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 05-22-2015, 02:36 PM   #11
David L Pulver
AlienAbductee
 
David L Pulver's Avatar
 
Join Date: Aug 2004
Location: In the UFO
Default Re: Spaceship based telescopes

Quote:
Originally Posted by Anthony View Post
True. It's also useful in radar -- aircraft are reasonably likely to be a blurry blip, but you can usefully aim at the center of the blur as long as they're in midair.

A lot of the problem with statistics is that figures like 'magnification' aren't actually meaningful -- you can magnify by as much as you want. What you want is resolution.
The magnification number is just a colorful but inaccurate way of tracking bonuses to the roll; the real number of import is the bonus.

A 800x magnification = +8 (or +16 with narrow focus). If that represents a hubble/KH-11, the question is whether that is sufficient?

The range penalty for 250 miles or so is -32. If you have an analyst with skill 14 and a +16 bonus and perhaps a +2 time spent bonus you end up with effective skill 32.

If the range penalty for 250 miles is -32, this gives a 0 chance of success.

Anthony, this suggests that 800x cannot - in GURPS terms - adequately represents a telescope of hubble sized (KH-11) pointing down. What am I missing?
__________________
Is love like the bittersweet taste of marmalade on burnt toast?
David L Pulver is offline   Reply With Quote
Old 05-22-2015, 04:32 PM   #12
Anthony
 
Join Date: Feb 2005
Location: Berkeley, CA
Default Re: Spaceship based telescopes

Quote:
Originally Posted by David L Pulver View Post
The range penalty for 250 miles or so is -32. If you have an analyst with skill 14 and a +16 bonus and perhaps a +2 time spent bonus you end up with effective skill 32.

If the range penalty for 250 miles is -32, this gives a 0 chance of success.

Anthony, this suggests that 800x cannot - in GURPS terms - adequately represents a telescope of hubble sized (KH-11) pointing down. What am I missing?
+10 for in plain sight, to start with, and typically target size, spy sat pictures usually look at buildings, vehicles, and crowds, not individual humans. The equivalent situation with naked eye observation is an analyst looking at 35mm pictures taken from a plane at 500 meters -- range penalty -15, skill 14, +2 time bonus, modified skill 1.
__________________
My GURPS site and Blog.
Anthony is offline   Reply With Quote
Old 05-22-2015, 05:48 PM   #13
Ulzgoroth
 
Join Date: Jul 2008
Default Re: Spaceship based telescopes

Quote:
Originally Posted by Anthony View Post
+10 for in plain sight, to start with, and typically target size, spy sat pictures usually look at buildings, vehicles, and crowds, not individual humans. The equivalent situation with naked eye observation is an analyst looking at 35mm pictures taken from a plane at 500 meters -- range penalty -15, skill 14, +2 time bonus, modified skill 1.
According to Powers: Enhanced Senses, that +10 also is supposed to become +20 for focusing in on small details as opposed to scanning.
__________________
I don't know any 3e, so there is no chance that I am talking about 3e rules by accident.
Ulzgoroth is offline   Reply With Quote
Old 05-22-2015, 06:14 PM   #14
David L Pulver
AlienAbductee
 
David L Pulver's Avatar
 
Join Date: Aug 2004
Location: In the UFO
Default Re: Spaceship based telescopes

Good point about the +10.

Quote:
Originally Posted by Ulzgoroth View Post
According to Powers: Enhanced Senses, that +10
also is supposed to become +20 for focusing in on small details as opposed to scanning.
Sounds like an odd ret-con to me - are you sure it's intended to apply to sensors? I have to admit I don't understand that. Isn't that what the "double the telescopic vision" bonus was for?
__________________
Is love like the bittersweet taste of marmalade on burnt toast?
David L Pulver is offline   Reply With Quote
Old 05-22-2015, 06:24 PM   #15
David L Pulver
AlienAbductee
 
David L Pulver's Avatar
 
Join Date: Aug 2004
Location: In the UFO
Default Re: Spaceship based telescopes

Quote:
Originally Posted by Anthony View Post
+10 for in plain sight, to start with, and typically target size, spy sat pictures usually look at buildings, vehicles, and crowds, not individual humans. The equivalent situation with naked eye observation is an analyst looking at 35mm pictures taken from a plane at 500 meters -- range penalty -15, skill 14, +2 time bonus, modified skill 1.
Ah, forgot the +10 in plain sight. Okay, the 800x should just about work for that then.

If I may ask again, could you follow up more on the scaling factor?

I'm still not sure whether you meant to say the "square of the magnification" for weight is a good relationship? The relationship I'd been assuming is:

1x = +0 = 1 x weight
2x = +1 (+2 if zooming in) = 4x weight
4x = +2 (+4 if zooming in) = 16x weight
8x = +3 (+6 if zooming in) = 64x weight
16x = +4 (+8 if zooming in) = 256x weight
512x = +9 (+18 if zooming in) =262,144x weight

(Actually, I might assume 8x or below might actually be roughly linear in weight due to the extra effort needed to miniaturize - plus the weights of scopes given in HT support that - and the 4x for each +1/+2 only kicks in at 16x and up).

