Need help Designing A Sub-Light Ship [Updated Again]

[Solomani666]

I need to design a ship that can travel 1 to 2 parsecs using maneuver drive only.

The ship will use gravitic fuel scoops.

This is a TL16 design.


From stem to stern I see the following sections:

1. Shield Section
Widest section of the ship.
Forward part of this section is armored to 32. (2 x TL)
Massively radiation shielded.

1a. Bussard Collector
Gravitic collector.
Its field extends several kilometers beyond the diameter of the ship and collects free hydrogen from space.
No refinement is needed.

2. Collector Boom
Isolates the Bussard collector from the rest of the ship.
2 x Solar panels line its length.
Collectively both solar panel arrays provide enough power for 1 g maneuver, fuel refinement, or sensors, but only 1 at a time.

3. Bridge / Crew Quarters
20 crew members at most.
The ship will be highly automated with expert systems and repair robots.

4. Cargo
2 x 1000 ton modules
03% for supplies and spare parts.
2 x Pinnace.

5. Fuel Tankage
Fuel and refining equipment.

8. Engineering
TL16 Variable Array Power Plant 6. (Adjustable power output and fuel consumption)
Maneuver Drive 6 in 2 separate pods. The fields can be reversed to decelerate the ship
An emergency Jump 1 drive.


The Bussard collector will probably not collect all of the hydrogen needed to fuel the ship, but it should increase its range significantly.

Also the ship should reach 99c in about a year, after which the drive would be cycled down to Maneuver 1.

On longer journeys the drives might be shut off entirely after a year (.99c) and the Bussard collector used as a break. By the time the drives are turned on for the final deceleration the tanks should be full.

Depending on which rules I use and the size of the Bussard Collector, I might be able to fit everything into a 20,000 ton ship.



I would like your opinion on the following:

I am considering using the fuel rules from S&P 76. Anyone else use them?
(If I use these rules, I am going to nix the Bussard Collector entirely)

Assuming I don't use the rules above, what bonuses do you think are appropriate for a TL16 design built for maximum power efficiency?

How big do you think the Bussard Collector needs to be in tonnage?

Anything else I haven't thought of?

.

 

[DFW]

This should help

http://mysite.verizon.net/res148h4j/javascript/script_starship.html

 

[Jeraa]

If you assume a maneuver drive can eventually exceed the speed of light, a 1 parsec journey at 6gs acceleration would take 75 weeks. 2 parsecs take 106 weeks. (I used the formula given in Classic Traveller, and believe my math is correct.)

If you cap the maximum velocity at 0.95c, that will take longer. How much longer I don't know. I'll let someone better at math work that out. But the link DFW provided won't let the ship reach light speed, so is probably the quickest way to find out.

Edit: Lets see, according to that handy link, a 1 parsec journey would mean 3.5 years pass on the home planet, while the ships crew experiences 1 year of time, and reach a maximum velocity of 99.59% of the speed of light.

A 2 parsec journey, reaching a maximum velocity of 99.88% of the speed of light, would mean 6.8 years pass on the home planet, while the crew of the ship experiences 1.2 years of time.

 

[locarno24]

A 2 parsec journey, reaching a maximum velocity of 99.88% of the speed of light, would mean 6.8 years pass on the home planet, while the crew of the ship experiences 1.2 years of time.

1.2 Years of fuel is probably best dealt with by fission power; fission plants run a year on the reactor volume a fusion plant needs for two weeks.

For reactor-6, you'll need 5% of the hull, and 4/3 of that is enough power for two years of operations (i.e. the specified journey, assuming no problem with obtaining fissile material at the other end).

Don't forget the Endurance section as well - for every month after the first, 1% of your volume will be needed for spares. For two years, therefore, that's 23% of your volume as spares storage!

a 100,000 dton hull isn't going to have a problem with cargo of the size you describe.

 

[Solomani666]

If you assume a maneuver drive can eventually exceed the speed of light, a 1 parsec journey at 6gs acceleration would take 75 weeks. 2 parsecs take 106 weeks. (I used the formula given in Classic Traveller, and believe my math is correct.)

No it can not exceed the speed of light.

.

 

[rust]

- deleted, I confused sub-light / maneuver drive with reaction drive, ob-
viously need more coffee ... -

 

[Solomani666]

This should help

http://mysite.verizon.net/res148h4j/javascript/script_starship.html

Thanks DFW, this is EXACTLY what I needed.

.

