travel time

Dorlar · Unread post by **Dorlar** » Tue Jul 18, 2006 5:22 pm

Old Gm attempting space travel scenarios.

How do you figure travel time?

I'm having a difficulty understanding travel time within the Dimensions.
Ive read the books, but it just doesnt all make sense.

I understand what a light year means, so to speak.
the hardest part for me is figuring the Factors in.

Also is there any information listed for distances to these systems/planets

Esckey · Unread post by **Esckey** » Tue Jul 18, 2006 6:40 pm

And for long distance hauls, fly outside of the galaxy.

shadrak · Unread post by **shadrak** » Thu Jul 20, 2006 5:24 pm

[quote]
so a ship that travels at Mach 2 (about ~1200 to ~1500 mph) means it's going to take 8.3 hours to reach the 10,000 mile mark, however long it takes to travel at FTL, then another 8.3 hours in from the 10,000 mile mark on the arrival world. this doesn't apply when you're heading/leaving a space station or small moon with micro-gravity.
[quote]

I think we should have speeds for space vehicles in G's of acceleration.

Dorlar · Unread post by **Dorlar** » Thu Jul 20, 2006 5:46 pm

how do you figure out Factors in this?

Developing ships and ships listed in the Galaxy guide have factors.
Are these the light speeds?

How do you determine what a ship has for FTL?

Also, just want to make sure i understand.
If a ship has a FTL x2 its basically saying it can travel 2 light years per hour? To travel 20,000 light years its going to be 10,000 hours?

Aramanthus · Unread post by **Aramanthus** » Thu Jul 20, 2006 9:29 pm

This is one of those situations where it'd be nice for a galactic map of 3Gs, but it's really up to the GM to come up with a standard for their game and to make sure not to violate it, unless they have a good story reason, say a nebula or some ssort of ion storm. THose are just some thoughts.

Nekira Sudacne · Thu Jul 20, 2006 9:57 pm

I think i'm probablly one of the few that actually really LIKES the fact that it takes, on the outside, approximately 2-5 years to get from oen end of the three galaxies to the other. I also like how there's no FTL messaging systems other than courrier ships.

To me, it's vital to the setting. Galatic travel within your lifetime IS possible. it's still no quick trip, not to mention you'll ONLY have message by ship.

What this does is serves to isolate worlds from any world not in a realtivly close star cluster.

I think that kind of freedom a lack of communication gives is vital to the feel of the setting.

If a large group of space pirates attack a backwater world, it will be weeks to months before help can arrive.

shadrak · Unread post by **shadrak** » Fri Jul 21, 2006 9:35 am

Actually I don't think starships have Gs when accelerating. They ought to have some kind of dampering fields, else all the crews will hit the back wall upon acceleration to light speed and beyond.

G's for interplanetary travel, not FTL travel.

Aramanthus · Unread post by **Aramanthus** » Fri Jul 21, 2006 5:52 pm

I know that I accept a compensator in my ships in phase world. But imagine a compensator failure. It would mean the death of the entire crew unless they were MDC. And even then they might not be able to do anything about it untl it was too late.

Aramanthus · Unread post by **Aramanthus** » Fri Jul 21, 2006 6:55 pm

Yeah, the average starship from Phase world would probably be at least 10 to 100 times more complicated. There are a lot of ways for things to go wrong. (And those numbers are being conservative.)

glitterboy2098 · Sat Jul 22, 2006 1:47 am

gadrin wrote:Light Speed Factors are for Faster than Light Travel.

Factor 2 = 2 times the speed of light, so a planet that's 4 LY away will take you 2 years to reach it. Pretty slow.

phase world uses Lightyears per hour (here abbreviated Ly/H). so if your ship can go 2 Ly/h, you can make the trip from earth to alpha centauri (a 4.5 light year distance) in only 2 hours and 15 minutes.

Aliens Unlimited (AU) uses factors, which are just multiples of lightspeed. these are pretty slow. you have to travel 8766 times the speed of light to travel 1 Ly/H. most AU ships have a hard time beating 20 factors. so AU craft at best can only travel .00228 Ly/H. about 1 light year every 18 and a half days.
the majority of AU are only about 5 to 10 factors, taking months to travel one lightyear. a trip to the nearest stars would take years.

G's in other games are something like 12,000 to 20,000 mph (I've forgotten exactly). So to reach the 20,000 mile mark from a planet should take you about an hour in a spaceship that can pull 1G. Taalismn can probably explain it better.

one g is an accelleration of roughly 11 meters per second per second (11m/s^2). each second under accelleration, the craft gains 11 meters per second (m/s) of velocity. so after one second, your going 11m/s. after two seconds, your travelling at 22m/s. after 3 seconds, 33m/s. ect.
the advantage is that under 1g of accelleration, the passengers in the craft will feel the same gravity as if they were on earth. (accells over 1.5g's are not recommended for extended times, since it tends to have bad effects on the body. thus the scifi things like inertial dampeners, which would allow much higher sustained accelleration, since the crew doesn't feel more than a few g's of it.)

after about 365 days at 1g, you hit .9999999...... c, or as close to the speed of light as you can get. (asuming a drive with reletivistic exhust velocity [or alternately reactionless drive], and ignoring the effects of reletivity. most space drives will lose effect long before that because you can't accellerate to a velocity faster than the velocity of your exhust. likewise reletivty will drive your mass up, reducing the effectiveness of the drive as the energy needed to move that mass goes up.)

getting up to speed is only half of it though. since in space, there is no friction to slow you down, you can cut your drive at the desired velocity and coast. to slow down, you have to turn your drive on opposet your flight path, and run it for as long as you took to accellerate.
while coasting, you'd be in freefall (at least, without scifi artificial gravity, created either by centripidal force or by super-science.). while decellerating, you'll feel the same 1g of gravity. (best design for such a ship would be one drive, with it doing a turn over halfway. then you can build it with only one floor per room.)

no need to go that fast though.
a trip across the solar system, from earth to neptune, would only take about a week at 1g of continuous accelleration (with turn over and decell included), and a trip from earth to mars would only take a few days. earth-moon would take almost no time at all.

personally, i messed around with an accelleration based system, found it to be far too clumsy to work well with the current game. so i junked it, and now i'm using units of one light second per day, or 12500km/h (about 3.47km/s, or about 3 times higher than the escape velocity of earth.) known as marks.
to handle accelleration i just defined it as military (1 'mark' per melee(, civilian (1 mark per minute), or primitive (or 1 mark per day).
much simpler, and works way better. ships can now reach velocities reasonable for space travel, and the velocity is defined in such a way to make travel time easy to find. (just divide the distance in light seconds (300,000km) by the mark #, and add the time to accel and decell.)

Esckey · Unread post by **Esckey** » Sat Jul 22, 2006 4:38 am

Just a side note here, I have on occasion used start up rules. I used something like 1 hour per 100m of ship for a "dry start"(from 0 power to full power and ready to get underway) and for the regular start up I went with 30 minutes per 100m. So just under an hour for a Hunter class to go from off to ready to move, and 30 minutes for a noraml start up. Sounds reasonable. Till you see the Battleships and Deadnoughts.

Just watched Appolo 13 and, as a comparison, on it they said it would take 3 hours to get the LEM up and running through their checklist