Realism Overhaul

[Razorcane]

ISS project isn't dead at all. Yogui is working on Cupola, Z1, Pirs and Poisk. I'm also going to contribute with config edits and BobCat will probably model some missing truss pieces and experiments. It's moving slowly, but far from dead.

Well the thing is, it doesn't get updates anymore, so I assume that it's dead based solely on that. And anyway, in order for my ideas to work, those models would have to be changed quite a bit.

Edited November 11, 2013 by Razorcane

[Razorcane]

So I don't know if anyone uses it because of all of the issues it has, but I changed the CSS to somewhat realistic measurements. Note that you WILL require Modular Fuels AND CSS Mod(since I don't give all the parts) to make this work, as I use LOX/LH2 as fuels. Note that I recommend using Mechjeb for control, but don't even think about using it for ascent autopilot, as it messes up because of the SSME compensation. But, because of the mod, you will need a way to control the craft within the atmosphere.

Here it is:

http://www./?mupvy92r4xzjqtj

Note that it's not 100% realistic. There is no information on the SRBs other than thrust and burn time, which I've matched. For the External Tank, I went with the extra light version, so I'm not sure what the overall weight of the craft is, but it does match the data from wikipedia. As far as the shuttle goes, I didn't change any of the settings, so it still weighs about 30t, give or take. I didn't want to go in and incrementally change the mass of every piece, since there are quite a few of them. For safety measures, I also included an updated strut connector part.cfg, since I'm not sure the default ones would be able to handle nearly 32,000kN of thrust.

Here's a picture of it in orbit if you don't believe me:

Apigee: 410km, Perigee: 362km

Still had quite a bit of fuel to spare, in case it needed to go further.

[Captain_Party]

Whats its top payload mass?

[Razorcane]

Whats its top payload mass?

Eh, well, the total mass is around 1800 tons, but the actual space shuttle is 2030 tons or so, so I imagine that if you can fit it in the bay, you can get it into orbit. The external tank had quite a bit of fuel left in it, probably about 2km/s delta-v, so as long as your payload is under 100t, you should be able to get it into LEO.

[Guest]

Nice. I'll release a proper update when the next version of the Shuttle is finally done (no ETA yet, but BobCat's working on it, so I wouldn't worry. ).

[Razorcane]

Nice. I'll release a proper update when the next version of the Shuttle is finally done (no ETA yet, but BobCat's working on it, so I wouldn't worry. ).

Proof? Has he posted any spoiler screenshots or anything?

Also, I'm going to go in and fix up the shuttle configs a bit.

[Guest]

I'm working on this with him, as a matter of fact. And I'll take care of fixing all configs when he's done.

[Captain_Party]

Realism fanboy

[MKSheppard]

I know this is kind of late to quote the starting post in a thread but:

Now, engines.

Engines in KSP have TWRs in the range of 5 (the LV-1) to 10 (LV-909, Poodle) to 14-17 (LV-Ts, Skipper) to 20 (48-7S) to 25 (Mainsail).

Now it just so happens that a flat multiplier of 6x works pretty well here, yielding TWRs of 30 (about right for a tiny vacuum engine) to 60 (upper stage) to 102 (lower stage) to 150 (Merlin 1D, best TWR ever).

Conversely, that means dividing engine mass by 6.

Actually, for pretty much all liquid rocket engines; you can simply use the real thing's TWR ratio when making the Kerbalized version.

I did a lot of looking into this using Glenn Research Center’s RocketThrust Simulator v1.5b and found the following rules of thumb worked sorta:

Thrust Scaling

Quadruple Thrust: Scale up size by a factor of 2 (200%)

Double Thrust: Scale up size by a factor of 1.415 (141.5%).

Half Thrust: Scale down size by a factor of 0.71 (71%)

Quarter-Thrust: Scale down size by a factor of 0.5 (50%)

Dimensional Scaling:

Quadruple Size: Scale up thrust by a factor of 16 (1,600%)

Double Size: Scale up thrust by a factor of 4 (400%)

Half Size: Scale down thrust by a factor of 0.25 (25%)

Quarter Size: Scale down thrust by a factor of 0.0625 (6.25%)

(A more complete discussion is at my site: Link to Rocket Engine Scaling.)

For KSP's 64% scaling; that translates into KSP engines having 0.4096x the thrust of their real life equivalents; e.g. the F-1A puts out 1.8 million pounds of thrust; but if you scaled her down to 64% for Kerbalkind, she'd only put out about 737,280 lbf of thrust and weigh 7,782.96 lb (F-1A's TWR was 94.73 at sea level).

The one thing where all this rubber banding doesn't work is...nuclear. Nuclear needs a minimum critical mass for fission, among other things. If you want to maintain realism for nuclear thermal rockets; you need to look for actual NASA nuclear thermal designs in the 30,000 lbf thrust range and use them; instead of simply scaling a 75,000 lbf NERVA down.

[SFJackBauer]

@Razorcane what info you need? I went through this data collection about the shuttle while doing mine:

Here is what I have:

- Boosters

Dry mass: 90.65t

Liftoff mass: 590t of solid propellant (66,666 units)

Thrust: It follows a peculiar curve so I used the engine controller (and booster itself)

from this link by HoneyFox and Hakari

. It is important for the SSRBs to follow this curve.

