Re: Pokey Starships?
I might as well throw in my two cents worth here.
First of all, trying to be completely realistic in regard to starship movement is practically impossible. You end up with hideously complex formulas for acceleration based on the amount of reaction mass the ship carries, cargo on board, gravitational effects of the nearest significant stellar body, etc. For the campaign I'm running, a lot of realistic physics have been thrown out the window in order to make the game fun and playable for my group, most of which could care less about physics.
However! I didn't want to go completely Space Opera on them, so I worked up some simplified rules and made a spreadsheet to do the calculations for them.
1) I used something similar to Talon's realistic flight adv/lim. Speeds for space vehicles are given as acceleration, not velocity. A ship with 100" of flight can accelerate 100" per phase. So in the first phase it takes a movement, it moves 100". In the second phase, it adds another 100" to its movement, reaching 200" of velocity. Its total movement in phase two is then 300" from when it started. This continues on until the ship stops applying thrust, or reaches the speed of light, whichever comes first. (Guess which one USUALLY comes first? ) Even when a ship has stopped applying thrust, its momentum continues to carry it forward at the velocity it had attained prior to shutting off its drive.
2) In order to simplify calculations, I state that one gravity of acceleration provides 10 meters per second per second. (9.8m/s^2 just makes the numbers too funky for players who don't care.)
3) Another simplification for the math. I assume that a ship is applying thrust every segment, even if it doesn't have a 12 speed, but I only add the inches of flight on the ship's phase. This, coupled with 10m/s/s as 1 G, means that a ship needs to be able to accelerate to 60" of movement in one turn to have 1 gravity of thrust. (1" = 2m, so 60" movement = 120m = 10m/s * 12 seconds)
4) I have stipulated that if a ship is applying its full acceleration, it is using noncombat movement. So a ship needs 30" of movement with a x2 NCM for 1 gravity.
This all boils down to mean that we have a hard and fast rule for how many inches of flight a ship with X speed nees to attain Y gravities of thrust. Namely: (30 * GRAVITIES) / SPD = inches of flight.
So, with this calculation, a fighter ship with a five SPD that can pull 50 gravities needs 300 inches of flight. This same fighter craft can reach Mach 20 in just under 14 seconds (Mach 1 ~ 1225km/hr. Mach 20 ~ 24,500 km/hr. 50 Gravities = 500m/s/s = 0.5km/sec/sec = 1800km/hr/sec. 14 turns = 168 seconds. 1800 * 13 = 23,400), or .5c in about three and a half days. (Assuming the fuel supply in your campaign can maintain that kind of thrust for that long.) It could travel from the Earth to the Sun (1AU, or 150 million km) in 4.8 hours.
Another fun thing this means in game mechanics is that you can set up cargo ships to be fast on flat-out runs, but slow in combat. For example:
Cargo Ship, SPD 2. Main Drive: Flight, 90", x8 NCM (190 Active Points); OIF Immobile (-1 1/2), Only Functions in Space (-1/2), Costs Endurance (-1/2), Non-Combat Movement Only Functions in Straight Lines (-1/4), Increased Endurance Cost (x3 END, Only for NCM, -1/4) -- Real Cost 47 points. Provides 48G in NCM, and 6G in regular flight. 19 END/phase in combat movement, 57 in NCM.
Fighter Ship, SPD 5. Main Drive: Flight, 150" (300 Active Points); All Limiters as above. Real Cost 75 points. Provides 50G in NCM, 25G in regular flight. 30 END/phase in combat, and 90/phase in NCM.
So in combat, the fighter ship can run rings around the cargo ship, but is eating through its endurance reserve like crazy, if it does. Also, the added active and real cost of the drive in the fighter ship is used as production cost, when I'm worried about that kind of thing. It's a hell of a lot simpler to make the type of drive you put in a cargo ship (Big, not very maneuverable) as opposed to the kind you put in a fighter craft (compact and highly maneuverable).
REMEMBER! All of these numbers are estimates! This is a simplified mechanism that helps give my game a realistic feel without being too bogged down in math. I've got an Open Office spreadsheet set up that will calculate all this stuff for me. I'll share if anyone's interested. Drop me a line at kintar01-heroboard@yahoo.com if you want a copy of it, and state if you want .SXC or .XLS file. (That's an anti-spam address, and I'll only keep it up for about two months.)
Anyway, I hope all this helped somebody, somewhere. =)
-- Kintar
P.S. How many people want a HeroDesigner plugin that will do those calculations? I've been thinking about writing it, but can't decide if it's worth the trouble. If I do an HD plugin, I'll make the number a bit more accurate, too.
