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 04-07-2017, 05:57 AM   #1
vicky_molokh
GURPS FAQ Keeper
 
vicky_molokh's Avatar
 
Join Date: Mar 2006
Location: Kyv, Ukraine
Default [Spaceships] The value and realism of +24 if Silhouetted Against Deep Space . . .

Greetings, all!

I remember encountering comments that perhaps the +24 for Silhouetting is too much and/or should not stack with the Plain Sight bonus (+10). Is there any realistic/mathematically-justified basis for such doubts? Even if not, is it possible to make the numbers lower by e.g. adjusting the CMBR somewhat (without totally screwing up everything else in the setting)?

I am interested primarily in the former, but a latter is a standby idea, since lower numbers would be more convenient for my upcoming campaign (but I don't want to just arbitrarily nerf them).

Thanks in advance!
__________________
Vicky 'Molokh', GURPS FAQ and uFAQ Keeper
vicky_molokh is offline   Reply With Quote
Old 04-07-2017, 07:17 AM   #2
weby
 
weby's Avatar
 
Join Date: Oct 2008
Default Re: [Spaceships] The value and realism of +24 if Silhouetted Against Deep Space . . .

The +34 is actually bit low compared to real values as it means a detection of fusion rocket ship in the +60 to +65 order of magnitude example: +24(space) +10(plain sight),+8(example ship size),+8 fusion rocket,+12 (example sensor magnification)=+62, that would give a detection range of maybe an astronomical unit when taking time.

For more see: http://www.projectrho.com/public_htm....php#nostealth

Of course if your space is filled with ether or similar it may dampen detections.. :)
__________________
--
GURPS spaceship unofficial errata and thoughts: https://gsuc.roto.nu/
weby is offline   Reply With Quote
Old 04-07-2017, 08:09 AM   #3
vicky_molokh
GURPS FAQ Keeper
 
vicky_molokh's Avatar
 
Join Date: Mar 2006
Location: Kyv, Ukraine
Default Re: [Spaceships] The value and realism of +24 if Silhouetted Against Deep Space . . .

Quote:
Originally Posted by weby View Post
The +34 is actually bit low compared to real values as it means a detection of fusion rocket ship in the +60 to +65 order of magnitude example: +24(space) +10(plain sight),+8(example ship size),+8 fusion rocket,+12 (example sensor magnification)=+62, that would give a detection range of maybe an astronomical unit when taking time.

For more see: http://www.projectrho.com/public_htm....php#nostealth

Of course if your space is filled with ether or similar it may dampen detections.. :)
A fusion rocket is a signature modifier, SM is SM etc. I'm curious specifically about the silhouetting number and its comulativeness with the Plain Sight modifier.
__________________
Vicky 'Molokh', GURPS FAQ and uFAQ Keeper
vicky_molokh is offline   Reply With Quote
Old 04-07-2017, 08:36 AM   #4
Nemoricus
 
Join Date: Mar 2013
Default Re: [Spaceships] The value and realism of +24 if Silhouetted Against Deep Space . . .

A sanity check: Long range is -42. For "In plain sight" and "silhouetted against deep space", positive modifiers are +34. Assuming an SM+9, TL10 ship, the array provides another +8. Net modifier is +0, plus the SM of the target ship. Assuming a modestly competent operator with skill 12. and no stealth systems on the other ship, they'll detect any ship within 10,000 miles automatically.

This seems like a fairly reasonable result. In fact, you have to go beyond combat ranges before you start taking net penalties. An active ship is even more obvious, which boosts the detection range potentially out to several light seconds. This still seems sane.

If you're targeting an SM+10 ship running a super conversion torch engine, you can theoretically detect them out to 100 AU or so. This seems *conservative*, given that Project Rho suggests that you can detect torchships from neighboring star systems.
Nemoricus is offline   Reply With Quote
Old 04-07-2017, 08:54 AM   #5
Fred Brackin
 
Join Date: Aug 2007
Default Re: [Spaceships] The value and realism of +24 if Silhouetted Against Deep Space . . .

Quote:
Originally Posted by Nemoricus View Post
If you're targeting an SM+10 ship running a super conversion torch engine, you can theoretically detect them out to 100 AU or so. This seems *conservative*, given that Project Rho suggests that you can detect torchships from neighboring star systems.
Back during the Transhuman Space playtests someone calculated that while you couldn't see a Nuclear Pulse Drive ships leaving Mars orbit with the naked eye from the surface of Earth, a pair of binoculars would be plenty. It might well be a naked eye object from Earth orbit.

