Pondering starship evolution

[Spinward Flow]

Over in the LBB 3 Tech level thread, @atpollard posed the following question (4 days ago).

What about the possibility of converting used Scout ships (seekers) into Passenger/Freight micro-traders?

I never ran the numbers, but always wondered about the possibility of a VERY SMALL merchant to cover the Low Pop/Low Trade backwaters.

Since then, I've been "crunching numbers" (off and on) trying to work out an "optimal fit" for a sub-200 ton microtrader, while "borrowing" from all of my extensive research during the course of this thread here.

Some of the scenarios for starship class design have been the "all in one" traditional starship design, where you put big drives in the starship (for decent maneuver performance) and you arm the starship itself with a turret and a decent computer in order to be "combat capable" (as opposed to being "combat helpless" when the shooting starts). The alternative to that is the line of thinking that I've been working on throughout this thread of setting aside some tonnage for a small craft escort fighter to provide (shoot to mission kill) defense.

Both approaches have their merits and demerits associated with them.

Ultimately, however, I'm thinking of angling towards a 184 ton starship, which can externally tow a 16 ton Escort Fighter (TL=9) for a combined 200 tons in terms of drive performance. The starship would mount LBB2.81 B/B/B drives (25 tons), yielding a performance profile of J2/2G/PP2 @ 200 combined tons displacement (and J1/1G/PP1 @ 201-400 tons combined displacement).

---

184 ton custom hull (configuration: 2, streamlined)

25 tons for B/B/B drives (code: 2/2/2, TL=9, civilian)
56.8 tons for J2 @ 184 tons fuel + 20 tons power plant fuel
9 tons for fuel purification plant (TL=9)
20 tons for bridge
1 ton for model/1bis computer
8 tons for 2x single occupancy crew staterooms (pilot, ship's boat/gunner)
0.2 tons for cargo hold (intended for life support consumables reserves)

• 0.2 tons for 30 person/weeks of life support consumables

64 tons for internal hangar bay (ordinary launch facilities)

1. 16 ton Cargo/Environment Box
2. 16 ton Cargo/Environment Box
3. 16 ton Cargo/Environment Box
4. 16 ton Cargo/Environment Box

External Docking capacity: 208 tons (ordinary launch facilities)

1. Escort Fighter (16 tons)
2. 
   
3. 
   
4. 
   
5. 
   
6. 
   
7. 
   
8. 
   
9. 
   
10. 
    
11. 
    
12. 
    

25+56.8+9+20+1+8+0.2+64 = 184 tons

---

Crew salaries would calculate like so, per 4 weeks:

1. Pilot-1 = Cr6000
2. Ship's Boat-2/Gunnery-2 = ((6000*1.1)+(1000*1.1))*0.75 = Cr5775

Add on Cr2000 per person every 2 weeks for life support expenses, plus Cr100 for 6 days of berthing fees per destination ... and assume wilderness refueling and fuel purification ... and the total overhead expenses per month (2 jump commercial tempo) totals out to Cr19,975 (not including annual overhead maintenance expenses).

Operated as an "interstellar packet delivery courier" delivering mail only under subsidy (and no additional cargo) would yield Cr25,000 per month on 2 deliveries to destinations during 1 month after the 50% revenue rake for being subsidized.

---

Napkin math analysis of the construction costs of the starship (only, no sub-craft) details yields a single production (100%) construction cost of MCr70.926.
The Escort Fighter in single production (100%) adds another MCr35.288 to the bill total.
Cargo Boxes in single production (100%) have a construction cost of MCr1.152 each.

Single production (100%) construction costs:

• Starship + Escort Fighter + 4x Cargo Boxes = 70.926+35.288+(1.152+0.9216*3) = MCr110.1308
• Annual overhaul maintenance = Cr110,131 per year ... divide by 12 months (out of 13) per year of operations = Cr9178 per month

Volume production (80%) construction costs:

• Starship + Escort Fighter + 4x Cargo Boxes = 56.7408+28.2304+(0.9216*4) = MCr88.6576
• Annual overhaul maintenance = Cr88,658 per year ... divide by 12 months (out of 13) per year of operations = Cr7389 per month

So for a "hot swap/reconfigurable" interstellar dispatch merchant that is operating a volume production copy of the class would have operational overhead expenses of Cr340,133 per year if jumping twice per month for 12 months (out of 13 on the imperial calendar) to reach 24 destinations per year.

The break even profit point then becomes 340,133/12 = Cr28,420 in ticket revenues per month to pay for ALL operating expenses (except a bank loan mortgage).

Anything that an operator can transport beyond those minimums ... is profit ... unless if you've got a mortgage to pay off.
A mortgage on a volume production copy of the class would demand 88,657,600/240 = Cr369,407 per month for 480 months. (LBB2.81, p23)

Suffice it to say, if you've got bank loan financing, you had better get into the speculative goods arbitrage business in a hurry!
And even if you don't have bank loan financing, you're still going to want to dabble in speculative goods arbitrage whenever the odds are in your favor with this class.

---

Note that this napkin analysis is of a 184 ton starship + escort fighter + 4x Cargo Boxes ... and the "credits density" of volume production construction costs comes out at MCr88.6576 for 184+16*5=264 tons of hulls. That's a credits density of MCr0.33582424 per ton of hull(s) ... and you've got a crew of 2 plus 0 passenger capacity (with standard life support overhead expenses) and 64 tons of cargo capacity. No additional cargo load can be moved to the exterior while retaining J2/2G/PP2 drive performance.

Compare and contrast that with a 236 ton starship + escort fighter + 2x Stateroom Boxes + 1x Laboratory Box (Type: V-c) + 1x Environment Box + 1x Cargo Box ... and the "credits density" of volume production comes out at MCr124.4724 for 236+16*6=332 tons of hulls. That's a credits density of MCr0.37491687 per ton of hull(s) ... and you've got a crew of 5 plus 3 high passengers capacity (with life support expenses waived by the Laboratory Box) and 32 tons of cargo capacity (16 tons environmentally controlled, the rest are not). 4x Boxes can be moved to the starship's outer hull for external towing, increasing internal cargo capacity from 32 tons to 64 tons inside the internal hangar bay, when necessary (increasing overall cargo transport capacity to 96 tons) while retaining J2/2G/PP2 drive performance.

The 236 ton design IS more expensive ... but it is also a lot more FLEXIBLE and capable (overall), making it (in my opinion) the superior option when looking for J2 and/or J2+2 capability for merchant operations.

 

[Spinward Flow]

Rule of Man Long Trader (TL=9)
236 tons starship hull, configuration: 1
35 tons for LBB2.81 standard C/C/C drives (codes: 2/2/2, TL=9)
68 tons of total fuel: 232 tons @ J2 = 47.2 tons jump fuel + 20(.8) tons power plant fuel
9 tons for TL=9 fuel purification plant (200 ton capacity is minimum)
20 tons for bridge
2 tons for model/2 computer
97 tons for hangar berths capacity

1. Environmental Box = 16 tons
2. Cargo Box = 16 tons
3. Cargo Box = 16 tons
4. Stateroom Box = 16 tons
5. Laboratory Box (Type V-c regenerative biome life support) = 16 tons
6. Stateroom Box = 16 tons

• 97 tons capacity Collapsible Fuel Tank = 0.97 tons

* External Docking: 364 tons capacity

1. Escort Fighter = 16 tons
2. 
   

5 tons for Cargo Hold

= 35+68+9+20+2+97+5 = 236 tons + 16 tons (Escort Fighter) = 252 combined tons

Crew = 5

1. Pilot-2/Navigator-2
2. Ship's Boat-2/Gunner-2
3. Engineer-1
4. Steward-1/Steward-1
5. Medic-3

Revenue Tonnage @ J2

• 3x high passengers
• 16 tons environmentally controlled cargo
• 16+16+5=37 tons standard cargo
• 48 tons additional cargo (when 1x Environmental and 2x Cargo Boxes moved to exterior)

Revenue Tonnage @ J2+2

• 3x high passengers
• 16 tons environmentally controlled cargo
• 16+16+5=37 tons standard cargo

Drive Performances with External Loading

• 236 + 4*16 = 300 tons = J2/2G/PP2
• 236 + 22*16 = 588 tons = J1/1G/PP1
• 236 + 1.1*100 + 15*16 = 586 tons = J1/1G/PP1
• 236 + 1.1*200 + 9*16 = 600 tons = J1/1G/PP1
• 236 + 1.1*236 + 6*16 = 591.6 tons = J1/1G/PP1
• 236 + 1.1*300 + 2*16 = 598 tons = J1/1G/PP1

Decided to take another crack at doing a D/D/D drives (codes: 2/2/2, TL=9) design and see what might tumble out of it using the modular 16 ton Box system.

