[0.25]KSP Interstellar (Magnetic Nozzles, ISRU Revamp) Version 0.13

[Fractal_UK]

Fair enough on the fuel material. Any thought on the third "expended fuel" category so a player can easily tell how much fuel has been permanently used?

I'll look into it, I don't want to add another resource because there is already quite a lot of clutter in the resource bar but I can probably find another way of displaying that information.

Also, I need to ask as I'm having trouble with this right now, exactly how does one get a 3.25m reactor off the ground? The problem I'm facing is that the reactor model in game has NO attachment points on it's surface for reinforcement struts, thus it's only attachment to the lifter is the single point which immediately snaps under the 43 ton burden at even the slightest hint of acceleration (I attempted a slow take off throttle up with a mechjeb limited acceleration of 15m/s, and even that was too much for the single attachment point and on a few occasions just loading in was enough stress to collapse it).

Basically, the trick is to strut from the other parts to the reactor. Although starting struts on the big reactors is not possible, ending them there works perfectly well. That's how I've always done it. I hope that works for you.

[Yaivenov]

I shall test and report back. Thus far whenever I try to strut TO the reactor it has acted as if I'm clicking on thin air. Also another concern is I don't want a bunch of expended strut feet excessively adding to the part count of my completed craft.

ETA: Huh, the struts worked that time.

[Gaius]

Well that was fun! Decided to bring that research ship back home to Kerbal to collect the final Science from it's trip to Jool. Kind of disappointed though, the expendable probe I dropped into Jool's atmo worked great....except there was no land/impact, it just fell through the surface.

As it should, assuming it's anything like the "surface" of Jupiter, which is really just an arbitrarily defined point in the atmosphere.

... Also another concern is I don't want a bunch of expended strut feet excessively adding to the part count of my completed craft.

Only one end of a no longer attached strut is saved with the craft. You can see the other end during the session in which the strut is broken, but upon reloading the craft after a save, all those "feet" are gone.

[Imca]

Ummm, is there any downside to leaving a plasma thruster running constantly, even in atmosphere?

[SorensonPA]

I'm really diggin' this mod, but one thing I've noticed as I start thinking about setting up infrastructure for the antimatter endgame is that there isn't anything for RCS, thus limiting you to monoprop manually launched from Kerbin. Would downscaled plasma thrusters work for that? Hydrogen and Argon is scoopable and a probe-scale thruster would give about 14.6 Kn thrust at 1,116.27 Mj (handy for heavier vessels) while something scaled down to an RCS block would give 1.8 at 139.53.

[Cairan]

Ok, I've been trying for three hours to kick an upgraded 3.75 m antimatter reactor and generator group into space from kerbin, but so far the solution eludes me... Just with the reactor core and the generator, you already have nearly 70 tons!

I'm open for suggestions!

[Imca]

The smaller ones provide plenty of power?

[Lalwcat]

So, deuterium, aside from having a science lab floating in the water next to the KSC and using a truck to fuel up craft leaving Kerbin, how do you get more? All I can find is "Jool has some", but no specifics how to get it.

Also, anyone mind posting a screenshot of their lab getting deut from water? I tried building a floating lab with structural fuselage around the bottom to float, but no go. Even if I raised the float point up so the bottom of the lab was definitely in the water, still getting 0.00d.

Edited October 27, 2013 by Lalwcat

[Cairan]

I think you need to scoop it out of Jool's atmosphere ... but I'm not sure yet ... BTW finally managed to build a bare-essential stack that could kick my antimatter warp core barely into orbit... Orbital assembly in progress!

[AlchemicalAgent]

Ok, I've been trying for three hours to kick an upgraded 3.75 m antimatter reactor and generator group into space from kerbin, but so far the solution eludes me...

If you have KAS or something similar you can bring antimatter from orbit back to the launchpad and fuel the ship before it takes off. I've had 500+ ton ships that were SSTO with that method.

[Yaivenov]

As it should, assuming it's anything like the "surface" of Jupiter, which is really just an arbitrarily defined point in the atmosphere.

Only one end of a no longer attached strut is saved with the craft. You can see the other end during the session in which the strut is broken, but upon reloading the craft after a save, all those "feet" are gone.

Thank you, regarding the strut feet. And as for Jool/Jupiter, yeah, it was just kind of a let down not to get that final "crunch" of atmospheric pressure or an impact. Lots of excellent science made on the way down though!

Ok, I've been trying for three hours to kick an upgraded 3.75 m antimatter reactor and generator group into space from kerbin, but so far the solution eludes me... Just with the reactor core and the generator, you already have nearly 70 tons!

I'm open for suggestions!

