Non OTU: Bussard Ram Jet ships added to my Traveller ?

[JimMarn]

I know basically how they work, after reading several sf stories that included them. Huge magnetic screens pulling in hydrogen gas, that gets burned by lasers creating a plasma jet out the back.

I am looking for ideas, I may or may not modify, on how a Bussard Ram Jet would work in CT or MgT Traveller.

I was thinking about making them slightly slower than jump drive.

Maybe 1 parsec in 3 weeks.

What are your thoughts on this ?

Thanks !

 

[whulorigan]

I know basically how they work, after reading several sf stories that included them. Huge magnetic screens pulling in hydrogen gas, that gets burned by lasers creating a plasma jet out the back.

I am looking for ideas, I may or may not modify, on how a Bussard Ram Jet would work in CT or MgT Traveller.

I was thinking about making them slightly slower than jump drive.

Maybe 1 parsec in 3 weeks.

What are your thoughts on this ?

Thanks !

A Bussard Ram Jet is still going to be limited by the lightspeed barrier. It is a slower-than-light Interstellar Drive. So even if it could accelerate (relatively) quickly to 0.99c, it would still take about 4.5 years to get to the nearest star, Alpha Centauri, which is about 1.3pc (Jump-2) away.


If I may ask: Is your desire to include Bussard Ramjets based on wanting to use that particular drive system (i.e. you like the Bussard Ramjet concept), or is it based on a desire to have an interstelllar drive that is slower than Jump, and the Bussard Ramjet simply came to mind?

 

[JimMarn]

I like the idea of it, and was looking for a way to add it.

I was going to 'tweak' it in my universe and say it would travel FTL speeds, albeit slower than Jump drive. I don't want it to overtake/dominate Jump drive. I want to use it as a slower, but still over FTL speeds, means of getting from solar system to solar system. Hmm... and I would like to kinda keep it Travellerish.

The travel would be from 100d in one solar system to 100d in another solar system.

So, I guess referee decision to use it as FTL, but I would like something closer to Traveller physics, without getting it to be something I just dreamed up.

edit: I hope that makes sense.

 

[whulorigan]

I like the idea of it, and was looking for a way to add it.

I was going to 'tweak' it in my universe and say it would travel FTL speeds, albeit slower than Jump drive. I don't want it to overtake/dominate Jump drive. I want to use it as a slower, but still over FTL speeds, means of getting from solar system to solar system. Hmm... and I would like to kinda keep it Travellerish.

The travel would be from 100d in one solar system to 100d in another solar system.

So, I guess referee decision to use it as FTL, but I would like something closer to Traveller physics, without getting it to be something I just dreamed up.

In that case, a Bussard Ramjet will not work on its own for this purpose (unless you are ignoring Special Relativity, of course). You could add it as a primary propulsion component in a drive system that includes some variant type of "Warp Drive" perhaps.

As an aside, a Bussard Ramjet (by modern technology considerations) would need some form of separate propulsion to get the ship up to about 0.1c (this is roughly the necessary speed for the magnetic "intake" to be gathering enough interstellar hydrogen per unit time to sustain a continuous fusion reaction).


The Bussard Ramjet would certainly work as a long-term interstellar drive for cultures that have not achieved FTL drive technology, of course. Or as a means of moving very large objects from one star system to another for which Jump technology is impractical or non-viable (as long as a several decade trip is acceptable).

 

[JimMarn]

In that case, a Bussard Ramjet will not work on its own for this purpose (unless you are ignoring Special Relativity, of course). You could add it as a primary propulsion component in a drive system that includes some variant type of "Warp Drive" perhaps.

As an aside, a Bussard Ramjet (by modern technology considerations) would need some form of separate propulsion to get the ship up to about 0.1c (this is roughly the necessary speed for the magnetic "intake" to be gathering enough interstellar hydrogen per unit time to sustain a continuous fusion reaction).


The Bussard Ramjet would certainly work as a long-term interstellar drive for cultures that have not achieved FTL drive technology, of course. Or as a means of moving very large objects from one star system to another for which Jump technology is impractical or non-viable (as long as a several decade trip is acceptable).

I do have a small empire, about 6 systems in a sub-sector, where I posit they used generation ships to move some items between systems before someone came along and showed them Jump drive.

I could use it there... I was thinking about putting asteroid generation ships there with no clear idea on propulsion. Bussards would work for this area.

For the Starship Wanderer on my site, I could just strap a Jump drive on it for faster speeds. It is large enough to carry tremendous amounts of fuel.

 

[whulorigan]

For the Starship Wanderer on my site, I could just strap a Jump drive on it for faster speeds. It is large enough to carry tremendous amounts of fuel.

Here's a thought (and the reason why I asked my question in my first post):

You could introduce an "inferior" stutterwarp technology (ala Traveller:2300). Jump 1 is an effective speed of about 170.0c. If you take a standard stutterwarp from Traveller:2300 and divide the efficiency by 50-100 (give or take), you can exploit the FTL speeds that are significantly below Jump 1. And since the efficiency of stutterwarp drops off to .0001 of normal in gravity greater than .0001g, it means that the said "inferior stutterwarp" would be fairly useless as an in-system drive, and require an alternate Maneuver-Drive for in-system maneuver.

It shouldn't break the Traveller paradigm: Jump would still completely outclass the inferior stutterwap at FTL, and would not replace M-Drives for STL/In-system travel. Just a thought.

 

[aramis]

For comparative reference, J1 is nominally 170C, but can be as high as 189 C or as low as 154 C and still be in the "normal jump" range.

