OTU Only: A Funny Thing Happened on the Way from Collace

[Grav_Moped]

I've spent a little bit of time (ha!) working out the "Book 2 Loophole" ships for Tech Level 13, specifically with respect to Collace/District 268. These are the ships that LBB2 '81 allows that are TL-limited by LBB5. Collace could build them under LBB5's rule allowing indigenous naval procurement despite available starport facilities (LBB5 '81, p. 20 under Technological Level). Under the '77 rules, this wouldn't even be a challenge...

These ships are:
6Boat:
It’s possible at TL 12 to build a 400Td J6 Xboat using the "Xboat fuel loophole" (Jump fuel requirement, plus only 1 week power plant fuel at Pn 6 for the time in Jump). It's pretty darn cozy in there: the 6-man crew is in double-occupancy and there’s only 3Td left over for either cargo, message databanks, or a token maneuver drive (Size A for 0.5G) and 2Td fuel (24 Hrs at Pn 6). The design is entirely LBB2 ‘81 compliant aside from the power plant fuel allocation, but that’s a “cheat” that is more than supported in canon. (Click spoiler for explanation of the XBoat.)

Spoiler:

The canon XBoat is a straight ’77 rules design and broken by the ‘81 requirement to have a powerplant. Canon (S-9) says it needs no power plant fuel despite the rules change. It does work under the ’81 rules with 10Td (1 week only) of powerplant fuel, but the “extensive message transmission equipment and storage data banks” must be handwaved as being part of the bridge allotment since there’s otherwise no room left. If that’s unsatisfactory, 3Td for that equipment can be gained by reducing the single stateroom to a half-stateroom and the computer to a Mod/3bis (interpolated from the computers table). So, either “doesn’t need fuel” or “only 1 week of powerplant fuel” are valid “cheats” under the ’81 rules, in canon. The latter seems more in keeping with the “powerplant must match Jump drive” rule change.

Wait, 0.5G? That's not on the Drive Potential Table on p.22!

Spoiler:

Annic Nova had 0.1G from a pair of pinnaces acting as tugboats, which means fractional-G acceleration capability is allowed.

Game Effects: No agility in HG, 1/2G vector in LBB2, 1 hex acceleration must be irrevocably declared 1 turn in advance for Mayday.

Basically, it's useless in combat; instead, it's just for repositioning -- and that's on a boost-coast-decel course, given the limited fuel.

Further rules-lawyering and maybe a house-rule or two can make it a lot more interesting, but this is what you get without bringing in LBB 5, TCS, and LBB 8 (Robots).

Jump-5 in a 600Td Hull
Variants:
Basic Box Freighter: J5/Pn5/2G, 56Td cargo, 1 turret MLS. Crew: 8. Streamlined. Passenger quarters (and Steward, if desired) can be carved out of cargo space. Approx MCr 416.
Dropping MD to 1G frees up 6Td and saves 12MCr.

Yacht: As above, but with 3 turrets MLS. Streamlined. Crew: 11 including 3 gunners and a steward. 8 High Passengers. 1 pressurized, armed, and armored limousine (Cost and stats as G-Carrier). No Cargo. Approx: MCr 419.

Escort: As above, but J-5/Pn5/5G, 6 turrets (2 ea. MMM, 2 ea. LLL, 2 ea SSS), no passengers (but doubling up 5 engineers and 5 gunners frees up 5 staterooms if needed). 10Td cargo, no carried craft or vehicles. Streamlined. Approx. MCr456.

Anyhow... I went as far as figuring out procedures for the Yacht and its escorts. The Yacht always runs with 2 escorts. If there's any potential threat, the VIPs from the yacht get split between the Escorts as soon as the flotilla comes out of Jump (gunnery and engineering crews have to double-up to accommodate them). Once either under the destination's planetary defenses or back out at Jump Limit, the VIPs are re-transferred back to the Yacht. Officially the VIPs don't ever leave the Yacht... this secrecy is partly for operational security, and partly because the accommodations are embarrassingly déclassé.

At which point I checked the map of District 268 and Glisten Subsectors, and realized that Collace has no need for either a J-6 XBoat or a J-5 Yacht, let alone escorts for it!

The main destination for a message-boat network from Collace would be Glisten/Glisten -- which is 8 parsecs away. Neither J-6 nor J-5 can cross that faster than a standard XBoat. And there's nothing else in Collace's sphere of control worth a J-6 comms link, and little that would require a VIP delegation to use J-5.

*Sigh* The escorts might be useful for anti-piracy patrols. The 6Boats would be cool technology demonstrators, but mostly a waste of credits. The Yacht's just for "hey, we can build 'big' J-5 ships like we're TL-14!" bragging rights.

The 600Td J-5 freighter might be able to run TL-13 spec cargoes (computers, electronics, etc.) from Collace out to a 5-pc radius to Coreward or into Five Sisters Subsector profitably, though.

