[WIP] Nert's Dev Thread - Current: such nuke, wow

[Captain Sierra]

The water ISRU concept brought up is an interesting one. While arguably out of scope of NF NTRs, that certainly opens some cool doors.

[Fraz86]

7 hours ago, riocrokite said:

@Fraz86

From my perspective a substantial penalty for ZBO tanks makes sense since it allows to build more interesting gameplay. For example just-in-time ISRU production of fuel or storing LOX/LH2 on orbital stations as water (then all those fancy heat radiators and big panels on space stations finally make sense since it takes quite a lot of energy or heat dissipation to convert lh2/lox into water and other way round ;)) I'm thinking here about a gameplay without stock ISRU since it's imho too op (should be able to produce only oxidizer from ore and at much slower pace).

Firstly, I believe balance decisions should be made independently of third-party mod mechanics/resources. Nertea's mods have always been tuned for stockalike gameplay.

Secondly, frankly, over-incentivizing this kind of complex gameplay (just-in-time ISRU, etc.) is exactly what I'm worried about. Regardless of what balance we choose, it will be possible to utilize lifting tanks on interplanetary missions (in place of ZBOs) by relying on ISRU. If the performance gap between lifting tanks and ZBOs is too large, ISRU-based missions become basically the only smart way to use atomic rockets, and ZBOs will have limited use cases.

We should remember that Nertea was very reluctant to implement boiloff at all - and for good reason! Boiloff has the potential to be an annoying, un-transparent, and un-fun game mechanic. Nertea only decided to implement boiloff because we couldn't think of a better way to make one set of tanks advantageous in atmosphere and the other set advantageous in space. There is a strong temptation to give boiloff highly sophisticated gameplay implications, but I believe it would be wise to stay focused on the original goal: ZBOs for space, lifting tanks for atmosphere. This goal is best accomplished with a small dry mass advantage for lifting tanks, in order to avoid creating too much incentive to find ways to use lifting tanks in space (though the option will still exist for those who are motivated to do so).

Edited January 13, 2016 by Fraz86

[Psycho_zs]

Seeing various planetary resources with CRP installed I think that putting everything through stock Ore>ISRU is not a way to go.

Add more mining capabilities to drills and ore tanks, since mechanically there is much less difference on what solid stuff to crunch through and haul, but chemically ISRUs should be very different. I would happily mine the Mun for water ice and have a separate electrolysis ISRU on board to produce LH2/OX.

I have two heavy miner ships in main career providing LF/OX infrastructure for Kerbin SOI operations. I've designed these ships to also being able to haul lithium tanks, since currently NFP adds this capability to ISRU. But I would happily accept the challenge of making a miner ship with interchangeable ISRUs, that would be super cool!

[Jimbodiah]

If you use NF Propulsion you can have craft that will shuttle to/from Kerbin and be able to land on the Mun/Minmus with only a little fuel used. One ore miner on Mun and one on Minmus, and a small station in orbit of each moon (with modded, non-OP, ISRU) will give you a complete setup for career mode without dependency of fuel being launched up from Kerbin. LH2 would not really be all that practical vs the electrical engines using Xe/Ar/Li (at the cost of heat/electricity rather than fuels). The same setup can be used if you want to stick with the CryogenicEngines pack, everything will just be bigger/heavier, but still self-sustaining in terms of fuels. Mining water or ore is the same thing, you mine something and stick it into an ISRU to get something else. If you want to do it properly you will indeed need to mine for water, but if you are using LF than you would need to find both Ore and Water as you need C and H molecules. In the end it's not about being true-to-life, but having a fun experience with at least some effort required to regain your resources. Wether that is mining ore or water is really just semantics..

[Psycho_zs]

Tunguska Chelyabinsk is making constant noise when stowed. Sort of flameout sound playing in rapid cycle.

Edited January 13, 2016 by Psycho_zs

[Nertea]

Is this a new thing? Or was this an old cryoengines bug?

[Psycho_zs]

I never used Cryo before recently and I only actually launched fully functional Tunguska yesterday, so I do not know how old this bug can be. I'll try other foldable engines later today.

[Nertea]

Maybe hold off on that. I wrote my own extendable nozzle module to get around some other peculiarities of BDAnimationModules, will be test released tomorrow morning (~10 hours from now). This may fix some problems. 

@Starbuckminsterfullerton, I can't repro the pipes disappearing. It's probably because they're a skinned mesh, and KSP hates those randomly... maybe the next version will fix it (I rexported)?

Edited January 14, 2016 by Nertea

[Captain Sierra]

1 hour ago, Nertea said:

Is this a new thing? Or was this an old cryoengines bug?

