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-   -   Re-imagining the Book-2 drives (http://www.travellerrpg.com/CotI/Discuss/showthread.php?t=38294)

Carlobrand September 30th, 2017 12:13 AM

Re-imagining the Book-2 drives
 
•The Scout/Courier, Free Trader, and Subsidized Merchant benefit from a standardized hull. Typically these hulls are not new construction but, taking advantage of their ubiquity, are recycled from older ships that have been scrapped. Their hull cost therefore reflects the builder's cost to acquire the hull and remove its contents, less any scrap value for the contents.

•The TL9 Model A maneuver drive is a 3dT gravitic thruster producing 2025 metric tons thrust, sufficient to provide 1.01G to a typical 200 dT ship. Its chief advantage is low power consumption: it requires only 202.5 Mw power to deliver the needed thrust, which leaves power available for other needs (such as a laser). Its chief disadvantage over the traditional maneuver drives is that, as a thrust-based propulsion drive, it sets an upper limit on ship mass: the 200 dT free trader is limited to a maximum 1000 metric tons of cargo - less on heavier worlds, more on lighter worlds - in order to maintain 1G, or it can only travel from orbit to orbit while moving at reduced acceleration.

(Maximum load is world-dependent:
•A: 600 t, a=1.25g •5: 2200 t, a=0.625g
•9: 778 t, a=1.125g •4: 3000 t, a=0.5g
•8: 1000 t, a=1g •3: 4333 t, a=0.375g
•7: 1286 t, a=0.875g •2: 7000 t, a=0.25g
•6: 1667 t, a=0.75g •1: 15,000 t, a=0.125g

A further disadvantage is that performance falls as the thruster moves farther from a gravitational source, dropping to half thrust at 10 diameters, reducing the free trader to 1/2g when fully loaded. For scout/couriers, the drive provides 2g within 10 diameters of a world and 1g beyond that. This is not a concern in a freight ship on a well-patrolled route, but it makes the unit impractical for warships and problematic for a civilian ship that finds itself under attack.

(Coincidentally, a grav-based maneuver drive costs about the same as a Book-2 Model A maneuver drive. I had to borrow some volume from the power plant to make it work. For High Guard purposes, the Model A maneuver drive draws 1 EP and produces agility 2 in a 100 dT scout/courier or an unloaded 200 dT free trader, or agility 1 in a fully loaded 200 dT free trader, when within 10 diameters of a world. The ship has half agility beyond, rounded down. For Book-2/Traveller-Book purposes, a ship at 1/2g makes a vector change every other turn: the player must wait one turn after making a change before another can be made.)

Some captains have been known to turn a disadvantage into an advantage by dumping cargo to improve acceleration when under attack: the free trader can double its speed when fully unloaded. A rapid cargo dump is accomplished by cutting cargo ties, shutting down the gravity field in the cargo bay, opening the bay doors, then applying thrust to move the ship on a vector opposite the cargo doors. This "sea cucumber" defense may also distract a piratical attacker. Scout/couriers do not carry enough cargo to meaningfully execute a "sea cucumber" defense, though dumping the contents of the small cargo bay or jettisoning the air/raft might persuade an attacker to stop for loot rather than continue exchanging shots, especially if the dump limits the attacker's window for retrieving loot by placing the contents on a vector to impact with a nearby planet or other body.

•The TL9 Model A power plant is a 2dT frontier variant power plant that produces 500 Mw at 1/3 the size and less than half the cost of a standard TL 9 power plant. Its chief disadvantage is low efficiency: it requires 5 times as much fuel to produce that level of power. It is more cost-effective than TL9-12 standard plants, the loss of cargo space being more than compensated by the decreased cost, but the added fuel requirements make it impractical for warship construction, where space rather than cost is a priority.

(Again, I borrowed some of the power plant space to make the maneuver drive work.)

•Because of the liabilities of the Model A maneuver drive, the Model A power plant is designed to function also as an auxiliary propulsion unit. By passing additional hydrogen fuel through the plant, it acts as a fusion thruster to produce another 1000 metric tons thrust to compensate for the maneuver drive's loss of thrust or, in certain circumstances, to provide added boost: a scout/courier within 10 diameters of a world can achieve 3G thrust when using the fusion thruster, while an unloaded free trader can achieve 2G beyond 10 diameters and 3G within 10 diameters. The feature is only used for combat as it consumes fuel quickly: one ton of fuel will provide two turns of thrust. Thus, a scout/courier or free trader with 10 dTons of power plant fuel has 19 burns available during a combat (reserving 1/2 dTon for power, which will last about 3 days) before going into its jump fuel; after a jump,it would have 7.5 dTons fuel remaining, leaving 14 burns available.

