KSP Interstellar Extended Continued Development Thread

[raxo2222]

Btw, from my understanding, the efficiency of VASIMR should depend on the Vapor pressure of the propellant. I have not taken this into account yet.

Hmm... so hydrogen may get higher thrust and hydrazine get lower thrust?

Ill make another test with biggest tanks and 100% thrust to see what changes.

[FreeThinker]

Hmm... so hydrogen may get higher thrust and hydrazine get lower thrust?

Ill make another test with biggest tanks and 100% thrust to see what changes.

Yes, but the problem is I don't understand how to take this into account. From my understanding the Vapor Presure of Hydrogen is very high, this fact combined with its low melecular mass should make it more effective. Right now, I only take Mass and released enery into account. Hydrogen should also get some bonus at very high tempertures when the H2 decomposes into atomic Hydrogen, which aplies to the Vasimr which is basicly a thermal rocket with magnetic confinement and heated by microwave which heats the propellant to very high temperatures. It should be enough to atomise all hydrogen, which should give it an considerable thust and isp bonus.

Edited August 13, 2015 by FreeThinker

[ABZB]

Yes, but the problem is I don't understand how to take this into account. From my understanding the Vapor Presure of Hydrogen is very high, this fact combined with its low melecular mass should make it more effective. Right now, I only take Mass and released enery into account. Hydrogen should also get some bonus at very high tempertures when the H2 decomposes into atomic Hydrogen, which aplies to the Vasimr which is basicly a thermal rocket with magnetic confinement and heated by microwave which heats the propellant to very high temperatures. It should be enough to atomise all hydrogen, which should give it an considerable thust and isp bonus.

the mass flow remains constant, presumably. all other than mass-per-particle is reasonably constant (I hope). mass per particle (H2) is twice mass per particle (H). ratio of squares of exhasut velocities V(H)^2/V(H2)^2 = 2. Ratio of velocities is square-root(2).

total exhaust mass per unit time is same. presumably then ISP is multiplied by square-root(2)....

It should be noted that there would possibly not be a thrust bonus from H->H2 reactions in exhaust, as pure monatomic hydrogen REALLY does not like to react with itself to form the diatomic molecule. There might be enough impurities in exhaust or just floating around to make it happen though... couldn't find data on the energy release from that reaction though - it basically never happens. (In early universe, bleeping Helium-4 likely acted as a catalyst for the formation of H2, which was in turn necessary for the primordial gas clouds to be able to emit sufficient black-body radiation for them to cool off enough to collapse to form stars...) nowadays, everything else on the table exists, and likes to grab it up really fast.

[raxo2222]

Yes, but the problem is I don't understand how to take this into account. From my understanding the Vapor Presure of Hydrogen is very high, this fact combined with its low melecular mass should make it more effective. Right now, I only take Mass and released enery into account. Hydrogen should also get some bonus at very high tempertures when the H2 decomposes into atomic Hydrogen, which aplies to the Vasimr which is basicly a thermal rocket with magnetic confinement and heated by microwave which heats the propellant to very high temperatures. It should be enough to atomise all hydrogen, which should give it an considerable thust and isp bonus.

Hmm maybe changing min/max efficiency for every fuel would do something. For example hydrogen would have 90-60% efficiency or so.

Heres biggest tank at max thrust tests:

Javascript is disabled. View full album

Best DV for fixed volume goes to Hydrazine. Highest TWR is for liquid fuel - 1.44. Hydrazine was second with 1.37. Liquit fuel wasn't choosable in small fuel tank in previous test.

5 fuels, that Vasmir could use weren't tested - not available for that interstellar tank: Lithium, Monopropellant, Xenon, Argon and Neon.

Wonder if one of these would have better DV than hydrazine....

5 digit DV

Heres actually reasonable thrust for less DV

I think this is enough to go to pluto and go to orbiyt in year if not very limited range microwave network.

