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[v1.2]KSP - Silisko Edition


NovaSilisko

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I really want to make a witty remark about the combustible properties of electricity but I\'m way too scared of the !!science!! around here.

Something like: \'refill\' a battery? You can\'t fill a battery. Or not? :P

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You can make solar battery and solar wind particle collector to fuel ion engine, but will it be enough even to overcome light and solar wind pressure? Or that\'s the same perpetuum mobile project as solar powered photon engine?

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Bah, we need all systems requiring electrical power.

Capsule would have a battery good for a while but if you don\'t have solar panels or a suitable service module with fuel cells, you would eventually run out of electrical power and end up with unhappy Kerbins (and shutdown of most systems).

Until that point, solar panels = cool shiny things for show.

They are far too weak for any truly useful propulsion except very very weak ion drives (think 'months to change orbit')

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Indeed. IIRC, the VASIMR ion engine which provides 5N of thrust requires something like 200kW to function. To give an idea, each solar array wing on the ISS weighs 1,088 kg and provides approximately 31kW of power. To get 200kW, you\'d need 7 of these arrays -- weighing 7.616 metric tons. The engine itself weighs 300kg, bringing the full mass of the system to approximately 7.9 metric tons.

To put this in KSP terms, an ion engine/solar array combined system would weigh 7.9 units, and provide 0.005 units of thrust. Fuel consumption (based on the VASMIR specific impulse of 5,000 sec) would be 0.0000231 fuel units (based on the stock fuel tank\'s propellant mass) per second, for a total burn time from one can of fuel of 249 days (21.5 million seconds).

Great for long-term exploration missions at 10,000x warp. Not so great for orbital maneuvering. The efficiency is there, and it\'s significant: 107,500 N*s (total thrust) for the VASMIR vs. 12,500 N*s for the stock engine. But the weight and the extremely low power are crippling.

Using compact nuclear reactors can bring the engine weight down, but that doesn\'t solve the whole 'extremely crippled thrust' issue. It might be cool to model this engine with small nuclear reactors: there\'s a reactor being developed now that produces about 100kW at a reactor weight of 500kg. That would allow a 0.005 thrust engine with a weight of 1.3, and a simpler 3D model. This could be a cool mod project for massive interstellar spacecraft designs.

Sources:

http://world-nuclear.org/info/inf82.html

http://en.wikipedia.org/wiki/Specific_impulse#Specific_impulse_as_a_speed_.28effective_exhaust_velocity.29

http://en.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket#VF-200

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The service module functions as an RCS tank currently.

Besides, solar panels refilling fuel tanks makes absolutely no sense at all.

lol sorry man. I feel like such a dumb ass now... Must have been really tired to have thought solar panels can create fuel lol. My apologies guys for saying something so stupid.

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IMPORTANT INSTALLATION INSTRUCTIONS

[list type=decimal]

[li]Download a fresh copy of KSP[/li]

[li]Install it into a new folder[/li]

[li]Go into the 'Parts' folder[/li]

[li]Delete everything in there, and replace it with the contents of Kerbal Space Program - Silisko Edition.zip[/li]

You can get the first release here:

http://dl.dropbox.com/u/575558/Kerbal%20Space%20Program%20-%20Silisko%20Edition.zip

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I don\'t get the values in this pack. The \'800\' capacity tank weighs more when full, but the same when empty, as 4 of the \'200\' tanks :-\. If anything, I thought the advantage of 1 large tank over several small ones was the fact that volume increases faster than surface area - more fuel inside the same amount of metal. Since the larger tank is in fact a larger diameter, this should definitely be the case.

Also, where is this extra mass coming from? *boggles* It\'s the same when empty: 1 ton (for the \'800\') or 1 ton (4*0.25 for the \'200\'s). So it\'s not the metal. The \'200\'s each contain 200 units of fuel in their remaining 1.75 tons of mass, whereas the \'800\' contains 800 units of fuel in its remaining 8 tons of mass. The \'1600\'s are similar - they\'re exactly twice the mass of the \'800\'s (full or empty). At least that\'s consistent (and since they are simply twice the height, I wouldn\'t expect any particular improvement due to the geometry like I would coming from the 1m \'200\'s.)

Literally the only thing I can see that\'s an advantage is the doubled (or quadrupled, in the case of the \'1600\' tank) impact strength - which, again, I found bizarre - if anything I thought that in general, the larger tanks were more fragile (the Atlas would collapse under its own weight if not pressurized, etc.)

The extra mass and subsequently reduced performance are just ..weird, though. If nothing else you could put the fuel into the same (rough) shape as a stack of 4 tanks, but use stringers instead of actual partitions between the \'tanks\' and still accomplish a weight savings that way, albeit much less than the improvement from improved geometry.

Testing confirmed the crappier TWR - straight up, full throttle, got to 58.5km @ ~2700 m/s using 4x \'200\' tanks, while only reached 51.5km @ 2440 m/s using a single \'800\' tank. These numbers are at burnout.

tl;dr - Why are the larger tanks heavier instead of lighter than the small tanks?

PS - for what it\'s worth, the \'compressed\' fuel tank seems correct to me. You pay more of a mass penalty for such a small tank - running 4 of them (200 units of fuel) gives a crappier TWR than a single \'200\', as it should be. However, the name is deceptive! Allllll the other tanks, even the FL-R25 RCS tank, have the numbers indicating fuel capacity. This one is called the \'M100\' but has only a capacity of 50.

PPS - I think using the 100:1 fuel to weight system that the \'200\' tank was supposed to weigh 2.25, not 2.0. If that was the case it would be functionally identical to the other 3 tanks .. which is still wrong, the fuel:structure weight ratio should improve with tank size, but it would at least be a start.

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if anything I thought that in general, the larger tanks were more fragile (the Atlas would collapse under its own weight if not pressurized, etc.)

The old Atlas missiles use \'balloon\' tanks, meaning the design deliberately leaves out most structural support and depends on the tank being pressurized to hold up its weight.

This isn\'t an example of behavior for large tanks in general, quite the opposite in fact. The massive external tank on the shuttle stack supported the entire weight of the orbiter when on the pad.

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Great pack. Since I don\'t usually keep my KSP along for long I really don\'t care for compatibility. Some textures, like the FL-TX Fuel Tank Adapter look a bit too 'burnt out', as if they had too much specular power on them. I don\'t know.

Anyway, love it.

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