Temperature effects

[Spartan159]

One of my various projects is to adapt T5's temperature rules into my heretically modified MgT game.

One of the things I'm looking at is the effect of heat upon starships, such as the correlation between starship armour values and heat resistance, the effects of added heat shielding, and the effect of tech levels on both.

Another thing I was looking at is how to calculate heat from a star given distance and stellar temperature and/or luminosity.

Anyone have any input or formulas?

 

[kilemall]

i don't have those kind of values, although I suppose you could start with the temperature hard steel melts, most of the Traveller versions have steel as a starting materials tech and extrapolate what sort of heat resistance the more advanced tech materials have.

I figure Reflec is really a heat shield good enough for lasers, and so I'm inclined to think all streamlined ships have a coat of it for reentry which might help survive stars and other heat sources.

For myself I had already resolved to make space 'spacier' and that includes making stars the terrifying death dealers they can be up close. So for instance any kind of shuttle or mining transport to Mercury would be max armored, and tend to make approaches as much as possible behind the 'shadow' of the planet.

Don't forget just heat, but also radiation AND solar flares as a destructive plasma storm. Near as I can tell both Mongoose versions have a pretty consistent approach to 'rads are bad', although I sure would like to know how a drug can flush rads out of the body (maybe more repair damage?).

Another technique might be to be jump ready to escape any lethal flare. Depends on whether one applies the 100D rule to stars, or if one has to be on-vector to destination to jump there. Either one could render jump escape moot for many approaches.

 

[flykiller]

I sure would like to know how a drug can flush rads out of the body (maybe more repair damage?).

there is no drug that can "flush rads" out of the body, anymore than there is a drug that can flush "bullet damage" out of the body. there are drugs that can displace radioactive isotopes, such as iodine, but that's about it. in the future there may be drugs that promote healing and prevent cancer.

 

[kilemall]

there is no drug that can "flush rads" out of the body, anymore than there is a drug that can flush "bullet damage" out of the body. there are drugs that can displace radioactive isotopes, such as iodine, but that's about it. in the future there may be drugs that promote healing and prevent cancer.

That's the best take I've got, but the Mgt1E wording makes it sound like flushing is happening.

That's some damn fine tech, you have that ability Anagathics should happen a lot earlier.

 

[flykiller]

you have that ability Anagathics should happen a lot earlier.

they would in fact be anagathics.

 

[jcrocker]

A bit ago I used the Inverse Square Law:

I = P/A = P/4 pi r-squared

where I is intensity, power per unit squared and r was the distance from the source. Edit - and P is total power radiated from a point source, sorry I forgot it earlier.

I was trying to figure how far out a planet would have to be from a star of a given type to be in the habitable range, and after far too long came out with an answer. Huzzah!

Then I was flipping through MT system generation, and oh look, there's the tables of star types and where the habitable orbits are. And hey, that little table has about the same answer I came up with...

But at least it was good to have the information confirmed.

 

[Enoki]

There are other possible ways to protect a vessel in space besides armor.

You could use a material that is good at absorbing neutrons for example, like boron. A borated foam a couple of feet thick on the outside of the hull of a ship would negate most or all neutron radiation for example.

Since the possibility exists within the game, using a much more dense material... say one that has been made far more dense by packing the molecules closer together than would naturally occur, would make that material more resistant to radiation penetration. There'd be more "stuff" in the way to block gamma rays from penetrating it.

You might use a powerful magnetic field to shield the ship. Power shouldn't be a problem in terms of the game.

For purely thermal radiation, you could go with materials other than metals. A ceramic for example will take far more heat than metals will in most cases.

You could also put an expendable shield out in front of the ship to simply absorb the bad stuff.

There are alternatives.

 

[Spartan159]

I fully agree that there are other methods, I was simply trying to associate the existing armor and heat shielding of MgT with the heat and cold tables of T5. I was also thinking of stating out temperatures for spacecraft at the various planetary orbits just as a general idea, how close you can pass a star might not be something that ever comes up, but you never know.

jcrocker, I will look that up, thanks. An example would rock if you happen to have that data still.

 

[jcrocker]

I did look to see if I still had my example, but no, sorry.

It was pretty general - I was looking for a type K-something star, K6? and I couldn't find anything on that one, but I did find a wikipedia entry on a star that happened to be the next number up, K5, and it helpfully said "this star is X times as luminous as the sun" so I just used that number.

I wasn't looking for ships at different distances, but once you figured what the star's output would be, you certainly could, just vary the r.

Was my math good enough for a PhD thesis? No. But it got me close enough for what I needed, and like I said, the table in the book had the same answer if you allowed for a certain margin of error.

 

[Spartan159]

While googling the interwebz, I came across this gem:

http://www2.ignatius.edu/faculty/decarlo/SurfacePower/Pages/InverseSquareLesson.htm

Now for me to understand this puppy.

