons of bridge is only going to occupy 15 tons when berthed? or maybe 10? That 16 tons of cargo you just delivered is still going to be 16 tons when you move it to the cargo bay...

Modern fighters get up to around 8 to 10 tons of actual volume (the F-15 is probably that big), but as we've already discussed, the box required to hold said fighter in operable condition (landing gear, wings, and tailfins extended) is much, much larger. The amount of space required to launch and retrieve that fighter is many times larger than the stowage space, due to it being a working airframe vehicle with a high stall speed.

Spacecraft in the Traveller mold, with relatively compact forms and good drive systems, will require a lot less unless the subcraft mission requires a high delta-V (like fighters), but will still need a lot more than 130% if you want the SF trope of walking across the bay to your craft and walking up the ramp to board, or having the drive in pieces all over the bay floor during repairs, or indeed any function other than as a claustrophobe's nightmare.
 
I have played a bit with toy aircraft, toy soldiers and shoe boxes (you
should have seen my girlfriend's look ... :shock: ), and this not exactly scien-
tific experiment has led me to the conclusion that 200 % of a craft's vo-
lume really are the minimum size for a hangar. :)
 
Really, for shoehorn accomodations, I can live with the form-fitting 100% (what TNE called a "Docking Ring"), and/or the 130% "wiggle room" number. What really bothers me is the assertion that such can be called a "hangar bay" and blithely described as having enough room for real repair work.

The various systems as presented give *missiles* more facility space (in proportion to carried volume) than manned subcraft.
 
And Aircraft are not a good model for most small spacecraft.

200% is about 5/4ths on each dimension. Airframes, however, complicate things immensely, since they are very high surface area to volume, and thus the bounding box is much larger.

Type A's can be packed pretty tight, so can the standard Type S.

On a single deck, bounding boxes are more important, and especially with airframes.

In a 0-G bay, you can pack far tighter, even more so it you use first-in-last-out layouts.
 
the extra space is for maintaince and minor repairs only
your not going to be able to do major repairs

if the hull is warped or bent you could not get into the tube/bay any way
and I ment rotating it in the tube

anything sticking out can be cut off or that piece of the hull plating can be removed

if the vehicle is bent then the keel is whacked and the vessel would need to be stripped of useful parts and dumped

if say 10 ton fighter needs 13 tons of space so maintaince can be done then what if you had say 10x 10ton fighters that would be 130 tons
you allocate 10 tons to place each fighter(snug fit)you have a 30 ton space to do what ever needs to be done to the fighter or 2
in an emergency you could hold 2 extra fighters but you cannot work on any others as there is no swap space(to be used should the other 2 fighter's mother ship where destroyed or the bay wrecked)

and just because the boat may be oval does not mean the tube has to be
there could be cradles that the boat rests on and then you can rotate it

look at the Hornet for the Doolittle raid on Tokyo in 1942
she could not use her flight deck for her regular aircraft till the bombers had taken off
Hornet was never ment to do that but people learned to improvise and it got the job done

as for the flight commander ask him if he wants his craft serviced or not
reloaded or not

try thinking outside the box
it helps dispel tunnel vision

GypsyComet said:
Beastttt said:
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...
 
Beastttt said:
the extra space is for maintaince and minor repairs only
your not going to be able to do major repairs

if the hull is warped or bent you could not get into the tube/bay any way
and I ment rotating it in the tube

anything sticking out can be cut off or that piece of the hull plating can be removed

if the vehicle is bent then the keel is whacked and the vessel would need to be stripped of useful parts and dumped

if say 10 ton fighter needs 13 tons of space so maintaince can be done then what if you had say 10x 10ton fighters that would be 130 tons
you allocate 10 tons to place each fighter(snug fit)you have a 30 ton space to do what ever needs to be done to the fighter or 2
in an emergency you could hold 2 extra fighters but you cannot work on any others as there is no swap space(to be used should the other 2 fighter's mother ship where destroyed or the bay wrecked)

and just because the boat may be oval does not mean the tube has to be
there could be cradles that the boat rests on and then you can rotate it

All of these ideas only work *before* you start working with actual spaces, or in the case of that last, before you do the math.

A strictly cylindrical bay big enough to rotate the oval MGT Cutter in will have a cross section of roughly 44.2 m2, while the cutter itself has a cross section of 26.5 m2. So the cradle is already 167% of the size of the craft, and you still don't have a flat floor to work on. Presuming that the bay goes for full floor space under the cradle (so repairs happen "up", like the craft was on a jack stand) that increases the cradle bay's cross section to 57.6 m2, or over twice the size of the craft being parked there.

Note that this arrangement also happens to be three decks high.

You can't just look at volume. You must also look at shape, especially if you are doing deckplans. I've been doing Traveller deckplans for many years, so some of this stuff is second nature to me.

As for "stacking" fighters, the ability to do so in a way that unifies their 30% surplus implies that you already have a lot more than that 30%.