 

[RichardP]

Black globe is a no go. When the globe is up it provides a barrier against physical objects, so it cuts the boom in half.

Why M6. This is an endurance race, swap it out with M1 and lots of extra fuel, very true if you are using some sort of reaction drive.

If you have White Dwarf 32 it had a nice article about STL ships including travel times for STL vessels at various fractions of C. I will see if I can find it and post across.

What about a solar sail. Cheap, but very very slow. There are some nice designs for a solar sail ship in the Sci novels by an author called Forward (Roche World Books)

Cheers
Richard

 

[Solomani666]

Don't forget the Endurance section as well - for every month after the first, 1% of your volume will be needed for spares. For two years, therefore, that's 23% of your volume as spares storage!

I think that a TL16 ship could be purposely built to require only 10% of the normal maintenance functions.

At .95c any systems failure is likely to be critical, so the ship would be built to last a decade without an overhaul.

.

 

[rust]

At .95c any systems failure is likely to be critical, so the ship would be built to last a decade without an overhaul.

Not really, unless the ship is in contact with anything outside the ship it
makes no difference whether the ship is at rest or at 0.95 c.

 

[Solomani666]

I think the ship will use a combination of small black globe generators and electromagnetic or gravitic fuel scoops.

From stem to stern I see the following sections:


1. Shield Section
Widest section of the ship.
Forward part of this section is armored to 32. (2 x TL)
Massively radiation shielded.
Contains 1 bank of 6 nuclear dampers.
Contains 2 banks of 3 black globe generators.
The black globe generators produce a shield only slightly larger than this hull section.

1a. Transfer Section (Possibly Omitted)
This section exists if it is unanimous on this forum that you can not stick a shielded power cable through a black globe field and transfer power through it.
This section is in-between the fields created by the two staggered black globe banks.
It contains capacitors that temporarily transfer power from the shields to the main capacitor bank as each bank alternates between total on and flicker.

2. Shield Boom
This section isolates the black globe generator field from the rest of the ship.
Solar panels line its length.

3. Bussard Collector
Electromagnetic or gravitic collector. (any idea which?)
Its field extends several kilometers beyond the diameter of the ship and collects free hydrogen from space.
No refinement is needed.

4. Collector Boom
Isolates the Bussard collector from the rest of the ship.
Solar panels line its length.
Collectively both solar panel arrays provide enough power for 1 g maneuver or fuel refinement.

5. Bridge / Crew Quarters
20 crew members at most.
The ship will be highly automated with expert systems and repair robots.

6. Cargo
2000 tons + 03% for supplies and spare parts.
2 x Pinnace.

7. Power Storage
Massive banks of capacitors and batteries.
Are charged by the black globe generators when traveling at relativistic speeds.
Stores power from the solar panels when in system.
Provides most or all of the ships power when travelling above .50c

8. Engineering
TL16 Variable Array Power Plant 6. (Adjustable power output and fuel consumption)
Maneuver Drive 6 as 6 separate maneuver drive 1's.
Maneuver Drives are in pylons and their fields can be reversed to decelerate the ship.
An emergency Jump 1 drive. (Optional)
Fuel purifiers.



What do you figure would be the minimum size for such a ship?

Should I allow a shielded power conduit to go through a black globe generator field?

Should the Bussard collector be electromagnetic or gravitic?
How much space should it take up?

Can you think of anything I forgot or left out?

Can you think of anything that needs to be changed?

Can you think of any reason that it won't work?


.

 

[DFW]

Don't forget the Endurance section as well - for every month after the first, 1% of your volume will be needed for spares. For two years, therefore, that's 23% of your volume as spares storage!

I pretty much ignore that rule as it is beyond ridiculous. Even low tech current day ships, that have MANY times the moving parts, don't replace/repair 11-12% of their equip (by mass) over many more years.

I use the same % as maint cost for required spares while away from repair facilities

 

[rust]

Can you think of any reason that it won't work?

Yep, the Bussard collector would hardly be able to collect enough fuel for
the fusion power plant, the amount of hydrogen in normal interstellar spa-
ce is very low, and collecting it would probably use up more energy than
the hydrogen would produce.

With an average of 0.2 to 0.5 atoms per cubic centimeter of the interstel-
lar medium and a fusion power plant which requires 10+ tons of hydrogen
per week, this is just not a plausible concept.

However, you can of course always handwave it and decide that there is
enough hydrogen available where the ship goes.

