Oolite Bulletins

Davemak wrote:

Well I was thinking along the lines of the different views (front/aft/port/starboard) that do not have linked cooling systems, so why would 2 lasers at the front be any different?

There’s this thing called game balance…

I have to say, in defence against that, NPC ships like the Rattle Cutter or the Wolf II do have multiple forward lasers. Giving the player such would rebalance it a bit.

drew wrote:

Also, I appreciate Oolite isn't 'real' (what, no? ) but todays industrial lasers are in the range of 10 Kilowatts continuous beam now, and their cooling requirements are quite modest. We're only talking 100 times the power (based on FE2/FFE canon) to get to a 1Mw beam laser. In a 1000 years of progress I would imagine that entry level beam lasers would be a very mature technology and cooling wouldn't be an issue. Lasers are actually pretty efficient devices when compared to say engines for example.

They are? I thought they were generally on the order of just a few percent efficient for the bigger lasers (I can imagine laser diodes being pretty efficient, but they are all low powered)

In any case, even a 90% efficient 1MW laser would need to dissipate 100kW of heat, which is still quite a lot (despite the efficiency). If an industrial 10kW laser is 90% efficient, it only has to shed 1kW of heat which is less than an electric kettle. Going up an order of magnitude requires getting rid of lots more heat, and in space heat is rather harder to dissipate.

Actually, so long as you can manage a high temperature, say 300C+ dissipating heat in a vacuum isn't too hard. You just radiate it away. The higher the temperature the faster you dissipate heat. In fact it goes as the 4th power of the temp.

Ooops, physics!

Yeah man - this is Oolite - physics from our universe don't count in the Ooniverse.

cmdr drayton wrote:

Actually, so long as you can manage a high temperature, say 300C+ dissipating heat in a vacuum isn't too hard. You just radiate it away. The higher the temperature the faster you dissipate heat. In fact it goes as the 4th power of the temp.

Ooops, physics!

Oops, physics indeed. Most semiconductors have long since burned up at 300 celcius. There would be limits to how hot you could allow your laser to become (regardless of the technology) which would also limit how fast you could radiate. Presuming a military laser would be (well, comparing to FFE) around 10MW, even if it were almost unattainably efficient (90%) you still have to radiate 1MW of heat and at the same time not exceeding a temperature that would melt the device!

Wiggy wrote:

Does anyone remember the RPG Traveller?

I bought Traveller because it looked cool, but never found anyone to play it. I even flicked through the rule book earlier this year for fun. I like the part on designing and upgrading spaceships.

It is acknowleged as one of the inspirations for Elite.

winston wrote:

Oops, physics indeed. Most semiconductors have long since burned up at 300 celcius. There would be limits to how hot you could allow your laser to become (regardless of the technology) which would also limit how fast you could radiate. Presuming a military laser would be (well, comparing to FFE) around 10MW, even if it were almost unattainably efficient (90%) you still have to radiate 1MW of heat and at the same time not exceeding a temperature that would melt the device!

There's no need to have semiconductors near the hottest part of the laser. And even semi-conductor lasers can run hotter than you might think. Small intricate semi-conductors like CPUs don't much like heat, but big crude power handling semiconductors can cope much better with heat. 300C probably isn't unreasonable, a Core Duo manages at 100C (according to sepcs) and it's going to way more sensitive. But in fact you'd probably use a gas laser for something like this, even though they're less efficient.

And don't forget the duty cycle of the laser. It's only producing heat while energy is being put into it. So when the temp is maxed out, the laser is running just a few percent of the time (assuming you're still trying to fire), which means although the beam power might be 10MW the averaged power input might only be a few tens of KW. And that amount of heat really is trivial to shift, even at 300C, at higher temperatures it becomes even easier.

We're assuming for beam and military lasers, a continuous beam rather than a short duty cycle, so (say) 10MW continuously. The duty cycle is only shortened when the laser reaches its temperature limits.

It's not just the laser itself, it's also the controlling gear (and barring any fundamental discovery about being totally wrong about the laws of physics) is likely to remain semiconductor. The vast amounts of power the controller is going to have to handle means it has to lose heat, too. Even a simple MOSFET tends to die long before reaching 300 celcius (I have first hand experience, and a little component bin called "Silicon heaven") - so even if you can make what's doing the emitting work at 6000 degrees - it's entirely plausable for Oolite's lasers to have the limit perhaps imposed by the control gear.

And I think originally that's what the whole thing was about.

Okay, a bit off-topic, but I always wondered:
Why can't you give a ship two or more cannons in the front? I tried it once with the same commands as with the exhaust, but it just shut off Oolite.