Ship concepts and workup's for T4

[warwizard]

Ok In the Glisten Subsector I have two high population industrial worlds 1 jump apart with enormous trade between (highly profitable in both directions)
Aki is A port Industrial TL 9 and Hi, while Glisten is AS IN and Hi A-15.

What shipping would we see going between the two worlds?

Concept TL 15 Jump tug 100 Td but the jump drive is sized for 2000 to 3000 Td and uses a drop tank with a twist.

All the grapples are on the drop tank and cargo modules which are designed as space ships with their own power plants and maneuver drives.

A quick rough estimate of the components

Hull <2m3 needed for the bonded super dense 20 armor factor USK spherical hull
605m3, 41mt cost and power can be ignored.
Jump drive for J1@2000 dt =40 Dt (-560m3 1120mt 168MCr -504mW)
Internal jump fuel for deadheading back if needed (-140m3 10mt)
Power plant for 510mw 5 Dt -70.5m3 141mt 14.1MCr +510mW
Computer is set to high automation to reduce crew requirements.
the remainder of the space is the minimal sensor suite, communications computer, controls, minimal maneuver drive, life support, food, and quarters.

45 Dt for all the rest of the goodies

cost is under 190 MCr for the first and around 150 Mcr for the follow on units.

The cargo module is 1900 Dt
has minimal maneuver drive and power and a grapple for a 100dt spherical hull
the usual mode is that it is remote controlled from the starport with some AI for the docking with the jump tug.

Reefer, bulk foods and modularized container versions are produced.

The "Drop tank" is about 220 Dt contains a grapple for a 100 Dt spherical hull and minimal sensors computer and maneuver drive and is always remote controlled and has AI pilot built in to ensure separation and safe distance from the jumping ship.

In practice the jump tug arrives in system and establishes communications and a vector is assigned to it by the starport. the port computers start calculating the outbound jump for the ship, while the inbound cargo module detaches and proceeds to the highport, the jump tug matches course with the outbound cargo module and fuel lighter (Drop tank). If needed a replacement crew is shuttled to the ship and the inbound crew takes a week off in system.

The starport communicates the finalized jump course to the ship which is connected to the outbound cargo and drop tank ships does final course corrections to match the required positioning from the jump tape.

The intent of this system is to maximize the number of jumps per year that this ship is able to accomplish, thereby increasing the profitability of the operation.

 

[mike wightman]

Nice idea, I quite like it.

It is similar to the GT LASH set up - lighter aboard ship.

The merchant is a jump frame , the cargo and fuel are in containers that are moved by insustem tugs.

All the jump frame has to do is jump - wait to be unloaded and then loaded with fresh cargo and fuel, and then it jumps again.

It becomes an express trading system, but requires infrastructure at both ends.

The advantage of having tugs at both ends for moving cargo and fuel is that your jump ship is only carrying what is necessary through jump space - all those maneuver drives, power plants and control systems on your modules and fuel pods are lost cargo.

 

[warwizard]

Due to the variability in arrival times and exit points you gain some time efficiencies by having a small delta V capability on the cargo and drop tank modules.

For the cargo module, the small HePLAR drives and power plants required are minimal.

12.6 MW Fusion plant @TL 15 =2m3
4800 KN HePLar m-drive =1.2 m3 -12MW
Fuel for maneuvering 10.8m3
total 1Dt

Of course the drop tank module does not enter jump so it's maneuver drive can be a bit more robust as I allotted 10 Dt for hull, power, heplar, sensors and control systems. (it carries 210 dt of fuel so it can offload some extra to top off the jump tug's internal tanks and have a good maneuvering reserve)

I am not saying you do not want tugs for express deliveries, a few Ghours on the cargo also serves to remove it from the jump arrival area and into the port's traffic system. But the bulk grain shipments from Aki they just need to nudge in the right direction and coast for weeks if needed, the buyers can go get the cargo module with their own tug .

 

[warwizard]

Ok finished the spreadsheet entries for the Jump tug

J1, 1g 100dt USL sphere crew 11 4.5 tons cargo 10 dt J-fuel 4.12 dt pp-fuel 1.43 dt m-fuel.
Maneuver drive has 4 hours of maneuvering time, though typical operations has the internal jump fuel also available for maneuvering, in which case some 48 hours of thrust can be sustained. PP-fuel supports 1 year of operation at maximum output.
Ship masses over 1mt/dt so acceleration is calculated on actual loaded mass.
1.001 g at full load, 1.04 g empty.
185 MCr ( 203 MCr including design fees) 148 MCr in quantity.