 

[AnotherDilbert]

It’s possible at TL 12 to build a 400Td J6 Xboat using the "Xboat fuel loophole" (Jump fuel requirement, plus only 1 week power plant fuel at Pn 6 for the time in Jump).
...
Canon (S-9) says it needs no power plant fuel despite the rules change.

So, either “doesn’t need fuel” or “only 1 week of powerplant fuel” are valid “cheats” under the ’81 rules, in canon.

No.

The X-boat "cheat" is to have no power plant, and hence no power plant fuel requirement. That is arguably legal in LBB2'77 if you squint hard enough, but certainly not in LBB2'81 or either HG. Note that it pays for it with a severely limited life support endurance.

A ship certainly cannot have an M-drive without a power plant to power it.

Wait, 0.5G? That's not on the Drive Potential Table on p.22!

No.

The result for an A drive in a 400 Dt hull is "-".
That is a clearly defined result:

It is important to note from the drive potential table that some drives will not produce results in some tonnages of hulls, as indicated by a dash instead of a number on the table; ...

Annic Nova had 0.1G from a pair of pinnaces acting as tugboats, which means fractional-G acceleration capability is allowed.

Another LBB2'77 artefact; note that drives in LBB2'77 are reaction drives. I can't find anything in the rules about allowing, or disallowing, strapping a rocket or other reaction drive to the hull for a bit of extra push.

Of course it would work, but it is extremely limited and ineffective compared to a gravitic M-drive.



Sorry to be a buzzkill, but what you have found is not a grey area, it's clearly outside the rules.

You can house-rule anything you want, of course...

 

[AnotherDilbert]

6Boat:

Something like this is legal in LBB2'77, but obviously not in LBB2'81:

QN-43611R1-000000-00000-0        MCr 193         400 Dton
bearing                                            Crew=6
batteries                                           TL=12
                         Cargo=30 Fuel=250 EP=4 Agility=1

Single Occupancy    LBB2 design                      30       193
                                     USP    #      Dton      Cost
Hull, Part Streaml  Custom             4            400          
Configuration       Cylinder           3                       40
                                                                 
                                                                 
Jump Drive          M                  6    1        65       120
Manoeuvre D         B                  1    1         3         8
Power Plant         B                  1    1         7        16
Fuel, #J, #weeks    J-6, 4 weeks            6       250          
                                                                 
Bridge                                      1        20         2
Computer            m/1bis             R    1         1         4
                                                                 
Staterooms                                  6        24         3
                                                                 
Cargo                                                30          
                                                                 
                                                                 
Nominal Cost        MCr 193              Sum:        30       193
Class Cost          MCr  40,53          Valid        ≥0        ≥0
Ship Cost           MCr 173,7                                    
                                                                 
                                                                 
Crew &               High     0        Crew          Bridge     2
Passengers            Mid     0           6       Engineers     3
                      Low     0                     Gunners     0
                 Extra SR     0      Frozen         Service     1
               # Frozen W     0           0          Flight     0
                  Marines     0                     Marines     0

 

[Grav_Moped]

No.

The X-boat "cheat" is to have no power plant, and hence no power plant fuel requirement. That is arguably legal in LBB2'77 if you squint hard enough, but certainly not in LBB2'81 or either HG. Note that it pays for it with a severely limited life support endurance.

A ship certainly cannot have an M-drive without a power plant to power it.

Yes. Did you read the entire spoiler? A 100Td XBoat actually works under LBB2 '81 with a powerplant B and 50Td fuel.
Breakdown behind spoiler:

Spoiler:

Component:     Tons:
Bridge          20  ("Mail server" replaces M-Drive control elements of bridge)
Mod/4            4
1 Stateroom      4  ('77 version had 2 staterooms.)
JD B            15
PP B             7
Jump Fuel       40
P'plant Fuel    10 (Just enough for Pn 4 during 1-week Jump, no extra.)
Total:          100

The point is, the XBoat as functionally described (100Td, J-4/0G, pilot only, does one J-4 and nothing else) can be legally built with LBB2 '81.
If you don't like the "databanks are part of the bridge" handwave, put the pilot in a half-stateroom to free up 2Td for the mail server.

It just can't be built as literally described (2 staterooms, 9Td of data banks, and neither a power plant nor fuel for it).

The fact that it can be built under LBB2 '81 as described above is justification for other ships with the same mission profile (one Jump and no fuel margin outside of that, serviced by tenders at both ends of the Jump).

No.

The result for an A drive in a 400 Dt hull is "-".
That is a clearly defined result:
...
Another LBB2'77 artefact; note that drives in LBB2'77 are reaction drives. I can't find anything in the rules about allowing, or disallowing, strapping a rocket or other reaction drive to the hull for a bit of extra push.