Best case for your approach would be a craft we shall call "the brick". One deck high, 6 m wide, 15m long, and as squarish as we can manage, for 20 displacement tons. If we stack five of these either atop each other or side by side, and "steal" the extra 30% (6 dtons each) for a single repair bay in front of one of them, that gives us a 30 dton bay. Very cramped, but doable for many, if not all, external repairs. One bay per ten would be better, but that's a quibble. The point is that, unless you can shuffle the other four around, only one of them will have access to the repair bay itself. Two others will (assuming this is a unified bay and you put the repair bay in front of the middle one) have a single side exposed (which makes a good argument for stacking the bricks vertically, as this gives better access to hull exteriors). But you still can't shuffle them.

So we go to a two-by-three arrangement, with the repair bay off of one of the sides. This is best done with six or more craft, as you need to use the "magic square" shtick and need the repair bay to be large enough to do actual work, so four isn't enough. You can't simply pad the space around one of the six, because then you can't use the magic square effect to shuffle craft into the repair space. That said, if you have enough extra volume to play with you'll probably want to pad that corner anyway in addition to the dedicated repair bay, as you can then work on two at once. Note that you'll need to get the ratio of craft per repair bay up a lot higher before you can work on the tops of the bricks (assuming a horizontal Magic Square).

Good lord, just give the craft more room to begin with. This sort of arrangement is not going to be installed in anything small, so you'll probably have the displacement to burn. Really.

The Magic Square also stops working immediately if the craft isn't a brick, as the ability to shuffle rounded forms around a combined deck is already eating your 30% and then some.
 
Gypsy: the one "exception" is that, if you have linear bay system, with a pull out, you can rotate them all through when in N-Space.

Take a 12 space linear bay: A,B,C,D,E,F,G,H,J,K,L,M, and 3 work pullouts: D', E', and F', I can get B,C,D,E,F,G,H in, in a single operation A is stuck, and JKLM are stuck.

If, however, I instead go with two shorter lines and the same 3 work bays between, I can now shuffle freely between all of them...
ABCDEF
_XYZ
GHJKLM


Now, the other thing: The shop space can be adjacent to the bay space, not part of it. In fact, the machine shop is likely to look like part of the bay, even tho' designed as separate.


Code:
+======+======+======+======+======+======+
|  F   |  E   |  D   |  C   |  B   |  A   |
+======+======+======+======+======+======+
       | Wk X | Wk Y | Wk Z |
+======+======+======+======+======+======+
|  M   |  L   |  K   |  J   |  H   |  G   |
+======+======+======+======+======+======+

    +==============+===================+==============+
   /           \       /           \       /           \
  /             \     /             \     /             \
 /               \   /               \   /               \
|      Flight     | |     Repairs     | |      Flight     |
|       Bay       | |       Bay       | |       Bay       |
 \               /   \               /   \               /
  \             /     \             /     \             /
   \           /       \           /       \           /
    +==============+===================+==============+
[/code]
 
True, but this is still a form of Magic Square, and falls apart for non-bricks since the mobility provisions down the row of bays will still eat all of your 30%. The one exception being when the row of bays are really a single tube that is six cutters (for example) long, loaded either from the ends or from the sides but clearly visible as a half-buried long tube with lots of hatches on the outside of the hull. Once you square off the hull around them, the 30% is lost to that.
 
Hi,

I just picked up a copy of High Guard today and got a chance to see the Light Fighter design included there. Although alot of the small craft in Traveller tend to be fairly simple in shape, this fighter is configured with large wing surfaces, some canard, and a vertical tail, that seems like it might result in it taking up a fair amount of space, in comparison to its size. As such, I put together a couple sketches based on it to see how it might fit into a bay.

On the right you can see the general outline of the craft. If you count the squares the add up to about 42 1/2. So if you assume that if each square is only about 1/2 height (especially since the wings and stuff should be pretty thin) then I think that this comes close to about 10dtons displacement.

In the middle picture I tried to lay out a single rectangular bay that appeared big enough to hold the craft. In High Guard they didn't show a detailed sketch of how tall the craft is, but there were some pictures so I made a guess. Overall I come up with a bay about 88dtons in size (or about 880% the size of the craft) to fit the 10 dton fighter (though it could be less if you assume a lower tail height).

In the left most figure I made a guess at what the craft might look like if the wings folded. Here I come up with a bay size of about 33.5 dtons (or about 335% of the craft size).

If you make some different assumptions on how the craft folds up you will probably come up with different numbers, but it would seem difficult to me to get it down to only 130% of the craft size for a small craft like this.

Anyway, just thought I'd share what I found.

Regards

PF

LtFtr.jpg
 
Evening GypsyComet,

Actually the hangar deck on modern aircraft carriers have retractable walls that are used to section off the hangar deck. The system is mainly for damage control.