Here's what happened.

---

Rule of Man Long Trader (TL=9)
320 tons starship hull, configuration: 1, fuel scoops
45 tons for LBB2.81 standard D/D/D drives (codes: 2/2/2, TL=9)
84.2 tons of total fuel: 320 tons @ J2 = 64 tons jump fuel + 20 tons power plant fuel
9 tons for TL=9 fuel purification plant (200 ton capacity is minimum)
20 tons for bridge
1 ton for model/1bis computer
160.8 tons for hangar berths capacity

1. Escort Fighter = 16 tons
2. Stateroom Box = 16 tons
3. Stateroom Box = 16 tons
4. Stateroom Box = 16 tons
5. Laboratory Box (Type V-d regenerative biome life support) = 16 tons
6. Laboratory Box (Type V-d regenerative biome life support) = 16 tons
7. Laboratory Box (Type V-d regenerative biome life support) = 16 tons
8. Cargo Box = 16 tons
9. Cargo Box = 16 tons
10. Environmental Box = 16 tons

• 80 tons capacity Collapsible Fuel Tank = 0.8 tons

* External Docking: 480 tons capacity

1. 
   
2. 
   
3. 
   
4. 
   

0 tons for Cargo Hold

= 45+84.2+9+20+1+160.8+0 = 320 tons

Crew = 6

1. Pilot-1
2. Navigator-1
3. Ship's Boat-2/Gunnery-2
4. Engineering-2/Engineering-2
5. Steward-1/Steward-1
6. Medic-4

Revenue Tonnage @ J2

• 6x high passengers
• 16 tons environmentally controlled cargo
• 32 tons standard cargo
• 80 tons additional internal hangar cargo (when 2x Stateroom Boxes, 2x Laboratory Boxes, 1x Escort Fighter moved to exterior)

Revenue Tonnage @ J2+2

• 6x high passengers
• 16 tons environmentally controlled cargo
• 32 tons standard cargo
• 80 tons collapsible fuel tankage (when 2x Stateroom Boxes, 2x Laboratory Boxes, 1x Escort Fighter moved to exterior)

Drive Performances with External Loading

• 320 + 5*16 = 400 tons = J2/2G/PP2
• 320 + 30*16 = 800 tons = J1/1G/PP1
• 320 + 1.1*100 + 23*16 = 798 tons = J1/1G/PP1
• 320 + 1.1*200 + 16*16 = 796 tons = J1/1G/PP1
• 320 + 1.1*300 + 9*16 = 794 tons = J1/1G/PP1
• 320 + 1.1*320 + 8*16 = 800 tons = J1/1G/PP1
• 320 + 1.1*400 + 2*16 = 792 tons = J1/1G/PP1

---

I probably shouldn't be surprised by the fact that moving from a 236 ton form factor to a 320 ton form factor (an increase of +84 tons) would ultimately yield +4 Boxes worth of internal hangar capacity (64 tons) ... allowing for an upgrade in life support (from Type V-c to Type V-d) which then makes possible a 2x high passenger capacity (from 3 to 6).

At J2, maximum cargo capacity increases from 85 tons to 128 tons, while at J2+2, maximum cargo capacity decreases slightly from 53 tons down to 48 tons ... an acceptable modulation, given all the other upsides.

However, at J1 (mains and microjumping), as well as J1+1 ... external load capacity increases to the point of being able to externally dock with and tow big craft of up to 436 tons on maneuver drive (1G) and jump drive (J1) to a wide variety of destinations. This also includes capacity for the external towing of up to 30x 16 ton Boxes, which can be used to move a lot of passengers/freight when necessary (or chartered to do so).



Overall, I'm thinking that this makes for a better "balance point" for the TL=9 J2(+2) design, even with the modification to the crew roster (6 instead of 5) requiring higher crew salaries. The increase in revenue tonnage transport capacity makes up for the increased expenses, I'm thinking, without breaking the bank (mortgage). The life support upgrade will also have interesting knock on effects for Quality of Life aboard, for both crew and passengers, which result in reputational advantages that will indirectly deter crews from being motivated to dabble in piracy (from time to time), lest they tarnish their reputation in ways that might be difficult to recover from.

 

[Spinward Flow]

Y'know, I think I'm onto something here.
The 320 ton form factor ALSO works for the J3 and J3+3 design @ TL=10.

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Rule of Man Clipper (TL=10)
320 tons starship hull, configuration: 1, fuel scoops
65 tons for LBB2.81 standard F/F/F drives (codes: 3/3/3, TL=10)
128 tons of total fuel: 320 tons @ J3 = 96 tons jump fuel + 30 tons power plant fuel
8 tons for TL=10 fuel purification plant (200 ton capacity is minimum)
20 tons for bridge
2 tons for model/2bis computer
97 tons for hangar berths capacity

1. Escort Fighter = 16 tons
2. Environmental Box = 16 tons
3. Cargo Box = 16 tons
4. Stateroom Box = 16 tons
5. Laboratory Box (Type V-c regenerative biome life support) = 16 tons
6. Stateroom Box = 16 tons

• 97 tons capacity Collapsible Fuel Tank = 0.97 tons

* External Docking: 880 tons capacity

1. 
   
2. 
   
3. 
   
4. 
   

0 tons for Cargo Hold

= 65+128+8+20+2+97+0 = 320 tons

Crew = 6 (Cr30,725 per 4 weeks crew salaries)

1. Pilot-1
2. Navigator-1
3. Ship's Boat-2/Gunner-2
4. Engineer-2/Engineer-2
5. Steward-1/Steward-1
6. Medic-3

Revenue Tonnage @ J3/3G

• 2x high passengers
• 16 tons environmentally controlled cargo
• 16 tons standard cargo
• 5*16 = 80 tons additional cargo (when Boxes docked externally)

Revenue Tonnage @ J3+3/3G

• 2x high passengers
• 16 tons environmentally controlled cargo
• 5 tons standard cargo
• 91 tons internal hangar collapsible fuel tankage (when Boxes docked externally)

Drive Performances with External Loading

• 320 + 1.0*5*16 = 400 tons = J3/3G/PP3
• 320 + 1.0*17*16 = 592 tons = J2/2G/PP2
• 320 + 1.1*50*16 = 1200 tons = J1/1G/PP1
• 320 + 1.1*100 + 1.0*10*16 = 590 tons = J2/2G/PP2
• 320 + 1.1*200 + 1.0*3*16 = 588 tons = J2/2G/PP2
• 320 + 1.1*200 + 1.1*37*16 = 1191.2 ≈ 1192 tons = J1/1G/PP1
• 320 + 1.1*300 + 1.1*31*16 = 1195.6 ≈ 1196 tons = J1/1G/PP1
• 320 + 1.1*320 + 1.1*30*16 = 1200 tons = J1/1G/PP1
• 320 + 1.1*320 + 1.1*320 + 1.1*10*16 = 1200 tons = J1/1G/PP1
• 320 + 1.1*400 + 1.1*25*16 = 1200 tons = J1/1G/PP1
• 320 + 1.1*500 + 1.1*18*16 = 1186.8 ≈ 1187 tons = J1/1G/PP1
• 320 + 1.1*600 + 1.1*12*16 = 1191.2 ≈ 1192 tons = J1/1G/PP1
• 320 + 1.1*700 + 1.1*6*16 = 1195.6 ≈ 1196 tons = J1/1G/PP1
• 320 + 1.1*800 + 1.1*0*16 = 1200 tons = J1/1G/PP1

---

Cross-compare the TL=9 J2/2G design with the TL=10 J3/3G design.

The crew is almost exactly the same except for the -1 downgrade in the life support laboratory box(es), from Type V-d in the J2/2G design down to Type V-c in the J3/3G design, which then reduces the medical skill needed (from 4 to 3). Otherwise, all other crew positions remain unchanged.

