Because I am both Lazy and Curious...

[Magnus von Thornwood]

I didn't feel like trying to wade through the 68 pages of the Fleet section, and I love posting and starting new threads...

I was thinking about the Famili History and such and the long ago days of the Interstellar Wars and came up with a possible design for a long range sleeper ship.

The design starts with the problem of refueling a sleeper ship enroute to it target location. To solve this I opted for a the old Hydrogen ram scoop to refill fuel tanks to jump capacity and of course have enough for other uses (sorry is late and am somewhat tired so the terms are all vague and stuff.)

Once the tanks are filled the computer then plots a Jump Line, powers up the Jump Drive and flash and away.

So, comments? Also once I get the scanner set up, probably some time this week I will sketch one up and post it. But for now since I promised my cat that we'd hit the rack after this post, I am being very short with this and will have to fill out details later. 'Sides that gives everyone to time to tell me it's retarded (by which I mean not terribly well thought out) or brilliant (as in why didn't I think of that).

mega:

 

[tim_manley]

I didn't feel like trying to wade through the 68 pages of the Fleet section, and I love posting and starting new threads...

I was thinking about the Famili History and such and the long ago days of the Interstellar Wars and came up with a possible design for a long range sleeper ship.

The design starts with the problem of refueling a sleeper ship enroute to it target location. To solve this I opted for a the old Hydrogen ram scoop to refill fuel tanks to jump capacity and of course have enough for other uses (sorry is late and am somewhat tired so the terms are all vague and stuff.)

Once the tanks are filled the computer then plots a Jump Line, powers up the Jump Drive and flash and away.

So, comments? Also once I get the scanner set up, probably some time this week I will sketch one up and post it. But for now since I promised my cat that we'd hit the rack after this post, I am being very short with this and will have to fill out details later. 'Sides that gives everyone to time to tell me it's retarded (by which I mean not terribly well thought out) or brilliant (as in why didn't I think of that).

mega:

Interesting...

I once built a sleeper ship using LBB2 rules waaaay back when. It was J1 1G and had enough fuel for a couple dozen jumps (don't recall exact #s... can re-do the math if needed) with no cabins, nothing but low berths.

The players used it to carry themselves and passengers across a divide. They used the computer to jump, plot, jump, plot, jump, plot, etc. And wake them up when they were done.

I like your idea... though the H2 ram scoop relies on moving pretty fast...

----

Okay, dumped these into a quick spreadsheet:
800dt hull
J/M/P D 45dt, J1, G1
Fuel 90dt (10p/m, 80j)
model2 comp
4 staterooms
250 low berths (not really colony ship...)
450dt fuel (+5 jumps)
cutter
with 36dt left over

Total cost MCr 223.58

 

[mike wightman]

If getting there quickly isn't a problem then forget the jump drive altogether.

Install a large fuel tank for the power plant, switch on the m-drive and accelerate to a high fraction of c. Then switch off the m-drive, power down the power plant and drift at near light speed until you are almost at your destination. Switch the power plant back on and use the m-drive to slow down.

Using a ram scoop you could cut down on the amount of fuel carried since you will be refueling enroute, and you will be able to keep the power plant opereational at above the trickle needed for the computer and low berths.

Note that this is how the early terran sleeper ships did it

 

[tim_manley]

If getting there quickly isn't a problem then forget the jump drive altogether.

Install a large fuel tank for the power plant, switch on the m-drive and accelerate to a high fraction of c. Then switch off the m-drive, power down the power plant and drift at near light speed until you are almost at your destination. Switch the power plant back on and use the m-drive to slow down.

Using a ram scoop you could cut down on the amount of fuel carried since you will be refueling enroute, and you will be able to keep the power plant opereational at above the trickle needed for the computer and low berths.

Note that this is how the early terran sleeper ships did it

Well there's trip duration and then there's trip DURATION.

 

[far-trader]

Unfortunately Science has killed the Fiction of the ram-scoop. A good explanation is found here:

Atomic Rocket - Bussard Ramjet

Fortunately, this being Traveller and still Science with Fiction feel free to ignore the above

 

[tim_manley]

Unfortunately Science has killed the Fiction of the ram-scoop. A good explanation is found here:

Atomic Rocket - Bussard Ramjet

Fortunately, this being Traveller and still Science with Fiction feel free to ignore the above

Hmm...