Of course it would work, but it is extremely limited and ineffective compared to a gravitic M-drive.

....

Sorry to be a buzzkill, but what you have found is not a grey area, it's clearly outside the rules.

You can house-rule anything you want, of course...

Yes. (Mostly). (And it's not that important for the base 6Boat, since for that it's just an answer to "why DON'T XBoats have maneuver drives?" This one does.)

LBB5 '81 states that 1G maneuver is available at TL-7, before any gravitic drives are possible. So, a TL-7 MD has to be a reaction drive, and any 1G or lower MD can be a reaction drive. Fuel burn rate is from the power plant requirement (this is a flaw in LBB5 -- reaction drives should take more fuel, but don't).

Annic Nova establishes that a small-craft with reaction drives can push a 600Td ship at fractional Gs, and therefore a small-craft reaction drive can do the same.

Minimum drive size from LBB5 is 1Td. The formula underlying the LBB5 MD Drive Potential Table formula is P=(3xG)-1, where P is the percent of tonnage required for a maneuver drive capable of acceleration of G. (Demonstration behind spoiler)

Spoiler:

Gs    Percent   
1         2          (3x1)-1=2
2         5          (3x2)-1=5
3         8          (3x3)-1=8
4         11         (3x4)-1=11
etc.

Solve for G, set P=0.25 percent, and a 1 Td maneuver drive yields 0.42G in a 400Td hull. (Math behind spoiler)

Spoiler:

P=(3xG)-1 is equivalent to (P+1)/3=G
In this case, P=.25 percent (i.e. 1/400), so
(.25+1)/3= 0.4167 Gs acceleration.

For fun, try figuring out what size a 1/4G drive comes out at.
(Hint: a 1/3G drive takes up 0Td.)

And, again, fuel burn rate is based on powerplant requirements -- which are much worse for LBB2 powerplants in this size range than LBB5 ones. Even then, Pn 6 in a 400Td hull only uses 2Td/day.

Of course you could argue that this is mixing LBB2 and LBB5 drives, but Annic Nova's setup argues otherwise. The clear intent of the no-mixing rule is to prevent building ships with Jump Drives from LBB5 but maneuver drives from LBB2 (and cherry-picking powerplants based on fuel requirements or drive tonnage).

Something like this is legal in LBB2'77, but obviously not in LBB2'81:

QN-43611R1-000000-00000-0        MCr 193         400 Dton
bearing                                            Crew=6
batteries                                           TL=12
                         Cargo=30 Fuel=250 EP=4 Agility=1
...

I said up front that doing it in LBB2 '77 isn't a challenge.

 

[Grav_Moped]

And to clarify: Having a fractional-G maneuver drive is basically for self-rescue.
It's the "Um... hey, guys... isn't there supposed to be a tender here waiting for us? Hello?" scenario.

In that event:
1. Set ballistic course for mainworld, make the initial burn.
2. Crew packs into single stateroom and takes Fast Drug
3. Power down everything except life support for that one stateroom
4. Coast to mainworld (this may take a while, hence the Fast Drug...)
5. Fast Drug either wears off or antidote is administered by timed injection
6. Power up to decelerate and put ship into orbit around mainworld
7. Power ship down again for long-term parking
8. Crew lands using grav belts

It's not cheap or pleasant, but it may be the only way out and down.
Cr617,400 for the whole crew (Cr100,000 per grav belt, Cr 2900 for individual doses of Fast and Fast Antidote).

 

[boomslang]

The 600Td J-5 freighter might be able to run TL-13 spec cargoes (computers, electronics, etc.) from Collace out to a 5-pc radius to Coreward or into Five Sisters Subsector profitably, though.

I am not seeing the need for speed, though, either for Collace's traders or her couriers.

A tried-and-true, TL11, LBB2-standard, 400dt, J-5 courier could easily transit through Egypt/Glisten (or Binges/D268, if desired) to Glisten/Glisten in two Jumps; anything faster still will not get you or the Mail to the hub at Glisten Belt any sooner.

Jump-3 gets a starship from Collace to Dallia/D268 in a week, and leaves more room for more cargo.

Given that the OTU does not charge haulage rates (for either passengers or freight) by the parsec but rather by the jump-week, a Jump-5 "Freighter" might better be characterized as you later implicitly describe it: a Jump-5 Trader. There is no point in building a Jump-5 Freighter in the OTU; a much, much cheaper to build and operate Jump-1 Freighter can generate five times as much revenue (admittedly taking five times as much time) over the same route.

The pressure on Traders, however, is to get the self-financed goods from the sourceworld to a lucrative marketworld before basic operating expenses are allowed to consume the entire profit margin. So speed is a factor there, but low costs are as well.