Decided to go with a crew of 6, rather than 5, with the difference being pilot and navigator as 2 people, rather than having a pilot/navigator as a single person. For a variety of simulation™/immersion reasons, having a bridge crew of 2 people makes it a LOT easier to maintain a 12 hours on/12 hours off continuous standing officer of the deck watch cycle at all times (during jump and during long interplanetary voyages). The RAW may not demand it, since a pilot/navigator single person IS permissible, but in terms of human (or aslan or vargr or droyne or etc.) endurance, it makes more sense to have 2 bridge personnel to share the standing watch duty cycles rather than just a 1 person (who needs to leave the bridge to sleep, etc.).

This also means that all crew billets (except for medical) are interchangeable between the two "cousin" classes of starship ... with the J2/2G Long Trader requiring a higher medical skill in order to maintain the higher quality regenerative life support biomes (3, rather than just 1) sustaining a larger number of high passenger accommodations (6 vs 2).



All other factors remain broadly congruent, including the principle of exchanging drive output performance/range for external load capacity.

Trivia notes:

• 320 tons (base-10) = 500 tons (base-8)
• 16 tons (base-10) = 20 tons (base-8)

This trivia note is primarily for Aslan, whose numbering system uses base-8 (because 3 fingers plus opposable thumb), as opposed to Humaniti using base-10 (because 4 fingers plus opposable thumb).

Additionally, the slight "decompression" of the crew compliment from 5 to 6 makes it easier for (traditionalist) all Aslan crews, that require strict adherence to gender roles, to have either the Navigator or the Medic pull double duty as the ship's Purser (CT Alien Module 1, p32) in order to conduct mercantile business operations.

For Droyne adapted variants of this design, the Stateroom Boxes would have different interior layouts (for more communal living) and since Droyne consume 1/2 the life support of humaniti, each 16 ton Stateroom Box would be capable of hosting up to 8 Droyne. Since 6 Droyne (1 of each caste) makes for a complete Tyafelm (single family), the J2/2G (Droyne) Long Trader variant of this design could host up to 4x Tyafelm of a single Dreskay when necessary. Likewise, a J3/3G (Droyne) Clipper variant of this design could host up to 2x Tyafelm with sufficient stateroom accommodation capacity remaining for 2x humaniti high passengers or 4x droyne high passengers.



Additional fun fact:

I took a preliminary look at the J-5 Trans-Rift Hierate Route on through the Riftspan Reaches sector on Travellermaps.

• A J5 starship can complete an end to end run in 10 starports/10 jumps/20 weeks when spending 1 week conducting business at each starport along the route
  • 10 * 2 = 20
• A J3+3 starship can complete an end to end run in 9J3, 2J3+3, 1J3+2 ... 12 starports/15 jumps/27 weeks when spending 1 week conducting business at each starport along the route
  • (9 * 2) + (2 * 3) + (1 * 3) = 27

In other words, a double jumping J3(+3) capable starship CAN run the J-5 Trans-Rift Hierate Route and almost complete a round trip in just slightly over 1 (humanti calendar) year (54 weeks round trip). Considering that a J5 starship would be FAR more expensive(!) to construct, crew and maintain, would need to be a LOT larger in order to carry any "useful" load (as @Grav_Moped proved with the Shugushaag design) and since the Hierate is limited to TL=14, you can't go any higher than Drive-U using LBB2.81 drives (as specified by LBB3.81, p15) ... which basically pushes anything in the direction of LBB5.80 for anything over 600 tons.

If you use my formulaic approach to computing drive performance outputs for LBB2.81 drives, then Drive-U (highest TL=14 standard drive) is code: 1 @ 3800 tons ... which means code: 5 @ 760 tons. Point being that J5 anything is going to be pushing HARD into the TL=13-14 realm for lots of drive tonnage (and the attendant engineering crew requirement) well in excess of what I can get away with in a 320 ton form factor capable of J3+3 and only takes +7 weeks one way running the route.

I would even go so far as to suggest that 2x (Aslan) J3/3G Clipper ships would probably cost approximately the same as 1x Shugushaag, but the 2x Clippers would be capable of moving more passengers and cargo/freight, making them much more economical/viable in the long run over routes where 5-6 parsec range limits are highly desirable.

 

[Grav_Moped]

@Spinward Flow : in that larger size range, consider HG ships with LBB2 drives, just to use their engineering crew size rules (1/100Td drives + officers, instead of 1/35Td drives total). Might pencil out, might not -- haven't checked, myself.

 

[Spinward Flow]

in that larger size range, consider HG ships with LBB2 drives

I did. The problem is the tech level limitation.
LBB2.81 drives only go up to Drive-U @ TL=14 ... which is code: 1 @ 3800 tons.

Only way to "go bigger" is to push up into the V-Z drives ... which are TL=15 ... and as I mentioned, the Aslan Hierate (much like the Zhodani Consulate) cap out @ TL=14.

3800 / 5 = 760 tons maximum with Jump-U drives @ TL=14.

You can, of course, "go bigger" than that with LBB5.80 drives @ TL=14 ... but at that point you're dealing with custom drives, not LBB2.81 standard drives anymore.

Construct a 1000 ton starship with (custom) LBB5.80 J5 @ TL=14 ... NO PROBLEM ... but you aren't doing that using a LBB2.81 standard jump drive.

just to use their engineering crew size rules (1/100Td drives + officers, instead of 1/35Td drives total).

The changeover for that happens with Hull: A (1000-1999 tons).
Anything that is Hull: 0-9 should be using LBB2.81 crew requirement rules ... so you need 1 engineer per 35 tons of drives at these hull sizes.

Note that LBB2.81 has an additional minimum crew rule that kicks in @ 1001+ tons ... you need 10 crew per 1000 tons, minimum.
Even if you (somehow) computed that you only need a crew of 5 ...

• 1 Pilot
• 1 Navigator
• 2 Engineers (E/E/E drives, code: 1/1/1 @ 1000 tons)
• 1 Medic

... because you're just an oversized cargo hold with drives strapped on, regulations could still require a 10 crew minimum on a 1001 ton starship (LBB2.81, p16). For the purposes of simulation, this would wind up being 2 complete crews of 5, alternating watch rotations, rather than a single crew of 10.

 

[Spinward Flow]

Remember how I settled on the 320 ton form factor as being a "sweet spot" for drive performance when accounting for external loading factors?

Rule of Man Long Trader (TL=9)
320 tons starship hull, configuration: 1, fuel scoops
45 tons for LBB2.81 standard D/D/D drives (codes: 2/2/2, TL=9)
84.2 tons of total fuel: 320 tons @ J2 = 64 tons jump fuel + 20 tons power plant fuel
9 tons for TL=9 fuel purification plant (200 ton capacity is minimum)
20 tons for bridge
1 ton for model/1bis computer
160.8 tons for hangar berths capacity

1. Escort Fighter = 16 tons
2. Stateroom Box = 16 tons
3. Stateroom Box = 16 tons
4. Stateroom Box = 16 tons
5. Laboratory Box (Type V-d regenerative biome life support) = 16 tons
6. Laboratory Box (Type V-d regenerative biome life support) = 16 tons
7. Laboratory Box (Type V-d regenerative biome life support) = 16 tons
8. Cargo Box = 16 tons
9. Cargo Box = 16 tons
10. Environmental Box = 16 tons

• 80 tons capacity Collapsible Fuel Tank = 0.8 tons

* External Docking: 480 tons capacity

1. 
   
2. 
   
3. 
   