A proton-proton fusion drive has an exhaust velocity of 12% c, so a proton-proton fusion Bussard Ramjet would have a maximum speed of 12% c. You may remember that a spacecraft with a mass ratio that equals e (that is, 2.71828...) will have a total deltaV is exactly equal to the exhaust velocity. So if a conventional fusion rocket with a mass ratio of 3 or more has a better deltaV than a Bussard Ramjet, what's the point of using a ramjet?

Isn't the point not carrying fuel on board? Why sailing ships were still used even though coal engines had been around... no place to get coal for your boiler so you'd use the sails.

anyway.... STL engines travelling to other stars and the time dialation makes it waaaay more than a one-way trip. It means everything you know is gone forever as your cold-sleep trip means millenia have come and gone back home....

 

[far-trader]

...anyway.... STL engines...

I think you mean FTL there, no time dilation issues with STL to worry about, just a long slow trip for everybody, aboard or not.

And yep, that's the point. If your STL fueled drives are better than ramjet performance at a point it's just as easy to carry the fuel for the trip. And Traveller thrusters are orders of magnitude more efficient than any possible ramjet drive. At least in our relatively empty bubble of space. In an area of higher interstellar hydrogen density you might make a better case for one.

 

[Ran]

It means everything you know is gone forever as your cold-sleep trip means millenia have come and gone back home....

And monkeys now rule the Earth!

 

[tim_manley]

I think you mean FTL there, no time dilation issues with STL to worry about, just a long slow trip for everybody, aboard or not.

No, I mean STL -- slower than light.

Time dilation occurs the closer you approach C.

There are two twin brothers. On their thirtieth birthday, one of the brothers goes on a space journey in a superfast rocket that travels at 99% of the speed of light. The space traveller stays on his journey for precisely one year, whereupon he returns to Earth on his 31st birthday. On Earth, however, seven years have elapsed, so his twin brother is 37 years old at the time of his arrival. This is due to the fact that time is stretched by factor 7 at approx. 99% of the speed of light, which means that in the space traveller’s reference frame, one year is equivalent to seven years on earth. Yet, time appears to have passed normally to both brothers, i.e. both still need five minutes to shave each morning in their respective reference frame.

FTL does away with both trip duration and time dilation due to the magical methods these drives work.

And yep, that's the point. If your STL fueled drives are better than ramjet performance at a point it's just as easy to carry the fuel for the trip. And Traveller thrusters are orders of magnitude more efficient than any possible ramjet drive. At least in our relatively empty bubble of space. In an area of higher interstellar hydrogen density you might make a better case for one.

In Traveller though you have a finite limit of fuel due to the amount you can carry for power-plant operation. You have created a relativistic rocket.

A good write up on the "The Relativistic Rocket" is here

 

[flykiller]

'fanyone's interested. The Argo

 

[tim_manley]

'fanyone's interested. The Argo

Not doing any math, but pulling from the chart at .77c looks like 1 year on ship equals 1.58 years on homeworld.

So time dilation on your ship (awesome btw -- thanks for the link) would be 6.8 years ship time 8.75 years homeworld time. Not that bad of a time dilation for a trip that short.

Well, it does mean don't leave your kids home. That'll be 18 years by the time your back at best estimate; of which 13 for you... grown up kid....

 

[far-trader]

No, I mean STL -- slower than light.

Time dilation occurs the closer you approach C.

Ah, right you are, I was thinking* ST(but not close to)L so minimal or no relativistic concerns.

* if my brain processes today can be considered thinking I think I'm half asleep but I don't have to operate any heavy equipment

 

[tim_manley]

Ah, right you are, I was thinking* ST(but not close to)L so minimal or no relativistic concerns.

* if my brain processes today can be considered thinking I think I'm half asleep but I don't have to operate any heavy equipment

heh... no worries

rocket chocolates

You get your chocolate AND your caffeine all in one tasty treat!

 

[flykiller]

Not doing any math, but pulling from the chart at .77c looks like 1 year on shop equals 1.58 years on homeworld.

if you'll verify those numbers, I'll include them in the description.

 

[tim_manley]

if you'll verify those numbers, I'll include them in the description.

It's from the chart given on this link here describing how relativistic rockets could work.

These equations are valid in any consistent system of units such as seconds for time, metres for distance, metres per second for speeds and metres per second squared for accelerations.  In these units c = 3 × 108 m/s (approx).  To do some example calculations it is easier to use units of years for time and light years for distance.  Then c = 1 lyr/yr and g = 1.03 lyr/yr2.  Here are some typical answers for a = 1g.