A subsidized merchant's B plant/drive is a duplex drive: a pair of A plant/drives designed to work in coordination with each other. It consumes correspondingly more fuel, providing one turn thrust per ton of fuel burned. The merchant has 10 dTons for 9 burns available before jump and 5 dTons, for 4 burns, on emerging from jump after a week in jump space.

When the power plant is being used for fusion propulsion assist, no extra power is available for other weapons; virtually all power not used by the maneuver drive is diverted to the thruster.

The fusion thruster should never be used near a planet's surface or in a planetary atmosphere. Doing so may result in seizure of the ship and arrest of its crew.

(For High Guard purposes, the Model A fusion thruster draws 1 EP when using a burn to provide thrust and produces an additional +1 agility in a 100 dT scout/courier or an unloaded 200 dT free trader, or +1/2 agility in a fully loaded 200 dT free trader. For Book-2/Traveller-Book purposes, a ship making a burn may increase its vector change by 1 for a 100 dT scout/courier or an unloaded 200 dT free trader, by 1/2 for a fully loaded 200 dT free trader.)

•The Model A drive/plant assembly can be arrayed in sequence to serve the needs of larger vessels. Fuel consumption increases accordingly. The Subsidized Merchant and Far Trader, for example, use a duplex unit. The 400 dT Merchant's 50 dT tank provides Jump-1 and 2 weeks' flight, while the 200 dT Trader's 50 dT tank provides Jump-2 and 2 weeks' flight, adequate for freight transport.

•Fusion Drives As Weapons: An advantage of fusion propulsion assist is that the ship may use its fusion thruster as a weapon when at short range, provided the drive is operational and fuel is available. When used, the ship attacks as with an energy weapon with a factor equal to its rating: an A is factor 1, a B is factor 2. The attack may be against another ship or craft, or the ship may use the drive against one missile attack: the missile attack must roll to penetrate. The ship may make a fusion drive attack without using additional fuel, if the fusion thrust is not also being used to change vector (or High Guard agility) during a turn: the ship makes a brief burn lasting only a few seconds, long enough for an attack but using minimal fuel. For the same reason, the power plant continues to deliver power for other uses.

The Model A drive/plant assembly is slightly more cost-effective than standard TL13 power plants, though the savings is not as significant; the deficiencies of the design lead most buyers to prefer standard TL13 technology from that point forward. TL15 standard power plants are more cost-effective than the Model A, being both less expensive and more efficient, and shipbuilding has been evolving toward a TL15 standard over the past 100 years, so the Model A is seldom seen in the Imperium except on low-tech worlds building ships under Imperial programs.

Carlobrand September 30th, 2017 12:13 AM

•The frontier TL9 Model A jump drive's chief advantage is that it can deliver Jump 2 in a 100 dT hull, something that ordinarily requires TL 11 technology. It accomplishes this at a cost in size, at 10 dT being more than three times the size of a TL11 jump-2 drive for the same size ship, though it costs a bit less. The unit can also deliver jump-1 in a 200 dT hull and is significantly less expensive than the standard jump-1 drive serving 200 dT hulls, though again being much larger. The increased size is not a concern in scout/couriers and, in combination with the Model A plant and maneuver drive, it provides a scout/courier at a cost that would otherwise require TL 15 technology to match. It is therefore a preferred model for the Imperial Interstellar Scout Service, since it allows the Service to meet its small-scout needs at reduced cost and with ships that can be repaired in the field on TL9 worlds, while supporting lower tech frontier shipyards with scout construction orders.

•The frontier TL9 Model B jump drive can deliver jump-1 in a 400 dT hull and is significantly less expensive than the standard jump-1 drive serving 400 dT hulls, though it is larger. There has also been a successful effort to adapt it to a 200 dT hull to deliver a jump-2 capability, again something that ordinarily requires TL 11 technology and which is accomplished at a cost in size, the drive being two and a half times the size of a standard TL11 jump-2 drive for the same size ship. The result has been the Far Trader, a successful engineering accomplishment though less successful as a merchantman: with larger drives and the added fuel demands, it costs more, delivers less, and in fact cannot fly profitably except under subsidy or in speculative trade, and lower demand for the design means the far trader hull does not benefit from the advantages of the standardized hulls, further increasing its cost.