0 tons for Cargo Hold

= 45+84.2+9+20+1+160.8+0 = 320 tons

Crew = 6

1. Pilot-1
2. Navigator-1
3. Ship's Boat-2/Gunnery-2
4. Engineering-2/Engineering-2
5. Steward-1/Steward-1
6. Medic-4

Revenue Tonnage @ J2

• 6x high passengers
• 16 tons environmentally controlled cargo
• 32 tons standard cargo
• 80 tons additional internal hangar cargo (when 2x Stateroom Boxes, 2x Laboratory Boxes, 1x Escort Fighter moved to exterior)

Revenue Tonnage @ J2+2

• 6x high passengers
• 16 tons environmentally controlled cargo
• 32 tons standard cargo
• 80 tons collapsible fuel tankage (when 2x Stateroom Boxes, 2x Laboratory Boxes, 1x Escort Fighter moved to exterior)

Drive Performances with External Loading

• 320 + 5*16 = 400 tons = J2/2G/PP2
• 320 + 30*16 = 800 tons = J1/1G/PP1
• 320 + 1.1*100 + 23*16 = 798 tons = J1/1G/PP1
• 320 + 1.1*200 + 16*16 = 796 tons = J1/1G/PP1
• 320 + 1.1*300 + 9*16 = 794 tons = J1/1G/PP1
• 320 + 1.1*320 + 8*16 = 800 tons = J1/1G/PP1
• 320 + 1.1*400 + 2*16 = 792 tons = J1/1G/PP1

Rule of Man Clipper (TL=10)
320 tons starship hull, configuration: 1, fuel scoops
65 tons for LBB2.81 standard F/F/F drives (codes: 3/3/3, TL=10)
128 tons of total fuel: 320 tons @ J3 = 96 tons jump fuel + 30 tons power plant fuel
8 tons for TL=10 fuel purification plant (200 ton capacity is minimum)
20 tons for bridge
2 tons for model/2bis computer
97 tons for hangar berths capacity

1. Escort Fighter = 16 tons
2. Environmental Box = 16 tons
3. Cargo Box = 16 tons
4. Stateroom Box = 16 tons
5. Laboratory Box (Type V-c regenerative biome life support) = 16 tons
6. Stateroom Box = 16 tons

• 97 tons capacity Collapsible Fuel Tank = 0.97 tons

* External Docking: 880 tons capacity

1. 
   
2. 
   
3. 
   

0 tons for Cargo Hold

= 65+128+8+20+2+97+0 = 320 tons

Crew = 6 (Cr30,725 per 4 weeks crew salaries)

1. Pilot-1
2. Navigator-1
3. Ship's Boat-2/Gunner-2
4. Engineer-2/Engineer-2
5. Steward-1/Steward-1
6. Medic-3

Revenue Tonnage @ J3/3G

• 2x high passengers
• 16 tons environmentally controlled cargo
• 16 tons standard cargo
• 5*16 = 80 tons additional cargo (when Boxes docked externally)

Revenue Tonnage @ J3+3/3G

• 2x high passengers
• 16 tons environmentally controlled cargo
• 5 tons standard cargo
• 91 tons internal hangar collapsible fuel tankage (when Boxes docked externally)

Drive Performances with External Loading

• 320 + 1.0*5*16 = 400 tons = J3/3G/PP3
• 320 + 1.0*17*16 = 592 tons = J2/2G/PP2
• 320 + 1.0*42*16 = 992 tons = J1/1G/PP1
• 320 + 1.3*42*16 = 1193.6 ≈ 1194 tons = J1/1G/PP1
• 320 + 1.1*100 + 1.0*10*16 = 590 tons = J2/2G/PP2
• 320 + 1.1*200 + 1.0*3*16 = 588 tons = J2/2G/PP2
• 320 + 1.1*200 + 1.3*31*16 = 1184.8 ≈ 1185 tons = J1/1G/PP1
• 320 + 1.1*300 + 1.3*26*16 = 1190.8 ≈ 1191 tons = J1/1G/PP1
• 320 + 1.1*320 + 1.3*25*16 = 1192 tons = J1/1G/PP1
• 320 + 1.1*320 + 1.1*320 + 1.3*8*16 = 1190.4 ≈ 1191 tons = J1/1G/PP1
• 320 + 1.1*400 + 1.3*21*16 = 1196.8 ≈ 1197 tons = J1/1G/PP1
• 320 + 1.1*500 + 1.3*15*16 = 1182 tons = J1/1G/PP1
• 320 + 1.1*600 + 1.3*10*16 = 1188 tons = J1/1G/PP1
• 320 + 1.1*700 + 1.3*5*16 = 1194 tons = J1/1G/PP1
• 320 + 1.1*800 + 1.3*0*16 = 1200 tons = J1/1G/PP1

I just found another configuration that makes for a "perfect fit" into a 320 ton form factor using LBB2.81 standard drives @ TL=10.

---

Rule of Man Fast Trader (TL=10)
320 tons starship hull, configuration: 1
65 tons for LBB2.81 standard D/H/H drives (codes: 2/5/5, TL=10)
114 tons of total fuel: 320 tons @ J2 = 64 tons jump fuel + 50 tons power plant fuel
8 tons for TL=10 fuel purification plant (200 ton capacity is minimum)
20 tons for bridge
4 tons for model/2fib computer
97 tons for hangar berths capacity

1. Escort Fighter = 16 tons
2. Stateroom Box = 16 tons (ship's boat/gunner, engineer/engineer, steward/steward, medic)
3. Stateroom Box = 16 tons (4x high passengers)
4. Laboratory Box (Type V-c regenerative biome life support) = 16 tons
5. Cargo Box = 16 tons
6. Environmental Box = 16 tons

• 97 tons capacity Collapsible Fuel Tank = 0.97 tons

* External Docking: 1280 tons capacity

1. 
   
2. 
   
3. 
   
4. 
   

8 tons for 2 single occupancy staterooms (pilot, navigator)
4 tons for Type V-c regenerative biome life support laboratory

= 65+114+8+20+4+97+8+4 = 320 tons

Crew = 6 (Cr30,725 per 4 weeks crew salaries)

1. Pilot-1
2. Navigator-1
3. Ship's Boat-2/Gunnery-2
4. Engineering-2/Engineering-2
5. Steward-1/Steward-1
6. Medic-3

Revenue Tonnage @ J2/5G

• 4x high passengers
• 16 tons standard cargo
• 16 tons environmentally controlled cargo

Revenue Tonnage @ J2/4G

• 4x high passengers
• 16 tons standard cargo
• 16 tons environmentally controlled cargo
• 80 tons additional internal hangar cargo (when 2x Stateroom Boxes, 1x Laboratory Box, 1x Cargo Box, 1x Environmental Box moved to exterior)

Revenue Tonnage @ J2+2/4G

• 4x high passengers
• 16 tons standard cargo
• 16 tons environmentally controlled cargo
• 48 tons collapsible fuel tankage + 32 tons additional internal hangar cargo (when 2x Stateroom Boxes, 1x Laboratory Box, 1x Cargo Box, 1x Environmental Box moved to exterior)

Drive Performances with External Loading

• 320 + 1.0*0*16 = 320 tons = J2/5G/PP5
• 320 + 1.0*5*16 = 400 tons = J2/4G/PP4
• 320 + 1.0*13*16 = 528 tons = J1/3G/PP3
• 320 + 1.1*100 + 1.0*6*16 = 526 tons = J1/3G/PP3
• 320 + 1.0*30*16 = 800 tons = J1/2G/PP2
• 320 + 1.1*100 + 1.0*23*16 = 798 tons = J1/2G/PP2
• 320 + 1.1*200 + 1.0*16*16 = 796 tons = J1/2G/PP2
• 320 + 1.1*300 + 1.0*9*16 = 794 tons = J1/2G/PP2
• 320 + 1.1*320 + 1.0*8*16 = 800 tons = J1/2G/PP2
• 320 + 1.1*400 + 1.0*2*16 = 792 tons = J1/2G/PP2
• 320 + 42*16 = 992 tons = J0/1G/PP1
• 320 + 1.1*600 + 1.0*1*16 = 996 tons = J0/1G/PP1
• 320 + 1.3*61*16 = 1,588.8 tons = J0/1G/PP1
• 320 + 1.1*1000 + 1.3*8*16 = 1,586.4 tons = J0/1G/PP1

 

[Spinward Flow]

That's ... an extremely remarkable mix of capabilities within the confines of a single form factor (320 tons) that can be achieved simply by modifying the drives installed into the drive bays.

Obviously, the interior layout of the deck plans would have some modifications to account for the 3 different variations on the same theme, but it's actually a bit remarkable that it's possible to make one of my old design goals for the Spinward X-Courier (TL=11, J2/5G, J2+2 capable, 194 tons, crew: 2, passengers: 0, cargo: 45 @ J2) using LBB5.80 take on a different form @ 320 tons using LBB2.81 drives as a "more capable merchant" starship in the form of the Rule of Man Fast Trader (TL=10, J2/5G, J2+2 capable, 320 tons, crew: 6, passengers: 4, cargo: 32 to 112 @ J2).