Cant say I can confirm as a standing cryo engine bug. Used it for a while and don't recall that ever being an issue.

[riocrokite]

20 hours ago, Fraz86 said:

Firstly, I believe balance decisions should be made independently of third-party mod mechanics/resources. Nertea's mods have always been tuned for stockalike gameplay.

Secondly, frankly, over-incentivizing this kind of complex gameplay (just-in-time ISRU, etc.) is exactly what I'm worried about. Regardless of what balance we choose, it will be possible to utilize lifting tanks on interplanetary missions (in place of ZBOs) by relying on ISRU. If the performance gap between lifting tanks and ZBOs is too large, ISRU-based missions become basically the only smart way to use atomic rockets, and ZBOs will have limited use cases.

We should remember that Nertea was very reluctant to implement boiloff at all - and for good reason! Boiloff has the potential to be an annoying, un-transparent, and un-fun game mechanic. Nertea only decided to implement boiloff because we couldn't think of a better way to make one set of tanks advantageous in atmosphere and the other set advantageous in space. There is a strong temptation to give boiloff highly sophisticated gameplay implications, but I believe it would be wise to stay focused on the original goal: ZBOs for space, lifting tanks for atmosphere. This goal is best accomplished with a small dry mass advantage for lifting tanks, in order to avoid creating too much incentive to find ways to use lifting tanks in space (though the option will still exist for those who are motivated to do so).

fair enough, just wanted to share different point of view

[Nertea]

Test X3

• Liberator art completion: normal maps, heat animation, FX pass
  • No shroud yet (haven't decided on design)
• Poseidon art completion: normal maps, heat animation, FX pass
  • No shroud yet (haven't decided on design)
• Completed art is now ddsed (won't load as white anymore)
• Added placeholder (kinda ok, kinda not) 1.25m NTR plumes
• Added WIP Stubber NTR
• Initial start balance vales for NTRs added in (please take a look)
• Newest balance fixes to CryoTanks fuel switch patches
• Few tweaks to boiloff code for speed and useability
• Fixed a bug where having no boilable fuel on a CryoTank would cause weird things to happen
• Fixed empty CryoTanks evaporating fuel elsewhere on the ship
• UI improvements for CryoTanks
• Switched from BDAnimationModules to custom DeployableEngines code for Liberator and Poseidon's deployable engines, fixing many problems (source is in the usual place). Note CryoEngines still use the old method, I'll move them over if there are no problems. 

Now taking balance notes on the 4 new NTRs (and the LVN for comparison). Here's the conceptual list:

• LV-N is entry-level 1.25m, can only use LH2, has no gimbaling. Mass reverted to 2.5t though and heating reduced.
• Neptune is advanced 1.25m, can use LH2 or LH2Ox for more thrust (less Isp). All specs slightly better than LV-N, weighs a bit more, higher cost. Also generates passive power (next test update will have this consume uranium)
• Stubber is specialized 1.25m, can use LH2 or LH2Ox. Lower footprint, better atmo Isp, but lower vac isp than LV-N
• Poseidon is initial 2.5m, can use LH2, LH2Ox. Should be about 4 Neptunes. Also generates passive power (next test update will have this consume uranium)
• Liberator is advanced 2.5m, can only use LH2 though. Generates much heat. Highest Isp, thrust. 
   

[Jimbodiah]

cool!!!  starting up KSP now

 

Will there be an engine between Tunguska and Odin someday?

Edited January 14, 2016 by Jimbodiah

[Captain Sierra]

Initial reports:

Liberator deploy animation works correctly in VAB but does not trigger when in flight.
Mechanically everything else appears to be working correctly (mostly VAB and pad testing as of current)
As per usual, the LOX augment mode is outputting more dV (disclaimer: I have not yet tried vessels on the magnitude of ridiculous yet) by a considerable margin. the Isp differential is not as potent as the mass differential even with the altered fuel ratio.

[blowfish]

48 minutes ago, Jimbodiah said:

Will there be an engine between Tunguska and Odin someday?

The Tunguska and Odin fill completely different roles (upper/vacuum and lower/lifter respectively).  Do you mean a sustainer type engine with both acceptable sea level and vacuum I_sp (but neither being optimal)?

19 minutes ago, Captain Sierra said:

As per usual, the LOX augment mode is outputting more dV (disclaimer: I have not yet tried vessels on the magnitude of ridiculous yet) by a considerable margin. the Isp differential is not as potent as the mass differential even with the altered fuel ratio.

This is with the same vessel mass but all the oxidizer tankage replaced with LH2, right?

