Rail Gun for Space weapon?
- Thread starter pendragonman
- Start date
I think you are vastly overestimating the amount of required velocity. But like all the other weapons in the rules a little bit of hand waving is probably appropriate.
If you go back a read my earlier post about which assumptions I am using you will see that I have taken the speed of the projectile into account with range penalties, i.e. even shorter ranged than Pulse lasers.
Hint, I stated the scale I am operating at. Which is 100 second turns with 1,000 km hexs.
(Note, if one doesn't include gravitic focusing of lasers 1,000 km hexs work better)
And finally, I assume that direct fire weapons are firing constantly throughout the turn and as such the roll To-Hit is not for a single shot but if a telling hit is score within the turn.
Acceleration is limited by Compensation as per CT's High Guard.
Also Note both T5 and Mongoose up the limit to 9....
FF&S goes to 9G as well - at TL 20
pendragonman
Absent Friends Margrave
That is exactly what the predict programs are for.
Yes. The target can travel that much. However, it is a standard vector math problem to determine where the target is likely to be when the payload arrives.
Since I can do this math on a TI-35 calculator in a few minutes, a 1 bis can do it in a few minutes.
Since 1000 seconds is ~16.67 minutes, this calculation can be done within the parameters of a firing sequence in one turn (CT turn, other versions have 20 minute turns).
Your argument is like trying to use the old MK 1 eyeball to shoot at the target. I am sure you have noticed how effective shot guns are at bringing down geese, who can also maneuver. Or do you dispute that geese (ducks, birds in flight) can maneuver unpredictably?
Or how modern fighter aircraft still have guns, and not just for ground support. Or do you dispute the unpredictability of opposing fighter aircraft?
I'm playing around with creating some visual range space combat variant rules. I can testify that it is indeed very, very bloody, if the ground combat rules are used as a template. On the other hand, if you're a TL 12 Sword Worlder trying to convince the Imperials that you're too expensive to bother with, then very, very bloody might be your only hope.
For one thing, all those computer bonuses and penalties don't happen. Folk are firing using the kind of image enhancement and optical magnification those grav tanks might be using. There's not much on an issue of spotting - at least for a decent computer-mediated imaging system - when the target's a building-sized IR source silhouetted against a backdrop of stars. For another, agility doesn't seem to be worth a damn - a lot of these targets are the size of office buildings, which makes them pretty hard to miss even if they can throw on 6G and move a couple meters in the time it takes you to react. For a third, those weapons are hitting pretty wickedly hard at that range.
It's kind of a kamikaze effort, fighting at that range, but I can see where it would be a useful way to convince the Imperials that the win might not be worth the price, so I can see it coming up as a desperation maneuver. I could see the Solomani doing it during the invasion of Earth, for example.
Railguns might be problematic as anti-ship weapons, but they could be pretty effective anti-missile weapons.
Condottiere
SOC-14 5K
Outside computer prediction, it also depends on the speed of the bullet.
I think in Mongoose it's described as near relativistic speed, with a possible maximum long range of upto twenty five thousand kilometres, which is one twelfth of a light second.
You can miss a ship, but I doubt you can miss a planet in a stable orbit at any reasonable distance, unless the twenty tonne ball bearing burns up in the atmosphere.
And it's theoretically possible with mixed propulsion to accelerate at twenty five gees at technological level thirteen, so inertial compensation becomes a somewhat pressing concern.
I think in Mongoose it's described as near relativistic speed, with a possible maximum long range of upto twenty five thousand kilometres, which is one twelfth of a light second.
You can miss a ship, but I doubt you can miss a planet in a stable orbit at any reasonable distance, unless the twenty tonne ball bearing burns up in the atmosphere.
And it's theoretically possible with mixed propulsion to accelerate at twenty five gees at technological level thirteen, so inertial compensation becomes a somewhat pressing concern.
AnotherDilbert
SOC-14 1K
We can predict where the current velocity vector will take the target, we cannot predict how the target will manoeuvre after we have fired out round or burst.
In our example we can predict where the target will be ±5000 km. That means that the target will be a ~10m circle somewhere within 5 000 000 m circle. Each round fired at a random location within that circle would have a 102 / 5 000 0002 ≈ 4×10-12 chance of hitting the target, so if we fired a hundred billion rounds we would have a good chance of hitting the target. I would consider that impractical.
A shotgun with an effective range of 50 - 100 m and a muzzle velocity of 500 m/s have a lead time of 0.1 - 0.2 s, not giving the bird much time for manoeuvres. Yet it is still quite possible to miss.