 

[Grav_Moped]

The other way to do a "real" maneuver drive in the 6Boat is to install a Size B unit (3Td, MCr 8) for 1G acceleration. It would fit, and it would work... with one major problem:
If you use it at all, the ship no longer has enough fuel for a Jump-6, and can only do J-5! If used for more than 24 days, the ship only has enough fuel left for a Jump-4. (This is before invoking the TCS power-down rule, but even then any M-Drive use still drops the ship below minimum "J-6 plus 1 week of Pn 6" fuel.)

Mechanically, it would work. In the OTU, constructing a ship with those constraints may not be authorized.

This would be used for logistical repositioning outside of the 6Boat network (such as returning to a depot by the most direct route, or getting into place for a J-6 leg of a route covered by a mix of J-5 and J-6 ships).

Basically, the operator has to choose (before Jump) between it being a J-6 Xboat or an ordinary ship with an oversized Jump Drive that can do Jump-5.

 

[Grav_Moped]

I am not seeing the need for speed, though, either for Collace's traders or her couriers.

A tried-and-true, TL11, LBB2-standard, 400dt, J-5 courier could easily transit through Egypt/Glisten (or Binges/D268, if desired) to Glisten/Glisten in two Jumps; anything faster still will not get you or the Mail to the hub at Glisten Belt any sooner.
...

You only need Jump-4 for that. (200Td, TL-10 for the Mod/4 computer. Or, you know, the canonical XBoat.)

This was exactly the "funny thing that happened" of the thread title. All that spreadsheet work, and it turns out that Collace wouldn't have any use for them! *sigh*

The pressure on Traders, however, is to get the self-financed goods from the sourceworld to a lucrative marketworld before basic operating expenses are allowed to consume the entire profit margin. So speed is a factor there, but low costs are as well.

The other thing is that Collace could build Jump-4 ships as big as they want to... under LBB5. (Within reason, of course. This is Navy procurement, not Class A Shipyard production.)

My point in this was to see what the LBB2 edge cases look like. While they are nifty, it turns out that they're not particularly necessary.

 

[AnotherDilbert]

Yes. Did you read the entire spoiler? A 100Td XBoat actually works under LBB2 '81 with a powerplant B and 50Td fuel.

The point is, the XBoat as functionally described (100Td, J-4/0G, pilot only, does one J-4 and nothing else) can be legally built with LBB2 '81.

No, since under LBB2'81 rules it would require a PP-4 (and fuel) to go with JD-4.

The fact that it can be built under LBB2 '81 as described above is justification for other ships with the same mission profile (one Jump and no fuel margin outside of that, serviced by tenders at both ends of the Jump).

But it is clearly not correct under LBB2'81 rules, only (arguably) under LBB2'77 rules.

LBB5 '81 states that 1G maneuver is available at TL-7, before any gravitic drives are possible.

Using the LBB2 system the TL requirements are defined by the table in LBB3, p15. An A drive (of any type) is a TL-9 component.

So, a TL-7 MD has to be a reaction drive, and any 1G or lower MD can be a reaction drive. Fuel burn rate is from the power plant requirement (this is a flaw in LBB5 -- reaction drives should take more fuel, but don't).

LBB2'81 and HG'80 M-drives very specifically do not use any fuel or propellant, hence they cannot be reaction drives. That is one of the major differences between LBB2'77 and LBB2'81.

Annic Nova establishes that a small-craft with reaction drives can push a 600Td ship at fractional Gs, and therefore a small-craft reaction drive can do the same.

Annic Nova is as far as I know an alien ship not using the standard system. But, OK, pushing other ships is a reasonable house-rule.

Solve for G, set P=0.25 percent, and a 1 Td maneuver drive yields 0.42G in a 400Td hull.

But Annic Nova does not use that formula, but a much worse arbitrary 0.1 G.

Presumably a LBB2'77 style pinnace has an M-drive A giving a 200 Dton ship 1 G, a 40 Dton craft 5 G, or a 600 Dton hull about ¹/₃ G. Still the pinnace can only push Annic Nova at 0.1 G using 6 Dton fuel per hour.

Of course you could argue that this is mixing LBB2 and LBB5 drives, but Annic Nova's setup argues otherwise. The clear intent of the no-mixing rule is to prevent building ships with Jump Drives from LBB5 but maneuver drives from LBB2 (and cherry-picking powerplants based on fuel requirements or drive tonnage).

I see no such blanket ban in HG'80. The rules say you can use LBB2 drives, it does not say you have to use only LBB2 drives in such case.

Custom-built drives must be produced and installed while observing restrictions as to tech level and interior space. It is possible to include standard drives (at standard prices) from Book 2 if they will otherwise meet the ship's requirements; such drives use fuel as indicated by the formulas in Book 2.

An even worse exploit is of course that standard (LBB2 lettered drives) are apparently exempt from TL limitations.

