[Space] FTL Ideas/Thoughts

[ericthered]

Originally Posted by Fred Brackin

You learn something every day. This is awesome. Any idea how this fits into power points in spaceships?

If your emergency power is rtgs (such as deep space probes normally use) you'll have a constant power output for decades.

You learn something every day. This is awesome. Any idea how this fits into power points in spaceships?

------------------------------------------

With leaving the fusion plant on -- leaving a fusion power pant running without supervision sounds quite scary. Particuarly if I'm counting on it running in order to survive. I suppose if you have a good enough automated system you could wake the tech's up if there is a problem, but still --- I'd prefer to find a way to turn the thing off.

[Flyndaran]

Power Points in Spaceships aren't realistic. Most non-nuclear plant should give at most 1/10 PPs, while Solar should give 1/100 PPs.

There are ways to squeeze out efficiency from RTGs, but you'll never get more than half the thermal output of the radioactives, about 0.5 kW/kg for Pu 238. But Plutonium 238's half life of 87.7 years gives a nice long usefulness.

[Fred Brackin]

Originally Posted by ericthered

You learn something every day. This is awesome. Any idea how this fits into power points in spaceships?

.

Spaceships can be tricky to work with. It trades flexibility for simplicity. Still working with Ve2 numbers for TL7 RTGs are roughly 6 x massive as comparable Fission reactors for the same output. A ratio of 5 or 6 to 1 tends to remain between RTGs and comparable nuclear power plants at higher TLs.

This would have RTGs producing less than 1 pp per 5% of ship's mass in Spaceships if being fully realistic (which Spaceships isn't always about marginal power plants and drives).

Refreshing my memory the Ve2 rule of thumb was that a RTG's power output dropped 10% per period of 14 years. Old Ve2 hands tended to install RTGs large enough to power the life support systems as emergency/back up power plants.

Not only can rtgs run for long times but they have no moving parts or even much in the way of weakpoints in their structure. They are ideal for long term/emergency uses that don't have high power requirements.

I once gave the PCs a ship that had an RTG that was 120% of what was needed for life support when new. That meant it produced enough power for 42 years. Their ship was older than that though and the back up RTG was only capable of powering 90% of life support. :)

[Flyndaran]

Originally Posted by Fred Brackin

...
Not only can rtgs run for long times but they have no moving parts or even much in the way of weakpoints in their structure. They are ideal for long term/emergency uses that don't have high power requirements.

I once gave the PCs a ship that had an RTG that was 120% of what was needed for life support when new. That meant it produced enough power for 42 years. Their ship was older than that though and the back up RTG was only capable of powering 90% of life support. :)

Only the very inefficient bottom line forms have no moving parts. Some of the more advanced versions are Stirling radioisotope generators that produce 4 times the energy of basic RTGs.
I do love bulkier petering out generators bought on the cheap for those not willing to process its purity back up.

[Fred Brackin]

Originally Posted by Flyndaran

Only the very inefficient bottom line forms have no moving parts. Some of the more advanced versions are Stirling radioisotope generators that produce 4 times the energy of basic RTGs.
.

That's still worse than fission/fusion at the same TL and a _lot_ less reliable than the ones with no moving parts. Appears like a solution looking for a problem to me.

[Flyndaran]

Originally Posted by Fred Brackin

That's still worse than fission/fusion at the same TL and a _lot_ less reliable than the ones with no moving parts. Appears like a solution looking for a problem to me.

Fission/fusion require huge minimum sizes, and waste heat that would be a problem in any vaguely realistic ship. Of course, FTL isn't super realistic either, but I prefer to keep my super sciences to a minimum.

But true, chasing high efficiency can lead to over designing an old technology making it less effective in the one niche it out performs newer techs.

[scc]

One thing I've got to work out is how fast the original colony ships went. Depending upon how much boost I give them (Which is partly dependent upon TL) I'm getting figures ranging from 550 years at the high end, right down to 37 years at the low end

[Anaraxes]

Originally Posted by Flyndaran

Fission/fusion require huge minimum sizes

Well, if your definition of "huge" includes objects that are cylinders some 22 cm in diameter and 40 cm long, weighing about 300 kg. It doesn't really take much demand for electricity before fission reactors are more efficient than RTGs.

[Flyndaran]

Originally Posted by Anaraxes

Well, if your definition of "huge" includes objects that are cylinders some 22 cm in diameter and 40 cm long, weighing about 300 kg. It doesn't really take much demand for electricity before fission reactors are more efficient than RTGs.

Tiny for a fission reactor and really not awesome compared to RTGs of similar outputs. So I will adjust my statement to that of, "...with safety shielding, nuclear reactors are rather large."