I usually go with some Saturn-1C boosters for the really heavy lift jobs, but I'm assuming you want a stock solution. Here's my fuel tanker I sent to Jool, it has a slightly greater mass of around 86.75 tons, boosted fully to a 100km parking orbit using 14 mainsails and 21 SRB's. This was done without touching any of the payload's own fuel, either mono-prop or liquid fuel. Fair warning, this is a 335 part count booster, but it sheds parts pretty quickly. After having trouble of getting the towers to release reliably and not hang-fire due to lag, I finally just made a tower-less assembly. That's right, it just sits on the pad until launch!

The payload:

The booster:

Hard to see but important, there are radial RCS mono-propellent tanks mounted to the final mainsail booster so I don't have to dip into the payload's maneuvering fuel during launch.

Noted launch events.

Launch preparation note: The outer mainsails are starting with their gimbals locked, and the payload's mono-propellant tank is locked out to prevent use. A gravity turn starting at 8km and proceeding at 100% until 70km is utilized. Target apogee is 100km

1: All SRB's and the Stage-1 mainsails are fired. These mainsails are not asparagus stacked and are treated as a unitary booster (I know, I probably could have made this more efficient, but I did this for simplicity of the assembly at this point.

2: Stage 1 SRB Separation: Using terminal velocity limitation, the stage 1 mainsails will throttle back and allow them to save enough fuel to outlast the SRB's by a few seconds.

3: Stage 1 Separation: Stage 2 asparagus stacked mainsails fire.

4/5: Stage 2-4, 2-3 are shed during climb to 100km apogee.

6/7: During coast to apogee stage 2-1 mainsail engine is gimbal locked and RCS takes over attitude control. Stage 2-2 is shed during circularization burn.

8:Stage 2-1 is shed after fine-tuning orbit, with a surplus of 70m/s dV remaining.

(Note: thrust was not limited to 20m/s, only to terminal velocity.)

The clock is running!

Max-Q (for my purposes anyway).

SRB sep. and throttle up.

Stage 1 sep.

Stage 2-1 sep. proceeding through the turn nicely.

Stage 2-2 sep.

Main engine shut down and coast to apogee.

Circularization burn.

Sorry, missed the stage 2-3 seperation.

Final orbit established, and not a drop of payload fuel expended!

Edited October 27, 2013 by Yaivenov

[cy-one]

While it looks less "rockety" than Yaivenovs (because it's flatter ) this ugly beast gets somewhere between 100 and 120 tonnes into LKO.

I never did a real stress test, but the 3.75m-Drive-Section (Alcubiere, AM-Reactor, Thermal Nozzle, Generator) had a mass of 95 tonnes... And when I reached (stable, circular) orbit, the central tanks where yet untouched. So with a 1.5 Jumbo-Tanks (the grey one on the bottom is just 1/2 of a Jumbotank) worth of fuel, 100-120 tonnes should be possible.

http://www.file-upload.net/download-8168370/LV-I-5.craft.html

It should be completely stock (IIRC, not even MJ is on it).

[Jasmir]

Hi fractal,

with the plasma-thrusters (and your own ressource-manager) the Mechjeb-autoprediction when to start burn don't work. I think, it's because of the reactor-shutdown when the throttle is reduced, so that mechjeb get the last (and very low) max-thrust. Is there a way to work around this?

[Fractal_UK]

So, since I have a bit of free time, I thought I'd write something about one of the features forthcoming for version 0.8.

Much of this feature comes down to a paper that Conti read about microwave launch systems. The idea is very similar to that of a nuclear reactor/thermal rocket but instead of heating propellant with a reactor, you instead have the power generation installed either on the ground or in space and beam the power onto a spot on the side of the rocket which contains some kind of ceramic heat exchanger with veins of propellant running through it.

Conti then set about trying to implement this feature and managed to get it working after a great deal of work. For me, this was largely a matter of taking his code and integrating it with the new thermal nozzle code and thermal power system that I set up behind the scenes in the 0.7.2 update.

So, how does it work?

Well, the first thing I did was head to the spaceplane hangar - I wanted a rover with the biggest nuclear reactor/generator I could find and a Phased Array Microwave Transmitter. So, after a few moments of playing with parts, I came up with this

I didn't want to be short on power so I decided to line up a little cavalcade on the western edge of KSC. Putting them further from the launch site is important because the microwave spot needs to be projected onto the side of the rocket, which actually makes position of the transmitters on the ground fairly tricky to get right.

I then asked around at Kerbal Space Centre for a Kerbal volunteer to try going into space without any onboard power source. Of course, it was that crazy Kerbal Jebediah who stepped forward. A small rocket is constructed out of spare parts and launched skyward.

As I get a bit higher, I start to have problems. There are beamed power transmitters at the yellow circles shown but they are all now starting to get "behind" my rocket. In order to get the best performance from the rocket, we need the angle between the rocket's path and the transmitters (Æ) to be as close to 90 degrees as possible but here they're becoming worryingly close to parallel.

