Are ship based ballistic weapons practical?

[BetterThanLife]

As previously pointed out near light speed weapons that fire projectiles are covered in the rules. Particle Acceleratoors, Fusion Guns and Plasma Guns. Now these are larger and more power intensive than the typical Laser. Propelling a 7.62mm bullet to those kind of velocities would require much more space and energy. So to be realistic in the science presented something with that kind of muzzle velocity wouldn't fit in the light weight, low power question originally asked.

Taking a Muzzle Velocity of 150Km/second, (100 times the muzzle velocity of a Gauss Rifle according to LBB4) firing at short range, (T20 defines short range as 45,000Km, MT defines Near as 50,000Km) it takes a bullet at that velocity 300 Seconds or 5 minutes to reach its target. At 1000 times the muzzle velocity of a Gauss Rifle, 1500Km per second, it still takes 30 seconds to reach your target.

In 1 minute a 1G evasively manuevering ship from time of fire to time on target can be anywhere in a 35Km Sphere. In 30 seconds it is an 8.8Km Radius Sphere. In 5 minutes it is a 882Km Sphere. (1G=9.8 Meters per second per second.) The 3D math is complicated, extremely since the weapon will be firing in a cone out from a moving firing platform through a sphere with enough denisty to cover the entire sphere. Lets just settle for the target to move in only 2 dimensions. An 8.8Km radius circle has an area of 244.392 square Kilometers. A 200DTon Spherical Target has a radius of 9.5 Meters. To generate one hit you would need 1 round in each 9.5 Meter radius circle within the 244.392 Square Km Circle. Or Approximately 861966 rounds to generate one hit. That is one hell of a cyclic rate and definitely not in the low mass, low energy range in the original question.

Some people may call that a practical weapon, I certainly wouldn't. (Especially against high agility targets.)

If you can guarantee your target won't see you or see the bullet coming and will decide to cooperate and fly straight and level without varying speed or at least vary direction and speed in a predictable pattern, then sure you can hit it every time. In actual combat conditions how likely do you think that actually is? That doesn't take into account the possibility of shooting down your bullet on the way in.

Ballistic weapons that aren't a large fraction of light speed in Traveller are virtually useless at normal combat ranges and in normal combat conditions. If you can get your muzzle velocity up to the point or the range down to the point where the flight time is down to 2-3 seconds then a Vulcan style weapon or a VFR Gauss Gun might prove effective. But why waste spce and energy on a weapon system that is that limited. Under T20 I hesitate to put Fusion Weapons on smaller starships as they are no longer capable of point defense and their range is extremely limited in comparison to the rest of the starship weapons. (Though when you get in range they kick serious butt.) Something with even more limited range and capabilities would never find its way into one of my ship designs.

 

[BetterThanLife]

Originally posted by Aramis:

Acceleration of target (At) in m/s, for Traveller, that's a convinient 10m/s

Shouldn't that be 10 meters per second squared? Making time between firing and time hitting the target area the big problem?

Velocity = Accelleration times Time. Velocity being meters per second, Accelleration meters per second squared, time in seconds.

 

[MR TEK]

Back to the original point. If a ship is constantly jinking and changing course, all of the time, ballistic weapons are worthless.

Erratic maneuvers would make the weapon so much wasted space.

Otherwise the only things that matter are the

speed of the rounds, (affect flight time.)
Velocity of target at intercept. (determines the area of space the round must occupy at the same time as the target to strike.)
The angular accuracy of the detection gear at the range at time of firing. (How much space the target might occupy because of uncertainties in detection.)
And the angular accuracy of the firing mechanism at the target range.
Velocity, acceleration, and all of the other factors are irrelevant. Course, velocity, acceleration are all absolute known quantities to the accuracy of the detection gear, and assuming acceleration does not change during the time of flight, do not change.

Back to the NASA Spacecraft, All objects are under constant acceleration. And Some of the those accelerations are MUCH more complicated that anything that a ship is capable of. Orbital perturbations are quite complex multiple body equations that can take months of high-end computer time to calculate. The accuracy has been compared to making a basket in D. C., from LA.

Given, an accurate relative velocity, a relative course, and acceleration, I can do the calculations to hit every time on a pocket calculator in a couple of minuets. It is the equivalent of a marksman hitting a target at the long end of his range.