 

[RichardP]

The black globe will cut your ship in half when you turn it on (See CT adv 12 secrets of the ancients where a globe cut a researcher in half).

The globe will have to surround the entire ship and then you can't see out and can't accelerate. Black globes are for stealth or for a warship, why is an STL vessel carrying one?

Cheers
Richard

 

[RichardP]

Isn't the point of the bussard ram to gather enough hydrogen atons in deep space to power your engines (both fuel for fusion plant and reaction mass), so why are you using batteries powered by energy absorbed by a black globe.

The ram field is normally magnetic but don't see why it can't be gravitic instead given TL16.

Cheers
Richard

 

[Solomani666]

At .95c any systems failure is likely to be critical, so the ship would be built to last a decade without an overhaul.

Not really, unless the ship is in contact with anything outside the ship it
makes no difference whether the ship is at rest or at 0.95 c.

Space is NOT empty

It contains an average of 2 molecules of hydrogen per cubic centimeter.
At .95c this will turn and unarmored and unshielded ship into dust in seconds.

If you are travelling toward a star, the light and other EM radiation from that star is going to blue shift into x-rays, gamma rays etc at hundreds of times higher than a lethal dose.


.

 

[DFW]

Space is NOT empty

It contains an average of 2 molecules of hydrogen per cubic centimeter.
At .95c this will turn and unarmored and unshielded ship into dust in seconds.

If you are travelling toward a star, the light and other EM radiation from that star is going to blue shift into x-rays, gamma rays etc at hundreds of times higher than a lethal dose.

The molecules aren't going to destroy the hull, based on MGT hull strength. The particles/dust in system you encounter while transiting interplanetary space are millions of times more massive that H2 molecules and you aren't traveling millions of times faster for your near c trip.

The amount of EM energy is the same whether moving or, at rest.

 

[rust]

If you are travelling toward a star, the light and other EM radiation from that star is going to blue shift into x-rays, gamma rays etc at hundreds of times higher than a lethal dose.

Thanks to the inverse-square law you would have to be rather close to a
star to get a high enough dose of radiation to make this a danger for the
ship or its crew, the radiation in interstellar space would still be much less
than the average radiation in an inner system.

As for the hydrogen, it would be 0.2 to 0.5 atoms (not molecules) per cu-
bic centimeter of the average interstellar medium, very far below the le-
vel where it could become a problem for a ship designed to travel through
the much more dangerous interplanetary space.

 

[Solomani666]

Isn't the point of the bussard ram to gather enough hydrogen atons in deep space to power your engines (both fuel for fusion plant and reaction mass), so why are you using batteries powered by energy absorbed by a black globe.

The ram field is normally magnetic but don't see why it can't be gravitic instead given TL16.

Cheers
Richard

The idea is to use both.

The black globe is to protect the ship when it travels at relativistic speeds.
As particles collide with the ship, the impact is absorbed by the shield and converted into energy to power the ship.
It serves the same purpose as the deflector dish does in Startrek.

It also has a Bussard collector field that extends many kilometers beyond the the ships hull and feeds the ships power plant directly.


.

 

[locarno24]

1. Shield Section
Widest section of the ship.
Forward part of this section is armored to 32. (2 x TL)
Massively radiation shielded.
Contains 1 bank of 6 nuclear dampers.
Contains 2 banks of 3 black globe generators.
The black globe generators produce a shield only slightly larger than this hull section.

As noted, black globes are almost 'event horizon' level impenetrable shielding, and you'll cut the section free of the hull.
If it was me, I'd go for the classic sci-fi, low-cost solution - an ice shield (used in Songs of Distant Earth by Arthur C Clarke and about 2^12 times since).

Ice is a good radiation shield, and good ablative protection from particle collisions if it's thick enough. With grav technology and a convenient ocean, it's not excatly costly to create, or else just split a big ice asteroid in half and use that.

However - going with what you'd described, I'd ignore the black globes. If you want extra protection, I'd go for reinforced hull several times on the forward section (the closest the rules come to ablative plating).

How are you modelling the double thickness armour? Just going for two layers? Personally I'd increase the cost/volume requirements for the second layer - producing an armour value twice as high with the same materials as is normally possible will take special effort to my mind - there must come a point where simply slapping more bonded superdense on the front provides diminishing returns...