•The frontier TL9 Model C jump drive can deliver jump-1 in a 600 dT hull and, like its smaller cousins, is significantly less expensive than the standard jump-1 drive serving 600 dT hulls, though larger. The Model C has been successfully tested in a Jump-1 configuration, but there are presently no designs using the Model C, freight traffic being adequately served by 200 dT, 400 dT and 1000 dT freighters. It has also been successfully tested as a jump-2 drive in a 300 dT ship, but again there are no standard designs currently using the C. Efforts to achieve jump-3 range in a 200 dT hull mounting this drive have so far been unsuccessful: larger size could not compensate for the technological shortcomings of a TL 9 drive when trying to maintain a stable Jump-3 envelope.

•The frontier TL9 Model D jump drive can deliver jump-1 in an 800 dT hull and is significantly less expensive than the standard jump-1 drive serving 800 dT hulls, though larger. There are presently no 800 dT designs using the Model D, but it has been successfully tested as a jump-2 drive for 400 dT hulls and is used in some modified subsidized merchants. Like the Model C, efforts to achieve greater jump range by using this drive in smaller ships have been unsuccessful.

(The other drives are not used.)

Ships constructed with this technology are still somewhat inferior to TL15 designs. For this reason, this technology is not seen in production of commercial shipping except where supported by Imperial programs. The Imperium promotes a program of loan guarantees that allows merchant captains with sufficient capital to obtain loans to purchase free traders. It also operates a subsidy program to connect the more isolated worlds of the Marches by underwriting coalitions of small worlds or other entities that subsidize the purchase and operation of small merchant ships by entrepreneurs. The Scout Service sees clear advantage in having scouts that can be produced at lower cost and maintained at any lower tech A-port. Construction is steered toward smaller, lower tech worlds to promote their space industries, and the annual maintenance needs of the couple of thousand ships of the small-ship merchant fleet and the Scout Service scout/courier fleet promotes the space industries of worlds throughout the Marches.

Changes:
The scout/courier and free trader use the same power plant/propulsion system. The plant draws 10 dT fuel per month for each. The Scout/Courier's 40 dT fuel load therefore supports power plant operations for 4 weeks with one Jump-2 and an option for an immediate Jump-1 if the ship finds itself jumping into a dangerous situation or needs extra range.

The Subsidized Merchant's Model-B maneuver drive and power plant are duplex plants - essentially two Model-A systems designed to coordinate operation to serve the larger ship. The subsidized merchant's 50 dT fuel load provides for 1 jump-1 and two weeks of operation, generally sufficient for the typical jump. If more fuel is desired, demountable tanks must be added in the cargo bay.

Other ships using the drives include the AAA 200t yacht, the ABB 200t safari ship, the BBB 200t far trader, and the BDD 400t lab ship. None are capable of a "sea cucumber" defense, though again dropping something of value while fleeing may distract a piratical attacker. With its larger power plant, the safari ship and lab ship can manage 2g inside 10 diameters when doing a fusion burn, 1.5g outside of 10 diameters.

Brandon C September 30th, 2017 09:16 AM

*If hulls are reused, then they are old and stressed from decades of use. They should take greater damage in combat and require more maintenance.

Also, it means that if a ship class is built with a nonstandard hull, but in sufficiently large numbers, decades down the line as the ships are retired those hulls will become available as standard hulls.

I think it is just easier to assume a standard hull is freshly built to a fixed pattern and are just empty shells awaiting internal components.

*I think it's safe to say that a fusion drive will be prohibited near an inhabited world, which is is exactly where you have it operating. Also, range as a weapon would be quite short.

Carlobrand October 1st, 2017 12:19 AM

Quote:

Originally Posted by Brandon C (Post 574425)
*If hulls are reused, then they are old and stressed from decades of use. They should take greater damage in combat and require more maintenance.

Also, it means that if a ship class is built with a nonstandard hull, but in sufficiently large numbers, decades down the line as the ships are retired those hulls will become available as standard hulls.

I think it is just easier to assume a standard hull is freshly built to a fixed pattern and are just empty shells awaiting internal components.

*I think it's safe to say that a fusion drive will be prohibited near an inhabited world, which is is exactly where you have it operating. Also, range as a weapon would be quite short.