Jump drive able to drive 2000 dt into J-1 needing 200 dt of fuel. Ship is capable of performing J-1 for just itself on internal tankage.,
Ship does not carry fuel purification or scoops and the hull is not streamlined.
Two airlocks are mounted one designed to mate with the airlock in the cargo module, the second opens to space even when docked to both a cargo module and a drop tank.
Crew standard is 11 people with the engineering section led by an engineer-4 though there is provision for a 12 person crew with 12 small staterooms.
1 maneuvering crew
1 electronics crew
9 (*8) Engineering crew *Engineer-4 counts as two.
1 command crew

Life support is class IV extended with complete air and water recycling, though food is a consumable. Fresh foods can be stored aboard for 60 days there after it's standard rations. If needed crew can subsist for 1 year on food stored in the internal cargo hold, though the standard is crew rotation when the fresh food runs out, and the internal cargo hold is given over to the crew as a lounge/galley as well as food storage.

Electronics: Three computers are carried CP 4 CM.25, PEMS array sens 12.5 AEMS array sens 11.0 Laser com 1000 AU tight beam radio 500 million Km range.
Environmental gravity is provided for 1 G, no inertial compensation is fitted.

There are no weapons installed or any provision for weapons, no hard point.

Operations This ship is able to conduct cargo operations near the jump entry into the system throw 2D for hours till able to jump back out DM-2 (minimum time 1 hour) if realspace 6g tug available to bring the cargo module and drop tank to the ship

 

[warwizard]

point defense missiles

Point defense missiles are under done in Traveller IMO.

So we have the offensive missile that has a chemical rocket capable of 6g's for 20 min (6g6 rating in the missiles supplement) and either a chemical blast fragmentation warhead or a nuclear powered X-ray lazing array capable of 72 km/second at the end of it's burn. (7 min per 30,000 km hex).

That's a pretty tame missile, though it is cheap.

Offensive missile using Heplar
Hull
TL 15 Enhanced bonded superdense 1m3 armor 11 stressed to 19 g's toughness 47.1 density 15
Sphere 1.24m dia 4.84 m2 SF = .0000044
Armor 11/47.1 (minimum.25cm) .25cm * 4.84/1000 = .0121m3
SF 19*.0000044= .0000836
Total armor volume .0122 mass .183mt
Power (nominal1 MW) TL 15 fusion .168m3 .336 mt 1.008MW -.001m2
pp fuel .008m3 .00057mt 292 days endurance
Heplar .1m3 .1mt -1MW 200KN
Payload .1m3 .16mt SR 10kt nuc det laser DE200 DV50 PV286 (3 major hits per BL)
Computer CP1.67 .005 m3 .01mt -.001MW -.0043MW
Battery .05m3 .05mt [.3MW/h]
PEMS Sensor sens 12.5 .05m3 .05mt -.005MW-.1m2
LIDAR Tracker sens 13.5 .1m3 .2mt -.05MW -.05m2
Maneuver fuel .55m3 .039mt (2.2 hours @17 g's)
1000Au Laser comm .015m3 .03mt -0003MW -1.0 m2
Total Mass 1.14mt + maneuver fuel/2 =1.16mt
1.07/200=186m/s or 19 g's at Earth 9.8m/s G's (18.8g at standard)

missile Fusion Heplar 1.07 mt 1.0m3 19g84 (30 min turns) performance 200 DE 50 DV PV286 (3 major hits) 1.009MW no stealth or masking features
(IR sig -1) (Visible sig -2) (active sig -.5)
now that's a much more robust missile and it's 1/7the the volume of the classic 1/2 dt missle

What do we need to hit it with a point defense missile?
well the design goal is to have > 76 g's to counter it's 19 g's, so we will dispense with the sensors and trackers, and battery, the guidance will be command guidance massing 3kg and a 60,000 km laser comm, massing 6 kg payload will be a 40kg blast fragmentation warhead with a 400 m kill radius, the fuel only needs to last 10 minutes it takes to reach 30,000km+ for the intercept
still need the power plant and something of a hull, but smaller looks like .3m3

PP and it's fuel still the same so copying that and the HEPLAR entry...

