Marginal early stellar TL ship

[McPerth]

This ship is designed with MT rules for a system with TL 8, but space and computer achievement TL 9, or a TL 9 system slightly underdeveloped in energy (energy TL 8).

Craft ID: Frigate , Type: GF, TL: 8-9 , MCr: 1912.72

Hull: 900 / 2250 Disp: 1000 , Config: 1 SL , Armor: 40 D
Unloaded: 12997 ton, Loaded: 84852 ton

Power: 86 / 172 Nuclear Fission 2600 Mw, Duration: 90 / 270

Locco: 18 / 36 Maneover: 1 , 18 / 36 Jump: 1, NOE: 40 , Cruise: 750 kph, Top: 1000 kph, Agility: 0

Commo: Radio system x3
Maser Far Orbit x3

Sensors: Radar Far Orbit x3
Ladar Far orbit x3:
ActObjScan: Routine , ActObjPin: Routine
PasObjScan: NA, PasObjPin: NA
PasEngScan: NA, PasEngPin: NA

Off: Missile X 0 2 Blaser X X 3
Batt 4 2
Bear 4 2

Deff: DefDM: +3
Sandcasters X X 3
Batt 4
Bear 4

Controls: Computer: 3x3, Panel: computer linked x 6700
Environ: Basic env, Basic LS, extended LS

Accom: Crew: (bridge: 6, engeneering: 12, gunnery: 6, command:
4, steward: 1, Maintenance l:, Troops 10). Staterooms: 4,
SmallStaterooms: 26,

Other: Fuel: hydrogen 2700 kl ( 200 ton); Radioctives 5616 kl
(416 ton) Cargo: 1460 kl ( 108 ton) Hydrogen fuel for 2
jumps 1. Fuel scoops. Purifiers (48h). 40 battery rounds
(1 battery round = 3 missiles)
ObjSize: average , EmLevel: moderate

I designed this ship after talking on other threads about how could Arden (TL 8) home built ships (assuming their achievement TLs are as required, and using rules that allow you to build ships planetside if you have no A or B starport, as HG page 20 says) and about fision powered ships.

I also put computer achievment TL as 9 because at TL 8 the best computer allowed is 2bis, with a CP limit of 15000, and that would not allow this ship (CP's over 16000) unless many HUD's were used, too many for this crew to control, IMO. EDIT:As I said in other threads too, I've always seen the use of more computers to forfeit this limitation as cheating the spirit of the rules, even if at least one official design uses this trick (Xboat tender, as shown in HT, page 81) END EDIT.

To avoid the prototype of dubious reliability sentence from WBH about achievement TLs, it could also be seen as a ship from a TL 9 planet with energy TL just at 8.

I gave it 90 days endurance for the PP for I assume they want to have more than 30 days due to de difficulty to obtain such fisible materials. Note though, that the lack of artificial gravity (sorry, this cames at TL 10) would make advisable not to have the crew without planet landings for long time, to avoid bone and muscular mass loss, so effective endurance on mission would be much lower.

Cargo could be used to carry more troops (by installing staterooms or habitat modules on it), more missiles, more fuel, small crafts, etc... This space is to adapt the ship to its intended mission.

 

[McPerth]

One thing I had doubts when designing this ship was about the true feseability of jump drives at this energy TL.

As is described on traveller, jump drives are fusion plants that burn fuel very quickly (albeit inefficiently) to charge the cappacitors, and then release it to the jump gird.

If fusion power is not fully controled, I'm not sure those plants are possible, and so, I have my own doubts about this design being coherent with the spirit of the traveller jump, but as rules don't talk about that and allow it to be built, I've done it neverless.

 

[Xerxeskingofking]

thing is, without the requirement for thirsty fusion based J drives, the OTU falls apart, since as soon as you let long endurance fission ships make jumps, then they rapidly start becoming more profitable than fusion based ships.

remember that your grav-plate less ship has no compensators as well, so they crew are going to be under 1G envrioments every other week when they are burning in system and outsystem. the main decks are going to stacked form bow to stern, not top to bottom, or your corridors are going to turn into shafts every time to boost to the jump point.

maybe add a grav deck based on centrifgual force (i.e. a spinning ring), which limits manouverbility, but gives the crew access to 1g envrioments pretty much all the time.

 

[Rigel Stardin]

Just remember, Prototypes are proof of concept, the ship only proves a fesibility that Jump is possible. They also would be smaller because of cost and the fear of losing the crew if something went wrong.