 

[endersig]

Again, Balistic Weapons are only useful at close, CLOSE ranges, as we have all pointed out in our various posts. So, to make a balistic weapon useful, you would need a vessel intend for getting close to the enemy.... like a Fighter. Strap a 1 ton missile on its underside, run straight at the opposing ship, release missile, pull up and let inertia do the rest. A particullary good fighter would be one capable of higher than 6-gs. Hence, a new thread is born.

 

[endersig]

Again, Balistic Weapons are only useful at close, CLOSE ranges, as we have all pointed out in our various posts. So, to make a balistic weapon useful, you would need a vessel intend for getting close to the enemy.... like a Fighter. Strap a 1 ton missile on its underside, run straight at the opposing ship, release missile, pull up and let inertia do the rest. A particullary good fighter would be one capable of higher than 6-gs. Hence, a new thread is born.

 

[veltyen]

Close? Maybe.

Looking at the ranges (from T20):

PA Spinal 1.6 gm = 5 ls
Missile 1.35 gm = 4 ls
Pulse Laser 0.7 gm = 2 ls
Beam Laser 0.45 gm = 1.5 ls
Fusion Bay 0.225 gm = 0.7 ls
Fusion Turret 0.07 gm = 0.2 ls
gm = gigametre = 10^9m
ls = light second = 3*10^8m

Now since the smaller PA's have a shorter range, as well as less damage, I have to make the assumption that the range on the spinal weapon is based on a large cross-section of attack.

If it was a point attack, and the time to react is effectively zero then that leaves a 10 second prediction as the outside of the adequate prediction range. This also assumes a near light-speed sensor and weapon velocity.

Anything that doesn't have a significant speed-of-light velocity is pretty much relegated to point blank range. Shorter even then Fusion or plasma turrets (which with a 10 second predict have a velocity around 0.02C).

Particle Accelerators aren't a bad model for a faster type of weapon. Maybe without the radiation damage, unless you are using ammo that is radioative or otherwise "special". The increased range dependant on the size of device is a nice touch. The turrets would be firing approx 0.2C projectiles, with either a fragmentary round or a rapidfire mechanism to obtain an effective cross section. Spinals would be near light speed accelerators, or have extremely large area of effect rounds. I'm thinking slightly lower tech (2 tech levels?) and no radiation. I'd probably leave the energy requirement the same, I'm torn on whether they should have an ammo requirement though. This allows TL6+ spinal weapons and large bays, TL8 small bays, and barbettes at TL12.

The fighter delivery system isn't the best idea. The advantage of mass rounds is the lack of signal, the fighter gives off neutrinos and gravatic anomolies making it a far easier target, the same reason missiles are easier to intercept. The fighter has the nessecity of lining up the target vessel for the last push, which leaves the fighter a sitting duck to defensive weaponry. If you are going to go down this path go the whole hog and make piercer ships, the torpedo bombers are already going to require drastic armor and high thrust to survive defensive fire put a sharp nose on that sucker and drive the ship into the target. Stake ships for fighting vampire fleets

 

[BetterThanLife]

Kinetic Energy Weapons are not useless in space combat. Guns firing low speed (Relatively) projectiles are useless in space combat. A Missile, that can track its target, follow it, accellerate to very high relative velocities, and then right in front of its target use a fletchette style or shotgun style warhead would be very effective. (But would only be truly useful for very long range, closing shots.)

 

[veltyen]

Getting to significant fractions of the speed of light with traveller maneuver drives is somewhat time consuming.

6G is 60m/s/s acceleration. 0.2C is 60,000,000 m/s. That's a high thrust ship taking 1 million seconds (about 11.5 days) to get to 20% of the speed of light. The target is likely to be in sensor range for less then 10 seconds. Remember that this 11.5 days thrust needs to be directly towards the collision point.

For hitting planets, this is a fine and dandy tactic, something SDB's would handle quite well.

With an insane astrogator there is another option, choose a high exit velocity jump, to gain a head start.

 

[aramis]

Originally posted by Bhoins:
</font><blockquote>quote:</font><hr />Originally posted by Aramis:

Acceleration of target (At) in m/s, for Traveller, that's a convinient 10m/s

Shouldn't that be 10 meters per second squared? Making time between firing and time hitting the target area the big problem?

Velocity = Accelleration times Time. Velocity being meters per second, Accelleration meters per second squared, time in seconds. </font>[/QUOTE]yup... but spellcheck obliterated it... Grr... as I wrote it as 10m/s/s rather than 10m/s^2