Launch Tubes

[phavoc]

I thought I'd start a separate thread from the Ship Design Philosophy thread since the launch tube discussion was taking away from the original topic.

First, the original rules stated small craft can be launched 1 per turn, per 10,000 tons displacement. In TCS, the rules get changed to one small craft per turn, period.

Classic Traveller High guard brings out the first mention of Launch tubes. There's no mention of how fast you can launch/recover out of one. It's not till Adventure 5 - Trillion Credit Squadron that launch tubes get mentioned again. There it states up to 40 craft/turn can be launched or recovered. Megatraveller keeps the same rules. I skipped to GURPS for the next info.

In GURPS, launch tubes are mass-drivers, giving launching fighters their full speed upon launch. 40 craft may be launched per turn, but recovery is not possible through a launch tube. Instead craft must be recovered separately, usually through a hangar bay. GURPS also specifically mentions that the tube is for launching only, and then you must set aside additional space for staging before the craft is placed in the tube.

Only GURPS specifically mentions anything about the launch tubes being used to accelerate the craft to full speed immediately upon launch. And only GURPS says you can't recover a vessel via the tube. Carrier pilots have it tough already trying to land on a carrier... can you imagine having to fly down a TUBE? Any mistake and not only are you screwed, you've now blocked the capability of your ship to use that launch tube to recover anything else till the wreck is cleared and the damage repaired. It would kinda suck if you were stuck out in space till things got cleaned up.

MGT - High Guard goes back to the original concept of launch/recovery. The change here is that ships may only launch/recover TEN small craft per turn (I may have missed that in an earlier post). No reason is given why things have changed so drastically.

 

[Condottiere]

At some point, like their twenty first century forebears, naval policy makers have to ask themselves at what point are the tubes no longer viable as launch facilities.

 

[dragoner]

Shivva hangs fighters on the outside, which makes me wonder: why have a big target ship at all?

 

[Condottiere]

Same reason you have CVNs today, in the long run you have strategic mobility on a very large platform that can support large numbers of aircraft and their requisite launch facilities.

It's once you start deconstructing some underlying game mechanics and assumptions that it starts looking shaky.

You could put each craft in it's own airlock/hangar in a streamlined hull, open the hatches and let them all launch in the same turn. The reason they don't is probably due to expense, hull integrity and flexibility in carrying smallcraft of various sizes.

 

[F33D]

MGT - High Guard goes back to the original concept of launch/recovery. The change here is that ships may only launch/recover TEN small craft per turn (I may have missed that in an earlier post). No reason is given why things have changed so drastically.

None of these rules are well thought out. The rate of launch would be determined by the configuration of the fighter bays (which includes how large the points of egress are and the tonnage of the fighters being launched).

Anything else is just an arbitrary.

(launch tubes would be a waste of ship tonnage.)

 

[dragoner]

Same reason you have CVNs today, in the long run you have strategic mobility on a very large platform that can support large numbers of aircraft and their requisite launch facilities.

It's once you start deconstructing some underlying game mechanics and assumptions that it starts looking shaky.

You could put each craft in it's own airlock/hangar in a streamlined hull, open the hatches and let them all launch in the same turn. The reason they don't is probably due to expense, hull integrity and flexibility in carrying smallcraft of various sizes.

Modern CV's are probably going the way of the BB though, with aircraft having virtually unlimited range.

The game says that large spinal carrying ships, basically heavy cruisers, will dominate. So in that, the traditional carrier will be very vulnerable and instead of losing one ship and thus losing the entire fighter complement.

 

[Condottiere]

You need the launch tubes if you need to deploy in a hurry; it's been implied that dispersed structures underlie a substantial speed penalty, since their component parts might fly off in all directions as acceleration places an undue stress on the connecting steel beams.

Because the fighters might be less than ideally shaped, turning them into bullet shapes should make them able to more efficiently use the energy expanded by the mass driver (assuming that is what impels them forward), meaning that you could have smaller launch tube facilities.


I've noticed that the Imperium fields far fewer warships than my original impression, which means that they would be far less able to rely on cruisers, so swarms of fighters do serve a tactical purpose.

As to the future of naval aviation, your guess is as good as mine, but I think you have two issues, navies want/can afford smaller platforms, and catapults are a nuisance, so the development of the F-35 and/or a cheaper alternative is probably critical.

 

[F33D]

You need the launch tubes if you need to deploy in a hurry; it's been implied that dispersed structures underlie a substantial speed penalty, since their component parts might fly off in all directions as acceleration places an undue stress on the connecting steel beams.

Not at all. A very large cargo door can see more ships launched than one at a time tubes.

 

[phavoc]

Not at all. A very large cargo door can see more ships launched than one at a time tubes.

Without launch tubes a ship may only launch one small craft per turn. If you had a number of hangars you should be able to launch one per hangar, assuming they are properly spaced. But hangars aren't the answer for something like that, since they have a high space wastage.

If you had 10,000 tons in fighters, you'd need 13,000 tons is displacement to house them.

 

[Condottiere]

I concede your point.