 

[McPerth]

thing is, without the requirement for thirsty fusion based J drives, the OTU falls apart, since as soon as you let long endurance fission ships make jumps, then they rapidly start becoming more profitable than fusion based ships.

I disagree they are more profitable than fusion powered ships. You must take into account that, to fuel this ship, you need to refuel the radioctives every 90 days (about half so if you don't combat, as lasers use roughtly half of the enery), at 75 kCr/kl (so, over 420 Mcr worth fuel).

In less that two years (four if you don't use your lasers) you've paid more in fuel than the cost of the ship itself...

remember that your grav-plate less ship has no compensators as well, so they crew are going to be under 1G envrioments every other week when they are burning in system and outsystem. the main decks are going to stacked form bow to stern, not top to bottom, or your corridors are going to turn into shafts every time to boost to the jump point.

True, if you keep it moving all time. The time you spend in orbit, patroling, etc... you probably won't be using full thrust.

maybe add a grav deck based on centrifgual force (i.e. a spinning ring), which limits manouverbility, but gives the crew access to 1g envrioments pretty much all the time.

I thought about that, but that would prevent it to be streamlined, as you'd need a large ring to avoid this same spinning you use to produce artificial gravity to disorient the crew, due to inner ear equilibrium sensing, affected by a spinning to quick.

I think I remember to have readed somewhere that, to avoit that, you'd need the spinning circumference to be more than 40 meters radius or diameter (I'm not sure, I readed it long time ago). Too large a diameter in any case to make it feasible.

 

[aramis]

One thing to remember: Fission reactors lose fuel mass even when sitting idle; you're not really going to save much by not firing the lasers.

 

[steventirey1985]

I disagree they are more profitable than fusion posered ships. You must take into account that, to fuel this ship, you need to refuel the radioctives every 90 days (about half so if you don't combat, as lasers use roughtly half of the enery), at 75 kCr/kl (so, over 420 Mcr worth fuel).

Why only 90 days? We have nuclear powered vessels (fission reactors) now, and they don't have to refuel for 20 years. (Nimitz-class carriers)

 

[mike wightman]

One thing to remember: Fission reactors lose fuel mass even when sitting idle; you're not really going to save much by not firing the lasers.

That's what control rods in reactors do - throttle back the nuclear reaction and thus conserve fuel.

Fission plants do not operate at peak output 24/7.

Trouble is the range of output you'll require your fission plant to have.

So definitely calculate fuel duration based on non-combat operations, possibly even consider a smaller power plant for everyday operations and capacitors for combat.

 

[mike wightman]

One thing to remember: Fission reactors lose fuel mass even when sitting idle; you're not really going to save much by not firing the lasers.

Why only 90 days? We have nuclear powered vessels (fission reactors) now, and they don't have to refuel for 20 years. (Nimitz-class carriers)

Because the folks at DGP didn't base their fuel usage rates on the real world

 

[McPerth]

Why only 90 days? We have nuclear powered vessels (fission reactors) now, and they don't have to refuel for 20 years. (Nimitz-class carriers)

Have you seen the mount of radioactive fuel needed for those 90 days? Adding one more month (30 days) would need 1872 kl more, more than the cargo space this ship has.

I guess DGP people made the fision PP a little (sic) inefficient. They explained that's because it's supposed to be containers from which the radioactive material itself it's only a small amount. Even so its weight is 12.5 ton/kl. Pure uranium would be about 19.7 ton/kl, so I guess the containers themselves are quite heavy or the fisible portion larger.

If you try to make this design with MGT rules, where fision plants are quite more efficient, your fuel needs would be about 10-14 dton/year, for 1000 dton ship to obtain performance 1.

So definitely calculate fuel duration based on non-combat operations, possibly even consider a smaller power plant for everyday operations and capacitors for combat.

It could be an option, but have you seen the efficiency of TL 8 batteries?

At TL 8, to store 1500 Mw hour (the power needed for the two laser batteries for 1 hour, or 3 combat rounds), you'd need 3750 kl of batteries, with a cost of 121.875 Mcr. As you see, you have no space for more combat endurance (unless wanting to sacrifice other performances), as one more turn would add 1250 Kl of batteries, leaving you without cargo space, or renouncing to you seccond jump, limiting your ship to mains.

On the plus side, you may save you about 750 kl of PP (at a cost of 75 Mcr), and reduces your fuel needs by 1080 kl month (wich, at Kcr 75/kl, its a good saving), and probably your engineering section in 1-2 people (I had to run the numbers). So your saving would be about 3990 kl (against 3750 kl needed), and 81 Mcr/month against an initial inversion of about Mcr 47...

