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 01-10-2019, 06:57 PM   #1
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Spaceships as characters—edge cases

It's useful to know how to build spaceships as characters for a few reasons. Robot PCs might actually be capable of spaceflight. Furthermore, a PC might want to buy a spaceship as an Ally, or using the hybrid Signature Gear/Ally approach in Supers (pp. 84-85). And the rules do support this—but there are some edge cases where the right approach isn't clear.

A major one is operating spacecraft in atmosphere. The default for Flight (Newtonian Spaceflight) seems to be something like ram-rockets: you have limited delta-V in space, but can fly indefinitely in atmosphere. This is not how many spacecraft work, however. Pure rockets burn fuel just as fast in atmosphere as in space, while some spaceplanes rely on jet fuel for atmospheric maneuvers. In either case, you can use Maximum Duration to represent this. I wouldn't worry about "double dipping" by claiming a discount for both Newtonian Spaceflight on your Enhanced Move(Space) and Maximum Duration on your Flight. "Spaceflight Only" is -75%, so there's nothing unfair about claiming a -50% discount because you can fly in atmosphere, but only for a few minutes (for a pure rocket).

For high-acceleration designs, I'm unclear on whether you need to buy Air Move and Space Move separately. Transhuman Space: Shell-Tech seems to assume you don't, when it includes the limitation "Space acceleration only; atmosphere move and space delta-v are unaffected, -80%" (for buying down air move). If that approach is right, "air move only" should also be a possible limitation (for craft that can pull higher accelerations in air than in space), though I'm not sure how much it would be worth. This can get quite complicated—hybrid rocket/jet designs may also care about the fact that jets can be stealthier than rockets, and I'm not totally sure how to represent that. Thoughts on that issue appreciated.

It's also unclear how to represent spaceplanes that need wings in atmosphere, but not in space, since the modifiers "Space Flight" and "Winged" are listed as incompatible. "Gliding" is also technically not allowed in combination with Space Flight, though it would make sense for spaceplanes designed to land safely after they've exhausted their fuel. Some kind of official guidance on how to handle those issues would be very helpful.

Finally, there's the issue of very low-thrust spacecraft. Transhuman Space: Shell-Tech again has a write-up for a service nanosat where 0.01G acceleration, with fuel stored in the Payload, is a perk. ISP for this thruster is not given, but 3000s would be reasonable if it's an ion thruster. At some point higher ISP low-thrust thrusters should probably be more expensive, though it's not clear by how much.

These are the main tricky cases I know about, and I only have an idea of how to solve some of them. I also don't know if there are other useful sources of worked examples other than Shell-Tech. Does anyone know of any?
Michael Thayne is offline   Reply With Quote
Old 01-10-2019, 07:04 PM   #2
whswhs
 
Join Date: Jun 2005
Default Re: Spaceships as characters—edge cases

Quote:
Originally Posted by Michael Thayne View Post
A major one is operating spacecraft in atmosphere. The default for Flight (Newtonian Spaceflight) seems to be something like ram-rockets: you have limited delta-V in space, but can fly indefinitely in atmosphere. This is not how many spacecraft work, however. Pure rockets burn fuel just as fast in atmosphere as in space, while some spaceplanes rely on jet fuel for atmospheric maneuvers. In either case, you can use Maximum Duration to represent this. I wouldn't worry about "double dipping" by claiming a discount for both Newtonian Spaceflight on your Enhanced Move(Space) and Maximum Duration on your Flight. "Spaceflight Only" is -75%, so there's nothing unfair about claiming a -50% discount because you can fly in atmosphere, but only for a few minutes (for a pure rocket).
I don't think that's the case. A standard Machine has the property of not eating, but needing to refuel every eight hours. You can take Doesn't Eat or Drink, Reduced Consumption, or Increased Consumption to alter this. You can just define the fuel as its "food," in effect.
__________________
Bill Stoddard

A human being should know how to live fast, die young, and leave a beautiful corpse. Specialization is for insects.
whswhs is online now   Reply With Quote
Old 01-10-2019, 07:08 PM   #3
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: Spaceships as characters—edge cases

Quote:
Originally Posted by whswhs View Post
I don't think that's the case. A standard Machine has the property of not eating, but needing to refuel every eight hours. You can take Doesn't Eat or Drink, Reduced Consumption, or Increased Consumption to alter this. You can just define the fuel as its "food," in effect.
Right. I've seen builds for flying robots that put "Maximum Duration" on Flight, but I've also seen ones that use "Temporary Disadvantage, Increased Consumption". Though the way this is handled in the rules is a bit weird—a spaceship with an RTG might be able to operate non-thruster systems indefinitely, even after reaction mass has been used up. But maybe that's just a normal part of how Increased Consumption works for machines—car batteries to run a car's non-engine systems after you're out of gas are just a feature, I guess.
Michael Thayne is offline   Reply With Quote
Old 01-10-2019, 07:38 PM   #4
Fred Brackin
 
Join Date: Aug 2007
Default Re: Spaceships as characters—edge cases

Quote:
Originally Posted by Michael Thayne View Post
It
For high-acceleration designs, I'm unclear on whether you need to buy Air Move and Space Move separately.
It would be my closest reading of the RAW that you do. In particular see the calculation of Move under the Space Flight Advanatage and subsequent purchasuing of Enhanced Move (Space).

It's RAW that I'd ignore when wearing my GM hat. I'd be more likely to go back to the relevant 3e rules (including Hyperflight).
__________________
Fred Brackin
Fred Brackin is offline   Reply With Quote
Old 01-10-2019, 08:11 PM   #5
jason taylor
 
jason taylor's Avatar
 
Join Date: Aug 2005
Location: Portland, Oregon
Default Re: Spaceships as characters—edge cases

One method is the McCaffrey one of using disabled people with their brains disembodied. In a way that is kind of romantic and it does provide disables with a purpose in life though some have criticized it as a type of exploitation. It does not really matter as there is no reason a future society has to be without flaws.