Radiation dampers aren't too much use; I suppose the shield hull would be getting a bit of radiation bombardment but not enough to start undergoing fission. Remember a radiation damper doesn't get rid of a gamma particle flying through it, it just prevents fission occuring in the first place, and you shouldn't be encountering much free-floating U-235.

1a. Transfer Section (Possibly Omitted)
This section exists if it is unanimous on this forum that you can not stick a shielded power cable through a black globe field and transfer power through it.
This section is in-between the fields created by the two staggered black globe banks.
It contains capacitors that temporarily transfer power from the shields to the main capacitor bank as each bank alternates between total on and flicker.

Don't quite understand your meaning. A black globe produces a sphere. Anything intersecting that sphere is cut, so even if it's flickering it'd slice itself off.

2. Shield Boom
This section isolates the black globe generator field from the rest of the ship.
Solar panels line its length.

Solar sails aren't a bad plan once you arrive in a system; once down to orbital speed you can coast for a bit. Pretty irrelevant at a system's edge or beyond, of course.

3. Bussard Collector
Electromagnetic or gravitic collector. (any idea which?)
Its field extends several kilometers beyond the diameter of the ship and collects free hydrogen from space.
No refinement is needed.

Without knowing what exactly the hydrogen processor is processing for, my default reaction would be to say no, but on the other hand you're not processing fuel for a jump drive, only a power reactor.
H-1 to H-1 fusion works - albeit not so well as some of the isotope combinations. I'm not convinced the hydrogen density in interstellar space is enough to provide meaningful power for a 6G gravetic ship, though. And if you use a j-drive, you will need a fuel processor.

It's never been said what a fuel processor is processing for - chemical impurities, isotropic impurities or for all we know bloody quantum state impurities. Without any clarification, smile, nod and fit the things.

4. Collector Boom
Isolates the Bussard collector from the rest of the ship.
Solar panels line its length.
Collectively both solar panel arrays provide enough power for 1 g maneuver or fuel refinement.

Observation - as ever, your game, your rules, your physics. But solar sails explicitely do not provide enough power to run a manouvre drive in the core rules, and the further from a star you get (i.e. making an interstellar run)

5. Bridge / Crew Quarters
20 crew members at most.
The ship will be highly automated with expert systems and repair robots.

Fair enough. High Guard will give you crew requirements - just include a sufficient number of repair drones and subsidiary computers to compensate.

6. Cargo
2000 tons + 03% for supplies and spare parts.
2 x Pinnace.

If you're explicitely declaring 10% of maintenance needed, fair enough.

At .95c any systems failure is likely to be critical, so the ship would be built to last a decade without an overhaul.

As noted, I don't see that the speed makes the failure any more or less critical; it's not like you're going to hit anything.

7. Power Storage
Massive banks of capacitors and batteries.
Are charged by the black globe generators when traveling at relativistic speeds.
Stores power from the solar panels when in system.
Provides most or all of the ships power when travelling above .50c

First:
Classic black globe annihalates anything it touches (as noted, slicing the generator off the end of a boom).

Second:
Black globes cut the inside of the sphere off from the rest of the universe, which is why you can't accelerate whilst using one on full and reduce your manouvrability when it's flickering.

Third:
Even assuming 100% efficiency, I don't know if you'd be gaining enough energy to run your ship off relatively sparse interstellar particles; bear in mind that black globe equipped ships shunt the shrapnel from a torpedo (i.e. several massive chunks of solid material) into whatever annihalatory nonspace it uses with barely a flicker.

8. Engineering
TL16 Variable Array Power Plant 6. (Adjustable power output and fuel consumption)
Maneuver Drive 6 as 6 separate maneuver drive 1's.
Maneuver Drives are in pylons and their fields can be reversed to decelerate the ship.
An emergency Jump 1 drive. (Optional)
Fuel purifiers.

If you need an emergency jump you will need hydrogen fuel tankage.

Manouvre drives can accelerate the ship anyway. It's never been said to my knowledge that a g-drive ship has to turnover to decelerate. Compared to the miracle of deforming spacetime at a whim, being able to slew whatever projector is needed without needing a rotating mounting or whatever is child's play.

Note that multiple manouvre-1s may not combine in the same way. Multiple reaction-1s obviously stack - double the rocket's impulse, double the momentum gain. But when dealing with a device designed to project an induced gravetic field, focusing two on the same point may or may not stack their effects in a linear fashion.

The capital ship drive volume, for example, is not a linear progression.
On the other hand, six M-1s are twice the volume of 1 M-6 so it's not a bad fudge to make.