On the minus side, it limits the use of your lasers to an hour, and would take a while to recharge, if you maximize the PP reduction. That would not be a problem if you combat and then jump, as you have a full week to recharge them (and, as in jump you don't use your maneover drives, you can recharge them faster), on patrol it can reduce your punch...

All in all, I think that's a good idea, well worth to be studied...

TY for your proposal

 

[mike wightman]

Not batteries - use jump capacitors.

 

[McPerth]

Not batteries - use jump capacitors.

It might be a nice idea... if there were rules for that.

AFAIK tose rules don't exist. If you know better, please, tell me where can I find them.

Aside from that, from what I've readed about them, I see jump capacitors as batteries with a very short release time, and, as I understand them, Too short release time to be useful to feed energy weapons for more than one shoot (and I say one shoot, not even one turn).

 

[steventirey1985]

Have you seen the mount of radioactive fuel needed for those 90 days? Adding one more month (30 days) would need 1872 kl more, more than the cargo space this ship has.

I guess DGP people made the fision PP a little (sic) inefficient. They explained that's because it's supposed to be containers from which the radioactive material itself it's only a small amount. Even so its weight is 12.5 ton/kl. Pure uranium would be about 19.7 ton/kl, so I guess the containers themselves are quite heavy or the fisible portion larger.

If you try to make this design with MGT rules, where fision plants are quite more efficient, your fuel needs would be about 10-14 dton/year, for 1000 dton ship to obtain performance 1.

The fission reactors listed are more than a "little inefficient". The radioactive fuel would last for years at a minimum. The only thing that may need to be replaced more often than that is the cooling medium, which can be as simple as sea water. Definitely not something costing millions of credits.

From Atomic Rockets:"The table tells us that if you wanted to generate 1000 megawatts for an entire year (3.15×107 seconds), it would only take a measly 380 kilograms of uranium-235. That's concentrated, a coal-fired power plant typically burns closer to 4 million tons in a year. "

And they got fusion reactor efficiency very wrong as well. A small amount of fuel would last well over a year. I know it is just a game, but come on. How about putting some science in a science fiction game? The only justifiable reason for such short durations is to keep the players from exploring at their whim, and force them to stay in a relatively small area of space.

 

[Rigel Stardin]

...I know it is just a game, but come on. How about putting some science in a science fiction game?...

Amen.

 

[mike wightman]

It might be a nice idea... if there were rules for that.

AFAIK tose rules don't exist. If you know better, please, tell me where can I find them.

Aside from that, from what I've readed about them, I see jump capacitors as batteries with a very short release time, and, as I understand them, Too short release time to be useful to feed energy weapons for more than one shoot (and I say one shoot, not even one turn).

Look at the entry for black globes - the stats for jump capacitors are given there.

 

[McPerth]

I guess DGP people made the fision PP a little (sic) inefficient.

The fission reactors listed are more than a "little inefficient".

I agree. The particle sic means that I doubt about the same thing I just said.

And they got fusion reactor efficiency very wrong as well. A small amount of fuel would last well over a year. I know it is just a game, but come on. How about putting some science in a science fiction game? The only justifiable reason for such short durations is to keep the players from exploring at their whim, and force them to stay in a relatively small area of space.

I agree with that too. The amount of fuel used should be quite less in any fusion PP, but that's what rules say...

Look at the entry for black globes - the stats for jump capacitors are given there.

True, but there are some details not said in the rules. How long can you store energy on capacitors? I guess just for a relatively small amount of time, as they are not thought to store energy for long times, but to store for a short period, while produced, and then release it (and this is reversed when used as capacitors for BG).

There has also been a discussion in various threads about how much energy do the capacitors really hold. Book says 650 Mw, but that's power, not energy. Are they Mw hour (IS units)? are megawats turn (as it is what they absorb/release each turn)? On another thread we (more or less) ended accepting this last number (and so, 216 Mw hour/kl).

If they can be used as conventional batteries, to store energy for the lasers to be used in needed, you'd only need about 7 kl, at a undetermined cost (I've been uncapable to find it in MT PM nor in HG, at least).

Then why do batteries exist? What advantage have over those sinks? Even at TL 15 you'd need 214 kl at a cost of MCr 216 to store that amount of energy in batteries (curiously, at TL 14 you'd need 375 kl, but at a cost of Mcr 187.5).