What I'm thinking is that she will have kind of a weird brain arrangement to allow for fast thinking required for controlling itself in FtL and the shift for StL but still incredibly fast speed.

She can also process incredible amounts of information. It has to account for that.

She would have to have a reason why it has to interact with a biological crew.

She would have interesting concepts of privacy. There was one time in Andromeda when Ronnie turned herself off inside the shower. The ship's own privacy as while as the crew's would come off odd.

As a ship can last for generations it would have different notions of time as well as space.

She would certainly be cultured. You could find some amusing notions with a spaceship pondering Epicitus or playing Mozart.

She would definitely have an engineer's knowledge of physics. That does not mean she is a physicist-that's as may be. But she is definitely an engineer.
__________________
"The navy could probably win a war without coffee but would prefer not to try"-Samuel Eliot Morrison
jason taylor is offline   Reply With Quote
Old 01-10-2019, 08:43 PM   #6
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: Spaceships as characters—edge cases

On closer investigation, I've found three sources with three different approaches to flight with limited fuel: the brilliant missiles in Ultra-Tech have Limited Use, 1 minute. Flying robots in Reign of Steel: Will to Live have Maximum Duration. And flying cybershells in Transhuman Space: Shell-Tech have Temporary Disadvantage, Increased Consumption. In the latter case, the disadvantage is usually only applied to Enhanced Move (Air), but is sometimes applies to both Enhanced Move (Air) and Flight. In one case, the fact that Temporary Disadvantage, Increased Consumption only applies to Flight is specifically noted to mean it has greater endurance flying at low speeds.

Let's use the Increased Consumption approach for a basic torchship—say a nuclear saltwater rocket with one engine and 4 fuel tanks (2G/10 mps). Burn endurance is a little under 15 minutes, so that's Increased Consumption 5. Air/Space Move is 20. According to Spaceships, top airspeed in yards per second should be 1750. That implies Enhanced Move 6.5 (Air) [130]. Space move requires Enhanced Move 10 (Space; Newtonian Spaceflight, -50%) [100]. That's... altogether surprisingly reasonable, in terms of being less complicated than I thought it would be. Later I can take a second pass for looking at more complicated designs, like jet/rocket combinations.
Michael Thayne is offline   Reply With Quote
Old 01-10-2019, 10:05 PM   #7
Rupert
 
Rupert's Avatar
 
Join Date: Aug 2004
Location: Wellington, NZ
Default Re: Spaceships as characters—edge cases

Quote:
Originally Posted by Michael Thayne View Post
Let's use the Increased Consumption approach for a basic torchship—say a nuclear saltwater rocket with one engine and 4 fuel tanks (2G/10 mps). Burn endurance is a little under 15 minutes, so that's Increased Consumption 5. Air/Space Move is 20. According to Spaceships, top airspeed in yards per second should be 1750. That implies Enhanced Move 6.5 (Air) [130]. Space move requires Enhanced Move 10 (Space; Newtonian Spaceflight, -50%) [100]. That's... altogether surprisingly reasonable, in terms of being less complicated than I thought it would be. Later I can take a second pass for looking at more complicated designs, like jet/rocket combinations.
I was going to suggest an Alternate Ability for the cheaper Enhanced Move, but as they don't overlap at all that seems dubious.
__________________
Rupert Boleyn

"A pessimist is an optimist with a sense of history."
Rupert is online now   Reply With Quote
Old 01-10-2019, 10:30 PM   #8
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: Spaceships as characters—edge cases

Quote:
Originally Posted by Fred Brackin View Post
It would be my closest reading of the RAW that you do. In particular see the calculation of Move under the Space Flight Advanatage and subsequent purchasuing of Enhanced Move (Space).
This isn't totally clear to me from the rules. It's possible regular "flight Move" and Enhanced Move work differently. The write-up for the "backyard moon rocket" from Pyramid #3/46 definitely does seem to support them being separate things though. Honestly I never would have questioned that... except Shell-Tech seems to make the opposite assumption.
Michael Thayne is offline   Reply With Quote
Old 01-11-2019, 02:12 AM   #9
Refplace
 
Refplace's Avatar
 
Join Date: Nov 2008
Location: Yukon, OK
Default Re: Spaceships as characters—edge cases

Quote:
Originally Posted by Rupert View Post
I was going to suggest an Alternate Ability for the cheaper Enhanced Move, but as they don't overlap at all that seems dubious.
Alternate ability is based on the powers having the same source not how closely the abilities overlap. I would say two thrust abilities overlap as much as a dazzling light and innate attack, in any case..
__________________
Looking for group in my area
My GURPS official contributions
My GURPS fan contribution and blog:
REFPLace GURPS Landing Page
My List of GURPS You Tube videos (plus a few other useful items)
Refplace is offline   Reply With Quote
Old 01-11-2019, 04:08 AM   #10
Rupert
 
Rupert's Avatar
 
Join Date: Aug 2004
Location: Wellington, NZ
Default Re: Spaceships as characters—edge cases

My reasoning is that you shouldn't get a cost break for something that doesn't limit your use of the abilities. As the abilities cannot be used at the same time anyway, allowing one to be bought at a huge discount in exchange for the abilities locking each other out is more than a little dodgy, IMO.

Would you let someone buy normal ground Move and Swimming Move with one the AA of the other?
__________________
Rupert Boleyn

"A pessimist is an optimist with a sense of history."
Rupert is online now   Reply With Quote
Reply

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 02:39 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.