The difference here is that the starship design I made 3+ years ago (by now), was a starship with a turret ... and this new version is a starship with a fighter escort (and much better amenities improving quality of life aboard). Although a 320 ton Rule of Man Fast Trader will no doubt be more expensive to construct, crew and maintain, relative to the more specialized (and therefore, limited) 194 ton Spinward X-Courier design I made all those years ago ... I'm thinking that the Return On Investment (ROI) would make the higher expense for a Rule of Man type of starship for a merchant operator plying their trade along the fringes of the frontier "worth" the price. For one thing, the flexibility in routine operations with one of these Rule of Man type designs is MUCH higher, enabling a wider range of potential windfall profit opportunities (come what may) when operating as a speculative tramp (subsidized or not).

The real kicker is that the Rule of Man Fast Trader looks like it would make for an excellent blockade runner/smuggler starship, capable of evading a surprisingly large number of system defense policing as well as pirate patrols. Conversely, it would also make for a superb Search & Rescue craft, capable of responding with alacrity (5G acceleration in a clean configuration) to dispatches, in addition to all kinds of interplanetary "circulator" roles ... up to and including use as a microjumper to distant orbits with a substantial external load capacity. That opens up all kinds of Disaster Relief opportunities, when a lot of cargo needs to be moved quickly from place to place on an interplanetary and/or J1 basis to meet crisis needs. It could even be used as a Salvage & Retrieval Ship, capable of externally towing "dead hulks" of up to 400 tons @ J1/2G, or up to 1000 tons @ J0/1G to a staging area (starport, hidden rebel base, etc.).

In other words, the sheer amount of capability and flexibility that I've been able to cram into these 320 ton hulls is starting to look mighty tasty indeed as an ACS that Travellers could use as their livelihood/base of operations and get up to all sorts of interesting adventures with while still keeping things "small scale enough" for a Referee to manage reasonably well (particularly if the Referee is well familiarized with the details of the 3 Rule of Man classes of merchant starships and their modularized 16 ton Box system of containerization). Best of all, the specifics of the designs are not "so unique" as to only "work" for a single polity or jump faring species. Any of the branches of humaniti, clans of Aslan or even Vargr would be able to "copy" the design features of the 3 classes with relatively little effort, since TL=9-10 merchant starships built using LBB2.81 standard drives don't contain a whole lot of military secrets that can be kept from prying eyes. The "genius" of the Rule of Man classes is in the systems integration, their design and the application ... not in the tech level of the construction.

Chalk one up for Solomani ingenuity.

 

[Spinward Flow]

D'oh!
Can't believe I overlooked this detail up until this point.

Hull codes: 6-9 require a minimum computer model/1 (fib and bis are irrelevant for this).
Hull codes: A-C require a minimum computer model/2 (fib and bis are irrelevant for this).

Therefore, any craft that wants to have a combined displacement with external loading of 1000+ tons requires a model/2 computer (of some flavor) at an absolute bare minimum.

• 320 ton J2/2G Rule of Man Long Trader has 800 combined tons maximum capacity = model/1 required
• 320 ton J3/3G Rule of Man Clipper has 1200 combined tons maximum capacity = model/2 required
• 320 ton J2/5G Rule of Man Fast Trader has 1600 combined tons maximum capacity = model/2 required
  
  
• 320 ton J2/2G Rule of Man Long Trader is designed with a model/1bis computer
• 320 ton J3/3G Rule of Man Clipper is designed with a model/2bis computer
• 320 ton J2/5G Rule of Man Fast Trader is designed with a model/2fib computer

Whew!
For a moment there I was concerned I might have flubbed the minimum computer for largest hull size/combined tonnage limit somewhere.



The important takeaway is that the 320 ton J2/5G Rule of Man Fast Trader cannot use a model/1bis without limiting its maximum combined tonnage to 999 tons or less, which would basically reduce the 1280 ton external load capacity by more than -600 tons if a model/2 computer (of some flavor) were not used in the design.

Okay, important safety tip. Thanks, Egon.

 

[Spinward Flow]

Remember how I settled on the 320 ton form factor as being a "sweet spot" for drive performance when accounting for external loading factors?

Now that I've got 3 starship variants all using the exact same displacement/form factor, I've been working with the spreadsheet details in the naval architect's office to do my best to "regularize" the differences between the variants in ways that will minimize the amount of interior details/deck plan rework that will be needed when it comes time to copy/paste the common details into each variant. Once of those "measure twice thrice, cut once" kinds of bits of detail work.

Part of that effort is going into making sure the 3 different variants are "reasonably close" (enough) to each other in their particulars such that there is a sort of "family feel" to them. Once you're familiar with and qualified to crew one of them, you're probably good enough to work on any of them (except for, maybe, the medical position).

Tweaked the crew skills requirement slightly so as to make the two pilots interchangeable (previously: pilot-1, ship's boat-2/gunnery-2) (now: pilot-3/gunnery-2 (chief), pilot-3/gunnery-2) for the crew positions of starship pilot and fighter pilot. The advantage here is that the starship is unarmed, so the starship pilot can apply their full pilot-3 skill and achieve a +1 Agility to maneuvering (and the all important Break Off By Acceleration maneuver). This increases the crew salaries from 6000+5775=Cr11,775 per 4 weeks up to 6300+6225=Cr12,525 per 4 weeks (an increase of Cr750 per 4 weeks), but the Return on Investment in crew skills (and flexibility) is worth the added expense if it makes (unwanted) intercepts by pirates (and/or system defense/local policing) even more of a challenge while maneuvering between points of interest. After all, keeping combat engagements SHORT helps to limit risks (battle damage that is expensive to repair being chief among them).

 

[Spinward Flow]

Been doing a bit more "doodling" behind the scenes (offline) and I've hit an important limitation ... which has come up in this thread before ... the starship BRIDGE.

Intellectual Honesty™ demands that if drive performance can scale with hull size, along with fuel demand (bigger displacements require more fuel to jump, generically speaking) ... other factors involved with a varying total displacement (due to external loading) ought to follow suit. Where this leads to in terms of the starship bridge line item is that if a starship is intended to (routinely) dock with and tow external loads, not only should there be enough (defined at construction) external docking capacity to do so (costing Cr2000 per ton of external capacity) but the starship bridge requirement should follow suit as well.

Up until this point, I've been designing with the 2% (minimum 20 tons) requirement for the constructed starship's hull displacement.
A 320 ton starship requires a 20 ton bridge costing MCr1.6 ... same as the tonnage and credits cost of any other starship of 320 tons with no external loading capacity.

But now I'm reconsidering this interpretation.
Because the more Intellectually Honest™ way to approach the question would be to determine the maximum displacement @ J1 when towing an external load and then use THAT value for determining the 2% bridge tonnage and cost. Doing so removes an "unfair advantage" of designing "small" starships that can tow "exorbitant" amounts of external loads. For example, a 400 ton starship capable of towing 1600 tons externally for a combined 2000 tons (code: 1 @ Drive-K) only needing a 20 ton bridge costing MCr2 ... when a 2000 ton starship hull would require a 40 ton bridge costing MCr10.



This requirement to "size the bridge in such a way as to account for external loading" then creates a very obvious breakpoint at 1000 tons of starship+external load, because that's the inflection point where 2% = 20 tons.

Point being that a 320 ton starship with F/F/F drives that would be capable of code: 1/1/1 drive performance at 320 tons of starship + 880 tons of external load = 1200 combined tons displacement really ought to have a "1200 ton rated" bridge to control the whole thing ... and 2% of 1200 tons is 24 tons @ MCr6 ... not 20 tons @ MCr1.6 for a 320 ton hull.



All of which pushes things back down into the E/E/E drives or lower regime, because E/E/E drives "top out" in performance with code: 1 @ 1000 tons (combined) displacement ... which means a "1000 ton rated" bridge allocation costing 20 tons @ MCr5.

It's not that higher/later combinations of drives can't be used ... but the "displacement rating for the bridge" ought to be another chokepoint/requirement to enabling/allowing the towing of external loads, in addition to the construction cost requirement of (external) Ordinary Launch Facilities (at Cr2000 per ton of external load capacity) to enable the routine addition of significant external loading.



Which means all those design plans I had for F/F/F drives and H/H/H drives in a 320 ton form factor, that were already pushing the limits of what their hulls could contain, suddenly "don't work anymore" if I need to put a 24 ton bridge (1200 combined tons control) or a 32 ton bridge (1600 combined tons control) inside of them which had not been budgeted for previously. They could still be done ... but a 20 ton bridge would limit them to 1000 combined tons for the purposes of jump and maneuver, which isn't necessarily a Bad Thing™.

