Steve Jackson Games - Site Navigation
Home General Info Follow Us Search Illuminator Store Forums What's New Other Games Ogre GURPS Munchkin Our Games: Home

Go Back   Steve Jackson Games Forums > Roleplaying > GURPS

Reply
 
Thread Tools Display Modes
Old 05-31-2017, 04:00 AM   #1
scc
 
Join Date: Mar 2013
Default [Spaceships] Control Rooms With Reactionless Drives

I've seen it said a few times around here that Control Rooms come with a small Delta-V reserve (0.3 mps) to represent the RCS systems that they include.

That's fine for chemical propulsion systems, but what about ships that use Reactionless Engines? Well in that case Delta-V doesn't matter (I'd assume that the Control Room includes a Power Plant that also powers the life support system, you worry more about running out of air then juice for the drive) but how much thrust can this system generate? And can I pay to get a more powerful drive?
scc is offline   Reply With Quote
Old 05-31-2017, 07:31 AM   #2
RogerBW
 
RogerBW's Avatar
 
Join Date: Sep 2008
Location: near London, UK
Default Re: [Spaceships] Control Rooms With Reactionless Drives

Quote:
Originally Posted by scc View Post
And can I pay to get a more powerful drive?
Smaller Systems, in multiple increments?
RogerBW is online now   Reply With Quote
Old 05-31-2017, 08:31 AM   #3
ericbsmith
 
ericbsmith's Avatar
 
Join Date: Aug 2004
Location: Binghamton, NY, USA. Near the river Styx in the 5th Circle.
Default Re: [Spaceships] Control Rooms With Reactionless Drives

The RCS is designed to be minimal thrusters. They might very well be Reactionless Drives, once Reactionless is available. Even then I'd expect them to be 0.01-0.02G at most, as they're really designed for fine maneuvering and docking, not for travel.

If you want more thrust then install an actual Reactionless Engine, either as a Smaller SM System or a full system. There's no "upgrading" the basic thrusters in a Control Room.
__________________
Eric B. Smith GURPS Data File Coordinator
GURPSLand
I shall pull the pin from this healing grenade and...
Kaboom-baya.
ericbsmith is offline   Reply With Quote
Old 05-31-2017, 08:51 AM   #4
Fred Brackin
 
Join Date: Aug 2007
Default Re: [Spaceships] Control Rooms With Reactionless Drives

Quote:
Originally Posted by scc View Post
I've seen it said a few times around here that Control Rooms come with a small Delta-V reserve (0.3 mps) to represent the RCS systems that they include.
0.3 mps sounds more like the Shuttle's Orbital Maneuvering System rather than its' Reaction Control System. The OMS is for changing orbits and de-orbit burns. The RCS is for changing which way the vehicle points and drifting into docking.

The OMS is less than a full-sized Chemical Rocket module in Spaceships terms but with thrust equal to 0.06 Gs it might be more than you should sweep into a rounding error on Spaceships' 5% of vehicle total mass modules. The RCS is definitely well below the resolution of Spaceships.

It's the RCS-equivalent that every Control Room comes equipped with and it is very definitely too small to represent any significant fraction of a module and its' thrust and Delta-V is likewise below the threshold of resolution.

Spaceships really is build on a 5% principle and does not resolve much smaller than that at all.
__________________
Fred Brackin
Fred Brackin is online now   Reply With Quote
Old 05-31-2017, 09:05 PM   #5
scc
 
Join Date: Mar 2013
Default Re: [Spaceships] Control Rooms With Reactionless Drives

Quote:
Originally Posted by ericbsmith View Post
If you want more thrust then install an actual Reactionless Engine, either as a Smaller SM System or a full system. There's no "upgrading" the basic thrusters in a Control Room.
If both Standard and Hot Reactionless Engines are available in a setting I'd expect both to be options for Control Rooms, and which is used would depend upon the ship. Military designs would obviously use hot ones for better maneuverability and I suspect that passenger liners and smugglers would as well. This would both cost money and increase performance.

