The feasability of point defense missiles in T4 using FF&S II

[warwizard]

I was designing up some small missiles the other day for use by small craft and came up with some interesting designs, for example: a less than 1 cubic meter missile with a HEPLAR drive a slightly over 1 MW fusion plant and reaction fuel that pulls 80 to 120 g's depending on TL, a 50KG blast fragmentation warhead rounds out the package with a command guidance and laser comm reciever.
at 80 g's... reaches 4 light seconds after 1/2 hour of thrust that's 40 hexes in brilliant lances terms, and 160 hexes after a 2nd half hour.

However that is not the point, the missile is intended to reach the 1-2 hex distance (where incomming nuclear det missiles are within their attack range), within 6 minutes, make it's attack and free up another Master Fire Director (MFD) slot for another shot, giving a ROF of 10 per MFD channel.
Given a TL 15 MFD you get a total of 60 launches and intercepts you could do in a 30 minute turn, using 1 MFD and 1 turret with auto launchers and a magizene feed. Though you may need a dedicated sensor and tracker to give each turret it's 20 targets to track.

The missile easilly has 4X the target's manuver to devote to intercept maneuvering, and the blast fragmentation warhead gives a 700m kill envelope. The high intercept velocity gives even small fragments the kenetic energy to kill an incomming missile (36 Km per second + the explosion).

For anti ship duty the blast fragmentation warhead's proxemity fuze is disabled and the missile maneuvers for a hull contact hit. I leave it to the physicists here to tell us just how much armour it would take to stop some 200 to 400 KG of mass moving at 30 to 300 KPS, impacting on a 10 cm diameter area.

House rule: a maneuvering object attempting a direct contact hit on an evading object must spend 4 times the thrust of the target's agility on interception maneuvering or it is automatically a miss. Additionally if the light speed delay is great enough for the target to change it's vector by a distance equal to 1/2 times it's diameter before the MFD can see the vector change and command the missile to respond, that also is an automatic miss.

This means a non evading target can be pegged at up to 8X the MFD's or the tracking sensor's short range whichever's shorter. So ships in orbit, space habitats, orbital docks and such are subject to being hit by long range point defense missile shots. The fighters that nobody takes seriously, can now carry a significant threat to ships

TL 16 point defense missile:
.19 M3 251Kg, 81 G's CR 52,500 6 minutes endurance
Visable signature IR Signature Active Signature
-2 -1 -0.5

This missile is powered for 6 minutes at 81 G's, allowing a powered intercept on targets within 32 hexes
The missile uses command guidance, and has a 50,000km range laser comminicator
The 15cm blast fragmentation warhead (HE) has been removed to allow a higher acceleration and longer range, and is intended for a direct contact engagement

and the anti ship version
1.0 M3 and CR 92,800 30 minutes of thrust/endurance
73 G's, and it has it's blast frag warhead
Signatures -1.5, -1, -.5

 

[whartung]

You say 80 to 120 Gs of maneuver, but for how long? What's the G rating of the drive and how many G turns total of fuel?

120Gs of anything is, well, a lot!

 

[HG_B]

The high intercept velocity gives even small fragments the kenetic energy to kill an incomming missile (36 Km per second + the explosion).

How many seconds of thrust at how many G's?

 

[warwizard]

How many seconds of thrust at how many G's?

The .19 cubic meter version has 360 seconds at 81 g's, thats approximately .8 Km/s per second for 360 seconds. 285 KM/s total velocity at burnout. Distance travelled 51438 KM assumming continous thrust. That puts it firmly in the 2nd hex out, coast a few seconds and save a few seconds of thrust for terminal maneuvers, and there you have your missile intercept outside nuclear det laser head standoff range. Coasting for the remainder of the 30 minute combat turn gives approx a 460,ooo Km distance or 1.5 light seconds

The 1.0 cubic meter version has 1800 seconds at 73 g's with a burnout distance of 1,163,000 Km 38 hexes, 3.8 light seconds. It has a whopping 1,287 Km/s velocity at burnout! crossing a 30,000 KM hex every 23.3 seconds.

Dialing back the power and maneuver thrust to the minimum Heplar size drops the g's to 55 g's but it gives you 3 hours of thrust at that 55
G's, or 330 Gturns of thrust. It's not practical for a missile cause you outrun the extreme range of the MFD! 5821 Km/s at burnout, 1.9% light speed. price drops to nearly the same as the .19 m size missile.

Now these are using TL 16 fusion power, drop to TL 14
and the performance drops to 16.8 g's for 2.3 hours (77 g turns) and increase price by some 30k. Not enough G's to beat a 6 G evading target.

 

[HG_B]

Now these are using TL 16 fusion power,

I thought something seemed odd about that. Thanks for the figures though. Very interesting.

 

[warwizard]

TL 14 the fusion plants produce 3 MW/m3 and weigh 3 tons/m3, add in the .1 ton of HEPLAR and you have a therotical max g of of 20 g tons/1.1 tons= 18 g's therotical max.

TL 15 the fusion plants produce 6 MW/m3 and weigh 2 tons/m3, add in the .1 HEPLAR and you have a therotical max g of 20 g tons/.2666 tons = 46 g's therotical max.

TL 16 the fusion plants produce 7 MW/m3 and weigh 1 ton/m3, add in the .1 HEPLAR and you have a therotical max of g of 20 g tons/ .2428 tons = 82 g's therotical max.

so TL 14- point defense missiles are just not fast enough to beat a target with 6 agility.