This is perhaps a better analogy given computer assisted sights and manoeuvrability in the same order of magnitude as Traveller spacecraft. Current fighters seems to fire at roughly 0.5 - 2 km with a muzzle speed of 1000 m/s, giving a lead time of 0.5 - 2 s. Yet killing an enemy in a dogfight is far from trivial. According to some random internet source (https://defenseissues.net/2015/02/01/fighter-aircraft-gun-comparision/) a fighter generally carries ammo for 6 - 12 half second bursts, enough for one or perhaps two kills. That gives us a kill probability of perhaps 10 - 20% for each burst for a lead time of 0.5 - 2 s. Firing with a 1000 s lead time would get us ~0% kill probability.
AnotherDilbert
SOC-14 1K
MgT2 reaction drives can achieve 16 G at TL15, apparently without loss of comfort.
Or 25 G with M-Drive + reaction drive...
AnotherDilbert
SOC-14 1K
Certainly, yet neither the ship nor the bay will be 400 m long.
Only TNE goes into detail about this:
According to the tables in FF&S, p11-12 a 5000 Dt ship with needle configuration can be up to ~150 m long.
A 100 Dt bay can be approximately 16 m long:
FF&S, p112.
Yet earlier editions say something similar without the detail.
The Configuration and Streamlining table on p63 of the MT RefMan shows that a Needle configuration hull has a mass of ~1.25 times as much as a spherical hull.
A spherical 1000 Dt hull would have a radius of ~15 m and a surface of ~2800 m2.
A 40:8:1 pyramid would be ~250 m long and have a surface of roughly 25000 m2.
The hull would mass in the region of 10 times as much as a sphere with the same volume, not 1.25 as MT specifies.
A bay is an interchangeable standard mount:
HG'80, p30.
In order to be a standard mount that can mount any type of weapon it has to be fairly boxy.
I see nothing unreasonable about using bays as spinals in a small ship universe, but it is a house-rule.
A "wall of steel" at short range has a lot going for it.
Also, useful for repelling boarders. A rapid-fire, point-defense light railgun is more useful than a sandcaster with speciality rounds (MgT1 HG) and doesn't eat as much energy as a starship laser.
pendragonman
Absent Friends Margrave
A reminder to all of the nay sayer posters:
As the OP, I remind you that my originating post posited that such a weapon is possible. So constantly arguing that it is not possible is not helping the thread. Neither is hijacking the thread to argue about spinal dimensions with regard to ship geometry.
Not to put too fine a point on it, but is it ok if we answer the original questions before we try to make everyone agree with our position on existence? Since, well, existence is not part of my question?
In Mathematical proof techniques, this is NOT argument by contradiction, where you go along with the original hypothesis and show, by pointing out the consequences of such a hypothesis IN THE RULES, not your opinion.
Nor is this argument by contrapositive, where you switch the places of the conclusion and hypothesis then see where that leads.
So please, please, cease and desist with the "rail guns are not possible" arguments.
As I have said at least a couple of times, it is possible to mathematically predict a target's movement. It is relatively easy Calculus, or slightly harder 3 dimensional trig/vector algebra. You can look up the basics for these calculations in the vector chapter of any Calculus or Trig book. There are many of these books available as free pdfs on the internet.
So a successful hit is possible. Please notice I don't say that there is ALWAYS a hit. It is a probability, so misses are possible. Hence the need for a die roll.
What I have asked for, at least twice now, is the potential stats of said weapon. What I have asked for is whether or not there are multiple sizes (turret only, or there also a bay version or only a bay version, or is there a spinal version or is there only a spinal version). What I have asked for is the range of said weapon.
Since T5 limits lasers to around 50,000 kilometers, and it was posited that was max range, and that was accepted (probably since it is in a range in a published canon rule set) we have established that MAX range is 50,000 km.
It was recently posited that the effective (most efficient) range, the range at which hits are most likely, is 25,000 km. No supporting evidence (support from a rule book) so far, but half of max sounds more than fair.
There has been a point about Mongoose TCS but no specific support for this/from this ruleset.
There have been a couple of different offerings on damage (ISTR a CT::HG damage, and a Mass Driver/Striker offering).
It would be useful if someone who had the direct quote from Mongoose let us know what it said, so then we would have an established "canon" source for our range and damage estimates. This would also give us the weapon size answers that I am looking for.