 

[AnotherDilbert]

And to clarify: Having a fractional-G maneuver drive is basically for self-rescue.
It's the "Um... hey, guys... isn't there supposed to be a tender here waiting for us? Hello?" scenario.

It would prove to be impractical at least in the Annic Nova case, since 0.1 G for an hour or two would often not be enough velocity to match vectors with the target planet or star.

Both planets and stars can be expected to have velocities in the tens of km/s relative each other. 0.1 G for an hour is just 3.6 km/s.

You would often either fail to catch up with the planet or crash into it at speed...

 

[Grav_Moped]

No, since under LBB2'81 rules it would require a PP-4 (and fuel) to go with JD-4.

The breakout behind the spoiler shows that it included a PP-B. The space for the fuel and powerplant come from removing one of the two staterooms and the 9Td of "data banks"

One more time, out of the spoiler but with emphasis added:

Component:     Tons:
Bridge          20  ("Mail server" replaces M-Drive control elements of bridge)
Mod/4            4
1 Stateroom      4  ('77 version had 2 staterooms.)
JD B            15
[B]PP B             7  <-----[/B]
Jump Fuel       40
P'plant Fuel    10 (Just enough for Pn 4 during 1-week Jump, no extra.)
Total:          100

The point is, the XBoat as functionally described (100Td, J-4/0G, pilot only, does one J-4 and nothing else) can be legally built with LBB2 '81.
If you don't like the "databanks are part of the bridge" handwave, put the pilot in a half-stateroom to free up 2Td for the mail server.

But it is clearly not correct under LBB2'81 rules, only (arguably) under LBB2'77 rules.

Which is sort of the point. As I said in that spoiler:

It just can't be built as literally described (2 staterooms, 9Td of data banks, and neither a power plant nor fuel for it).

In other words, this is as much of the '77 version as can be salvaged under the '81 rules. It obeys the matching-powerplant and powerplant-fuel-rate rules at the expense of the implied "computers are huge" concept. The only other option is to declare that the XBoat can do something -- not use a powerplant during Jump -- that no other ship except maybe Annic Nova can do (after 1981). Or build it under LBB5 '80 -- but then it's TL-13, not TL-10.

Using the LBB2 system the TL requirements are defined by the table in LBB3, p15. An A drive (of any type) is a TL-9 component.



LBB2'81 and HG'80 M-drives very specifically do not use any fuel or propellant, hence they cannot be reaction drives. That is one of the major differences between LBB2'77 and LBB2'81.

The drives themselves do not use fuel. They require support from a powerplant that does use fuel, however -- and did in '77, too.

Did HG '80 make grav drives available at TL-7 without telling anyone? If not, then TL-7 maneuver drives cannot be grav drives, but their powerplant fuel requirements are the same. Again, this is a glitch in LBB5, but probably left unnoticed since players never bothered building TL-7 fleets because why would you?

Annic Nova is as far as I know an alien ship not using the standard system. But, OK, pushing other ships is a reasonable house-rule.



But Annic Nova does not use that formula, but a much worse arbitrary 0.1 G.

Presumably a LBB2'77 style pinnace has an M-drive A giving a 200 Dton ship 1 G, a 40 Dton craft 5 G, or a 600 Dton hull about ¹/₃ G. Still the pinnace can only push Annic Nova at 0.1 G using 6 Dton fuel per hour.

The pinnace is using the exhaust from a small-craft powerplant to feed its reaction drive. The 6Boat is feeding it with the output from a Size M Power Plant that uses 1/6Td per hour.

I see no such blanket ban in HG'80. The rules say you can use LBB2 drives, it does not say you have to use only LBB2 drives in such case.

That's a fair reading. If this use case needed a full fuel loadout (it doesn't, and it wouldn't fit anyhow) then the 11Td larger TL-13 PP from LBB5 would be worth the 36Td power plant fuel savings. In this case, the drive size is the limiting factor, so it isn't.

An even worse exploit is of course that standard (LBB2 lettered drives) are apparently exempt from TL limitations.

BINGO! This here is the entire point of this whole exercise. (LBB2 '81 allows J-6 at TL-12 as an edge case, and J-5 up to 600Td at TL-13).

The closest thing to a TL limitation in LBB2 (and not in the '77 version) is that the Model/4 is TL-10 so a TL-9 XBoat, though build-able, could only do J-3.

It's a different paradigm. LBB2 is "bigger is better, and higher TL enables bigger". LBB5 is "higher tech is always better in any size."

The way the game implemented these two different paradigms apparently allows exceptions to the blanket TL requirements of LBB5. Exceptions are interesting.

 

[Grav_Moped]

Exceptions are interesting.