[Jimbodiah]

@blowfish Yes, there is not much between the 275/116 of the Tung and 1000+ of the Odin. I tend to like something around 600 for smaller rockets as a primary, or a sustainer for heavy 2nd stages.

[Captain Sierra]

9 minutes ago, blowfish said:

This is with the same vessel mass but all the oxidizer tankage replaced with LH2, right?

I was using a mock-up interplanetary vessel which uses ZBO tanks and the Posdeidon NTR (also tested at one point with 3 neptunes). I was swapping between LH2/Ox and pure LH2 in the fuel switch options. The only thing I was changing was what was in the tanks. All other things held constant.

[Fraz86]

13 minutes ago, Captain Sierra said:

I was using a mock-up interplanetary vessel which uses ZBO tanks and the Posdeidon NTR (also tested at one point with 3 neptunes). I was swapping between LH2/Ox and pure LH2 in the fuel switch options. The only thing I was changing was what was in the tanks. All other things held constant.

Total vessel mass needs to be held constant for a fair test. Fuel-switching alone will result in much lower fuel mass for the LH2-only mode, which will of course have lower Delta-V. LH2 needs much more tank volume.

[Nertea]

1 hour ago, Jimbodiah said:

Will there be an engine between Tunguska and Odin someday?

Pretty unlikely. CryoEngines is done until next cycle. 

47 minutes ago, Captain Sierra said:

Liberator deploy animation works correctly in VAB but does not trigger when in flight.

Are you suuuure? I tested this this morning with no problems....

48 minutes ago, Captain Sierra said:

As per usual, the LOX augment mode is outputting more dV (disclaimer: I have not yet tried vessels on the magnitude of ridiculous yet) by a considerable margin. the Isp differential is not as potent as the mass differential even with the altered fuel ratio.

Yes it does, because adding OX adds lots of fuel mass. When you switch to LH2/OX mode, it's like adding another few tons of LH2. Its denser. Without adding more fuel volume you'll always increase DV in this case.

[Psycho_zs]

Regarding LH2/OX ratio, I wonder if there is a point somewhere nearby at which it would be possible to match the ratio with reasonable quantity of separate tanks, something akin Orion craft.

[Jimbodiah]

15 mondo-60 tanks for LH2, and 1 mondo-60 for Oxidizer.

[Captain Sierra]

I had a theory about what may be going on and decided to test it. Using two tanks, one LH2 one LH2/OX, and the neptune engine, I tracked the fuel draw of LH2 across both modes.

In LH2 mode, the Neptune draws approx. 95 units of LH2 per second according to the resource panel.
In LOX augment mode, it draws roughly 72 units per second by the same measurement.

LH2 usage goes down when injecting LOX, despite this not being the realistic case. Exactly what this means and the effects it has are not entirely clear. While certainly not the only contributing factor to better dV in LOX augment mode, it certainly warrants further experimentation.

This is an artifact of how the stock game works. I believe it can be fixed by nerfing Isp. Alternatively the effects may be so minimal that it can be safely ignored. As previously stated, further testing is required.

1 hour ago, Nertea said:

Are you suuuure? I tested this this morning with no problems....

Yes I'm suuuure.

[Fraz86]

1 hour ago, Jimbodiah said:

15 mondo-60 tanks for LH2, and 1 mondo-60 for Oxidizer.

15:1 is the unit ratio. The volume ratio for LH2O is 3:2 (LH2:OX).

@Captain Sierra If it's important for LH2 consumption to remain constant between modes (which I'm not sure that it is truly important), we need a total fuel mass burn rate for augmented mode that is ~5.706x that of LH2-only. Basically, the Augmented:LH2-only thrust ratio divided by the Augmented:LH2-only ISP ratio needs to equal 5.706. This would certainly be doable, it just depends whether or not Nertea cares enough about this detail to tune NTRs around it.

Edited January 14, 2016 by Fraz86

[Jimbodiah]

You guys spoil all the fun!

[sashan]

On 13.01.2016 at 6:01 PM, Jimbodiah said:

Right now I have zero boil-off if cooling is used, would it not be more realistic to have a very small boil-off even though it is being cooled? Else there is no real disadvantage to using LH2 in space as you don't lose any anyway. I need about 12Ec/s to keep a Mondo-60 cooled, which is not much, but I would expect to still keep losing some LH2.

IMO the boiloff could really be zero. But the cooling plant should be separate part, produce lots of heat and absorb lots of electricity, like ISRU.

[Jimbodiah]

Even with cooling, you would expect some kind of loss. A lossless system IRL would be larger than the tanks themselves. Liquid N also just evaporates, even with 20cm of insulation and storage in a freezer.