Power (nominal1 MW) TL 15 fusion .168m3 .336 mt 1.008MW -.001m2
pp fuel .008m3 .00057mt 292 days endurance
Heplar .1m3 .1mt -1MW 200KN
Telegidance+ command guidance .0003m3 .0003kg
Blast Freg warhead .004m3 .004mt
Total so far.2643m3
we need .25/6 for 10 min maneuvering fuel =.042m3
.2643+.043 = .3073 volume and .431 mass
so we'll make the hull .31m3
a quick ball park on the accel gives us 46.4, well below the design goal
in fact at TL 15 the best we can do is .424mt for our 200KN to get 471m/s^2

what does TL 16 give us one wonders... let's see 7mw/m3 for starters and the scale efficiency is better but we'll still not reach scale efficiency. but the mass is 1mt/m3
Hull .3m3 .083m dia 2.16m2
enhanced bonded super dense toughness 47.1 mass 15
Armor 11/47.1*2.16/1000 =.0005m3
SF.0000013 accel 80 =.0001m3
hull mass .009mt
TL 16 Fusion .144m3 .144mt 1.008MW -.001m2
pp fuel .008m3 .00057mt 292 days endurance
Heplar .1m3 .1mt -1MW 200KN
payload and guidance .0043m3 .0043mt
Fuel .051m3 12.24 min endurance

Total mass less maneuver fuel .258mt for 77.5 g's so if we import TL 16 power plants for our point defense missiles we can intercept a 19 g missile

How fast does this missile get out to the intercept?

It has 734 seconds of thrust at 77 g's for a top speed of 565km/s or 207,421KM at burnout, ok that reaches any range nuclear det laser, and beyond 60,000 km we start taking chances with the laser comm dropping connection, but that's still good to 120,000 km before becoming a difficult task
so up to 2 hexes easy. up to 4 hexes standard out to 6 hexes difficult and an intercept beyond 6 hexes impossible

 

[warwizard]

Now think of mounting external canisters of offensive and point defense missiles on small craft. We now have a reason for fighters once again, missile defense of another ship.
You get 12 offensive missiles or 42 point defense missiles per Dt of canisters so it does not take a lot of cargo to have a goodly supply of these missiles.
Enjoy!

 

[robject]

[FONT=arial,helvetica]What shipping would we see going between the two worlds?[/FONT]

[FONT=arial,helvetica]
My opinion: regular shipping will be in critical goods at least 50% of the time (call it 2/3 of the time for a good guess), with remaining cargo space shipping imbalance items.

The volume will be whatever you think an interstellar system's infrastructure needs from a complementary trading partner system.

Irregular, speculative shipping is another thing entirely.


[/FONT]

 

[warwizard]

Well as Aki houses it's population in 5km high cities reserving the surface of the planet for agricultural production it exports a large amount of grains to The Asteroid colonies of glisten, otherwise it's industrial at TL-9 making the cheap goods to sell to the mass market at Glisten and importing the TL 15 luxury goods in return.

The pair make for a quite remarkable volume of trade in the T4 rules with great profits.
Trade codes Glisten A-15 As IN Hi Cp Cost Cr 1,500 (4000 base -1000 each for A port AS, Hi and In + 1500 for tech)
Trade codes Aki A-9 IN Hi Cost 1,900 (4000 base - 1000 each for A port Hi and In + 900 for TL)

Glisten selling to Aki: has 4 pluses from AS to IN, HI to In and IN to both IN and Hi so (5000 base + 4000) +another 60% multiplier due to T/L differences gives a Cr14,400 price for selling goods that cost you 1,500, add in a level 4 broker... 1/12 chance of X4, 1/12 chance of X3 and so on. It gets wickedly profitable even paying the broker 20%.

Now the return trip AKI to Glisten Hi to Hi and IN to As, Hi and IN for +4000 gives us the nearly identical 9000 price, but then we reduce it by 60% due to the TL is against us giving a price of 3600 and cost of 1900 still better than freight and then there is that +4 broker...

 

[warwizard]

There is very little freight to be had as nearly everybody that can ships for the speculative trade. The governments have to produce hulls and offer subsidies requiring some % of the cargo to be filled with government freight to get their red tape shipped to each other, typically these small operators make their contacts and start getting enough folks at the glisten communities to sell to them that they buy out their subsidy after only a few years, you'll almost never see a subbie that is >10 years old still on their contract. (the buyout is enough for the government to build another hull!)