What the launch tube does is throw out the fighters, whereas coming out of a bay would require them to do so under their own power, which if in the same direction of the starship, means that the smallcraft have to be faster, assuming I have my physics correct, and not get in each other's way.

If they went out the rear, this probably wouldn't matter.

 

[F33D]

Not at all. A very large cargo door can see more ships launched than one at a time tubes.

Without launch tubes a ship may only launch one small craft per turn. If you had a number of hangars you should be able to launch one per hangar, assuming they are properly spaced.

Read above comment on thread. THAT is an INSANE rule. Ya need to scratch insane stuff as you find it. If your hanger door was 50 meters wide... :lol:

 

[phavoc]

Read above comment on thread. THAT is an INSANE rule. Ya need to scratch insane stuff as you find it. If your hanger door was 50 meters wide... :lol:

Oh, I do understand. I spent a lot of time pouring over the materials to figure out what game system said what. The GURPS version made the best sense - making the launch tube useful because it accelerated the ship to full speed upon launch.

I didn't understand why the downgraded the launching capabilities by 300% for no apparent reason. That makes launch tubes even less useful.

I would think a designer would not have that many huge hatches in the hull. A hangar hit would destroy all the fighters in that hangar.

The way Star Wars launched their fighters, they did launch in ones and twos from the hangars. There shouldn't be a reason why you couldn't. Just have to find what makes most sense.

 

[Rockymountainnavy]

Regarding launch rates take note that each TURN in Classic Traveller is 1,000 seconds (just over 16 minutes) whereas each turn in MongTrav is only 6 minutes. Adventure 5 TCS does not define a time for each turn but the assumption I have seen is about 20 minutes. That goes a long way towards explaining the 40vs10 rate.

 

[phavoc]

Regarding launch rates take note that each TURN in Classic Traveller is 1,000 seconds (just over 16 minutes) whereas each turn in MongTrav is only 6 minutes. Adventure 5 TCS does not define a time for each turn but the assumption I have seen is about 20 minutes. That goes a long way towards explaining the 40vs10 rate.

That does help make up for the difference. Classic Traveller allows for a launch every 24 seconds, where MGT launches every 36 seconds. Still a 33% change. Which kind of detracts from the idea of having a launch tube to begin with (i.e. rapid launch).

I am wondering if this is one of those changes that was put in for no good apparent reason (like MGT totally changed the jump drive to be a jump bubble, whereas previous versions had the lanthanum grid built into the hull. It provides no net positive effect, with the negative effect of old materials being republished with the original grid tech in place). I know it's a minor thing, but stuff like that annoys me to no end.

 

[locarno24]

None of these rules are well thought out. The rate of launch would be determined by the configuration of the fighter bays (which includes how large the points of egress are and the tonnage of the fighters being launched).

Anything else is just an arbitrary.

(launch tubes would be a waste of ship tonnage.)

Oh, agreed. But then the entire ship design and combat system is mostly arbitrary.

There needs to be some mechanism in the rules to determine how those bays are set up, because there should logically be some difference in launch rates between the handful of smallcraft on a 'gun deck' warship and the fighters which form the 'main battery' of a dedicated carrier.

I don't like the rules for tubes but always assume that the 'launch tube' isn't necessarily a battlestar galactica type catapult but that the personnel are local flight controllers, and that the volume earmarks what proportion of the bays are up against the surface (with amoured airlocks, etc).

A hangar is principally a storage and maintenance space, after all - you wouldn't want to be loading hot TAC missiles on it if you can avoid it and wouldn't want to have to depressurise/repressurise it. Using aircraft carrier analogy, launch tube is the top deck, hangar is the deck below.

I still don't think it should be so big though; if 130 dTons is a full maintenance hangar for ten light fighters, why do I need almost exactly twice that volume - 250 dTons - as a launch deck?

 

[steve98052]

Regarding launch rates take note that each TURN in Classic Traveller is 1,000 seconds (just over 16 minutes) whereas each turn in MongTrav is only 6 minutes. Adventure 5 TCS does not define a time for each turn but the assumption I have seen is about 20 minutes. That goes a long way towards explaining the 40vs10 rate.

There is no one answer for how a Classic Traveller turn is defined:

• - High Guard (1980) says a turn is 20 minutes, and that a launch tube can launch 40 craft per turn: 30 seconds per craft.

• - Starships (1977, 1981) says a turn is 1000 seconds, and doesn't mention launch tubes.

• - High Guard (1981) doesn't define a turn, but it lists only High Guard (1980) in its required materials list, which means that its 20 minute turn applies, not the 1000-second Starships turn.

That does help make up for the difference. Classic Traveller allows for a launch every 24 seconds, where MGT launches every 36 seconds. Still a 33% change. Which kind of detracts from the idea of having a launch tube to begin with (i.e. rapid launch).
. . .

If one wanted to make Mongoose consistent with High Guard (1980), while preserving the six-minute turn, the simple fix would be to rule that launch tubes can launch 12 craft per six-minute turn, rather than just ten.