Edited August 13, 2015 by raxo2222

[FreeThinker]

Found some intresting document on efficencies of VASIMR. At http://spaceflight.nasa.gov/shuttle/support/researching/aspl/reference/f_aiaaass2004.pdf

Perhaps we can use it somehow

- - - Updated - - -

One thing I don't understand why Hydrazine isn't mentioned as a propellant for high temperature engines (VASIMR, NTR). I must be overlooking something obvious. Hydrazine creates a lot of extra gas, but perhaps it products (H2 + N2) don't scale so well in vapor presure compaired to pure hydrogen, or there are inherent problem of ionizing it, I simply don't know.

Edited August 13, 2015 by FreeThinker

[ABZB]

I notice in the VASIMR config file that there are these two line in ModuleEnginesFX:

		runningEffectName = run_vasimr_argon_core
		powerEffectName= run_vasimr_argon_glow

are these doing anything right now?

[raxo2222]

Hmm magnetic nozzle at 63% throttle has around same ISP as VASMIR engine.

Vista - ISP of Vasmir at 10% at 51.5% throlle.

So if you want to use hydrogen just use this magnetic nozzle or Vista engine.

Edited August 13, 2015 by raxo2222

[ABZB]

Hmm magnetic nozzle at 63% throttle has around same ISP as VASMIR engine.

Vista - ISP of Vasmir at 10% at 51.5% throlle.

So if you want to use hydrogen just use this magnetic nozzle or Vista engine.

but what are the relative thrusts? keep in mind that the VASIMR and the other electric engines have thrusts that depend on the available MW (up to a limit). The magnetic nozzle's thrust is a function of the charged particle properties of the available reactor(s). only the vista gives a fixed thrust for a given throttle % (it draws a constant amount of MW).

Edited August 13, 2015 by ABZB

[raxo2222]

but what are the relative thrusts? keep in mind that the VASIMR and the other electric engines have thrusts that depend on the available MW (up to a limit). The magnetic nozzle's thrust is a function of the charged particle properties of the available reactor(s). only the vista gives a fixed thrust for a given throttle % (it draws a constant amount of MW).

Here we go: Every ship has same amount of hydrogen.

There is Magnetic Nozzle with antimatter reactor, Vista engine with DT fuel and 4x Vasmir engine pack.

Javascript is disabled. View full album

Magnetic nozzle has highest thrust of them all at Vasmirs max hydrogen ISP.

BTW why max size for VASMIR is 2.5 meter?

Edited August 13, 2015 by raxo2222

[FreeThinker]

BTW why max size for VASMIR is 2.5 meter?

Because it is the maximum size of MPD, which largest always have been 2.5m. I guess it was to promote VISTA which starts at 3.75, which is realy small btw.

- - - Updated - - -

H

Magnetic nozzle has highest thrust of them all at Vasmirs max hydrogen ISP.

Indeed, But note it's actualy even better if you had made the radiators smaller, as Magnetic nozzle have the same cooling effect as thermal nozzle, which effectively means you need 90% less radiators, saving a lot of mass which will translate into a significant gain in delta V.

[raxo2222]

Because it is the maximum size of MPD, which largest always have been 2.5m. I guess it was to promote VISTA which starts at 3.75, which is realy small btw.

- - - Updated - - -

Indeed, But note it's actualy even better if you had made the radiators smaller, as Magnetic nozzle have the same cooling effect as thermal nozzle, which effectively means you need 90% less radiators, saving a lot of mass which will translate into a significant gain in delta V.

Always? O.O since I remember I could resize MPD (plasma thruster) to 10 meters.... so it must be bug lol

Edited August 13, 2015 by raxo2222

[okder]

Inertial confined fusion with thermal nozzle and hydrazine blowsup when mechjeb trying to land (it can't predict correct max thrust, and so uses engine in impulse mode, this causes critical overhead, using engine just in max thrust mode don't overhead engine)

refinary don't mine water in moon best water spot (crater on equator) and still don't create uranium nitride (grayed out) even all components available.

P.S. mechjeb landing don't work anymore (even initial stage) with thermal nozzle (it did worked though in 1.2.*).

mechjeb maneuver execution don't work with magnetic nozzle (same incorrect max thrust prediction).