For example, an H/H/H drives starship could be designed with an 800 combined tons limit on starship+external loading, which would yield code: 2/2/2 performance out of the drives at maximum external load. However, a code: 1/1/1 performance @ 801-1000 tons would "not be available/permitted" because the bridge of the starship would be rated for the control of 800 combined tons of starship+external loading. An "800 tons rated" bridge would require 20 tons @ MCr4.



Yes, this was recommended earlier in the thread and I rejected the notion at the time ... but now I'm really "stress testing" the notional ideas and foundational underpinnings of the concept(s) behind modular containerization and HOW that could be realized and implemented in a (faithful) CT design context which doesn't violate the spirit of LBB2.81 or LBB5.80 when extending and interpolating into the realm of House Rules to cover topics that CT is more or less silent on.

Most "normal" builds using CT don't have these kinds of variable displacement considerations, except in the realm of External Drop Tanks ... and even then, the RAW is sadly deficient at adequately explaining the proper interpretations and methods of implementation that were intended to be used to make these external loads "work" as an extension of the design rules. Internal loads are easy enough to deal with, but external loading was a bit of a blind spot for CT.



Note that the "bridge tonnage rating" interpretation that I'm using here is mainly meant to be something of a "designed to deal with this sort of thing on the regular" type of deal. It's meant to make external docking and towing of external loads "routine" in a way that wards off disputes and Rules Lawyering (see: Intellectual Honesty in design). It wouldn't "prevent" ad hoc docking and towing with external loads by other classes of craft, however such ad hoc arrangements would be anything BUT routine and may require somewhat extensive/expensive work by crews to achieve on an emergency basis (as per LBB A5, p35 for linking of starships, use the Jump Failure rules).

A different way of approaching this issue is to view the RAW regarding bridge displacement and credit costs as being the MINIMUM required for big craft hulls.

• A 100 ton starship bridge needs to be 20 tons @ MCr0.5 ... minimum.
• A 1000 ton starship bridge needs to be 20 tons @ MCr5 ... minimum.

For MOST design applications, that minimum requirement is all that we (as Referees and Players) really care about. We choose the minimum, it works, we move on (no fuss, no muss).

However, such an interpretation assumes that "overbuilding" won't be done.
Nobody is going to put a 200 ton rated bridge @ MCr1 into a 100 ton hull if they don't have to ... because why would you? You're basically increasing the construction cost (by +MCr0.5) for no useful purpose or return on investment. So why would anyone DELIBERATELY buy "more bridge than you need" to meet the minimum requirements for your hull displacement?

There's no RAW that stands against it ... there's just a practicality argument against it (why pay for what you don't need or won't be able to make good use of?).

I guess in that sense, it's a bit like buying 2x bridges (main+backup) for a craft that is intended to avoid combat. Why have a backup bridge when you aren't supposed to be shot at? Bridges can only be damaged by critical hits in combat ... so if the design is not intended to be a combatant, why have a backup bridge? It's just a "waste" to have 2 bridges, since the tonnage and construction cost expended on the backup bridge could be used for something else instead (presumably more useful). There's no RULE stating that you CAN'T have a backup bridge, so "overbuilding beyond minimum" is certainly permitted under RAW ... it just isn't very "efficient" from a class design standpoint for a lot of craft. I think the Kinunir class from LBB A1 and the Leviathan class from LBB A4 are the only examples of backup bridges in starship design that I can think of CT (there may be others, I'm just not remembering them while writing this).

Point being that if you WANT to "overbuild" beyond minimum required capacity YOU CAN (there's nothing stopping you, except good common sense) ... however, it a lot of applications, "overbuilding" your bridge is basically "wasteful" in starship design, so no one does it.

However, if there were a legitimate REASON for why a starship ought to be designed with an "excess capacity" in the parameters of its bridge, over and above the minimum required for the starship's unencumbered hull displacement ... the logical impetus for achieving a (sensible) return on investment into that kind of "overbuild" of bridge capacity would be ... docking with and towing external loads that increase the combined total displacement to be controlled from the bridge.

 

[Spinward Flow]

Same argument applies to (internal) fuel tankage requirements.
The RAW tells you what the MINIMUM requirements are, but allocating additional fuel above and beyond those minimum requirements is not prohibited.

Besides, if you increase the total combined tonnage (by external docking) you're trying to jump (or maneuver, really), the fuel requirements for doing so may change depending on the details ... so the minimum fuel requirements needed when unencumbered by external loading may wind up being inadequate to the task when needing to tow external loads (increasing combined displacement) through jump. One way to deal with that issue to allocate (seemingly) "unnecessary" extra fuel in the class design to preemptively handle such edge cases, because there's no "rule" against allocating more than the minimum requirement of fuel to a design (for a variety of reasons, with extending operational endurance at the top of the list).



Anyway, all of that means that I need to go back to the drafting board and rework my Rule of Man class designs YET AGAIN to account for this "new" way of thinking about the "bridge requirement" for craft that are intended to tow external loads (routinely).

Another major side effect of doing this is that if it's equally applied to small craft and their bridges, that puts some pretty STRICT upper limits on how much external loading a small craft can "support" with their bridge ... and if the bridge is "too small" for the combined displacement being maneuvered, the bridge "stops counting" and the computer model number gets treated as being -1 (the "no bridge" computer only penalty). So either build the small craft with "enough bridge to handle the external load(s)" or suffer reduced computer efficiency due to the external load(s). This would add an additional design consideration to small craft that are intended to be combatant fighters with a secondary logistics role as an external load transporter (where their combat characteristics are SEVERELY reduced while externally loaded).

 

[kilemall]

I don’t recall bridge sizes being a thing for TCS jump tugs. Not sure about Battle Rider rules. Those would be the RAW guidelines I would think.

 

[Spinward Flow]

For simplicity, I've pulled my copy of LBB A5 and searched it for the word "tug" (zero references) and "tender" (nine references).

p9:

not every ship in the squadron must be fitted with drives to meet or exceed the required level, but fleet tenders or fighter carriers must be included which are capable of carrying those ships and craft which not fitted with the required jump drives.

p17:

Fleet Tenders: For any given ship tonnage, a ship which is not burdened with jump drives and jump fuel can be better armed and armored than a ship which must carry those jump drives. The concept of fleet tenders takes advantage of this fact. A fleet tender i s a large jump-drive equipped ship which carries several big craft, each of which is well-armed, well-armored, and usually fitted with high acceleration maneuver drives.

Fleet tenders are generally produced with dispersed structure hulls (configuration 7) in order to allow simultaneous launch of all craft carried immediately as the ship arrives in a system. Since the tender cannot skim gas giants for refueling, the ships it carries must contain sufficient fuel tankage to refuel the tender in a reasonable time; often they must be streaml,ined to allow them to gather fuel from oceans if there is no gas giant in the system they move to.

Example: One jump-4 configuration-7 fleet tender massing 200,000 tons. Approximately 100,000 tons of the ship is free to carry fighting ships; this tonnage is allocated to hold ten 10,000-ton battleships built around a primary meson gun, 6-G maneuver drives, and the best computers available.

p35:

Jump Failure: Ships unable to jump because of critical hits on their power plant, jump drive, computer, or bridge present a special problem. If the bridge or computer is out, another ship may be linked to it for jump; the linking ship must have a computer and bridge as least as large as that of the damaged ship, and linking takes one week. Both move at the jump rate of the slowest ship and maneuver is impossible while linked. Roll for breakdown of the link after every jump; repair takes another week. Ships whose power plants or jdrives have been destroyed must either be transported to a starport inside a tender or must be repaired in place. To repair a ship in place, first a message must be sent to a starport capable of repair; a new drive must be transported to the damaged ship; and it must be inserted, taking double the normal repair time (although not double cost).

I want to highlight something in that p35 quote.

must either be transported to a starport inside a tender

I'm highlighting this point because it makes abundantly clear (to me, at least) that when CT was being written, everything was thought of in terms of internal transportation. There were NO EXTERNAL TOWING rules for either LBB2.81 or LBB5.80 ... and even when something akin to external loading rules ought to have been created to deal with External Demountable Fuel Tanks along with L-Hyd Drop Tanks, the RAW just glosses over the important bits of detail and encourages Referees/Players to more or less "wing it" without any real guidance as to how the calculations (and considerations) ought to be handled.

And even then, external fuel tankage (demountable or drop) is mostly a "temporary" condition, rather than a permanent one, such that the extra fuel load "counts" for drive performance and remarkably little else (because it's just fuel, who cares?).