    T          t         d          v                γ
    1 year    1.19 yrs  0.56 lyrs  0.77c                 1.58  
    2         3.75      2.90       0.97                  3.99
    5        83.7      82.7        0.99993              86.2
    8     1,840     1,839          0.9999998         1,895
   12   113,243   113,242          0.99999999996   116,641

So in theory you can travel across the galaxy in just 12 years of your own time.  If you want to arrive at your destination and stop then you will have to turn your rocket around half way and decelerate at 1g.  In that case it will take nearly twice as long in terms of proper time T for the longer journeys; the Earth time t will be only a little longer, since in both cases the rocket is spending most of its time at a speed near that of light.  (We can still use the above equations to work this out, since although the acceleration is now negative, we can "run the film backwards" to reason that they still must apply.)

Here are some of the times you will age when journeying to a few well known space marks, arriving at low speed:

4.3 ly        nearest star            3.6 years
27 ly         Vega                    6.6 years
30,000 ly     Center of our galaxy     20 years
2,000,000 ly  Andromeda galaxy         28 years
n ly          anywhere, but see next paragraph     1.94 arccosh (n/1.94 + 1) years

 

[Magnus von Thornwood]

Did I mention that math is no longer a strong suit...

Holy crap peeps, here I am throwing around some handwavium and I get a ton of math on top of it all, grrrr.

Still, interesting, and somewhat a PITA to try and work out, so I will let you all know that the Jump Drive is part of the equations to in fact cut the transit time. I mean that is why we use Jump right? To keep the trip shorter and keeping time dilation effects to a minimum. Still, love that Atomic Rocket stuff, and it did tell me that I was on the right track with warming up some of the crew regularly to keep them on track and healthy, though I merely thought it would be to make sure every thing was running right. Got to have that Human presence and control after all, though I always thought that Terrans might use the computer controls and monitoring and such more, as they don't have a big problem with using freaky new tech to their advantage, unlike a certain hide bound Race we all know and love.

Oh and now I have to add the ScramJet instead, and of course, Thruster Plates, though the Plates were always there just didn't mention them. Thruster Plates to get up to Scram speeds and then scoop up fuel and Jumpski.

 

[tim_manley]

Holy crap peeps, here I am throwing around some handwavium and I get a ton of math on top of it all, grrrr.

Still, interesting, and somewhat a PITA to try and work out, so I will let you all know that the Jump Drive is part of the equations to in fact cut the transit time. I mean that is why we use Jump right? To keep the trip shorter and keeping time dilation effects to a minimum. Still, love that Atomic Rocket stuff, and it did tell me that I was on the right track with warming up some of the crew regularly to keep them on track and healthy, though I merely thought it would be to make sure every thing was running right. Got to have that Human presence and control after all, though I always thought that Terrans might use the computer controls and monitoring and such more, as they don't have a big problem with using freaky new tech to their advantage, unlike a certain hide bound Race we all know and love.

Oh and now I have to add the ScramJet instead, and of course, Thruster Plates, though the Plates were always there just didn't mention them. Thruster Plates to get up to Scram speeds and then scoop up fuel and Jumpski.

What? No one told you there'd be math??

Cold Sleep colony ships would be useful for what? how many mas colony trips are there and how many cold berths can you put on a ship... how many jumps without fuel? etc....

Ships fit roles based on missions. A colony ship needs:
* population enough for gene pool
* starting equipment to produce food/shelter on their own
* destination

So, 3,000 adults (1500f, 1500m) is probably the minimum. For saftey sake probably 10x that; so 30,000 cold berths. Which means vehciles, food stores, tools, seed, etc...

On the other hand I can see a frozen form of mass transit. 1,000 for regular runs between subsector capitals..... problem is while you may sleep months have passed.....

 

[aramis]

Actually, several studies claimed a mere 300 colonists as potentially viable. 1000 sufficient for a safe margin and free choice of mate. I remember reading references and following up.

 

[Magnus von Thornwood]

I suppose I should jump in again...

Actually, I was making use of cloning and geneering to keep the numbers down and just cranking out the troops as needed close to the target...oh and it wasn't a colony ship so much as a deep strategic strike mission of desperation.

Well that was my idea, load them up and shoot them toward, say....the enemy's homeworld/capitol...:devil: