Need Help on "Semi-Hard" Classic SF Spaceship Design

[sir_pudding]

It seems like you just need a design switch that takes s suitable drive type and multiplies delta V by 10x or something per tank.

[Pomphis]

Originally Posted by Pursuivant

If there's interest in a fan-based SG GURPS supplement, I can create a dedicated thread for it.

There is interest

[Pursuivant]

Originally Posted by sir_pudding

It seems like you just need a design switch that takes s suitable drive type and multiplies delta V by 10x or something per tank.

That's one of the switches. Also having a Fusion Torch Drive which gives improved G and delta-v but which isn't as energetic as the Super Cosmic version.

I'll also have to brush off the Traveller 100-d Limit rule, which makes hyperspace travel impossible within 100 diameters of a large gravity well.

It fits well with the setting, since there are multiple references to having to avoid gravity wells when plotting hyperspace courses.

My points of reference are:

Ships need to travel some distance away from a planet or space station to enter hyperspace.

Ships appear to need to accelerate to some fraction of light speed to enter hyperspace.

Ships retain velocity, but not vector, when they emerge from hyperspace and need to decelerate if they're close to their destination.

For safety and to avoid overshooting, ships jump just a bit short of their destination.

Short range hyperspace jumps are tricky. It's easy to end up far from where you intended. At some point, it's simpler and faster to use sublight maneuver drives.

[Fred Brackin]

Originally Posted by Pursuivant

Ships appear to need to accelerate to some fraction of light speed to enter hyperspace.

Eh, any speed is "some" fraction of lightspeed though most will be very very small fractions.

Anyway, it's useful rule of thumb that (ignoring relativity) it takes 350 days to reach lightspeed at 1G. Or if the scale is more convenient it takes 84 hours to reach 1% of c at 1G.

If you keep this requirement and 1% is enough it'll still take something fast like the Ambulance ships 4.2 hours at 20 G. If you need a higher percentage or a shorter time you're going to end up at one of the Cosmic drives if not sub-warp.

As another measurement,at 20G continuous Mars will be less than a 1 day trip from Earth.

Also note that if you do accelerate at 20Gs in a straight line for 4.2 hours you'll be over 22 million km from your starting point. A literal 100D limit will have no effect on where ships can enter hyperspace though it might limit where they can emerge.

[Pursuivant]

Originally Posted by Fred Brackin

Eh, any speed is "some" fraction of lightspeed though most will be very very small fractions.

Err. Significant fraction.

In any case, there's the strong implication that you can't just jump into hyperspace from a standing start.

My rule mechanic assigns a -1 penalty per 10% less than the required minimum. Setting the minimum to ~0.1% c would just about match required acceleration times.

I can also fudge things by assuming that 5-G acceleration is actually a measure of felt acceleration and gravitic compensators deal with higher G forces. That matches "high speed" acceleration mentioned in the books. Personal antigrav belts further reduce felt G forces keeping ridiculously fragile species from being crushed.

Originally Posted by Fred Brackin

Also note that if you do accelerate at 20Gs in a straight line for 4.2 hours you'll be over 22 million km from your starting point. A literal 100D limit will have no effect on where ships can enter hyperspace though it might limit where they can emerge.

There are safety reasons for minimal hyperspace emergence distances. The assumption is that torch drives produce huge amounts of heat, short-lived radiation, and EMP, making it very dangerous to get too close to another vessel or to use torch drives to land in non-designated areas on "civilized" planets.

There's also the assumption that movement in space-faring star systems is governed by space traffic controllers. I'm assuming that you have to exit hyperspace in a designated zone, then join the queue of ships waiting to enter orbit around a planet. From there, you get permission to deorbit and are handed off to local ATC once you enter the atmosphere.

Away from "civilization" a space pilot can play fast and loose with the rules, like emerging from hyperspace in orbit around a planet.

[ericthered]

Originally Posted by Pursuivant

If there's interest in a fan-based SG GURPS supplement, I can create a dedicated thread for it.

That sounds like fun!


The books always make me laugh, because Dr. James White is the name of my father.

[dcarson]

I hadn't thought of Sector General for a campaign but it would be a good one. Please to post a link to the background when you are done.

[Pursuivant]

A big problem is that I've cut and pasted a fair bit of stuff from electronic versions of the books and then complicated things with a lot of "simulationist" design decisions.

I have to seriously simplify things and do some brutal editing.

I'm also reluctant to post an unlicensed game adaptation, or even a link to it, on a SJG official forum. Admittedly, James White has been dead for 20 years but his books are still in copyright.