Alternate Design Rule - VLS Launchers for Missiles

[DFW]

When I mentioned delta vee I wasn't talking rules wise, I was talking real world physics. I am a rocket scientist after all

LBH

If you are a rocket scientist then you know the delta vee of the missile due to its launch location on the hull is far less important than the relative vector and acceleration of the two ships in combat... 8)

 

[dreamingbadger]

you could also "soft launch" the weapon using a "gas cartridge" to have it clear the cell, have manoeuvring thrusters orientate the weapon and then fire a main engine burn for target capture/engagement

 

[Charakan]

Whats Delta Vee and a VLS? I'm a poorly educated bum in real life .

Actually I know what Delta Vee is from consuming so much science fiction and books on space travel when I was a kid, but I have no bloody idea what a VLS is!

 

[DFW]

Whats Delta Vee and a VLS? I'm a poorly educated bum in real life .

Actually I know what Delta Vee is from consuming so much science fiction and books on space travel when I was a kid, but I have no bloody idea what a VLS is!

VLS = vertical launch system. Like our nuke sub ballistic missiles.

 

[Charakan]

Thanks for enlightening me DFW, appreciated mate .

 

[phavoc]

you could also "soft launch" the weapon using a "gas cartridge" to have it clear the cell, have manoeuvring thrusters orientate the weapon and then fire a main engine burn for target capture/engagement

Yeah, a 'cold' launch can be mechanically (simplest) or gas-based. SLBMs (sub launch ballistic missiles) are ejected using gas go get them to the surface where they ignite their rocket motors.

But we are thinking similarly on this.

 

[phavoc]

Whats Delta Vee and a VLS? I'm a poorly educated bum in real life .

Actually I know what Delta Vee is from consuming so much science fiction and books on space travel when I was a kid, but I have no bloody idea what a VLS is!

Delta-vee refers to velocity. Traveller simplifies space combat so you really dont' have to worry about all the issues of velocity, which makes for a much easier playing system. In space (in real life) you always have to counter your velocity if you are going to change directions and you aren't wanting to continue to travel in the direction of your thrust.

As far as the VLS system, well, I took real-world examples of it. In the US Navy there are VLS systems on the Ticonderoga class cruisers and Arleigh Burke class destroyers. Older missile launchers usually had twin (and some had a single) arm that had to be rotated towards where you wanted to launch your missiles. Then when the rails were empty it had to return to the reload position where two (or one) more missiles were loaded onto the rails, then rinse and repeat. I know the Russians have deployed VLS on their Kirov class battlecruiser, but I'm not sure on what other ships they have installed it on.

VLS allows the operators to assign targets to the firing system and the computers can then pick the most appropriate missile for the mission and launch it. Since there are no launch rails to worry about the missiles can be ripple fired from the VLS array one after the other. The only limitation is making sure their rocket exhausts don't interefere with each other.

You can read more about VLS systems in real life by going here: http://en.wikipedia.org/wiki/Vertical_launching_system

 

[phavoc]

As I understood it, even a fixed mount still requires a hardpoint ("A ship has one hardpoint per 100 tons of ship and each weapon system takes up one hardpoint") there's just no tonnage associated with any slewing mechanism and no tonnage for fire control.

One thing to make sure that costs and volumes line up, and that VLS systems aren't just an out-and-out 'better' solution is to make sure you have a common start point. A single fixed mount missile launcher with one round available should be essentially identical to a one-cell VLS.

High Guard rules state that a 100 ton small craft can mount up to 5 weapons, and one hard point/turret is required for every three weapons installed. Which translates into a 100 ship being able to mount 5 missile tubes, with 3 in a turret, while the other two can be fixed mounts. Energy weapons have their own restrictions.

I had envisioned VLS arrays to be most effective in smaller ships, the type that players would be using.

A torpedo, with a 1 dTon-per-round volume, is a different animal entirely, and I'd suggest that any replenishment-in-space (which is more likely to be common for capital ships that you don't want to have to pull out of your battlegroup to re-arm if you can avoid it!) is going to require some sort of handling cranage.

Torpedoes actually take up 2.5tons per round according to the rule book. But I agree that since they are much larger and bulkier they will require longer reload times. And you correctly point out the downside to VLS - reloads. They have to be done externally.

Doesn't really matter - I don't feel there should be any cost penalty for using a bit of space for that rather than normal engine. As described, though, cold launch is only something to do for creating an impromptu minefield or alpha strike cloud (a la Honor Harrington missile pod laying). In either case, the big thing the missile canister now needs is sensor stealthing and some passive sensors of its own, which is what I was suggesting the cost increase for.

Agreed. 'Cold' launches would only be used if you were wanting to leave a few surprises for someone chasing you, reducing their time to engage the missiles. At long range the missiles should be pretty much invisible, but when you get closer sensors should start picking up anomaly's or ejected debris. Could make for some interesting PC interactions.

I can't claim that the idea was lifted from HH, but Weber does write some interesting space battles.

Easiest thing to do with that - if using the Ammunition cook-off rule or something like it - is to give a benefit to that roll. So, for example, a launcher with Armoured Compartments only suffers a Hull Breach on a 6 and will never suffer an Internal Explosion.

It might be worth associating some volume, as well as just cost, with that option - armour plate is definitely something that is tracked in Traveller. Granted we're not talking about a large proportion of the ship, but if it's going to contain several standard missile warheads going up in a confined space then its definitely going to be a non-trivial proportion of the volume of the launcher.

Definitely something to think about. Thanks!

"So....why did you put 30 VRF gauss rifle slugs through the mayor's windows?"

"Err....there was a pigeon?"

I knew those pigeons were Zhodani spies!

 

[Charakan]

Thanks, Phavoc, I was right when I about what I thought Delta Vee was, I've played a bit of Jumpgate online which uses a very realistic flight model and get what you mean about velocity and direction, it was a real pain in the behind to get used to. Thanks for the link about VLS as well.

 

[lastbesthope]

When I mentioned delta vee I wasn't talking rules wise, I was talking real world physics. I am a rocket scientist after all

LBH

If you are a rocket scientist then you know the delta vee of the missile due to its launch location on the hull is far less important than the relative vector and acceleration of the two ships in combat... 8)

True, but a steerable turret launcher can be used tocounteract that better than a VLS system.

you could also "soft launch" the weapon using a "gas cartridge" to have it clear the cell, have manoeuvring thrusters orientate the weapon and then fire a main engine burn for target capture/engagement

Soft launch or hard, it's still delta vee. Still needs to be accounted for.

LBH

 

[DFW]

True, but a steerable turret launcher can be used to counteract that better than a VLS system.

If you have to worry about that, your rocket is insufficient for ship to ship action anyway.

 

[locarno24]

At long range the missiles should be pretty much invisible

Depends. If you're dumping twenty missiles then that's 2 dTons of volume, and a much higher surface area than a single 2 dTon block, so you might get more of a return than you'd expect.

That's why I'd just incorporate the cost-per-volume for 'stealthy hull materials', straight out of the basic ship design rules. Then there's no argument that the pc's should have seen them before the GM says so.

If you have to worry about that, your rocket is insufficient for ship to ship action anyway.

Depends on what you consider the missile launcher to consist of. If it's just a rail that holds the missile whilst it accellerates from a standing start, and it can be programmed with a number of waypoints for the first stage of the flight, you can point the launcher in whatever direction you like, and use short, low-power burns to get yourself clear of the launching vessel and lined up on the target before hitting the gas on your main drive. Yes, it will take time, but not enough to register in a six-minute turn, and with a bit of intelligent Time-on-target work you can ripple-fire launchers in multiple directons so they form up into one big barrage when their drives light up.

However, if the launcher is something more than that (the canister contains a quick-burn drive, or is a small mass driver), then you will actually leave the launcher doing quite a sizeable clip in the wrong direction. You can't run 'out of range' of a ship to ship missile per se, but if you've got a mass driver launcher, linked up to the power plant and designed to punch you up to - say - twenty to thirty percent of your peak speed, not having that pointed according to an intercept solution is going to seriously impact your missile's performance.

 

[DFW]

Depends on what you consider the missile launcher to consist of.

Not worth considering compared with the relative vector & acceleration of the combatant ships.

 

[phavoc]

True, but a steerable turret launcher can be used to counteract that better than a VLS system.

If you have to worry about that, your rocket is insufficient for ship to ship action anyway.

I'm with DFW on this one. ANY object launched from a vessel under thrust is going to have the same vector and initial velocity. So a steerable turret won't give you any advantage if launching a missile that can control itself. Not as long as the launching mechanism is equivalent.

Traveller combat rounds, being six minutes long, are more than generous enough for a missile ejected from any point on the ship to maneuver using thrusters to orient towards the target - especially if the vessel is travelling under thrust. A stationary vessel, well, the missile would need to maneuver to clear the ship, but even so, under 1G of thrust it would easily clear a ship's bulk in one combat turn.

 

[phavoc]

At long range the missiles should be pretty much invisible

Depends. If you're dumping twenty missiles then that's 2 dTons of volume, and a much higher surface area than a single 2 dTon block, so you might get more of a return than you'd expect.

That's why I'd just incorporate the cost-per-volume for 'stealthy hull materials', straight out of the basic ship design rules. Then there's no argument that the pc's should have seen them before the GM says so.

If you have to worry about that, your rocket is insufficient for ship to ship action anyway.

Depends on what you consider the missile launcher to consist of. If it's just a rail that holds the missile whilst it accellerates from a standing start, and it can be programmed with a number of waypoints for the first stage of the flight, you can point the launcher in whatever direction you like, and use short, low-power burns to get yourself clear of the launching vessel and lined up on the target before hitting the gas on your main drive. Yes, it will take time, but not enough to register in a six-minute turn, and with a bit of intelligent Time-on-target work you can ripple-fire launchers in multiple directons so they form up into one big barrage when their drives light up.

However, if the launcher is something more than that (the canister contains a quick-burn drive, or is a small mass driver), then you will actually leave the launcher doing quite a sizeable clip in the wrong direction. You can't run 'out of range' of a ship to ship missile per se, but if you've got a mass driver launcher, linked up to the power plant and designed to punch you up to - say - twenty to thirty percent of your peak speed, not having that pointed according to an intercept solution is going to seriously impact your missile's performance.

I could see another type of missile, stealthy, that you could reduce the detection range by like a band or two, so long as the missile had not activated its drive.

Trav missile launchers don't, as far as I can tell, give the launching missile any extra momentum when launching. Not like what you are describing at least.

That could be another alternative rule - enhanced missile launchers that are in essence mass drivers and give extra speed to the missile. Call it a 'sprint' mode or something. I think there was something similar in Starfire (which David Weber worked on for trivia buffs)

 

[DFW]

That's why I'd just incorporate the cost-per-volume for 'stealthy hull materials', straight out of the basic ship design rules. Then there's no argument that the pc's should have seen them before the GM says so.

Here's the rub. What is the propulsion system for the missile? If it produces significant IR, there is NO way to make the missile stealthy in open space. In the far IR band it would stand out like a campfire on an open plain in the dead of night.

 

[phavoc]

Here's the rub. What is the propulsion system for the missile? If it produces significant IR, there is NO way to make the missile stealthy in open space. In the far IR band it would stand out like a campfire on an open plain in the dead of night.

I'm not proposing the drive system itself be stealthy. Just the missile itself, to reduce scanner returns. Thrusters can be gas-based which would give very little IR returns, if any. And I would think that at long distance the ship itself would cover up any sort of IR detection, not to mention ordanance already launched as well as energy weapon fire.

 

[DFW]

I'm not proposing the drive system itself be stealthy. Just the missile itself, to reduce scanner returns. Thrusters can be gas-based which would give very little IR returns, if any. And I would think that at long distance the ship itself would cover up any sort of IR detection, not to mention ordanance already launched as well as energy weapon fire.

"gas based"? Anyway, no the "ship" wouldn't mask the missile unless the ship was next to and, directly in line: Ship | missile <-----------> IR detector

Even our current tech could pick it up VERY easily at great distance, w/o active sensors.

Here's a good place to start reading if unfamiliar with the subject: http://en.wikipedia.org/wiki/Infrared#Astronomy :mrgreen:

 

[phavoc]

I'm not proposing the drive system itself be stealthy. Just the missile itself, to reduce scanner returns. Thrusters can be gas-based which would give very little IR returns, if any. And I would think that at long distance the ship itself would cover up any sort of IR detection, not to mention ordanance already launched as well as energy weapon fire.

"gas based"? Anyway, no the "ship" wouldn't mask the missile unless the ship was next to and, directly in line: Ship | missile <-----------> IR detector

Even our current tech could pick it up VERY easily at great distance, w/o active sensors.

Yes, gas. I'm not suggesting hydrazine (it burns hot), but any gas (or liquified gas) should be sufficient for orienting the missle.

To the best of my knowledge, the DSP detectors currently in orbit have never been tested trying to discriminate objects during a battle in space... It IS possible to defeat or generate false-positive IR signatures today against DSP satellites. And that's using today's tech. When you have megajoules of energy slashing through space and ship bodies giving off thermal energy (from thrusters, damage, whatever), it is possible to defeat passive and electo-optical IR detectors if you do it right. We can do it today with much lower tech (or, better stated, using today's tech we can defeat today's scanners. Not forever, but long enough.)

If you are referring to our using IR detectors to discriminate between ICBM's and decoys in orbit, that's a different story. The ICBM, being larger and having more heat stored in it, loses its thermal signature at a slower rate than the smaller decoy's. But we also dont' have the tech today to build decoy's that protect against it.

 

[DFW]

Yes, gas. I'm not suggesting hydrazine (it burns hot), but any gas (or liquified gas) should be sufficient for orienting the missle.

That's fine but doesn't do anything once the missile starts towards its target.

To the best of my knowledge, the DSP detectors currently in orbit have never been tested trying to discriminate objects during a battle in space... It IS possible to defeat or generate false-positive IR signatures today against DSP satellites.

In space that would require an IR source, again ineffective as the missile would be vectoring and easily distinguishable.

When you have megajoules of energy slashing through space and ship bodies giving off thermal energy (from thrusters, damage, whatever), it is possible to defeat passive and electo-optical IR detectors if you do it right. We can do it today with much lower tech (or, better stated, using today's tech we can defeat today's scanners. Not forever, but long enough.)

Umm, no. In space there is no atmospheric effects or absorption. Nothing
short of a direct IR laser hit against the sensors would do it.

If you are referring to our using IR detectors to discriminate between ICBM's and decoys in orbit, that's a different story. The ICBM, being larger and having more heat stored in it, loses its thermal signature at a slower rate than the smaller decoy's. But we also dont' have the tech today to build decoy's that protect against it.

Decoys won't work in space as the vectors would be too different. Given that the IR sig from the missile travels at 300,000 km/sec, there is zero problem with detection.