On 26/5/23 16:23, kaladorn at gmail.com (via tml list) wrote: > > On Reddit, I got told that m-drive was magic and you could just thrust > for a portion of a year at 1G acceleration and end up at the speed of > light. > > I did try to point out that exceeding about 30% of the speed of light > started to pull in relativity, but the person handwaved that away. > Apparently they think that Traveller m-drives and the ships on them > aren't affected by relativity. > > Now, I can't speak to MgT2, but I didn't see that in MgT1 in anything > in read and I don't recall anything like that in CT products or in MT > or DGP products (SOM v 1 particularly). Don't recall any question like > that in TNE period that I ever saw. > > Pragmatically, I'd think they'd burn all their power plant fuel and > m-drive fuel before you got anywhere near light speed. And I'd assume > (but the rules probably don't cover it in MgT1-2 because they like to > leave stuff to the GMs to deal with) that life support would probably > also be flatlined before a year of straight thrust would go. Now, > could you hop into a cold berth and try to cut the needs for food or > breathing? That part might be viable. But how many overhauls and > repairs would you need in a year? > > It's basically 1G continually thrusting over just a bit less than a > full year gets you to the speed of light if relativity is ignored. > > So what do the wise of this list say to the question of whether > m-drives and the ships on them are impacted by increasing mass/weight > from relativity? Can you really just thrust to the speed of light? > (And even sillier, if you could keep thrusting forever, what would > stop you going FTL just with your m-drive?) > > I think I would NOT allow this but maybe the rules now (or sometime > before that I just didn't absorb) says you can just thrust forever and > gain FTL or FTL+ speeds.... what do you say? > > TomB / kaladorn > > > On STL drives alone, I'd say no. As for relativistic FX: GT Interstellar Wars, p174, "Sublight Interstellar Travel" adds this: "The usual procedure for STL interstellar travel is for the ship to accelerate at maximum drive capacity until reaching about 0.8 c (where c is the speed of light, about 186,000 miles per second). This takes about two months for the fastest warships, or between 18 and 24 months for slow merchant vessels and colony ships. Although reactionless thrusters work at even higher velocities, 0.8 c is the highest safe speed – any faster, and even a heavily armored vessel faces too much risk from interstellar debris and hard radiation. At this “interstellar cruising speed,” a ship takes about four years to travel a single parsec (one hex on the standard subsector maps). The ship shuts down its drives and coasts through interstellar space, only beginning to decelerate when it approaches the target star." The _Churchill_ class battlewagon can boost at 4.5 G, while the _Richthoften_ missile corvettes can boost at 6 G, as can the _Phidippides_ fast courier. I'll count "fastest warship" as 6 G. 0.8 c is ~ 240,000 km/s, or (1 G-hour being delta-V of 35,280 m/s) 6,802.7 G-hours, or 1133 hours @ 6G, telling relativity to sod off. 47 days (283 G-days) under continuous boost would be stretching "about two months" as far as it would go, taking 1 month as 30 days. The delta-V accumulated (as _rapidity_, not _velocity_ - see https://en.wikipedia.org/wiki/Rapidity , if I haven't misunderstood it) over 360 G-days would be 305,030 km/s, and thus a _velocity_ of ~0.713c or 213,888 km/s (gamma being ~1.42 at that velocity). 0.8 c corresponds to a 400,000 km/s rapidity. That's 11,337 G-hours or 472 and a half G-days. Down the lower end of town, an empty Hero-class far trader can bucket along at 1.5 G. Captain L. R. Jenkins decides to slow boat it, boosting at that massive acceleration for 730 days (24 months or 2 years). 1095 G-days of acceleration accumulates a rapidity of 928,621 km/s. That works out to a _velocity_ of ~0.952c or 285,472 km/s - the _Ship of Fools_ may have a problem. Looks like GT: ISW accounts for relativistic effects. Alex
