Reducto Missiles

[Carlobrand]

The Traveller missile is a bit of magic in the first place. Once you accept the magic, odd things become possible. I call this the Reducto missile - from Reducto ad absurdum. You'll understand why in a minute.

Special Supplement 3 (Missiles) builds its missiles around a base 50kg model - performance of the rocket motors assumes the missile weighs 50 kg: "If, once the missile has been assembled, its mass is greater than, or less than, 50 kilograms, then its actual performance will be different."

Now here's where things get interesting. Take a 6g limited burn drive. Give it enough fuel for 1 burn. Slap on a controller and a radio sensor - and that's all. You now have a missile massing 16 kg, less than 1/3 the mass of the 50 kg. standard - and it does more than three times its rated acceleration:

Description: TL 15 18.8G1 Limited Burn, No warhead, Radio Sensor, Mass: 16 kg., Cost: Cr5140

From launch, it will get 94,000 km in one 1000-second turn; anything in that range gets hit. Outside of about 30,000 km, give or take, depending on the speed of the target, it will do one to three points of damage despite the lack of a warhead. It's a kinetic-kill vehicle: "If a missile contacts its target and the sum of the vectors of the missile and the target is greater than 300 millimeters, then one extra hit on the hit location table is allowed for each 300 millimeters of vector length. Ignore fractions remaining when dividing the vector by 300 millimeters."

(A millimeter represents 100 kilometers in that game.)

I guess that makes a certain amount of sense. Impact velocities at even 300 mm per turn are almost twenty times the velocity of an M-1 tank's round, and this thing's doing triple that. Stick a DU penetrator on there, it'd be even more wicked.

In fact, you can dispense with the controller and radio sensor as well, at least according to those rules; you now have a 12 kg., 25G1 missile capable of hitting anything within 125000 km on the first turn of movement, doing up to 4 points of damage, and there's no outrunning it: "Any powered missile will impact the target on the first turn of movement; initial guidance by the launch racks is sufficient in this case."

(How an unguided rocket takes 16 minutes to get from point-A to point-B and hit point-B even when point-B is running a maneuver/evade program is one of the great mysteries.)

My first thought is to wonder whether any guidance system can endure that acceleration - but then we put laser guidance on artillery shells, so that part of it's not impossible.

On the one hand - that's just weird. On the other, it does provide one possible answer to the problem of High Guard missiles hitting in the same turn as launch. You could even tack on another burn without losing too much - in fact, it hits harder after the second burn:

Description: TL 15 17.6G2 Limited Burn, No warhead, Radio Sensor, Mass: 17 kg., Cost: Cr6340 - 88,000 km in one 1000-second turn, another 176,000 km in the second turn with a vector that's generating 5 or more hits depending on the target's vector.

And, like the High Guard missile, it's weaker at short range.

 

[Timerover51]

The rocket equation, delta V = V(eff) X ln (mass(initial)/mass(final). If the mass ratio is approximately 2.72, and perfect efficiency is assumed, delta V is equal to the effective exhaust velocity of the propellant. Fifty kilograms divided by 16 kilograms gives you a mass ratio 3.125. Allowing for less than perfect efficiency, at best the missile's terminal velocity will equal the exhaust velocity.

From launch, it will get 94,000 km in one 1000-second turn

Based on that, and allowing for acceleration, the terminal velocity of the missile at Brennschluss has to be at least 94 kilometers a second, or about 308,000 feet per second. That would equate to a specific impulse of 9,585. The Space Shuttles engines, burning a mix of O2 and H2, had a specific impulse of about 455, and a good nuclear-thermal engine is expected to reach a specific impulse of about 1200.

What fuel is going to give a 50 kilogram missile that sort of specific impulse?

Absurdum is most definitely an accurate description of such a missile.

 

[HG_B]

The Traveller missile is a bit of magic in the first place. Once you accept the magic, odd things become possible.

I got rid of "missiles" long ago (not really possible as advertised). Only large grave drive Torps in my game.

 

[Carlobrand]

Ayup, like I said, it's magic-tech - you either suspend all logic and embrace it along with the other elements of Traveller magic-tech, in which case my hypervelocity missile becomes practical, or you end up writing it off.