Fortunately, I seem to have built up enough speed that the increasing loss of power isn't really hindering my way into space. I can afford to lose some of my TWR as my horizontal speed increases and ultimately my progress into space is not stopped.

Circularisation, however, is where I run into a problem. Due to all the velocity that I've gained by launching myself into space, close to orbital velocity, I've pushed myself over the horizon from all of my microwave transmitters.

Had I actually been concerned about making orbit with this, I would've placed some transmitters at the location I marked with a blue circle. These would help me to avoid both losing some of my power during my ascent as well as being in perfect position to beam power at 90 degrees to my rocket for my circularisation burn.

Hope you liked the look of this feature!

[Tharios]

So, since I have a bit of free time, I thought I'd write something about one of the features forthcoming for version 0.8.

Much of this feature comes down to a paper that Conti read about microwave launch systems. The idea is very similar to that of a nuclear reactor/thermal rocket but instead of heating propellant with a reactor, you instead have the power generation installed either on the ground or in space and beam the power onto a spot on the side of the rocket which contains some kind of ceramic heat exchanger with veins of propellant running through it.

Conti then set about trying to implement this feature and managed to get it working after a great deal of work. For me, this was largely a matter of taking his code and integrating it with the new thermal nozzle code and thermal power system that I set up behind the scenes in the 0.7.2 update.

So, how does it work?

Well, the first thing I did was head to the spaceplane hangar - I wanted a rover with the biggest nuclear reactor/generator I could find and a Phased Array Microwave Transmitter. So, after a few moments of playing with parts, I came up with this

I didn't want to be short on power so I decided to line up a little cavalcade on the western edge of KSC. Putting them further from the launch site is important because the microwave spot needs to be projected onto the side of the rocket, which actually makes position of the transmitters on the ground fairly tricky to get right.

I then asked around at Kerbal Space Centre for a Kerbal volunteer to try going into space without any onboard power source. Of course, it was that crazy Kerbal Jebediah who stepped forward. A small rocket is constructed out of spare parts and launched skyward.

As I get a bit higher, I start to have problems. There are beamed power transmitters at the yellow circles shown but they are all now starting to get "behind" my rocket. In order to get the best performance from the rocket, we need the angle between the rocket's path and the transmitters (Æ) to be as close to 90 degrees as possible but here they're becoming worryingly close to parallel.

Fortunately, I seem to have built up enough speed that the increasing loss of power isn't really hindering my way into space. I can afford to lose some of my TWR as my horizontal speed increases and ultimately my progress into space is not stopped.

Circularisation, however, is where I run into a problem. Due to all the velocity that I've gained by launching myself into space, close to orbital velocity, I've pushed myself over the horizon from all of my microwave transmitters.

Had I actually been concerned about making orbit with this, I would've placed some transmitters at the location I marked with a blue circle. These would help me to avoid both losing some of my power during my ascent as well as being in perfect position to beam power at 90 degrees to my rocket for my circularisation burn.

Hope you liked the look of this feature!

Sounds like a little effort could establish a solar power network capable of powering thermal rockets with no reactors or generators. The ultimate in safe, efficient, renewable space travel.

I like it...adds a new dimension of possibilities.

[forsaken1111]

Yes! I could totally see landing a series of nuclear powered microwave emitters in a pattern around Kerbin's equator to assist payload launches.

Can this system work in tandem with a craft's own reactor? As in can I have a craft with a reactor + thermal rocket also being assisted by the microwave beam?

Edit: Jeeze, snip out pictures when you quote something.

[Fractal_UK]

Can this system work in tandem with a craft's own reactor? As in can I have a craft with a reactor + thermal rocket also being assisted by the microwave beam?

Not by itself no, the thermal microwave receiver takes the place of the reactor so you can't use both with the same engine.

We have done some work on a heat exchanger system too, that would let you combine lots of thermal power sources together but the downside to that would be that the temperature of the heat exchanger would be ~1500K (something that can actually be feasibly pumped around) rather than the very high temperature you might find in the nuclear/antimatter reactor cores. 1500K means a maximum specific impulse with LiquidFuel of ~658.5s.

[Fractal_UK]

with the plasma-thrusters (and your own ressource-manager) the Mechjeb-autoprediction when to start burn don't work. I think, it's because of the reactor-shutdown when the throttle is reduced, so that mechjeb get the last (and very low) max-thrust. Is there a way to work around this?

It's probably because the plasma thruster max thrust isn't set until you actually start the burn, I think it should work if you throttle up the engines up and down a bit before starting the autopilot but I'm not sure. I will investigate when I get chance.

Ummm, is there any downside to leaving a plasma thruster running constantly, even in atmosphere?

How do you mean? Plasma thrusters produce a lot of WasteHeat so that could be a downside.

[sanoj688]

It doesn't have to be active, but you will need to switch back to the science lab after you've been time accelerating on other vessels before all your science will be retroactively added to the R&D centre.