If you think a different relationship - SPACESHIPS uses roughly 1-3-10 for every +1/+2 - is better, let me know!
__________________
Is love like the bittersweet taste of marmalade on burnt toast?
David L Pulver is offline   Reply With Quote
Old 05-22-2015, 06:59 PM   #16
Ulzgoroth
 
Join Date: Jul 2008
Default Re: Spaceship based telescopes

Quote:
Originally Posted by David L Pulver View Post
Sounds like an odd ret-con to me - are you sure it's intended to apply to sensors? I have to admit I don't understand that. Isn't that what the "double the telescopic vision" bonus was for?
It is in a box about the capabilities of the Mk I eyeball, but I don't see any reason why sensors would get the plain sight bonus but not get the focused plain sight bonus. Doubling the telescopic vision bonus for focused examination is cumulative with this.

It is certainly a retcon, but most new GURPS rules material is.
__________________
I don't know any 3e, so there is no chance that I am talking about 3e rules by accident.
Ulzgoroth is offline   Reply With Quote
Old 05-22-2015, 07:19 PM   #17
safisher
Gunnery Sergeant,
 Imperial Marines
Coauthor,
 GURPS High-Tech
 
safisher's Avatar
 
Join Date: Oct 2004
Default Re: Spaceship based telescopes

Quote:
Originally Posted by Ulzgoroth View Post
According to Powers: Enhanced Senses
Enhanced Sensors came long after UT/HT, for one. Secondly, as David said, the important thing in GURPS is not the color text, but the game effect. The suggestions in HT come from trying to figure what it would take in game terms to do what they claim, being generous in terms of how they would likely be used in an adventure game. Applying heavy science to those figures is likely to leave you frustrated.
__________________
Buy my stuff on E23.
My GURPS blog, Dark Journeys, is here.
Fav Blogs: Doug Cole here , C.R. Rice's here, & Hans Christian Vortisch here.
safisher is offline   Reply With Quote
Old 05-22-2015, 07:23 PM   #18
Fred Brackin
 
Join Date: Aug 2007
Default Re: Spaceship based telescopes

Quote:
Originally Posted by David L Pulver View Post
If I may ask again, could you follow up more on the scaling factor?
Considering only the mirror (and big modern telescopes are almost exclusively reflectors rather than refractors) I believe mirror weight might actually go up by the cube and not the square of an increase in diameter.

If you make your mirror wider you need to make the backing material thicker to keep it stiff under gravitational or inertial loads. There are thermal issues too.

The Keck design with its' geometric array of smaller mirrors might be a way around the "one big mirror" limit but it's not obvious that what you save in total weight from thinner mirrors you don't make up in the gear to finely control them.

It's hard to say much about competing mirror designs for large astronomical instruments. Every blessed one of them is a prototype. There are no production models and whatever design gets chosen is in the hands of whoever raised the money and set up the fabrication shop. The choice selected probably represents that person's individual preferences and experience.

Still, as a mirror gets bigger it would have to increase in weight by the square as a minimum and more likely the cube.
__________________
Fred Brackin
Fred Brackin is offline   Reply With Quote
Old 05-22-2015, 10:24 PM   #19
Anthony
 
Join Date: Feb 2005
Location: Berkeley, CA
Default Re: Spaceship based telescopes

Quote:
Originally Posted by Fred Brackin View Post
Considering only the mirror (and big modern telescopes are almost exclusively reflectors rather than refractors) I believe mirror weight might actually go up by the cube and not the square of an increase in diameter.
It actually goes up somewhere between the square and the cube, because bigger mirrors are designed differently.
__________________
My GURPS site and Blog.
Anthony is offline   Reply With Quote
Old 05-22-2015, 11:46 PM   #20
David L Pulver
AlienAbductee
 
David L Pulver's Avatar
 
Join Date: Aug 2004
Location: In the UFO
Default Re: Spaceship based telescopes

Quote:
Originally Posted by Anthony View Post
It actually goes up somewhere between the square and the cube, because bigger mirrors are designed differently.
I'm more concerned with _overall_ weight scaling for all the optical systems rather than just the mirror itself...

If a 16x optical sensor is 2 lb. (about right for a telescopic sight sort of thing, yes?) then a 800x sensor is 50 x that; if it's square, that's about 5,000 lbs.

Hmm. That's not too bad - IF - we make the assumption that HIGH TECH was talking about "total bonus" rather than "levels of telescopic vision". If we try to match 12-16 levels of TV, we have a sensor that is off the charts in weight. If it's scaled down to 1x sensor, however, we get 0.004 lbs. which seems a bit small for a TL8 cell phone camera...

Incidentally, overall weights for active sensors like radar seem to also scale with about the square of the range. (Not the fourth power, as we're talking total system, and increasing the overall weight of the systems simultaneously increases both system power and system antenna diameter, rather than just one of these.)
__________________
Is love like the bittersweet taste of marmalade on burnt toast?
David L Pulver is offline   Reply With Quote
Reply

Tags
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 04:00 AM.


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