Since I'm retired military I cut through Fort Lewis, WA to save time and gas going to work. On Gray Army Air Field they put up a tube and some sort of outer skin hangar that can fit a single Chinook Helicopter, without the rotor blades. From what I've been able to see there might be 3 or 4 feet of clearance for the rotor hubs. There are doors at both ends that fold up something like a Roman shade. The tallest section appears to provide 3 or 4 feet in front and behind the helicopter. Sorry I can't give dimensions of the hangar, but I think they migh have a problem with a sailor taking measurements on Army property.

They also put up similar vehicle repair hangars on the backside of North Fort Lewis. I'll see if I can find some dimensions.


GypsyComet said:
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.
 
When we're talking about hangar space, we're talking about mostly empty space required to manoeuver bulky maintenance equipment, personnel and spare parts. Such work require a lot of access space, but this space is just that - basically empty volume. As such it's contribution to the actual mass of the ship should be relatively low. Is it realy fair for this space to count fully against the cost of the ship drives? From an economic perspective imposing high ship displacement costs for carried craft unfairly inflate the costs of doing so, making such ships excessively expensive and inefficient.

I don't think it's reasonable to compare traveller ships with real world aircraft carriers because the tradeoffs are not the same.

Traveller abstracts a lot into 'Displacement Tons' and I'm glad the system doesn't dogmatically apply volume-only logic in the design system. I think it would be preferable if the rules clearly stated that displacement tons are an abstract value with notional meanings in terms of mass and volume, but I understand why it doesn't because of the potential to make the situation more obscure rather than more clear.

I think the design system as presented is a broadly fair one that ballances the tradeoffs for various options such as hangar space and other facilities in a fair and equitable way, and that's what counts.

Simon Hibbs
 
simonh said:
Traveller abstracts a lot into 'Displacement Tons' and I'm glad the system doesn't dogmatically apply volume-only logic in the design system. I think it would be preferable if the rules clearly stated that displacement tons are an abstract value with notional meanings in terms of mass and volume, but I understand why it doesn't because of the potential to make the situation more obscure rather than more clear.

Ah, but it does Simon, just like CT, Volume is the only statistic that is given and the examples bear this out. One of the big issues is that The displacement ton is explicit.
 
The displacement ton as defined in Traveller is actually a pretty big problem - one there is no easy answer to, other than people using their best judgement.

Design a 10,000 dT ship that consists of a single rectangular deck. Now take that ship, and "wrap it" around so that it makes a tube.

Is it still a 10,000 dT ship? Maybe. What if you "seal off" the ends of the tube with a single sheet of metal? Is it still 10,000 dT then? By strict definition, no - that inner volume is now part of the displacement Tons.


All of this really only becomes an issue if you're drawing deckplans. If you aren't drawing a deckplan, it's a simple matter of math, and for the most part, it works. If you are drawing deckplans, you have to take some liberties for a lot things like hallways, work spaces, access tubes, small craft, etc. Basically, I figure things like power plants/j-drives/etc will only take up about 80-90% of their designed size in terms of deckplan space, which allows for adding extra space in other areas.

Also remember that the two 1.5 meter squares on a deckplan drawing really only account for 13.5 cubic meters, leaving you an additional 4% or so to go "over" the supposed number of squares.


It would be nice if this was fixed once and for all, but I suspect the outcry would be on the order of the introduction of TNE.
 
I have the TNE books and the Minimal hangar is 200% of the small craft and the spacious is 400%. No matter how you look at it, this is alot more reasonable than the 130%. You can actually fit the small craft in and perform maintenance. Otherwise it would be like trying to fit the larger hummers into a garage meant for normal size cars. IT IS NOT GOING TO WORK!
 
The TNE books are also a lot more reasonable on a lot of things - like reaction thrusters, etc.

You either have to take the CT/MT/MgT design systems with a grain of salt and fudge things till they look right when drawing deckplans, or the entire system needs to be rebuilt.

For example, Power Plant size should be strictly based on ship's power needs, no other factors. Manuever Drives should be based strictly upon the ship's mass - not it's volume, but it's total mass. Jump drives should probably be based upon the ships total boundry volume, rather than it's strict displacement - IE, it should take a larger j-drive to create a j-field for a 10,000 dT dispersed structure ship than for a 10,000 dT spherical one.
 
kristof65 said:
The TNE books are also a lot more reasonable on a lot of things - like reaction thrusters, etc.

You either have to take the CT/MT/MgT design systems with a grain of salt and fudge things till they look right when drawing deckplans, or the entire system needs to be rebuilt.

For example, Power Plant size should be strictly based on ship's power needs, no other factors. Manuever Drives should be based strictly upon the ship's mass - not it's volume, but it's total mass. Jump drives should probably be based upon the ships total boundry volume, rather than it's strict displacement - IE, it should take a larger j-drive to create a j-field for a 10,000 dT dispersed structure ship than for a 10,000 dT spherical one.

In the parlance, this is called a "slippery slope".
 
Back
Top