That's with a hard science drive with an acceleration of .05Gs or so too. Unless you're dealing with ^ drives that have little signature a piece of ^ like a torch drive would be brighter just because it's putting out more energy.
__________________
Fred Brackin
Fred Brackin is offline   Reply With Quote
Old 04-07-2017, 09:22 AM   #6
vicky_molokh
GURPS FAQ Keeper
 
vicky_molokh's Avatar
 
Join Date: Mar 2006
Location: Kyv, Ukraine
Default Re: [Spaceships] The value and realism of +24 if Silhouetted Against Deep Space . . .

Quote:
Originally Posted by Fred Brackin View Post
Back during the Transhuman Space playtests someone calculated that while you couldn't see a Nuclear Pulse Drive ships leaving Mars orbit with the naked eye from the surface of Earth, a pair of binoculars would be plenty. It might well be a naked eye object from Earth orbit.
A Nuclear Pulse Drive is a Heat/Light Signature bonus. I'm trying to find the raw bonus.

E.g. the detection of a rock-hull ship with Minimal power, and that the comm/sensor array level is zero (e.g. a TL7 SM+4 sized array).

I'm asking because I'm curious about the Silhouette (and Plain Sight, to some extent) numbers specifically.
__________________
Vicky 'Molokh', GURPS FAQ and uFAQ Keeper
vicky_molokh is offline   Reply With Quote
Old 04-07-2017, 09:47 AM   #7
Fred Brackin
 
Join Date: Aug 2007
Default Re: [Spaceships] The value and realism of +24 if Silhouetted Against Deep Space . . .

Quote:
Originally Posted by vicky_molokh View Post
A Nuclear Pulse Drive is a Heat/Light Signature bonus. I'm trying to find the raw bonus.

E.g. the detection of a rock-hull ship with Minimal power, and that the comm/sensor array level is zero (e.g. a TL7 SM+4 sized array).

I'm asking because I'm curious about the Silhouette (and Plain Sight, to some extent) numbers specifically.
This predated Spaceships and was calculated from astronomical principles.

I suspect that your looking for something that doesn't exist. Spaceshps wouldn't be the place for it. Spaceships was designed mostly as a playable game with a good adherence to physics but within limits i.e. it wasn't designed as a reality simulator.

If you want something more like a reality simulator look at Ve2.
__________________
Fred Brackin
Fred Brackin is offline   Reply With Quote
Old 04-07-2017, 10:10 AM   #8
Humabout
 
Humabout's Avatar
 
Join Date: Aug 2008
Default Re: [Spaceships] The value and realism of +24 if Silhouetted Against Deep Space . . .

IDHMBWM, but an easy way to test this is see if yiu can detect Neptune with TL5 equipment wiithout it. Running the numbers on that should give you a domain of possible values for the Silhouetted bonus.
__________________
Buy My Stuff!

Free Stuff:
Dungeon Action!
Totem Spirits

My Blog: Above the Flatline.
Humabout is offline   Reply With Quote
Old 04-07-2017, 10:22 AM   #9
RyanW
 
RyanW's Avatar
 
Join Date: Sep 2004
Location: Southeast NC
Default Re: [Spaceships] The value and realism of +24 if Silhouetted Against Deep Space . . .

It needs to be a big modifier, at least when dealing with thermal (and that's the most logical way to search). If it's +10 to pick out a human against a ~300 K background, the modifier against a ~3 K background should be huge.
__________________
RyanW
- Actually one normal sized guy in three tiny trenchcoats.
RyanW is offline   Reply With Quote
Old 04-07-2017, 10:45 AM   #10
vicky_molokh
GURPS FAQ Keeper
 
vicky_molokh's Avatar
 
Join Date: Mar 2006
Location: Kyv, Ukraine
Default Re: [Spaceships] The value and realism of +24 if Silhouetted Against Deep Space . . .

Quote:
Originally Posted by Humabout View Post
IDHMBWM, but an easy way to test this is see if yiu can detect Neptune with TL5 equipment wiithout it. Running the numbers on that should give you a domain of possible values for the Silhouetted bonus.
Hmm. About 50 billion km is about the equivalent of 510^13 yards, right? So (-2+(-613)) = -80ish.
And Neptune is 50 million yards in diameter. So (2+(66)) = 38, bumped to 40 for being round.
Thus a need to offset about 40 worth of penalties using Silhouetting, Plain Sight, Signature, Zoom, Extra Time (and probably more than the 30-minute Extra Time limit normally allowed!) etc.

RAW Extra Time (+5), Silhouette (+24) and Plain Sight (+10) already account for 39. So probably a bit on the overkill side.
__________________
Vicky 'Molokh', GURPS FAQ and uFAQ Keeper
vicky_molokh is offline   Reply With Quote
Reply

Tags
cmbr, detection, plain sight, sensors, silhouette, space, spaceships, stealth

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 08:02 AM.


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