The HG Jn by TL rules and LBB2's exceptions thereto: ('81 rules)
TL 9: J1; except J2-3 possible for 100-200Td (note: constraint is computer, drives can be J4)
TL 10: J1; except J4 possible for 100-400Td, J3 100-600Td, J2 up to 800Td
TL 11: J2; except J5 possible for 200-400Td, J4 100-400Td, J3 100-600Td
TL 12: J3; except J6 possible for 400Td, J5 200-400Td, J4 100-600Td
TL 13: J4; except J6 possible for 400Td, J5 200-600Td
TL 14: J5; except J6 possible for 400-600Td
TL 15: J6, all hulls but you still can’t get J6 into a 100Td hull (that needs about 130Td)

Note that the following ships are "XBoats" (no maneuver drive, and just enough fuel to run the powerplant for the week in Jump, and needing support from tankers/tenders at both ends of a Jump):
J-4, 100Td (TL-10 through 12)
J-5, 200Td (TL-11 through 13)
J-6, 400Td (TL-11 through 14)

J-4 in a 200Td hull (TL-10), J-5 in a 400 or 600 Td hull (TL-12 & 13), and J-6 in a 600Td hull (TL-14) have full 4-week powerplant fuel allocations and room for maneuver drives.

 

[AnotherDilbert]

The breakout behind the spoiler shows that it included a PP-B. The space for the fuel and powerplant come from removing one of the two staterooms and the 9Td of "data banks"

But you obviously don't have enough fuel according to RAW, so it is not a correct LBB2'81 design:

At a minimum, ship fuel tankage must equal 0.1MJn+10Pn, where M is the tonnage of the ship, Jn is the ship's jump number, and Pn is the ship's power plant rating.

Minimum = 0.1 × 100 × 4 + 10 × 4 = 80 Dt of fuel tankage.


If you just want to keep the X-boat it can easily be built under LBB5'80 rules at TL-13+, no added house-rules or loopholes necessary.

Did HG '80 make grav drives available at TL-7 without telling anyone?

Yes, quite clearly and openly it made gravitic m-drives and fusion power plants available at TL-7. And they still are in T5 and MgT using tech stages.




The X-boat is clearly not possible under LBB2'81 RAW. If you just want to house-rule something reasonable why don't you skip the power plant and run the ship off batteries? It's not allowed by RAW, but if we are house-ruling anyway...

By LBB5'80 we know how capacitors work, and how much power the jump drive needs from the power plant or capacitors (in addition to jump fuel). A 100 Dt ship performing J-4 needs 8 EP IIRC.

Since a PP-1 (1 EP) can happily support enough power for life-support etc while still powering M-1 (using 1 EP), the life-support usage can't be all that much. Let's assume it's a tenth of PP-1 (0.1 EP = 25 MW for a 100 Dt ship), that is enough for a small town by current standards so perhaps not unreasonable (the ISS seems to have about 0.1 MW available).

8 EP for the jump plus 0.1 EP every 20 minutes for 10 days is 8 + 0.1 × 3 × 24 × 10 = 80 EP. Since capacitors can store 36 EP per Dt that is about 2.2 Dt capacitors at MCr 8.8 needed for an X-boat as a bare minimum.


But if you allow that who knows what other ships might use the same loophole and you might have obsoleted all standard designs and wrecked the economic model for small ships.

You can of course house-rule whatever you feel like, but remember:

Adaptations to the jump and maneuver drive systems and to our concept of jump space should be made only with care and consideration. The effects of modifications to these areas are wide-reaching and touch almost every rule in one form or another.

- Do not expect other Traveller materials to match your universe if you engage in large-scale modifications.

 

[Grav_Moped]

The problem I'm seeing here is that you're taking a game-play driven rule and treating it as a universe-defining constraint.

Jump Drives using 10% of tonnage in fuel per parsec is a universe-defining constraint.
Power plants using 2.5 tons of fuel per week per Pn (or 0.25% of tonnage per week per Pn, depending) is one too.
Power plants needing four weeks of fuel isn't such a constraint. It might be a best practice, it might be legally required in-universe, but there's no (fictional) physics reason that 4 weeks supply exactly is necessary.

For a practical example:
Take a Type A Free Trader and install internal demountable fuel tanks holding 60 tons of fuel (enough for 3 extra Jump-1s, for a total of four -- 90 tons fuel overall). Top it off from a tanker at the 100D limit, and have it do four consecutive Jump-1s (as in crossing a 4-parsec rift). This will take 4 weeks, so the power plant will sputter out due to fuel starvation just as the ship drops out of its fourth jump.* This ought to match rules-as-written. If it doesn't, why not?

Now, consider the fourth jump in that run. After the third jump, the Free Trader has 22.5 tons of fuel left, having burned 60 tons in the Jump Drive and 3/4 of the 10 tons of power plant fuel (7.5 tons). Again, this matches rules-as-written. If it doesn't, why not?