I invite someone to work out the joules of energy a 250 kg missile has at 1200 KM/s relative velocity. I rather suspect it will have the effect of a direct contact nuclear explosion without the radiation.

I'm going to say that as a HEPLAR requires a Fusion plant, the TL17+ antimatter plants cannot provide the input stage for the HEPLAR, and Fusion PLUS plants do not give off hot exhaust gas, they cannot power a HEPLAR either.

So this invites a review of tatics , long range high velocity missiles from a standoff platform , handing off missile control links to special small craft with 10 ro 20 G's agility that will vector in the 2-5% lightspeed missiles onto the targets, and any direct contact hit is a target vaporized on pretty much anything except the biggest of ships. fighters getting to close range and carrying dozens of box launchers full of sprint missiles. Point defense lasers with a ROF of 500 only getting off one to two shots as the long range missiles are crossing a 30,000 Km hex in 2 to 5 seconds.

 

[Starviking]

I'm going to say that as a HEPLAR requires a Fusion plant, the TL17+ antimatter plants cannot provide the input stage for the HEPLAR, and Fusion PLUS plants do not give off hot exhaust gas, they cannot power a HEPLAR either.

Seems like there's a market for a plasma generator there!

 

[HG_B]

I invite someone to work out the joules of energy a 250 kg missile has at 1200 KM/s relative velocity. I rather suspect it will have the effect of a direct contact nuclear explosion without the radiation.

180,000,000 MJoules

 

[warwizard]

180,000,000 MJoules

180 Million MJ, let's see the PV table for a kenetic penetrator, 12 MJ = DV 84, plus 1 PV per each MJ over 12 MJ....

I wonder how many KILOMETERS of bonded superdense that works out to?

It does not matter, just play it as a kill, ship vaporized. (proxemety fuzed blast fragmentation warhead spreads the PV over a 700 m diameter area).

 

[Xerxeskingofking]

So this invites a review of tatics , long range high velocity missiles from a standoff platform , handing off missile control links to special small craft with 10 ro 20 G's agility that will vector in the 2-5% lightspeed missiles onto the targets, and any direct contact hit is a target vaporized on pretty much anything except the biggest of ships. fighters getting to close range and carrying dozens of box launchers full of sprint missiles. Point defense lasers with a ROF of 500 only getting off one to two shots as the long range missiles are crossing a 30,000 Km hex in 2 to 5 seconds.

sounds a lot like the Honourverse ship combat, with exteme range C-fractional bomb pumped plasers being the standard ship killing weapon.

 

[HG_B]

180 Million MJ, let's see the PV table for a kenetic penetrator, 12 MJ = DV 84, plus 1 PV per each MJ over 12 MJ....

I wonder how many KILOMETERS of bonded superdense that works out to?

It does not matter, just play it as a kill, ship vaporized. (proxemety fuzed blast fragmentation warhead spreads the PV over a 700 m diameter area).

Depends how large the ship is. It wouldn't vaporize something the size of the Death Star.

 

[warwizard]

Seems like there's a market for a plasma generator there!

In MTU or YTU yes, but as written the rule requires a Fusion power plant.

 

[warwizard]

Depends how large the ship is. It wouldn't vaporize something the size of the Death Star.

agreed, but a mere 5000 Dt DE is going to be totally crushed.

In TNE (brilliant lances I'd apply 2d6 major hits to every facing hull section up to 700 meters from the impact point, with the actual DV of each fragment being randomly determined, and the range of DV available a function of relative velocity)

This would nicely solve the problem in BL of having to hit the hold 19 times on a cargo ship for every hit that could actually do anything usefull.

 

[Andrew Boulton]

Wouldn't it just punch straight through and keep going?

 

[HG_B]

Wouldn't it just punch straight through and keep going?

That is subjective to the size of the ship and what it passes through. If it was a very large ship and it passed through a large decompressed cargo area, yes it would more or less "punch through" as the scatter effect would be along the line of flight due to inertial effects.

Yet another good reason to decompress prior to combat...

 

[Ishmael]

180,000,000 MJoules

~43 kiloton yield nuke warhead

 

[robject]

Are these the corrected fusion power output numbers, or are they the published ones?

 

[warwizard]

Are these the corrected fusion power output numbers, or are they the published ones?

I was using FF&S II published without scale efficency TL13 &14 , 3 MW/ cubic meter, TL 15, 6 per, and TL 16, 7 per.

Checking the concolidated eratta... did not see anything revising the fusion power plants, perhaps you could give me a referance to what you have seen?

 

[robject]

Ah, you're using regular fusion power. That might be OK. Fusion+ was error-ridden -- much too powerful, breaking everything in Traveller which used energy (i.e. weapons and starships).

 

[warwizard]

Ah, you're using regular fusion power. That might be OK. Fusion+ was error-ridden -- much too powerful, breaking everything in Traveller which used energy (i.e. weapons and starships).

Yes standard fusion power plants. TL 13 can do these too but their minimum volume for the fusion pp is 1 m3 so they end up with their minimum missile size at 1.3 m3 + fuel, guidance, hull, communications and payload. Perhaps 1.5 to 1.6 cubic meters for a 12 minute sprint missile, with a cost of in the neighborhood of 250k. Not exactly cheap enough or fast enough for the point defense role.

The next development for these is to see how stealthy of a sensor drone you can get. Parameters are surface area <9 square meters, power less than 9 M/W, minimum passive ems array, IR masking, ultra black coating, meson communicator, secondary power system so the fusion plant can be shut down to reduce the IR signature even further, and a couple of hundred gturns of fuel.