The aim here is to bring Book 2 ships into the Book 5 universe by modifying the Book 2 drives enough to be compatible with the Book 5 setting. I probably should have said that at the outset.

The canon Book 5/Striker/MT hulls are as strong as a foot thickness of steel, comparable in strength to the belt armor of a Missouri class battleship. Retired scout/couriers are rehabbed into Seekers. See Supplement 7, Traders and Gunboats: "The hull and drives are at least forty years old, and may be far older." Lightning class cruisers Azhanti High Lightning, Haunting Thunder, and Bard Enterprise, laid down in 991 were converted into frontier cruisers in 1078, 107, and 1082 respectively, with Azhanti High Lightning and Bard Enterprise remaining in service as of 1107; see Supplement 5, Lightning Class Cruisers. Canon clearly supports the idea of these hulls still being serviceable and reusable after 40 years of use; two examples are still in use, after refurbish, more than a century after they were first laid down.

Missouri, as it happens, was laid down in 1941, refurbished and returned to service from 1984 through 1992 and, if that Life after People series is to be believed, is likely to remain intact for another couple centuries, and that in a planetary environment with no maintenance. Its weak points are the rivets; the hull could last 20,000 years.

And, yes, if a hull becomes popular enough over a long enough period, and is small enough, it will eventually join the ranks of standard hulls. For whatever reason, hulls at 800 dT+ cost the same whether they're standard or nonstandard. I don't really see a problem with other standard hulls showing up since that's in the hand of the game master; it won't be apparent unless he or she chooses to make one available to players or otherwise incorporate it into his or her setting. That's what the IMTU forum fundamentally about: exploring alternatives to canon.

As to the fusion drive, a few points to consider:
  • Fusion drives in inhabited space, and their use as weapons, are a common science fiction trope.
  • There are a number of common sci fi tropes that don't play out well in reality. Lasers, for example, aren't going to go anywhere near the ranges Traveller would like them to reach, not without the introduction of some handwavium technology. We nonetheless embrace them because we want those tropes in our game milieus.
  • This idea is drawn from CT Book 5, 1979 edition - probably because it is a common science fiction trope.
  • The drive as a weapon is described as being short range in the original post, as it is in CT Book 5, 1979. High Guard does not define short range - neither edition does - but energy weapons in High Guard are limited to short range. Borrowing from the Striker weapon design tables, that range is anythingfrom 28,000 km for the TL11 plasma gun to 60,000 km for a TL14 fusion gun. If for some reason you're taking High Guard to a hex board or range bands, you could probably limit range to 1 or 2 bands/hexes.
  • Yes, using the fusion drive in the orbital space of a trafficked world would probably be considered a no good, very bad thing, if for no other reason than that it plays hell with traffic patterns, since other craft need to stay clear of your back end and some of those might likewise have fusion auxiliary propulsion. Traffic control will not appreciate you and the other free traders making their job more complicated, not to mention putting other ships unnecessarily at risk. You'll rely on your gravs in those settings; how long it takes to get from jump to ground really isn't an issue in civilized space. However, those aren't the places where you're likely to get shot at and would need full speed, and the places where you're likely to get shot at are not the places where they're likely to be imposing rules about how you manage to get from jump to ground with their cargo without getting robbed. In fact, they're likely to cheer if you manage to cut a furrow in the hull of the corsair that's been prowling their orbital space.

Brandon C October 1st, 2017 06:00 PM

Quote:

Originally Posted by Carlobrand (Post 574465)
The aim here is to bring Book 2 ships into the Book 5 universe by modifying the Book 2 drives enough to be compatible with the Book 5 setting. I probably should have said that at the outset.

I would just use the drive and fuel formulas from Book 5 and ignore those in Book 2. This would require rebuilding Book 2 ships but any space discrepancies can be added/subtracted to/from cargo.

There is also the issue of streamlined hulls when it comes to standard hulls. If you are reusing a hull, the streamlining is decided for you. Streamlining can't be retrofitted and making a streamlined hull unstreamlined is just a waste of money for the basic hull.

Carlobrand October 2nd, 2017 12:57 AM

Quote:

Originally Posted by Brandon C (Post 574504)
I would just use the drive and fuel formulas from Book 5 and ignore those in Book 2. This would require rebuilding Book 2 ships but any space discrepancies can be added/subtracted to/from cargo.

There is also the issue of streamlined hulls when it comes to standard hulls. If you are reusing a hull, the streamlining is decided for you. Streamlining can't be retrofitted and making a streamlined hull unstreamlined is just a waste of money for the basic hull.