The fourth jump uses 20 tons of fuel for the Jump Drive, and the last 2.5 tons for the power plant. If it doesn't, why not?

Take that same ship and the same tanker at the 100D limit. This time, the Free Trader starts with empty tanks, and only gets 22.5 tons of fuel from the tanker. Can it do a Jump-1, burning the last wisps of its fuel as it leaves Jumpspace? If not, why not?

Once more: same ship, same tanker, same 100D limit. Strip out the demountable tanks and put a 7.5 Td block of cheese** into the main tank so that it only holds 22.5 tons of fuel. Fill the tank up from the tanker, and jump. How is this different from the previous example?

What rule has been broken here?†



The 10 tons per Pn (or) 1 ton per EP rules are the answer to a different kind of question (actually, two answers) than "how much fuel does the Jump Drive use?"
It's the answer to, "What's a good amount of fuel to set aside for the powerplant?' That answer: "Four weeks worth, so you practically never have to think about it during gameplay. And here's how much that is in tons." The follow-up question, "But what if I'm ok with tracking fuel use and making difficult decisions to manage limited resources?" isn't addressed in the rules, probably because the goal was simplified gameplay.

So, the alternatives in Second Edition are:
1. The XBoat never existed, as the three weeks of extra of powerplant fuel it MUST carry but will never use make it impossible to build. (If you're not allowing LBB5.)
2. The XBoat has always been TL-13 (LBB5 '80) rather than TL-10 (LBB2 '81). It would have room for a maneuver drive, so it may not be the canon XBoat.
3. The Second Edition LBB2 & LBB5 requirement of Pn=Jn is... optional?
4. For specialized use cases, ships can be built with razor-thin powerplant fuel margins while still adhering to the fuel use rates in LBB2 or 5 as applicable.

The fourth alternative does the least damage to the rules and the OTU canon. IMO, it doesn't even break the rules.




*You did send someone on ahead to tell 'em to expect you and have a tanker standing by when you arrived, didn't you?

**Because cheese is funny, that's why. Could be aluminum instead, could just be a bulkhead blocking off 7.5Td of the tank. You get the idea.

†There is no rule prohibiting putting a 7.5Td block of cheese into your ship's main fuel tank. I checked.
(Unrefined cheese may be problematic. Removal of the aforementioned 7.5Td block of cheese from the main fuel tank is left as an exercise for the student.)

 

[Grav_Moped]

Done editing, finally. (Bump).

 

[mike wightman]

The folks at GDW never worried about the rules getting in the way of the setting.

Dig out S:9 and check the entries for the scout and the x-boat.

They are both TL9, which contradicts the HG drive TL paradigm but conforms to the LBB drive TL paradigm, and the x boat has no pp or md which conforms to 77CT.

To finally get around to my point. the folks at GDW changed the rules regularly, but the setting was an interpretation that doesn't actually follow the rules as written and so rule changes rarely if ever actually affected the setting.

 

[Grav_Moped]

The folks at GDW never worried about the rules getting in the way of the setting.

Dig out S:9 and check the entries for the scout and the x-boat.

They are both TL9, which contradicts the HG drive TL paradigm but conforms to the LBB drive TL paradigm, and the x boat has no pp or md which conforms to 77CT.

To finally get around to my point. the folks at GDW changed the rules regularly, but the setting was an interpretation that doesn't actually follow the rules as written and so rule changes rarely if ever actually affected the setting.

Yep. They ignored that the rule changes broke those ship designs, because why let rules get in the way of a good story?

What that tells me is that the second edition changes were not done with the intent to prohibit the XBoat. There are a lot of potential ships that those changes intentionally precluded (for example, 400Td J-6/2G/Pn 2 with space left over), but that wasn't one of them. Hence, my effort to retcon the XBoat to align with LBB2 '81.

Something had to give, since it couldn't include everything from the '77 design. I kept the "big engines and a big fuel tank in a tiny hull that does J4, with just enough room for the pilot", which is what the XBoat represents. The powerplant went in because that's what the new rules said. I sacrificed the passenger stateroom and "big data banks" because they weren't central to the concept (especially looking at it from here in 2020 instead of the '80s -- Moore's Law and all that). And of course I left out the three extra weeks of powerplant fuel that an XBoat wouldn't need for getting to and from Jump Limit and maybe over to a gas giant to refuel (that's why there are XBoat Tenders!) Somehow, it all fit.

And since it does work under the current (for CT, anyhow) rules, I'm ok with using deckplans based on the earlier version because it's a game, not a simulation. Mostly.

 

[AnotherDilbert]

The problem I'm seeing here is that you're taking a game-play driven rule and treating it as a universe-defining constraint.

There are no universe-defining constants defined in CT ship design, only gamey game rules.

There are no definitions of what a power plant is or how it works, just that it is a black box that consumes fuel (hydrogen) and produces power. You might assume fusion is involved, but the rules can neither confirm nor deny.

