Space Combat and Missiles

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Mongoose10000
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Space Combat and Missiles

Postby Mongoose10000 » Thu Mar 22, 2012 6:50 pm

What is the thinking behind the rule that missiles cannot be used at Close or Adjacent Range (less than 10k)?
zero
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Re: Space Combat and Missiles

Postby zero » Thu Mar 22, 2012 7:29 pm

Perhaps the blast radius would include the firing ship?
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Re: Space Combat and Missiles

Postby Rusty_Unycorn » Thu Mar 22, 2012 7:36 pm

zero wrote:Perhaps the blast radius would include the firing ship?
Explosions propagate poorly in space. Very poorly.
It's more so about giving it time to get the engines up and acquire the target.
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Re: Space Combat and Missiles

Postby drkem99 » Thu Mar 22, 2012 8:55 pm

Wow, I'd better tell the Navy that their TL 8 anti-aircraft and anti-ship missiles are useless; if TL 13 -15 missiles can't accelerate and acquire a target inside of 10000 km, there's no hope for the TL 8 versions.

It's time to bring back the battleships!

Seriously, the missiles start at the velocity of the launching vessel and accelerate (even if you don't use my infamous Gauss Launch Tubes™.) By canon, I believe most common starship missiles depend on their ship's lock-on for navigation instructions until they reach terminal homing range.

The 10000 km limit is a poorly thought out idea, IMHO.
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Re: Space Combat and Missiles

Postby Captain Jonah » Thu Mar 22, 2012 9:54 pm

The sensors should be fine, let’s face it not being able to get a sensor lock at under 10k km is bizarre.

The missiles could be kinetic kill ones and need that distance to accelerate to a fast enough velocity to do something other than go splat against a ship’s hull. On the other hand since ships hulls are very resistant to such impacts it makes more sense that they are explosive or shaped charge in which case velocity makes no difference.

Add it to the list of "it’s the rules; it doesn't need to (insert one of)". Make sense, follow the rules of physics, sound reasonable, be capable with existing technology, be remotely plausible.
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Re: Space Combat and Missiles

Postby SSWarlock » Thu Mar 22, 2012 10:17 pm

You can also take part in the time-honored tradition of at least the last 40 years of role-playing..ignore any rule you don't like.
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Re: Space Combat and Missiles

Postby drkem99 » Thu Mar 22, 2012 10:53 pm

Rick Robinson's First Law of Space Combat states that "An object impacting at 3 km/sec delivers kinetic energy equal to its mass in TNT."

By definition, all space combat missiles are kinetic energy weapons because spacecraft and starships that launch them already have a velocity that translates to kinetic energy for the missile (which starts with the same velocity as the ship.) The International Space Station - in low orbit - has an orbital velocity of 7.7 km/s. A starship outbound to Earth's jump limit really needs to achieve a velocity of at least 10 km/s (escape velocity) to get there in any reasonable time frame. Unless your opponent is on a parallel course with similar speed, it's highly likely that the kinetic energy of your missile from your relative velocity with your target is the major component of your damage.

As an example, if my target is stationary in relation to Earth (having jumped in at 101 diameters and for purposes of this exercise has the exact same relative velocity vector as Earth) and I am at a velocity of 10 km/sec directly towards the target, I can push the missile out of a hatch with the engine off. Assuming my aim is precise and the target remains asleep, the missile will strike the target with a force of more than 9 kg of TNT for each 1 kg of mass of the missile with the missile having never accelerated a bit on its own.

A warhead is useful for those occasions where your velocities are similar (firing on the poor ISS just before you dock, for example) but in most cases it's not a requirement. Nor is a long period of acceleration (although it will, of course, increase your damage.)
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Re: Space Combat and Missiles

Postby rust » Thu Mar 22, 2012 11:21 pm

drkem99 wrote: A warhead is useful for those occasions where your velocities are similar (firing on the poor ISS just before you dock, for example) but in most cases it's not a requirement. Nor is a long period of acceleration (although it will, of course, increase your damage.)
There are also the probably quite common cases where the ship
is actually moving away from the missile's intended target, and
where just pushing the missile out of the airlock would result in
it moving away from the target at the ship's velocity ...
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Re: Space Combat and Missiles

Postby kermit » Thu Mar 22, 2012 11:34 pm

This thread has reminded me...I a have question on a related subject.

I just purchased High Guard. Maybe I'm blind, but what are the thrust and endurance of a torpedo? They list the dt, launcher stats, and damage but I can't find anything regarding their performance. Can some one clue me in here?