Thanks! .

[Scotius]

To be honest Fractal - while this feature is very interesting, i don't see much use for it on Kerbin. One would need a really huge amount of emitters to reliably get moderately sized rocket into orbit. Maybe if we could get dedicated, tight beam emitters with autotracking feature? But that's for Kerbin. On low gravity bodies it would be much more useful. I can see myself launching a nuclear powered emitter, landing it on Mun or Minmus on a big, equatorial kethane deposit. Then i would send a miner/tanker without heavy power source installed. It would use only radiated power to land and liftoff saving a lot of weight (and fuel) on the way.

[GabrielG.A.B.Fonseca]

Fractal, what about some Eeloo ISRU? Shouldn't we be able to electrolyze the surface ice too?

[Fractal_UK]

To be honest Fractal - while this feature is very interesting, i don't see much use for it on Kerbin. One would need a really huge amount of emitters to reliably get moderately sized rocket into orbit. Maybe if we could get dedicated, tight beam emitters with autotracking feature? But that's for Kerbin. On low gravity bodies it would be much more useful. I can see myself launching a nuclear powered emitter, landing it on Mun or Minmus on a big, equatorial kethane deposit. Then i would send a miner/tanker without heavy power source installed. It would use only radiated power to land and liftoff saving a lot of weight (and fuel) on the way.

It isn't actually so bad. Every basic Aegletes 2 you use is capable of getting about 262KN with liquid fuel at sea level, the upgraded versions can obviously get more. A pair of Aegletes installed at three or four strategic locations on Kerbin (say: west of KSC, island runway and continent east of KSC, maybe with a supplementary floating site) should get you Mainsail levels of thrust at nuclear engine specific impulses.

It does take a bit of setting up but it will let you get a significant increase in payload fraction going on. Should be good for that on low gravity bodies too, that said, optimal launch trajectories on low gravity bodies tend to be flatter which mean increasing need for multiple reactor and power beaming emplacements.

Fractal, what about some Eeloo ISRU? Shouldn't we be able to electrolyze the surface ice too?

I've been assuming that Eeloo is quite like Pluto in which case, although its an icy body, the surface is covered in a fairly healthy layer of Nitrogen ice that would make getting to the water fairly difficult. There may be something else I can do with the surface of Eeloo in the future though.

[Scotius]

I've been assuming that Eeloo is quite like Pluto in which case, although its an icy body, the surface is covered in a fairly healthy layer of Nitrogen ice that would make getting to the water fairly difficult. There may be something else I can do with the surface of Eeloo in the future though.

Monopropellant production? And nitrogen can be used as a propellant in many kinds of engines - especially thermal.

[Fractal_UK]

Monopropellant production? And nitrogen can be used as a propellant in many kinds of engines - especially thermal.

Monopropellant is something I'd really like to add some kind of ISRU support for but assuming Monopropellant is Hydrazine which is the standard, its production seems like a fairly complicated, multi-stage process so I don't really know how viable producing it in situ would be without really extensive chemical processing capabilities installed in order to process a large number of input chemicals and slowly work through a long chain of reactions.

Nitrogen would indeed be a good thermal engine propellant, albeit fairly low Isp, I'd just need to find some kind of elegant solution for fuel tanks. Adding lots more combinations of fuel tanks would not be ideal.

[Yaivenov]

Monopropellant is something I'd really like to add some kind of ISRU support for but assuming Monopropellant is Hydrazine which is the standard, its production seems like a fairly complicated, multi-stage process so I don't really know how viable producing it in situ would be without really extensive chemical processing capabilities installed in order to process a large number of input chemicals and slowly work through a long chain of reactions.

Nitrogen would indeed be a good thermal engine propellant, albeit fairly low Isp, I'd just need to find some kind of elegant solution for fuel tanks. Adding lots more combinations of fuel tanks would not be ideal.

Hydrazine is a fairly simple molecule, N2H4. Just do a Fischer-Tropsch synthesis, except instead of using carbon as your primary building block you use nitrogen. Liquid fuel (assuming LH2) plus nitrogen ice, plus a lot of heat and electricity equals hydrazine.

Now most used mono-propellant isn't straight hyrazine, it's actually a mixture of hydrazine and unsymetrical dimethylhydrazine, usually in a 50/50 mix called Aerozine 50. USDH has a molecular formula of C2H8N2. Still smack-dab in the realm of a FT fuel synthesis, just add CO2 ice to the mix and shake well.

Warning: Hydrazine and USDH is hypergolic when in contact with nearly all organic material: oxidizers, textiles, rocket technicians, etc.

ETA: Just a side note, with FT synthesis, you can make any chain hydrocarbon you want with nothing more than CO2, H2O, and a butt load of electricity. RP-1 anybody?

Edited October 27, 2013 by Yaivenov