Power plants using 2.5 tons of fuel per week per Pn (or 0.25% of tonnage per week per Pn, depending) is one too.

There is no definition of how much fuel is consumed per hour or week under different conditions in CT, only a hard game rule that says that you need a specified amount of fuel tankage and that "The stated fuel tonnage supports four weeks cruising (including time spent in jump space) before refuelling is necessary" or "Power plant fuel under the formula (10Pn) allows routine operations and maneuver for four weeks", i.e. normally the fuel lasts four weeks, but under unusual usage conditions it might last longer or shorter.

If you want that level of detail you have to turn to later editions such as MT or TNE.

For a practical example:
Take a Type A Free Trader and install internal demountable fuel tanks holding 60 tons of fuel (enough for 3 extra Jump-1s, for a total of four -- 90 tons fuel overall). Top it off from a tanker at the 100D limit, and have it do four consecutive Jump-1s (as in crossing a 4-parsec rift). This will take 4 weeks, so the power plant will sputter out due to fuel starvation just as the ship drops out of its fourth jump.* This ought to match rules-as-written. If it doesn't, why not?

It is not defined to that level of detail. A jump does not last exactly a week, but about a week, plus some time between jumps to maintain the jump drive and calculate a new jump, neither of which has a defined time set.

Normally it takes a few hours or days to travel to or from a world, so you have plenty of time before and after the jump for such tasks, hence no exact duration needed.

I would say it is likely that the fuel will run out before the fourth jump is complete, and that the ship will emerge with the crew cold, dark, and gasping for air, or perhaps dead...

Three jumps are probably OK though.

Now, consider the fourth jump in that run. After the third jump, the Free Trader has 22.5 tons of fuel left, having burned 60 tons in the Jump Drive and 3/4 of the 10 tons of power plant fuel (7.5 tons). Again, this matches rules-as-written. If it doesn't, why not?

The rules don't specify fuel consumption or jump duration in that detail, so you can't say that the rules specify exactly how much fuel you have left in that situation. If you try, the Referee has to make his own mind up, or perhaps roll a few dice?

Once more: same ship, same tanker, same 100D limit. Strip out the demountable tanks and put a 7.5 Td block of cheese** into the main tank so that it only holds 22.5 tons of fuel. Fill the tank up from the tanker, and jump. How is this different from the previous example?

What rule has been broken here?†

By RAW you no longer have enough fuel tankage.

By the Starship Economics chapter in LBB2 stuff (aka cargo) go in the cargo hold, people go in the "staterooms", and fuel go in the fuel tanks.

But I agree there is no specific rule against stuffing cheese in the fuel tanks, and it would probably be physically possible, but just as with a current car or ship I would not expect the craft to work normally or have the same fuel capacity after stuffing foreign substances in the tanks.

 

[AnotherDilbert]

And since it does work under the current (for CT, anyhow) rules, I'm ok with using deckplans based on the earlier version because it's a game, not a simulation. Mostly.

I think the point is that as Referee you can make anything you like work, but as a player you can't expect that to work the same in someone else's campaign.

You can probably expect the normal rules to work as usual, unless the Referee says something else.

So, if you build a ship according to RAW, you can probably use it in most campaigns, but if you build something like the Annic Nova you can't expect to use it without specific Referee blessing.

 

[mike wightman]

Something was ferreting away at the back of my mind and here it is, from the CT boxed adventure Beltstike and applies to LBB2 designed ships:

fuel Is the other factor. Fuel use during a prospecting and mining
expedition is significantly lower than in normal operations, since
constant acceleration is rarely undertaken.
The fuel consumption table on page 11 shows the requirements
of various types of maneuvering in terms of fuel use per hundred
tons of ship. Basic power is used at all times, including when
maneuvering. Every maneuver (matching course with an asteroid,
for instance) uses at least one hour's fuel at the 1G rate. The referee
and/or players should keep track of a ship's fuel supplies: the ship
should not be permitted to run out of fuel. It is possible to refuel
by locating ice chunks, skimming gas giants, etc.
Players will soon learn about fuel conservation, as they find that
each check of an asteroid burns needed fuel and shortens the expedition
by that much more.

and there is this event occurrence:

Excess Fuel Use: fuel use has been higher than necessary, due
to wasteful maneuvering. Subtract 1D x .001 tons from the ship's
remaining fuel.

Sadly I do not know how to post the fuel use table from page 11, but it gives the fuel consumed for daily/weekly basic power - 0.007per day or 0.05 per week, this is per 100t of ship but power plant number doesn't affect it.
Maneuver costs 0.002 tons of fuel per g per 100 tons of ship per hour, or 0.05 tons of fuel per g per 100t of ship per day and finally 0.35 tons of fuel per g per 100t of ship per week.