Which means that as far as spreadsheet math is concerned, Fleet Tenders (any size) were more or less intended to calculate the tonnage of their Battle Riders on the "internal stowage" side of the ledger ... even if the Battle Riders were "actually" docked externally onto the hull of the Fleet Tender (so that all the Battle Riders could be launched and recovered in a single combat round, because configuration: 7). By handling the spreadsheet accounting this way, Fleet Tender drive performance remains constant (codes do not go up when the Battle Riders are deployed, reducing overall tonnage, and codes do not go down when the Battle Riders are docked for transport, increasing overall tonnage).

It's pretty clear that this is how CT envisioned all starship designs working.
You could "put hulls INSIDE other hulls" just fine (using either a hangar bay and/or a cargo hold, difference being that a hangar could "launch/recover while in space" while a cargo hold could not) ... but there really weren't any RAW provided for how to "dock hulls OUTSIDE other hulls" and make them work together in CT.

Annic Nova does it with the twin pinnaces (kinda) ... but the "rules" for making Annic Nova maneuver around are kinda ... handwavy and are obviously not a starting point for a house rule of any kind.

The LBB S9 Jump Ship on p22-23 is rather explicitly meant to be an external loading starship meant to tow external loads (I mean, just look at the provided picture!) ... but the (too) hastily written rules for towing external loads do not make mathematical sense under LBB2.81 or LBB5.80 design paradigms, leaving a strong odor of "handwavium" that shouldn't be scrutinized too closely (lest the nonsense drive you mad).

So CT certainly DID have at least 2 canonized examples of external loading on starships ... both of which completely and utterly FAIL to provide any sort of guide or even sensible procedure to follow for making new starship designs intended to dock with and tow external loads (like modularized containers of a standardized form factor). Hence why I'm going to such lengths to work up the requisite ... rigor ... needed to house rule my way to necessary formulas and considerations, while doing so in a way that is respectful of the original source paradigms for how to do this kind of thing. I would prefer any kind of external loading starship design rules that I come up with to feel more like a logical extension of the design rules, rather than any kind of a "hatchet job" that can be exploited by munchkins and rules lawyered in bad faith by the unscrupulous (because we all know that such characters exist).

I have to extrapolate to "extend the map" into uncharted (design rules) territory, because I'm basically venturing into a "blind spot" for the RAW of CT, in order to create the necessary standards for what is (more or less) a variable hull displacement starship design that can dock with and tow external loads under maneuver drive and/or jump drive power. Neither LBB2.81 nor LBB5.80 are really set up to achieve that goal all that well, particularly since external fuel stuff came along "later" in the publication cycle, so I'm needing to consider all the factors required on my own and stress test them against min/max rules lawyering exploitation potential (because if I don't do it, someone else will).



Kind of like how "fast (drug) passage" wasn't really a "thing" in LBB2.81, but in hindsight obviously should have been.

 

[whartung]

Arguably the closest RAW gets to towing is the the dispersed structure hull. These were the typical tender ship design that could launch all of their ships at one go. It says the carried ships are mounted to the exterior. But, to me, I always felt that simply meant they weren't contained, rather than the ship was some kind of "ship" shape (i.e a box shape, or sphere, or anything else "ship" shape with other ships clicking on to it). Easy to visualize a framework style "hull" with the riders docked to ribs of the ship. More like the Aurora from TNE. It's basically drives, conduit, girders, and a box for the crew.

 

[Badenov]

Arguably the closest RAW gets to towing is the the dispersed structure hull. These were the typical tender ship design that could launch all of their ships at one go. It says the carried ships are mounted to the exterior. But, to me, I always felt that simply meant they weren't contained, rather than the ship was some kind of "ship" shape (i.e a box shape, or sphere, or anything else "ship" shape with other ships clicking on to it). Easy to visualize a framework style "hull" with the riders docked to ribs of the ship. More like the Aurora from TNE. It's basically drives, conduit, girders, and a box for the crew.

But critically, the exterior-mounted ships on distributed-config carriers were accounted for as part of the carrying ship's rated tonnage, so the calculations for engine size, bridge, and fuel are including the full volume, whether inside or outside. The difference with 'Towing' as published elsewhere, is that these factors are not considered (and I agree should be penalized some how). Now the arguement seems valid to me that if a towing ship does have large enough components, it's essentially operating as a dispersed-structure ship of the larger size (regardless of non-towing configuration, because a streamlined ship with another ship attached at a docking point is no longer streamlined). This is essentially redefining distributed carriers as 'towing' rather than 'carrying' subordinate craft with no change in how things are actually accomplished.

Side rant:
Even if both are streamlined, you will get unpredictable air currents between the vessels unless the connected structure is planned from the start to fly aerodynamically when assembled like a space-catamaran. Twin hulls can be built to fly through the air if designed for flying while attached, P-38 Lightning being the first example to come to mind. But you can't get that effect from two random hulls.

 

[Grav_Moped]

The other weirdness with LBB2 drives in variable-tonnage ships is the power plant fuel requirement.

My Impala (the LBB2-build for LBB2 combat version of the Gazelle) is a case in point. 200Td, but with 200Td of drop tanks.

Performance:
With tanks retained, 3G/J2/P3+an extra drive letter; can do two J2 plus 1J1.
With tanks ejected during Jump, J5
With tanks not installed, 6G/J0/P6+an extra drive letter
Note that underloading the power plant to Pn-2 (that is, not exceeding J2 or 2Gs) allows one J2 on internal tankage (TCS powerdown rule).

Now, the thing I didn't get into -- because it wasn't necessary -- is that with the 200Td of drop tanks attached, the ship was only Pn-3, and the 60Td of internal fuel would last 2 months instead of 1.

(Separately, idling back to Pn-2 lets you do 3J2 while keeping the tanks, under TCS powerdown rule.)

 

[Spinward Flow]

The other weirdness with LBB2 drives in variable-tonnage ships is the power plant fuel requirement.

My solution for getting around that problem (which, as you cite, was "unforeseen" in the LBB2.81 design paradigm and requires formulas to work, rather than lookup tables) is that the "clean" configuration/unencumbered by external loads hull form factor determines the Pn for fuel requirements.

The foundational notion is that the "unmodified" hull displacement sets the standard for fuel requirements and "baseline" drive performance.

So using your own Impala design criteria, the design requirements are for Pn-6 ... so with LBB2.81 drives, that means 60 tons of power plant fuel required (minimum).

Yes, when you add 200 tons of drop tanks to a 200 ton form factor hull, the overall drive performance drops from Pn-6 down to Pn-3 ... but the "extra displacement" doesn't modify the fuel consumption rate the way that you're thinking.

To explain, I'll need to resort to use of CT Beltstrike for fuel consumption formulas.



To simplify CT Beltstrike (for the purposes of conversation and illustration), there are 2 types of fuel consumption aside from jump.

1. Housekeeping/Basic Power (for life support, lighting, etc.)
2. EP Generation (for agility, maneuver, computers, weapons, screens, etc.)

Housekeeping power calculates out to being 1 ton of fuel per 2000 tons of (for our purposes, combined) displacement consumed per 7 days/1 week.

EP Generation power calculates out to being 0.35 tons tons of fuel per EP generated per 7 days.



So a 200 ton Impala class with a Pn-6 power plant + 1 extra drive letter above minimum would be mounting a Power Plant-G (since Drive-F is code: 6 @ 200 tons). LBB2.81 power plants generate 2 EP per drive letter ... so Power Plant-G would be generating 14 EP.



200 tons of housekeeping/basic power would require 0.1 tons of fuel per week ... and 14 EP would require 4.9 tons of fuel per week.
Total fuel consumption at max EP generation for 1 week = 0.1+4.9 = 5 tons of fuel per week when no external fuel tankage is mounted externally.

Adjust the (combined) hull displacement from 200 tons to 400 tons and you add +0.1 tons of fuel consumption per week to the housekeeping/basic power requirement in order to "power" the external fuel tanks (thermal regulation, fuel pumps, etc.).

So with an allocation of 60 tons of power plant fuel in the design, interplanetary endurance without external fuel tanks is:

• 60 / 5.0 = 12 weeks

But with the addition of external fuel tanks, the interplanetary endurance is:

• 60 / 5.1 = 11.76470588 weeks

Now, the thing I didn't get into -- because it wasn't necessary -- is that with the 200Td of drop tanks attached, the ship was only Pn-3, and the 60Td of internal fuel would last 2 months instead of 1.