 

[JimMarn]

What I remember of Bussards, it didn't work in system. While solar systems do move around the galaxy, a solar system's general area could be too clean of hydrogen atoms to provide fuel. Our solar system is in a 'local bubble' where the hydrogen gas and dst is sparse.

Jump 1 is two weeks to go 1 parsec.

So I could make a Bussard at x time for 1 parsec.

Half would be a month travel time. Still getting there, and not taking a lifetime or longer.

I can see where a Jump 1 drive would be added so that if the local stellar medium lacked the fuel for a Bussard, the ship wouldn't be stranded between star systems.

 

[JimMarn]

Hmm. 4.5 light years to Alpha centauri is 38.25 trillion miles.

170 C is 31620000 miles per second.

38.25 trillion miles divided by 186200 miles per second is 205424274.97 seconds

205424274.97 divided by 60 seconds in a minute = 3423737.92 minutes.

for 339.66 weeks.

84 months

which is 7 years for that trip at 85 C.

Probably messed that up somewhere. But 7 years isn't that bad.

 

[mike wightman]

In standard Traveler jump 1 is 1 week to travel 1 parsec.

How is you rocket exceeding the speed of light?

In Star Frontiers once a ship got up to a significant fraction of c it entered a sort of transit space that allows FTL travel.

 

[JimMarn]

In standard Traveler jump 1 is 1 week to travel 1 parsec.

How is you rocket exceeding the speed of light?

In Star Frontiers once a ship got up to a significant fraction of c it entered a sort of transit space that allows FTL travel.

7 years vs a week to travel 4.5 light years.

Unless I misunderstood what was posted earlier, and that is possible.

 

[aramis]

Hmm. 4.5 light years to Alpha centauri is 38.25 trillion miles.

170 C is 31620000 miles per second.

38.25 trillion miles divided by 186200 miles per second is 205424274.97 seconds

205424274.97 divided by 60 seconds in a minute = 3423737.92 minutes.

for 339.66 weeks.

84 months

which is 7 years for that trip at 85 C.

Probably messed that up somewhere. But 7 years isn't that bad.

A:

• Alpha C is only 4.37 LY, per current measurements
• B: C in the OTU is, per TNE's FF&S, C=300,000,000 m/s (Real world is a slightly less convenient 299792458 m/s).
• C: 1 Parsec is 3.08567758 × 10^16 meters; approximately 3.086e16
  1 LY is 9.460730472580800x10^15m, approximately 9.461e15

So... Working at 4 significant digits

9.461e15 m x 4.37e0 LY= 4.134e16 m

But it's just easier to work in fractions of a year. A week is 0.019178 years. For simplicity, 0.019 is close enough. It's 166 hours...

At 170 C, the 4.37 LY is 4.37/170 years... or 0.025705 years. Or 1.34weeks. (Due to the way Jump works in universe, it never sustains that 170C, and A-C is J2 away.)

At 85 C, 4.37/85 = 0.051411y = 2.68 weeks = 18.76 days.

At 0.85C, 4.37/0.85 = 5.14 y = 1875.5 days.

 

[JimMarn]

I'll take 5 years over 7. Still doable. But the ship has to get out past the Oort Cloud then get up to Bussard ram jet speeds.

Slow down at the other end, and then manouver at sub-light speeds until the ship can get into orbit around the planet they are heading for.

I'll handwavium it at a total of 7 years per 4.7 light years.

That will work for the small empire I decided to use this for. The Gresha Empire: http://travellergame.drivein-jim.net/articles/653/gresha-empire-still-here

Now to work on the wormholes I came up with for one sector, ancient technology. Less than 10 of them.

 

[mike wightman]

How about using a solar sail to get out past the Oort cloud and then switch to Bussard. It'll add a few more years to your trip time though.

 

[JimMarn]

How about using a solar sail to get out past the Oort cloud and then switch to Bussard. It'll add a few more years to your trip time though.

That could work, maybe a bit faster if the ship carried its own bevawatt laser to hit the solar sail with.

 

[mike wightman]

Keep the lasers as ground installations - reduces the mass of the ship.

 

[JimMarn]

Keep the lasers as ground installations - reduces the mass of the ship.

Wanderer is so huge, I don't think it would matter much if I added multiple lasers.

But for smaller ships, that mass could be a big limiting factor on cargo, living spaces, food, water, and air for the crews.

 

[mike wightman]

You can't use a solar sail powered by lasers mounted on the ship with he sail.

The momentum of firing the laser will cancel the momentum gained by the sail - you can't power a sailing ship with a fan

 

[Zutroi]

You can't use a solar sail powered by lasers mounted on the ship with he sail.

The momentum of firing the laser will cancel the momentum gained by the sail - you can't power a sailing ship with a fan

Install the laser firing forward for ionizing the hydrogen the ramscoop needs, as well as for in-system braking on arrival. Bounce it off the solar sail as you get up to speed as an addition to the total thrust...

(Pay no attention to the potential weaponry usage... Just move along now and forget all about 'the Kzinti Lesson')

 

[JimMarn]

You can't use a solar sail powered by lasers mounted on the ship with he sail.

The momentum of firing the laser will cancel the momentum gained by the sail - you can't power a sailing ship with a fan

I saw the fan and sailboat being debunked on Mythbusters.

But I'm going to handwavium, easier to find than unobtanium, the laser firing at the solar sail.

I just need to determine velocity gained, and how long it takes to get up to 0.1C.