Thanks,
Benjamin
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Re: Space Combat and Missiles

Postby rust » Thu Mar 22, 2012 11:58 pm

kermit wrote: Maybe I'm blind, but what are the thrust and endurance of a torpedo?
High Guard page 48 describes torpedoes as "heavy missiles", so
I suspect that they use the missile data from the core rules erra-
ta on High Guard page 47.
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Re: Space Combat and Missiles

Postby drkem99 » Fri Mar 23, 2012 12:05 am

I would like to quote a brief passage from the main Mongoose Traveller rulebook, p147 under fair use guidelines to answer kermit's question (modifying the table for the errata):

Launching Missiles
Unlike beam weapons, which travel at the speed of light and so hit the enemy vessel almost instantly, missile weapons take time to cross the gulf of space. Missiles travel at Thrust 10 towards their designated target and their position can either be tracked as additional craft in the battle or, for the sake of simplicity, they can be assumed to strike after a number of turns dependent on launch range:

Range - Turns to Impact
Adjacent - N/A
Close - N/A
Short - 1/2
Medium - 1/2
Long - 1
Very Long - 2 1/2
Distant - 5

Wow, that's interesting and it raises a lot of questions. If missiles have variable chemical thrusters (most likely; a tiny fusion plant and thruster plates would make the missile really expensive) and they can do thrust 10 for 10 turns, can they do thrust 20 for 5 turns? Can a missile with 100 thrust-turns of fuel come about and attack again if it misses a target at short or medium range? And, BTW, 10 G-hours of thrust is one heck of a lot for a chemical thruster. Maybe they really do have cheap thruster plates...

A tip of the hat to both SSWarlock and rust for valid points; rust's comment is why my campaign includes Gauss Launch Tubes™; it helps missiles run down those pesky fleeing targets.
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Re: Space Combat and Missiles

Postby Captain Jonah » Fri Mar 23, 2012 10:25 am

Here is a random (Russian) tech 8 anti missile missile used for the defence of moscow against ICBMs.

The numbers are subject to some doubt since the Russians don't publish them and the West doesn't seem to publish anything on its modern sprint missiles. This is from observations of its test firing in 2009.

The missile is able to intercept incoming re-entry vehicles at a distance of up to 80–100 km. 53T6 is a two-staged solid-propellant missile armed with 10 kt nuclear warhead. The missile is about 10 meters in length and 1 meter in diameter. Its launch weight is 10 tons.[1][3]

The 53T6 missile is kept in silo-based launch container. Prior to launch its cover is blown off. It takes the missile 3 seconds to reach a speed of 5.5 km/s at more than 100g acceleration. After 2 more seconds the missile reaches its combat height of 30 km.


Now allowing for tech advances to say tech 12 reducing the size of the Sprint drive down to the point where you can fit a cruise drive capable of making course corrections and a set the warhead with magnetic lenses or something like the germanium ( I think, at work so no books handy) rods to generate a focused energy burst and away you go. So you don't need to hit the target just get within 10 or 20 Km.

This is a crude Tech 8 missile accelerating at 100G. It doesn't matter if the solid fuel is used after a few seconds since by that point it is moving at better than 5km per second. How much better should the missiles the Imperium use be compared to this.

A solid fuel sprint drive at tech 12 should be capable of 150 to 200Gs, even if a hard physical limit on chemical expansion caps it at less than that the duration should be longer. 10 or 20 seconds at 100+ gravities, that is a heck of an initial burst before the 10+G cruise drive takes over.

As with much of Traveller it is a game written in the 1970s, set in the 1800s using technology from the 1950s :lol:
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Re: Space Combat and Missiles

Postby SSWarlock » Fri Mar 23, 2012 4:48 pm

drkem99 wrote:Wow, that's interesting and it raises a lot of questions. If missiles have variable chemical thrusters (most likely; a tiny fusion plant and thruster plates would make the missile really expensive) and they can do thrust 10 for 10 turns, can they do thrust 20 for 5 turns?
Weeell..no. As least the rules don't say you can and any combat examples I've seen don't use it. That and the facts that missiles mentioned in following rules expansions also don't mention the capability and said capability would be extremely effective in combat are what makes me extrapolate a "no".
Can a missile with 100 thrust-turns of fuel come about and attack again if it misses a target at short or medium range?
Now this gets a strong "yes" in my book. "Smart" missiles that miss can re-engage the following turn and keep re-engaging until they run out of endurance. That's stated in the Core Book.
And, BTW, 10 G-hours of thrust is one heck of a lot for a chemical thruster. Maybe they really do have cheap thruster plates...
They do IMTU. I've ruled that missile thruster plates are essentially very short-life, one-use versions of the ones on crewed spacecraft.
A tip of the hat to both SSWarlock and rust for valid points; rust's comment is why my campaign includes Gauss Launch Tubes™; it helps missiles run down those pesky fleeing targets.
Why, thank you! :) The time-honored tradition of ignoring rules goes much further back than the beginnings of RPGs..like to the days of the first biped figuring out how to craft a spear, much to the chagrin of its prey which played by the rules of fang and claw.

By the by, my campaigns also use a type of Gaussian-based launching system for missiles. The military version can provide a variable launch speed, allowing for low-signature ballistic launch of missiles that stay on the same vector until fired up. This, in turn, allows the tactic of "cold-launching" a large group of Smart missiles over a number of turns then activating them all at once to achieve a much more effective "time on target". I've surprised some pirates, a Midu-Agashaam class destroyer, and a GM that way, all using a standard yacht.
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