 

[AnotherDilbert]

One of the things I'm looking at is the effect of heat upon starships, such as the correlation between starship armour values and heat resistance, the effects of added heat shielding, and the effect of tech levels on both.

The concept you are looking for is basically black-body radiation.
https://en.wikipedia.org/wiki/Black-body_radiation

Everything radiates heat. You gain heat from external and internal sources. External sources are e.g. a star shining on you. Internal sources are the waste heat from the power plant and any power using equipment onboard.

Heat is energy, energy cannot be created or destroyed only transformed. Each Joule of energy produced on board (transformed from matter into energy) will become some other form of energy such as kinetic energy (motion), but most of it will eventually be transformed into the most dispersed form of energy: heat.

Even small starships produce massive amounts of energy. A Scout might produce 500 MW or 500 million joule / second useful energy (and a lot of waste heat). Much of the useful energy will be used internally and transformed into heat. Totally the Scout might need to get rid of 1000 MW of heat continuously.

The only way to get rid of heat in space is to radiate it away using a radiator.
https://www.nasa.gov/mission_pages/station/structure/elements/radiators.html

In Earth orbit the Sun's radiation is about 1300 W/m². The inverse square law (that you have used correctly) says that at twice the distance the effect is one quarter, and that at half the distance the effect is four times bigger. Mercury has an orbit round the sun about a third of Earth's, so the radiation is about nine times bigger, lets call that approximately 10000 W/m² for simplicity.

A Scout might have 37 m × 24 m / 2 ≈ 440 m² in the sunlight. It would absorb at most 440 m² × 10000 W/m² ≈ 4,4 MW as heat in Mercury orbit. But we already know that the Scout has to get rid of 1000 MW to be able to function. The added heat from the Sun is almost negligible.

Heat shielding will only slow down how fast you absorb the heat, not how much heat you absorb. It might be useful in a half hour landing operation, but not so much for weeks in space.

Another thing I was looking at is how to calculate heat from a star given distance and stellar temperature and/or luminosity.

https://en.wikipedia.org/wiki/Black-body_radiation
Scoll down to "Temperature relation between a planet and its star".

 

[kilemall]

Shouldn't the heat be able to be eliminated via reaction engines? And the power generation and therefore heat drops when weapons and engines are not being used?

And before I get the usual physics lecture, again most versions of our ships DON'T have radiators, so there has to be another solution/tech that is in the range of technobabble plausibility.

 

[mike wightman]

Gravitic heat sinks...

 

[Enoki]

Well, given a four inch thick rigid carbon foam insulation block, like the one illustrated below:

Used in a vacuum (easily obtained in space... ) will reduce 2000 C to about 100 C across it, and six inches (15 cm) will drop it to about 50C... You can easily get a hull insulated from heat even with current technology.

 

[AnotherDilbert]

Shouldn't the heat be able to be eliminated via reaction engines?

Sorry, I do not follow you. I do not see how that would work? Entropy would prevent us from using or concentrating the waste heat without using a lot more energy, hence producing more waste heat.

And the power generation and therefore heat drops when weapons and engines are not being used?

Yes, by a lot.

The cooling system must still be dimensioned to handle full power, otherwise we could not use full power.

And before I get the usual physics lecture, again most versions of our ships DON'T have radiators, so there has to be another solution/tech that is in the range of technobabble plausibility.

Actually most designs have big glowy things that might be radiators:

As discussed in other threads, I always assume what looks like exhaust nozzles on Traveller ships are actually very efficient excess energy dumps to direct waste away from the vessel in a particular direction in a manner as stealth planes vent exhaust to reduce the thermo signature of their engines.

http://forum.mongoosepublishing.com/viewtopic.php?p=912928#p912928

 

[AnotherDilbert]

Gravitic heat sinks...

What are those?

 

[mike wightman]

Traveller ships are fitted with an artificial gravity generation device that is handwaved away, as are the acceleration compensators.

There has never been any attempt ever to try and explain how these technologies actually work using the magitech physics of the setting... they just work.

If you want a handwavium technobabble heat sink then just link it to the other handwavium technobabble... namely gravitics/acceleration compensation fields.

 

[AnotherDilbert]

Ah, magic. Just like Tachyon cannons, right?

Well, that is one way to hand-wave it.


I'm not fond of the magic hand-wave. CT & MT was clear on what magical tech was used (anti-grav, artificial grav, thruster plates, jump, etc), but no other.

 

[mike wightman]

Nope - artificial gravity generation and acceleration compensation have been a part of the 3I setting since the first adventure, Tachyon cannons are:
a - based on discredited science
b - badly thought through - they violate causality
c - not part of the 3I OTU

Other than sub-space heat sinks (which also have never been part of the OTU ever) we a left with either:
a - an as yet unexplained magitech solution
b - use extant in universe handwavium technobabble, which is limited to some variation on gravitic technology or jump space due to the TL of damper technology
c - psionics

So I suggested a gravitic tech waste heat management system.