Only problem with writing it off, though, is that it changes the tactical situation under CT Book-2 combat: missiles were pretty useful for soaking up laser fire and persuading an attacker to keep his distance. Without that, the tactical situation changes somewhat - becomes a case of trading laser shots, popping sand and rolling dice until someone gets lucky. At that point, you might as well just be playing High Guard.

On the other hand, the hypervelocity missile might have that effect too.

 

[HG_B]

Ayup, like I said, it's magic-tech - you either suspend all logic and embrace it along with the other elements of Traveller magic-tech, in which case my hypervelocity missile becomes practical, or you end up writing it off.

I don't mind suspending physics for what is critically needed by the game (interstellar travel & reaction-less drives). Teeny, tiny space missiles without a possible motive source aren't critical to the game. Nuc torps are good enough.

 

[Khan Trav]

I play mostly through PBEM where some ship to ship combat happens. I run a basic classic era roughly 1103 to 1107 and the players normally operate in stock vessels described in the LBBs. In that setting a missile for me tends to be treated like a torpedo and or sometimes like say battlestar galactica where you might actually get to try to shoot it down before it hits.

I have the supplement missiles and I read everything you guys write on this site about missiles and fighters and other types of ship to ship mayhem. Generally I stay confused most of the time.

Keeping missiles within my campaign, how do I allow for it being fired, fired at being destroyed in flight or striking another ship?

Can someone give an example of say a fight between two 100 ton scout couriers that mount a missile and laser within the turret of each vessel. With everything else being equal?

 

[pendragonman]

Keeping missiles within my campaign, how do I allow for it being fired, fired at being destroyed in flight or striking another ship?

Can someone give an example of say a fight between two 100 ton scout couriers that mount a missile and laser within the turret of each vessel. With everything else being equal?

If you are strictly staying within LBB2, then it will depend on what programs are running on each Scout's computer. Suppose Ship A has Man/Evade and Return running and Ship B has launch and anti missile running. Suppose further that both ships launched missiles in the previous turn.

Ship A, expecting ship B to fire its laser, ran Return. No firing this round for A, even to try to shoot down the missile. No launches this round for A as it is not running launch. Should B's previously launched missile intersect A during B's movement phase, B's missile detonates causing damage to A.

Ship B, not as worried about A's laser as it is about A's missile, ran antimissile. Thus if A's missile intersects B on A's movement segment, B can try to shoot it down on a 8+. Further, B can launch another missile AND a can of sand this round.

Should A survive the missile detonation, combat continues.

 

[sabredog]

I play mostly through PBEM where some ship to ship combat happens.

Keeping missiles within my campaign, how do I allow for it being fired, fired at being destroyed in flight or striking another ship?

Can someone give an example of say a fight between two 100 ton scout couriers that mount a missile and laser within the turret of each vessel. With everything else being equal?

Since you run pebm style vector movement, which is how missiles in LBB2 combat work best, is probably not workable. When I run a game and can't, for whatever reason, use vector movement I houserule that missiles have a base 8+ roll to hit or not, modified by range. That's it. It makes them less of a sure thing and adds some more uncertainty to the whole process while keeping it fast and manageable for me and the players.

There are some exceptions to the above if I allow the players to start custom designing missiles. I almost never allow it, though, since then the only way to make sense of the custom designs in combat is to always use vector movement- something a lot of players either can't grasp or don't want to bother with. So I have standard missiles available to civilians that come in three flavors: the regular HE type (1D6 damage), an HEAP contact detonation type (3 hits to the same hit location), and an anti-missile missile (8+ to intercept incoming missile). Since I don't allow pulse lasers to be used in anti-missile fire the anti-missile missile lets crews with pulse lasers still have some added protection.

For your example of the the two scoutships, if not using vector movement to compute intercepts then I would determine range and then proceed as per the LBB2 turn sequence. Range determines certain modifiers for all weapons but here are the ones for missiles that I use:

Missiles: Missiles cannot be fired at Close Range. 8+ on 2D6 to hit at Short Range. 7+ to hit at Medium Range, 6+ to hit unless intercepted at Long Range.