That's because LBB2.81 (and LBB2.77 before it) didn't use formulas to calculate fuel consumption proportional to the hull size, so things "get wacky" below 1000 tons (and let's be honest, above 1000 tons as well!) using standard drives.

The thing is, even if the Pn changes because of a modification in (combined) displacement, the drives themselves ARE NOT CHANGING. The Pn code value is a convenience for combat resolution purposes rather than something that modifies fuel consumption rates. You don't have a "double the hull, halve the fuel consumption" phenomenon going on, just because you added external fuel tanks ... because that would be SILLY.

Yes, I know that the "structure" of the LBB2.81 lookup tables and fuel allocation formula suggests that the same drive letters in bigger hulls consume less fuel, because the Pn "yield" of those drives goes down as the hull size goes up, but that's essentially a function of the excessive oversimplification used in the presentation of details and information in the design sequence used in LBB2 (77 and 81).

The power plant fuel consumption formula for LBB2 (77 and 81) is basically "padded" in such a way as to force "extra endurance" onto ACS starship designs.



Take the classical 100 ton Type-S Scout/Courier, for example.

100 tons of hull requires 0.05 tons of fuel per week for housekeeping/basic power ... and Power Plant-A generates 2 EP which requires 0.7 tons of fuel per week to sustain.

• Maximum fuel consumption per week = 0.05+0.7 = 0.75 tons of fuel per week

At that rate of fuel consumption, 20 tons (minimum) power plant fuel will last for 20/0.75=26.66666667 weeks ... which for starship endurance purposes amounts to HALF A YEAR when Imperial calendar years are 52 weeks of 7 days duration, plus 1 day to make a 365 day calendar. Include a refuel at destination after jump and a Scout/Courier would have 40 tons of fuel capacity for maneuvering during an extended survey mission. Those 40 tons of fuel would be enough for 40/0.75=53.33333333 weeks of maneuvering @ 2G the entire time before needing to refuel again (and presumably jump back to base for an annual overhaul).

Presumably, a portion of the Scout/Courier's 3 ton cargo hold (or 2 tons if you bought the life support upgrade detailed in LBB S7) ought to be dedicated to consumable life support reserves so the crew+passengers can last that long without resupply.
Life support consumable reserves occupy 1 ton per 150 person/weeks and cost Cr150,000 ... which computes out to being the same price as the standard stateroom life support overhead expense of Cr2000 per 2 person/weeks (just add cargo hold requirement).

In other words, when using the fuel consumption formula from CT Beltstrike, a Type-S Scout/Courier has "ridonkulous" endurance on maneuver drive power alone (slightly over 1 year on a full fuel tank of 40 tons while generating 2 EP continuously), rather than "mere" 4 weeks of fuel endurance. That 40 tons of fuel (minimum) also gives the Type-S "some" margin of safety against collision/battle damage that hits the fuel tanks (which would be -10 tons of fuel per fuel hit).



As soon as you stop thinking of the 10Pn tons of power plant fuel as being a "this amount consumed in 4 weeks" fuel consumption rate ... and instead start thinking of the requirement as being more of a regulatory "safety" requirement that exceeds the amount of fuel consumed within 4 weeks, but which yields "about 4+ weeks of endurance" regardless of circumstances, it starts making a lot more sense. The 10Pn computation should wind up yielding 4 weeks MINIMUM power plant endurance, rather than yielding a 4 weeks EXACTLY result (every time).



Hope that makes sense to people.

 

[whartung]

But critically, the exterior-mounted ships on distributed-config carriers were accounted for as part of the carrying ship's rated tonnage, so the calculations for engine size, bridge, and fuel are including the full volume, whether inside or outside.

Indeed.

I think it can be argued that the ships docked with carrier are not just random boxes, but, perhaps, designed participate in the jump process. That is, assuming that the concept of a jump grid that's part and parcel to ship design, these riders snap into and interface with that grid so that under jump, while the ships are, technically, "outside" of the carrier, their hulls and jump grid components enable the total jump bubble projected by the carrier to enclose everything.

In contrast to a vast, enclosed bay which is essentially a huge, fully enclosed room. Anything can be in that bay, the existing hull is used to maintain the jump bubble.

This suggests that for these dispersed carriers, they can not just bolt anything and expect them to survive jump. You can't just make a 10,000 dton box and couple it to the carrier. The box must has some consideration for properly interfacing with the overall jump grid.

That doesn't mean the jump grid can't be dirt cheap (which is why it's not called out in the design sequence), maybe it is, maybe it's just a network of cabling built into the hulls. And we don't need to go digging into a bottomless hole about potentially damaged jump grids from combat damage.

I can see that a series of riders can be built to be compatible with a series of carriers, while at the same time, not letting any Tom, Dick, or Free Trader dock to one of these carriers. If you want universal carriage, stick it in a bay.

Finally, the primary benefit of this structure is simultaneous launch. Otherwise, just use a bay.

 

[Spinward Flow]

I think it can be argued that the ships docked with carrier are not just random boxes, but, perhaps, designed participate in the jump process.

Which is basically what I'm doing with my modular containerization research.

That is, assuming that the concept of a jump grid that's part and parcel to ship design, these riders snap into and interface with that grid so that under jump, while the ships are, technically, "outside" of the carrier, their hulls and jump grid components enable the total jump bubble projected by the carrier to enclose everything.

Depends on what you mean by "outside" really.

If you've got something akin to an "open frame" with open volume inside of it (for simplicity, think d12 that is just edges as structural trusses but no enclosing sides), you can move "stuff" inside the perimeter so it'll be "inside" the jump field, but which is technically "outside" (or at least separate from) the structural trusses of the tender's hull.

In contrast to a vast, enclosed bay which is essentially a huge, fully enclosed room. Anything can be in that bay, the existing hull is used to maintain the jump bubble.

The only real difference is "bulkhead walls" and pressurization defining an enclosed volume.
For the purposes of naval architect spreadsheet design accounting purposes, it's the difference between tonnage allocated INSIDE the hull (requiring what amount to hangar facilities) or tonnage allocated OUTSIDE the hull (meaning drive performance decreases when docking spaces are occupied). It's mainly a difference of accounting (in vs out) in the starship design sequence ... much like how External Demountable Fuel Tanks and L-Hyd Drop Tanks bolted on externally are supposed to "work" relative to internal integrated fuel tanks.

You can't just make a 10,000 dton box and couple it to the carrier. The box must has some consideration for properly interfacing with the overall jump grid.

As far as the spreadsheet math goes, it doesn't matter one bit.
As far as the Fluff Text™ and Simulation™ goes, it ought to matter a great deal ... but the RAW doesn't address the issue directly.

 

[Badenov]

Indeed.

I think it can be argued that the ships docked with carrier are not just random boxes, but, perhaps, designed participate in the jump process. That is, assuming that the concept of a jump grid that's part and parcel to ship design, these riders snap into and interface with that grid so that under jump, while the ships are, technically, "outside" of the carrier, their hulls and jump grid components enable the total jump bubble projected by the carrier to enclose everything.

In contrast to a vast, enclosed bay which is essentially a huge, fully enclosed room. Anything can be in that bay, the existing hull is used to maintain the jump bubble.

This suggests that for these dispersed carriers, they can not just bolt anything and expect them to survive jump. You can't just make a 10,000 dton box and couple it to the carrier. The box must has some consideration for properly interfacing with the overall jump grid.

That doesn't mean the jump grid can't be dirt cheap (which is why it's not called out in the design sequence), maybe it is, maybe it's just a network of cabling built into the hulls. And we don't need to go digging into a bottomless hole about potentially damaged jump grids from combat damage.

I can see that a series of riders can be built to be compatible with a series of carriers, while at the same time, not letting any Tom, Dick, or Free Trader dock to one of these carriers. If you want universal carriage, stick it in a bay.

Finally, the primary benefit of this structure is simultaneous launch. Otherwise, just use a bay.

I had it explained to me at some point as a sort of special mesh that is woven throughout the skin of the ship. The volume enclosed is what can jump, and the engines (M- and J-) have to be rated based on the volume that the mesh-size encloses. The thing about dispersed structures is that the mesh can link two ships by whatever mating couplings they use and the J and M drives operate on the collective combination of volumes.