The deck plans in the Azhanti High Lightning supplement Lightning Class Cruisers (1980), include two launch tubes (capable of launching craft up to 3 meters diameter, 12 meters length), two hangar decks, and a boat-dock deck. The upper hangar deck customarily uses the port launch tube, and the lower the starboard, but either deck can use either tube. The boat dock deck is equipped with seven boat docks (in addition to the launch tubes) of assorted sizes: 3 meters (four), 4.5 meters (one), 6 meters (one), and large docks (four) designed for the fuel shuttles. Both the tubes and the docks could be used to recover fighters.

I seem to recall reading somewhere that one launch tube was customarily used for launches and the other for recovery, but I didn't find that in the text. Either I saw it somewhere else (official or not) or I confused the note about upper and lower decks using port and starboard tubes.

- - -

Anyway, I agree with the idea that launch tubes seem like features that would allow rapid launch of fighters, but not such rapid recovery. It certainly makes sense that they'd allow faster recovery than a dock, but not as fast as launch.

On the other hand, 30 or 36 seconds is quite a decent amount of time, even for arrivals, as long as everyone is well trained, and both facilities and arriving craft are in good condition. But if the tubes suffer any battle damage (or crash damage), arrivals become dangerous -- and craft that arrive with battle damage are more dangerous and may be more urgent to retrieve safely.

I'd say that launch tubes would work best in the case of a busy starport, where almost everyone arrives in good condition, and those who arrive damaged can be diverted to an emergency dock. In a combat setting, they'd be great for launches, but somewhat riskier for retrievals.

 

[phavoc]

A hangar is principally a storage and maintenance space, after all - you wouldn't want to be loading hot TAC missiles on it if you can avoid it and wouldn't want to have to depressurise/repressurise it. Using aircraft carrier analogy, launch tube is the top deck, hangar is the deck below.

That got me thinking about how it's done in the wet navy. The hangar is for storage of the aircraft, and repairs, but that's it. Arming, fueling and launching all occur on the flight deck.

In the Star Wars universe you see the hangar as the single place for all work to occur. The difference is that the fighters are anti-grav capable, so they can be moved over other vessels. Adding in the 3rd dimension certainly gives you a lot more capabilities. The drawback to this is that recovery should not be as fast as launch (always harder to put shit where it goes than it is to take it out). Plus recovering AND launching out of the same door is problematic. You can all go OUT, or you can all come IN. But doing both would be dangerous. And, I think the other issue would be recovering damaged ships, as in where the hell do you put down in an emergency. Not to mention you'd run into some of the same problems flattops used to have before they had angled flight decks - a bad trap, equipment failure or pilot error and you just smash into the other aircraft in front of you.

And in Battlestar Galactica, you see the launch, recovery and hangar space all separate from each other. Though they don't have anti-grav, they do have the ability to physically move the vessels from place to place by towing/elevators. In many ways it's like a wet-navy carrier with an angled flight deck that allows simultaneous launching/recovery with the hangar also being available at the same time.

I suppose, except for the space issue, the BSG version makes the most sense for grav-capable flight decks. Launch tubes are a single point of failure for the entire system. Lose that and you've lost the ability to launch or recover, and your carrier is out of action unless its' got additional launch tubes. You should (I think) distinct areas to launch, store/repair, and recover your smaller craft.

I still don't think it should be so big though; if 130 dTons is a full maintenance hangar for ten light fighters, why do I need almost exactly twice that volume - 250 dTons - as a launch deck?

There should be no reason to have a launch tube for so few fighters. Unless you were taken by total surprise, you should be able to launch so few fighters before any enemy could close. Now recovering them quickly... that would not be able to happen.

 

[Condottiere]

You can always park the smallcraft in some corner, where it consumes only 110% space, until it needs to be maintained, or powered up in readiness. I read somewhere that theoretically you could launch through each airlock/dock a smallcraft, assuming it was already prepped to go, every turn or six minutes or whatever time measurement was, and that thirty minutes was from a cold start.

 

[locarno24]

In the Star Wars universe you see the hangar as the single place for all work to occur. The difference is that the fighters are anti-grav capable, so they can be moved over other vessels. Adding in the 3rd dimension certainly gives you a lot more capabilities. The drawback to this is that recovery should not be as fast as launch (always harder to put **** where it goes than it is to take it out). Plus recovering AND launching out of the same door is problematic. You can all go OUT, or you can all come IN. But doing both would be dangerous. And, I think the other issue would be recovering damaged ships, as in where the hell do you put down in an emergency. Not to mention you'd run into some of the same problems flattops used to have before they had angled flight decks - a bad trap, equipment failure or pilot error and you just smash into the other aircraft in front of you.

The most important thing star wars (and star trek) have going for them is...I don't know if they have a specific name?...the force field things over the launch bay - allowing you to have a pressurised bay and still have fighters and shuttles fly in and out without rigging the bay for decompression every five minutes.

 

[F33D]

The most important thing star wars (and star trek) have going for them is...I don't know if they have a specific name?...the force field things over the launch bay - allowing you to have a pressurised bay and still have fighters and shuttles fly in and out without rigging the bay for decompression every five minutes.

In Trav, crew are in pressure suits. At TL's 11+ they will be "unbulky" enough. Also, in MGT the craft have grav drives so they can go over other craft. One 'door' for launch, another for recovery.