Missiles intercept ships or other missiles in one turn per range limit: end of same turn launched for Short range, end of 2nd turn for Medium, end of 3rd turn for Long.

All other weapons have no specific range modifiers.

Range Rules of Thumb:

Long Range= 1001km+

Medium= barely visible as moving object, 100km-1000km+

Short= visible range…can visually ID target (“read tail numbers”), 1-99km+

Close= docking range, less than 100m

 

[Timerover51]

Missiles in Traveller

The problem with using missiles in Traveller at anything but extremely short range is that you have to assume an incredibly high fuel/mass ratio and an incredibly high specific impulse for small ones to be of any use. Once the missile hits Brennschluss, it has no way to change it velocity vector, and therefore avoiding it is simply a matter of changing ones course. Space is a vacuum, not the atmosphere, where with body lift and aerodynamic controls and some sort of onboard hydraulic power source a missile can continue to maneuver without thrust. Then you also have the velocity vector of the firing ship to take into account.

 

[Carlobrand]

If you are strictly staying within LBB2, then it will depend on what programs are running on each Scout's computer. Suppose Ship A has Man/Evade and Return running and Ship B has launch and anti missile running. Suppose further that both ships launched missiles in the previous turn.

Ship A, expecting ship B to fire its laser, ran Return. No firing this round for A, even to try to shoot down the missile. No launches this round for A as it is not running launch. Should B's previously launched missile intersect A during B's movement phase, B's missile detonates causing damage to A.

Ship B, not as worried about A's laser as it is about A's missile, ran antimissile. Thus if A's missile intersects B on A's movement segment, B can try to shoot it down on a 8+. Further, B can launch another missile AND a can of sand this round.

Should A survive the missile detonation, combat continues.

An accurate depiction. One point: the Return Fire program requires the Target program to be running as well. Ship A is running Target, Return Fire and either Maneuver/Evade 1 with room for one more small program, or Maneuver/Evade 2. Player A's choice is driven by the fact that Anti-missile requires two program slots; he'd have to either stop maneuvering or give up the ability to return fire in order to run Anti-missile.

Conversely, Anti-missile does not require Target. Player-B, with Anti-Missile and Launch, has one free slot available too - probably as Maneuver/Evade 1 or Auto-evade, since it doesn't make sense to use just Maneuver in a combat situation and he otherwise can't use his maneuver drive.

Those little computers are a real pain.

Now, correct me if I'm wrong on this, I've had people argue the point, but the laser can fire in each phase that laser fire is indicated and the prerequisites are in place: thus A can fire his laser in his laser fire phase and then again - if B fires a laser at him - in the return fire phase, assuming the necessary programs are in place. Player A is gambling that Player B will take a laser shot at him, so he gets two laser shots at B, but it leaves him vulnerable to the inbound missile.

The problem with using missiles in Traveller at anything but extremely short range is that you have to assume an incredibly high fuel/mass ratio and an incredibly high specific impulse for small ones to be of any use. Once the missile hits Brennschluss, it has no way to change it velocity vector, and therefore avoiding it is simply a matter of changing ones course. Space is a vacuum, not the atmosphere, where with body lift and aerodynamic controls and some sort of onboard hydraulic power source a missile can continue to maneuver without thrust. Then you also have the velocity vector of the firing ship to take into account.

Poor Brennschluss. He must get tired of being hit so often.

(Brennschluss = burn-out)

An option is to use missiles as a kind of space-mine. Only works if you're using hex-mapping (the old Mayday style of movement). Instead of putting it on the board, you record where you drop the missile and, if the opposing player passes through that hex, the missile fires up and you call a missile shot. Makes it somewhat more realistic - the missile only has enough delta-V to hit something in its own hex, the needed specific impulse drops by a bit over an order of magnitude. It allows the missile to be used defensively to make an attacker more cautious: he can't just run a stern chase, he has to either waste movement trying to avoid anything you might have dropped in your wake or keep an Anti-missile or ECM program loaded against any surprises.