That's been tried. The result is a Book 5 free trader that can't make enough money to pay for itself if it's constructed below TL13. You're left assuming everything's being built at TL15, and the low tech ports are left with nothing significant to build. I'd prefer a setting where the low tech A-ports have something to justify their construction capacity. You may of course choose to assume the low tech A-ports do not do any significant construction and focus on cargo and passenger traffic if you prefer.

Yes, if you are re-using a hull, the streamlining is decided for you. The scout, free trader, and subsidized merchant are streamlined designs. I'm not sure why that would be an issue.

Brandon C October 2nd, 2017 11:13 AM

Quote:

Originally Posted by Carlobrand (Post 574524)
That's been tried. The result is a Book 5 free trader that can't make enough money to pay for itself if it's constructed below TL13. You're left assuming everything's being built at TL15, and the low tech ports are left with nothing significant to build.

It's quite simple: a TL9 free trader has to charge more than a TL12 free trader, which has to charge more than a TL15 free trader.

Of course , this becomes a problem because of the deeply flawed way Traveller determines tech levels. In an empire over a thousand years old, most worlds should be no more than 2 or 3 TLs below the highest TL world in the subsector (or, say, within 6 parsecs).

Under this model, only exceptionally backwater regions will still be making TL 9 ships and only backwater worlds will build TL12 ships.

Likewise, a world can't support higher tech ships than it can build, so TL12 ships will rarely visit TL9 worlds since if they suffer a breakdown, they can't be fixed locally.

atpollard October 2nd, 2017 11:23 AM

Quote:

Originally Posted by Brandon C (Post 574533)
Likewise, a world can't support higher tech ships than it can build, so TL12 ships will rarely visit TL9 worlds since if they suffer a breakdown, they can't be fixed locally.

You mean the way modern aircraft don't land at any airport that cannot rebuild an engine if they need repairs? Isn't that why only steamships dock in some small countries like Haiti? ;)

Sorry, I couldn't resist teasing just a little.
I think you overlook a basic driving force of economics ... imbalance creates opportunity for larger profits.

Brandon C October 2nd, 2017 12:03 PM

Quote:

Originally Posted by atpollard (Post 574534)
You mean the way modern aircraft don't land at any airport that cannot rebuild an engine if they need repairs? Isn't that why only steamships dock in some small countries like Haiti? ;)

Haiti isn't TL5.

The gap between First World and Third World countries is rarely more than 2 TLs. In Traveller any two adjacent worlds can differ in TLs wildly, even if there is not a good reason for it (beyond a d6 being used to determine TL.

kilemall October 2nd, 2017 02:26 PM

There are ways to skin that TL ship profits cat.

1) Reduce costs by TL build

Use the Striker cost and/or TCS currency tables to price building ships.

If a ship costs 70% and therefore has 70% the mortgage, it will almost assuredly be profitable.

That begs the question, should a sub-TL15 ship get full fare?

I guess I would break it down as freight and mail tonnage is paid at full TL15 hard CrImp, and passengers would be charged with the TL/port currency multiplier of the ship's manufacture, because a fully high tech berth/trip is far more luxurious then a mere TL9 stateroom.

Maybe tie a functionality roll to that for boredom, the lower TL ships are that much cheaper but leave their passengers stir crazy and taking a temporary hit to their INT if they are not seasoned travellers and used to 'roughing it'.

Reference taking away a modern kid's cellphone/tablet/PC/TV privileges for a real world example.

Or perhaps pluses to ticket rolls, so larger Jump-2+ liners can reliably attract more passengers and a higher number of high passage.

That would support a tramp freighter feeder/large ship on J-4 route model.


2) More capability for higher TL

Not a lot doing with this using the base rules, but I can think of a few to make the higher TL ships pay more.

Go the other direction with TL/passenger pay, increase the value of a ticket on a higher jump vessel.

Tie the low passage survival roll to TL, roll below the ships' TL to live, with TL13+ being the point low passage is safe. That could be higher tech LP berthing, medtech for the bay recovering from the process, or a combination.

Obviously the higher tech ships should get a LP ticket bonus for the desirability of survival.

For combat, that could get involved, probably the simplest way for a CT:HG type resolution/modifer would be to add model level + TL to arrive at the computer level.

So a TL15 Mod 1 would be 16 and get a +2 advantage on a TL10 ship with Mod 4 for 14.


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