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 12-06-2014, 05:53 PM   #1
Kale
 
Kale's Avatar
 
Join Date: Aug 2005
Location: Cowtown, Canada
Default [Ultratech] Explosions, low atmo, MCP suits?

Hi all, looks like I will be running a game in a couple months that might involve some combat on planets with thin atmosphere and low gravity. I just want to fact check my memory on this, and ask some questions: I recall from somewhere that explosive force is multiplied by relative atmospheric pressure, so 0.2 ATM is divide dice by 5 for explosions? Is regular damage rolled for explosions that are in direct contact with a PC, for instance explosive bullets? Finally, I will be using mechanical counter pressure suits as the default space suit tech. How would an MCP suit stand up to explosions? Since it is so form fitting, would it count as 'sealed' armor against explosions?
__________________
FYI: Laser burns HURT!
Kale is offline   Reply With Quote
Old 12-06-2014, 07:25 PM   #2
Crakkerjakk
"Gimme 18 minutes . . ."
 
Crakkerjakk's Avatar
 
Join Date: Sep 2005
Location: Albuquerque, NM
Default Re: [Ultratech] Explosions, low atmo, MCP suits?

I believe you're correct on the explosive damage front. Regular damage for explosive bullets yes, they have their own oxidizers, and are as you note contact explosions so the low pressure to propagate a shockwave through won't be an issue. Counter pressure suits should count as sealed so long as they're good in vacuum and you have a helmet on.
__________________
My bare bones web page

Semper Fi
Crakkerjakk is offline   Reply With Quote
Old 12-06-2014, 08:47 PM   #3
Gigermann
 
Gigermann's Avatar
 
Join Date: Jul 2009
Location: Oklahoma City
Default Re: [Ultratech] Explosions, low atmo, MCP suits?

A related question that's been bugging me for a long time now: what happens when a MCP suit is holed in vacuum? It won't really leak.
Gigermann is offline   Reply With Quote
Old 12-06-2014, 08:51 PM   #4
Sindri
 
Join Date: Nov 2011
Default Re: [Ultratech] Explosions, low atmo, MCP suits?

Quote:
Originally Posted by Gigermann View Post
A related question that's been bugging me for a long time now: what happens when a MCP suit is holed in vacuum? It won't really leak.
You lose counterpressure at the specific area. That will cause bruising but won't compromise the general performance of the suit.
Sindri is offline   Reply With Quote
Old 12-08-2014, 11:08 PM   #5
Kale
 
Kale's Avatar
 
Join Date: Aug 2005
Location: Cowtown, Canada
Default Re: [Ultratech] Explosions, low atmo, MCP suits?

So when a contact explosion goes off on a MCP suit, it still protects, even though it is so skin tight? I always thought sealed armor got full DR against explosions because of the buffer of air between the suit material and your skin?

Gigerman & Sindri: If the hole in the MCP suit is big enough, your flesh starts to squeeze out through the hole...? (Eww...)
__________________
FYI: Laser burns HURT!
Kale is offline   Reply With Quote
Old 12-08-2014, 11:25 PM   #6
Sindri
 
Join Date: Nov 2011
Default Re: [Ultratech] Explosions, low atmo, MCP suits?

Quote:
Originally Posted by Kale View Post
Gigerman & Sindri: If the hole in the MCP suit is big enough, your flesh starts to squeeze out through the hole...? (Eww...)
Any hole in an MCP suit will eventually disimprove flesh left exposed to an extent depending on length of exposure and the part of the body in question. However the human body is much more resistant to the effects of vacuum exposure than people imagine. Tests have demonstrated that 1 mm˛ exposure for extended periods produced no side effects. Side effects will not be pleasant but will be substantially less graphic than what I suspect you are imagining.

Worth noting is that if a hole is caused while it is being worn (as opposed to beforehand) it is quite likely to draw blood. To speculate (though I will defer to anyone with better knowledge of the mechanics in question) I would say that at first blood will be draw out more dramatically due to the vacuum but then be minimized by the pressure surrounding the damaged area.