As the OP, I remind you that my originating post posited that such a weapon is possible. So constantly arguing that it is not possible is not helping the thread. Neither is hijacking the thread to argue about spinal dimensions with regard to ship geometry.
Not to put too fine a point on it, but is it ok if we answer the original questions before we try to make everyone agree with our position on existence? Since, well, existence is not part of my question?
In Mathematical proof techniques, this is NOT argument by contradiction, where you go along with the original hypothesis and show, by pointing out the consequences of such a hypothesis IN THE RULES, not your opinion.
Nor is this argument by contrapositive, where you switch the places of the conclusion and hypothesis then see where that leads.
So please, please, cease and desist with the "rail guns are not possible" arguments.
As I have said at least a couple of times, it is possible to mathematically predict a target's movement. It is relatively easy Calculus, or slightly harder 3 dimensional trig/vector algebra. You can look up the basics for these calculations in the vector chapter of any Calculus or Trig book. There are many of these books available as free pdfs on the internet.
So a successful hit is possible. Please notice I don't say that there is ALWAYS a hit. It is a probability, so misses are possible. Hence the need for a die roll.
What I have asked for, at least twice now, is the potential stats of said weapon. What I have asked for is whether or not there are multiple sizes (turret only, or there also a bay version or only a bay version, or is there a spinal version or is there only a spinal version). What I have asked for is the range of said weapon.
Since T5 limits lasers to around 50,000 kilometers, and it was posited that was max range, and that was accepted (probably since it is in a range in a published canon rule set) we have established that MAX range is 50,000 km.
It was recently posited that the effective (most efficient) range, the range at which hits are most likely, is 25,000 km. No supporting evidence (support from a rule book) so far, but half of max sounds more than fair.
There has been a point about Mongoose TCS but no specific support for this/from this ruleset.
There have been a couple of different offerings on damage (ISTR a CT::HG damage, and a Mass Driver/Striker offering).
It would be useful if someone who had the direct quote from Mongoose let us know what it said, so then we would have an established "canon" source for our range and damage estimates. This would also give us the weapon size answers that I am looking for.
Condottiere
SOC-14 5K
The default range spinal mounted railgun is medium.
If weapon options is permitted, you could raise that to long.
If weapon options is permitted, you could raise that to long.
pendragonman
Absent Friends Margrave
Just got a copy of the 1st edition version of Mongoose TCS. Hmmm, medium is 10,000 km, and a single round is 20 tons. Also, the damage example has a mistake in it as 300>299 and so should be a pen III hit, not a pen II.
I suppose if it is only available on large ships as a spinal, 20 tons is reasonable.
Suppose instead that the rail gun is a "spinal" for a small ship universe, what changes are required?
mike wightman
SOC-14 10K
Here is your original post:
Turret sized weapons would be pretty effective point defence against missiles, while bays would make mincemeat of smallcraft and escort class vessels within range.
A spinal version would make an effective planetary bombardment weapon and even threaten capital ships if they get within range.
Range is its biggest issue due to the time in flight of the projectiles.
1000km+ DM-2 to hit
2500km+ DM-5 to hit
Do you want to add them as a 'realistic' addition to the Traveller ship arsenal or do you want a cinematic Star Wars MgT treatment?
FF&S for TNE allows you to build mass drivers of any size you see fit, the limit is the effective range of the weapon due to the 'slow' projectile velocity compared with the movement capability of an evading target.
Turret sized weapons would be pretty effective point defence against missiles, while bays would make mincemeat of smallcraft and escort class vessels within range.
A spinal version would make an effective planetary bombardment weapon and even threaten capital ships if they get within range.
Range is its biggest issue due to the time in flight of the projectiles.
I would limit its range to 1000km with hefty penalties beyond this.
1000km+ DM-2 to hit
2500km+ DM-5 to hit
For which version of Traveller?
What if you only use missiles and railguns? No lasers, no high energy weapons.
Yeah, I've been watching The Expanse a lot ...
mike wightman
SOC-14 10K
Look at the ranges and travel times of the missiles and railguns in the Expanse...
the reason for the lack of lasers in a hardish sci fi setting is... heat.
the reason for the lack of lasers in a hardish sci fi setting is... heat.
Ok, I half answered that question. For my Mayday fork game Railguns are turret scale weapons. They have a -2 per hex range DM. A turn's worth of ammo is 50 kg, with 3 turns worth of ammo being included with the mount. A successful To-Hit roll does 1d6/2 Hits (Dropping fraction Minimum of 1). Point defence fire uses 1 turns ammo no matter how many missiles are fired at.