Quote:
Originally Posted by Fred Brackin View Post
0.3 mps sounds more like the Shuttle's Orbital Maneuvering System rather than its' Reaction Control System. The OMS is for changing orbits and de-orbit burns. The RCS is for changing which way the vehicle points and drifting into docking.

The OMS is less than a full-sized Chemical Rocket module in Spaceships terms but with thrust equal to 0.06 Gs it might be more than you should sweep into a rounding error on Spaceships' 5% of vehicle total mass modules. The RCS is definitely well below the resolution of Spaceships.

It's the RCS-equivalent that every Control Room comes equipped with and it is very definitely too small to represent any significant fraction of a module and its' thrust and Delta-V is likewise below the threshold of resolution.

Spaceships really is build on a 5% principle and does not resolve much smaller than that at all.
Some of what the Shuttle's OMS did would likely fall under whats covered here, this is for orbital fine tuning. For the Shuttle on a mission to dock with the ISS any orbit matching burns would be covered by this invisible reserve.
scc is offline   Reply With Quote
Old 06-01-2017, 06:43 AM   #6
munin
 
Join Date: Aug 2007
Location: Vermont, USA
Default Re: [Spaceships] Control Rooms With Reactionless Drives

Quote:
Originally Posted by scc View Post
… what about ships that use Reactionless Engines? … but how much thrust can this system generate?
Just for fun…

Looking at the crew stations in Ultra-Tech (p. 24), each Spaceships control station probably weighs 100 lb., so make up at most 3.33% of the Control Room's mass (at SM+5).

Looking at the computers in Ultra-Tech (p. 22) and comparing Complexity, the computer in a Control Room makes up at most 0.5% of its mass.

Compared to an Enhanced Array, the comm/sensor array makes up at most 10% of a Control Room's mass.

That leaves about 86% of the Control Room's mass for RCS. We have six possible rolls and six possible drifts (assuming reactionless engines can only thrust in one direction). If we divide the remaining mass between those (rolls might be engines or gyros, but call it the same mass), that's 7.17% per control. So each direction can generate 7.17% of what a full-size reactionless engine could generate.

Comparing the prices of a Control Room and Reactionless Engine, the RCS is probably based on a Rotary or Standard Reactionless, so 0.1 to 0.5 G times 7.17%? That could get you to Mars in a couple months.

Quote:
Originally Posted by scc View Post
… (I'd assume that the Control Room includes a Power Plant that also powers the life support system, you worry more about running out of air then juice for the drive) …
No, that's handled by auxiliary power (Spaceships, p. 10).
munin is offline   Reply With Quote
Old 06-01-2017, 03:20 PM   #7
scc
 
Join Date: Mar 2013
Default Re: [Spaceships] Control Rooms With Reactionless Drives

Quote:
Originally Posted by munin View Post
Just for fun…

Looking at the crew stations in Ultra-Tech (p. 24), each Spaceships control station probably weighs 100 lb., so make up at most 3.33% of the Control Room's mass (at SM+5).

Looking at the computers in Ultra-Tech (p. 22) and comparing Complexity, the computer in a Control Room makes up at most 0.5% of its mass.

Compared to an Enhanced Array, the comm/sensor array makes up at most 10% of a Control Room's mass.

That leaves about 86% of the Control Room's mass for RCS. We have six possible rolls and six possible drifts (assuming reactionless engines can only thrust in one direction). If we divide the remaining mass between those (rolls might be engines or gyros, but call it the same mass), that's 7.17% per control. So each direction can generate 7.17% of what a full-size reactionless engine could generate.

Comparing the prices of a Control Room and Reactionless Engine, the RCS is probably based on a Rotary or Standard Reactionless, so 0.1 to 0.5 G times 7.17%? That could get you to Mars in a couple months.
Personally I'd assume that the engines are gimbaled or something like that.

Quote:
Originally Posted by munin View Post
No, that's handled by auxiliary power (Spaceships, p. 10).
I'd assume that the mass for auxiliary power is included in the Control Room mass
scc is offline   Reply With Quote
Reply

Tags
reactionless drive, spaceships

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Fnords are Off
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 08:36 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.