Last edited by Sindri; 12-08-2014 at 11:51 PM.
Sindri is offline   Reply With Quote
Old 12-09-2014, 12:37 AM   #7
TallIan
 
Join Date: Oct 2014
Default Re: [Ultratech] Explosions, low atmo, MCP suits?

There are two types of explosive; low and high explosive.

Low explosive works by rapid combustion of a fuel in the presence of an oxidiser, usually contained within the explosive mixture. Gunpowder is a good example.

High explosive works by the instantaneous decomposition of a very complex, compact, unstable molecule into a number of smaller molecules that occupy a larger volume. eg C4

Either way the result is largely the same, just more effective with high explosive.

They will both have a concussive force created by their own volume, that will be largely unaffected by thin atmosphere but be very small, and a larger volume of concussive force caused by a compression of the surrounding atmosphere, that will be affected by the density of the atmosphere. If you have an "atmosphere" of something uncompressible, such as water, then the effects of the explosive are hugely magnified.

Unless you are dealing with a HUGE, concusive explosion, you can probably ignore the radius of the explosion that would be unaffected by atmospheric density, unless there is direct contact in which case death is most likely the result anyway.

As you say, multiply the damage by the atmospheric density unless its something like exploding rounds, where the initial impact will be unaffected, but secondary affects will be.

To complicate things slightly, fragmentation devices such as grenades would end up with a wider radius of damage from the fragments, as the fragments are propelled by the initial explosion and are then less affected by wind resistance. At the same time the concussive damage caused will be somewhat less.

Tall
TallIan is offline   Reply With Quote
Old 12-09-2014, 07:38 AM   #8
Humabout
 
Humabout's Avatar
 
Join Date: Aug 2008
Default Re: [Ultratech] Explosions, low atmo, MCP suits?

Quote:
Originally Posted by Gigermann View Post
A related question that's been bugging me for a long time now: what happens when a MCP suit is holed in vacuum? It won't really leak.
You get a space hickie.
__________________
Buy My Stuff!

Free Stuff:
Dungeon Action!
Totem Spirits

My Blog: Above the Flatline.
Humabout is offline   Reply With Quote
Old 12-09-2014, 07:52 AM   #9
Crakkerjakk
"Gimme 18 minutes . . ."
 
Crakkerjakk's Avatar
 
Join Date: Sep 2005
Location: Albuquerque, NM
Default Re: [Ultratech] Explosions, low atmo, MCP suits?

Quote:
Originally Posted by Kale View Post
I always thought sealed armor got full DR against explosions because of the buffer of air between the suit material and your skin?
Sealed armor doesn't have any holes for your low value on large area injury to be zero. Basically, nowhere for the shockwave to penetrate your protection.
__________________
My bare bones web page

Semper Fi
Crakkerjakk is offline   Reply With Quote
Old 12-09-2014, 07:59 AM   #10
Fred Brackin
 
Join Date: Aug 2007
Default Re: [Ultratech] Explosions, low atmo, MCP suits?

Just for the reco4rd, I'm pretty sure no one will be wearing MCPs without something like protective coverall over them. The MCP material might now even protect against the Solar UV. a mild problem compared to other space radiation but probably not something you could ignore either.

Then there are thermal issues. It would b very rare for any solid object you might touch in space to be neither much too cold or much too hot. So you need some insulation. Girls in literally skin-tight spacesuits would only show up on the heated runway of the Miss Sea of Tranquility beauty pageant.

Military users will be wearing at least a Tacsuit over their MCP and then could easily decide to spring for an Armored Vacc Suit instead just for simplicity..

So the protective qualities of an MCP alone against combat damage may not be as frequent a question as you might think.
__________________
Fred Brackin
Fred Brackin is offline   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 03:49 PM.


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