[Sacnoth]

From the latest changelog:

• Advanced Fission/Fusion Fuel Modes now require Science Lab
  

Can anyone explain a bit more how this works? which fuel modes are now locked? and do they require the tech node for the science lab to be unlocked? or a science lab on the ship with the reactor?

[FreeThinker]

Lol, I knew I made a mistake somewhere. The thrust multiplier of Hydrazine should be 1.8.6, not 2.5, big difference.

[raxo2222]

Lol, I knew I made a mistake somewhere. The thrust multiplier of Hydrazine should be 1.8.6, not 2.5, big difference.

lol

BTW are you adding remaining fuels to interstellar tanks like these I mentioned earlier above?

And it looks I build as tiny VASMIR rocket as I could with 2 longest fuel tanks. Result is 5 digit DV.

This is 0.625m rocket.

So 6 digit DV guarranted if I make it multistage 0.625>1.25>2.5>5m

[FreeThinker]

From the latest changelog:

• Advanced Fission/Fusion Fuel Modes now require Science Lab
  

Can anyone explain a bit more how this works? which fuel modes are now locked? and do they require the tech node for the science lab to be unlocked? or a science lab on the ship with the reactor?

Look at the table on the first page, it contains the information you need

[raxo2222]

This rocket has slightly under 1000000 m/s of DV.

Javascript is disabled. View full album

I bet if I made it magnetic nozzles it would have over 1000000 m/s DV lol

[FreeThinker]

This rocket has slightly under 1000000 m/s of DV.

http://imgur.com/a/cwXkz

I bet if I made it magnetic nozzles it would have over 1000000 m/s DV lol

Well after 30000 delata V , any higher becomes meaningless realy, unless you want to travel to other stars. Instead it allows you to use it for something useful, like for instance a multi mission Mother ship with SSTO to make a grand tour and take soil sample from all surfaces and bring them ack to kerbin.

- - - Updated - - -

refinary don't mine water in moon best water spot (crater on equator) and still don't create uranium nitride (grayed out) even all components available.

You cannot mine Uranium nitride directly, you first need to mine Uranium, which will be stored as EnrichedUranium. You should them be able to convert it to Uranium Nitride, but this doesn't work yet (due to flow issues)

Edited August 13, 2015 by FreeThinker

[raxo2222]

I have RSS, so it may be 10x more DV needed for grand tour over all planets and moons.

And how much DV you need to go to Jupiter, descend into lower atmosphere and go back to earth?

[FreeThinker]

I have RSS, so it may be 10x more DV needed for grand tour over all planets and moons.

And how much DV you need to go to Jupiter, descend into lower atmosphere and go back to earth?

Well there is also such things as Atmospheric scoop. You can use them to collect resource from the atmosphere or just above it. Upgraded VASIMR can even use compressed atmosphere as propulsion for virtual unlimited range in the atmosphere. With an inboard KSPI ISRU Refinery, you can convert raw resource like Water and Nitrogen into advanced propellant like Hydrazine

Edited August 13, 2015 by FreeThinker

[ABZB]

Would it be possible to alter the code in the plugin so thermal nozzles can use moduleenginesFX? is there any problem that module was having with it or something?

[FreeThinker]

Would it be possible to alter the code in the plugin so thermal nozzles can use moduleenginesFX? is there any problem that module was having with it or something?

In the past you could not but now it should work with any PartModule which implements moduleEngines, which includes ModuleEnginesFX

Now you can change it to ModuleEnginesFX if you want, you probably also need add some effects to get an exhaust and it should work

[ABZB]

In the past you could not but now it should work with any PartModule which implements moduleEngines, which includes ModuleEnginesFX

Now you can change it to ModuleEnginesFX if you want, you probably also need add some effects to get an exhaust and it should work

ah - excellent!

[ss8913]

update on the VASIMR thing, Freethinker - everything is fine as long as there's only one engine. Add more than one engine in any configuration and weird things start to happen. They don't seem to draw power evenly, or it creates that pitching issue, or both.

[Trolllception]

Is the Attila thruster supposed to display thrust and fuel information in the VAB? I don't have any options other than thrust limit and gimbal limit as if it were a SRB or something. Once I load the game everything is fine and I can view the thrust.