 

[McPerth]

And now, to add a little controversy, let's see how should such a ship feel (a TL 9 space/ TL 8 energy world built) with MGT rules:

Hull 1000 tons Hull 20 Mcr 110
Streamlined Structure 20
Armour Titanium Steel 9 points 225 dton Mcr24.75 Self sealing Mcr 10
Jump Drive E Jump 1 30 dton Mcr50
Maneover Drives E Thrust 1 9 dton Mcr 20
Power plant H Fision 25 dton Mcr64
Bridge 20 dton Mcr 5
Computer Model 2 Rating 10 Mcr 0.16
Electronics Civilian sensors -2 DM 1dton Mcr 0.05
Weapons 10 Hardpoints 4xPA bays 200 dton Mcr 80
Fire control 4d ton
4x double Blaser 4 dton Mcr 10 2x double scaster 2 dton Mcr2
Fuel (PP) Radioactives (1 year endurance) Mcr16
Fuel (JD) LHyd 2 jumps 200 dton
Cargo 186 dton
22 staterooms 88 dton Mcr 11
Extras Fuel scoops Fuel processors (100 ton/day) 5 dton Mcr 0.25 Ship’s locker
Software jump control/1 Mcr 0.1
Maneover/0 Included
Evade/1 Mcr1

Maintenance cost (monthly) Mcr0.032
Life support (monthly) Mcr0.116
Total Tonnage and cost 1000 dton Mcr379.31
Crew: 3 pilots, Navigator, 2 engineers, medic, 20 gunners, 10 troops, 3 officers. All in double staterooms except officers and medic (in single staterooms)

As you can see, the rules change the ship quite a lot.

First fusion is quite more efficient, needing only 16 dton of fuel to feed it for a year. Even so, price is quite hight (at Mcr 1/ton, you'd need 16 Mcr/ year to feed the PP).

Second, armor may be higher, making them nearly imprevious to missiles and lasers (pulse lasers and nuclear missiles have only 1/6 possibility to damage it, less if sandcasters are in use or lasers shoot at the missiles).

Weaponry may be quite more powerful, as there are no energy requirements and PAs are lower TLs (using core rules, there are no limits to bays. If it was built using capital ship rules, PP should be upgraded or only one energy bay would be possible).

Crew is distributed quite differently (more gunners, less engineers).

No mention in MGT about life support limits due to TL (grav plates, inertial compensators, etc), so not sure if they are supposed to be there.

Price is considerably lower (and no mass production discount is applied here).

 

[aramis]

McPerth: you're forgetting one aspect of MGT - margin of success adds to damage. A 1D laser with a good gunner can get a good shot and pen that armor.

 

[shield]

CT high guard says 1 tn capacitors holds 36EP, MT and striker say 250mw = 1ep.

Since the BG can feed the capacitors and then release the energy reasonably slowly (over several 20 minute turns using the CT HG rules, the capacitors must be able to hold that energy for a reasonable period of time rather than the short burst associated with jump drive operations.

 

[McPerth]

CT high guard says 1 tn capacitors holds 36EP, MT and striker say 250mw = 1ep.

True, and this is coherent with MT numbers (9000 Mw/dton for HG and 8775 Mw/dton for MT). As in both cases this is for 20 min, the storage capabilities are respectively 3000 Mw hour and 2925 Mw hour.

Since the BG can feed the capacitors and then release the energy reasonably slowly (over several 20 minute turns using the CT HG rules, the capacitors must be able to hold that energy for a reasonable period of time rather than the short burst associated with jump drive operations.

The real question here (IMO) is what do you thing a reasonable period of time is? Of course they may release its energy along several turns by feeding the ship's systems, but if any energy is left on them after the combat, can you store this energy on them (just in case) and use your PP to feed the ship? Can you have them normally charged as a reserve energy for if you need it?

I guess not. I guess capacitors must be discharged usually, being able to store energy just for a few hours at most (and that's a reasonable amount of time in combat). To store energy for combat, and so having a PP unable to sustain your weaponry, I guess batteries are needed, unless you have the time immediatly before the combat to charge your capacitors.

And I also guess no ship commander would be happy to have a weapon that needs to be prepared just before the combat (and so useless in unexpected combat). Surely they would be unhappy enough with the batteries proposal (and so limiting their laser use to one hour, and then having them useless for several days, or at least a couple of hours if you want to devote the power that usually goes to the maneover drives to recharge them).