• Welcome to the new COTI server. We've moved the Citizens to a new server. Please let us know in the COTI Website issue forum if you find any problems.
  • We, the systems administration staff, apologize for this unexpected outage of the boards. We have resolved the root cause of the problem and there should be no further disruptions.

acceleration limits?

spank

SOC-13
In standard ship designs, what is the max percent of lightspeed you can accelerate to? Is acceleration assumed to be constant up to this point, or does it fall off?
 
I do not remember ever seeing a limit in Classic Traveller.

FTL interstellar maneuver drives would appear to be a theoretical possibility.
 
In standard ship designs, what is the max percent of lightspeed you can accelerate to? Is acceleration assumed to be constant up to this point, or does it fall off?

There's no limit. You can push your 1G engine until you reach lightspeed and beyond. A good 10G engine will take you across interstellar distances in about 40 days.

But, Far-Trader's warnings apply.
 
There's no limit. You can push your 1G engine until you reach lightspeed and beyond. A good 10G engine will take you across interstellar distances in about 40 days.
That's good to know; 'cuz once we all get to Marc Miller's fabled "Heat Death of the Universe" T4 milieu, the interstellar distances are going to have stretched out to quite a bit further than your basic J-6 FTL ship can make.:nonono:
 
There's no limit. You can push your 1G engine until you reach lightspeed and beyond.
Heh. I know of no canon evidence for M-drive being able to exceed the speed of light, though I can't say it would horribly bother me, since it means that M-drives are necessarily pseudovelocity drives of some sort.
 
Heh. I know of no canon evidence for M-drive being able to exceed the speed of light, though I can't say it would horribly bother me, since it means that M-drives are necessarily pseudovelocity drives of some sort.
There is also no canon reference that denies it either.
 
There is also no canon reference that denies it either.
True, though there are enough cases of sublight colony ships that you'd think they'd mention FTL capability. In the Imperium boardgame, you can make sublight interstellar trips, but you cap out at about 0.9c.
 
True, though there are enough cases of sublight colony ships that you'd think they'd mention FTL capability. In the Imperium boardgame, you can make sublight interstellar trips, but you cap out at about 0.9c.

But then you can't use the travel time formula from LBB2. :)
 
Exactly. In short, then, fractions of C just aren't considered important to Traveller's rules, where jump is considered the fastest way to get anywhere, and relativity just sort of seems to be assumed not to matter.

Maybe drives shut down at a certain point. Or maybe ships break up. Or not. You might have to come up with something to fill that gap.
 
True, though there are enough cases of sublight colony ships that you'd think they'd mention FTL capability. In the Imperium boardgame, you can make sublight interstellar trips, but you cap out at about 0.9c.

0.5Pc hex (1.625LY) per 6 months? ISTR that light only goes 0.5LY per 6months...:devil:
 
If relativity applies, then jump drive would allow time travel into the past. (It's complicated, I know. It has to do with spacetime not being Euclidean.)

So it seems like only some relativity applies. :)

--Devin

Of course, you can always say those primitives back on pre starflight Terra just got it wrong and didn't figure out their mistake until they developed jump drive :)
 
I think the safest line to draw would be to say that Relativity is somehow bypassed by the Jump Drive (Myand Wave Theory), but the M-Drive still needs to account for it.

As a rule of thumb, you can use the book-2 formula derived from Newton's equations of motion up to about 0.1c. After that, you need to start using the Lorentz Transforms, and I never did entirely get my head around how to use the equations for Speed, Mass and Acceleration simultaneously, so I can't help much there. Figuring those out is somewhere near the bottom of my to-do list. :(
If you find out how to calculate it, let me know. :o

Unfortunately, even at 1G, you would experience relativistic effects before you reached the half-parsec turnaround point, so the standard formula is only good for in-system or far-companion range.
 
Last edited:
If you are using HePlar, then you will be limited by the exit velocity of the plasma from the exhaust nozzle.

Realistically, you would be limited to about HALF that speed since the difference in velocity would be reduced greatly reducing the thrust of the drive.

Current theory puts an upper limit at about 0.1 or 0.2c, but using gravitics and HePlar, maybe you could get to 0.5c.

Relativity and Lorenz Transformations are OK and DO play an effect at lower velocities, but until you get to about 0.5c, the time dilation isn't too bad, and you could probably ignore it in most games.

I DO have a book that has all the formulas for Relativity if anyone is REALLY interested. I could dig it out and send it along.

Here is a REALLY abbreviated form:

TOTAL MATH/SCIENCE/ENGINEER GEEK MODE ON

The key formula is the calculation of Gamma, which is:

Gamma = Sqrt(1/(1-(V^2/C^2)))

So, as velocity increases, the value of Gamma increases, but if V = C, then the denominator of the formula becomes Zero and the value of Gamma becomes Infinite (OK, actually undefined, but that is math, not engineering).

If V > C then you get a negative value inside your square-root and things become imaginary (not related to reality).

Gamma can be used to figure out the time dilation of a trip or the relative mass vs the rest mass of an object (it is a multiplier).

So if you are moving at 0.5c the value of Gamma is 1.15

So for every second on the ship, 1.15 seconds passes in the "real" universe. That is only a 15% difference, or about 1 in 6, so not too bad.

At 0.9c, the value of Gamma is 2.29.

TOTAL MATH/SCIENCE/ENGINEER GEEK MODE OFF

If anyone wants more details, PM me.
 
If relativity applies, then jump drive would allow time travel into the past. (It's complicated, I know. It has to do with spacetime not being Euclidean.)

Actually no. The equivalence of FTL travel to time travel is established by Special Relativity, which deals with Euclidean universes. It depends on simultaneity not being invariant. You don't need General Relativity (which deals with non-Euclidean universes) to demonstrate that FTL travel is time travel.
 
Back
Top