SL Isp - 269s

SL Vac - 287s

- ET

Dry mass: 26.5t

Liftoff mass: 762.1t of 295,170 units of LH2 and 110,217 units of LOX. I also shifted the CoM to about a third from the top, since the LOX tank is on top and corresponds to most of the mass.

- SSME

SL thrust - 1800kN

SL Isp - 363s

Vac Isp - 453s

Mass - 3.5t

- OMS

Thrust - 26kN

SL Isp - I dont know, why would you use it at SL?

Vac Isp - 316s

- Orbiter (with three SSMEs):

Dry mass: 57t

With OMS fuel: 78.5t, with 1,362 units of MMH and 1,873 units of N2O4.

Liftoff mass: max of 109t so it leaves 30t for payload MAX.

The orbiter should have 300m/s of delta-V after ET separation. Each of the two OMS engines has ridiculous thrust, 25 kN, to push a 100t truck.

Now the really tricky part is the re-entry and landing. In the end I used Procedural Wings with FAR so I could tweak the aero properties to get a controllable, high hypersonic AOA (40º reentry), and good subsonic maneuverability. I don't know what kind of aero tweaking that mod would need, or if it already works with far.

The most critical part of the orbiter is the re-entry CoM, therefore in mine I split the fuel in a forward and aft tank so the CoM could stay in a predictable spot, and then designed the wing around that.

Oh and for maneuvering, since the real orbiter used also MMH/N2O4 for the RCS but KSP RCS is monopropellant, I just used the equivalent mass in monopropellant for the OMS. The real orbiter RCS could only use a fraction of the fuel available in the OMS, but I don't think we will be able to simulate that... yet.

Edited November 12, 2013 by SFJackBauer

[SFJackBauer]

--Nevermind, double post--

[Razorcane]

@Razorcane what info you need? I went through this data collection about the shuttle while doing mine:

Here is what I have:

- Boosters

Dry mass: 90.65t

Liftoff mass: 590t of solid propellant (66,666 units)

Thrust: It follows a peculiar curve so I used the engine controller (and booster itself)

from this link by HoneyFox and Hakari

. It is important for the SSRBs to follow this curve.

SL Isp - 269s

SL Vac - 287s

- ET

Dry mass: 26.5t

Liftoff mass: 762.1t of 295,170 units of LH2 and 110,217 units of LOX. I also shifted the CoM to about a third from the top, since the LOX tank is on top and corresponds to most of the mass.

- SSME

SL thrust - 1800kN

SL Isp - 363s

Vac Isp - 453s

Mass - 3.5t

- OMS

Thrust - 26kN

SL Isp - I dont know, why would you use it at SL?

Vac Isp - 316s

- Orbiter (with three SSMEs):

Dry mass: 57t

With OMS fuel: 78.5t, with 1,362 units of MMH and 1,873 units of N2O4.

Liftoff mass: max of 109t so it leaves 30t for payload MAX.

The orbiter should have 300m/s of delta-V after ET separation. Each of the two OMS engines has ridiculous thrust, 25 kN, to push a 100t truck.

Now the really tricky part is the re-entry and landing. In the end I used Procedural Wings with FAR so I could tweak the aero properties to get a controllable, high hypersonic AOA (40º reentry), and good subsonic maneuverability. I don't know what kind of aero tweaking that mod would need, or if it already works with far.

The most critical part of the orbiter is the re-entry CoM, therefore in mine I split the fuel in a forward and aft tank so the CoM could stay in a predictable spot, and then designed the wing around that.

Oh and for maneuvering, since the real orbiter used also MMH/N2O4 for the RCS but KSP RCS is monopropellant, I just used the equivalent mass in monopropellant for the OMS. The real orbiter RCS could only use a fraction of the fuel available in the OMS, but I don't think we will be able to simulate that... yet.

I actually already had all that information, apart from the exact number of units of fuel in the tanks. How do you shift the mass? I'll work on these configs at some other time, since the carft is very hard to fly anyway, I don't think it's really worth putting a lot of effort into. Also, for the shuttle RCS, I could have configured it to use MMH/N2O4, but I didn't know it used that.

EDIT: Also, the units for the external tank have to be incorrect(or the weights in MFS are wrong), since using those numbers makes the external tank weigh over 2000t by itself.

Edited November 12, 2013 by Razorcane

[SFJackBauer]

I actually already had all that information, apart from the exact number of units of fuel in the tanks. How do you shift the mass? I'll work on these configs at some other time, since the carft is very hard to fly anyway, I don't think it's really worth putting a lot of effort into. Also, for the shuttle RCS, I could have configured it to use MMH/N2O4, but I didn't know it used that.

Hmm AFAIK RCS can only use only one resource, is there a way out of this limitation?

EDIT: Also, the units for the external tank have to be incorrect(or the weights in MFS are wrong), since using those numbers makes the external tank weigh over 2000t by itself.

I don't understand how could it be wrong:

- LH2 density: 0.00036 * 295,170 units = 106.26t

- LOX density: 0.00571 * 110,217 units = 629.33t

Density units from ModularFuelTanks\RealFuels\Resources\ResourcesFuel.cfg

[Razorcane]

Hmm AFAIK RCS can only use only one resource, is there a way out of this limitation?

I don't understand how could it be wrong:

- LH2 density: 0.00036 * 295,170 units = 106.26t

- LOX density: 0.00571 * 110,217 units = 629.33t

Density units from ModularFuelTanks\RealFuels\Resources\ResourcesFuel.cfg

I was able to use both MMH and N2O4 as RCS fuels, however I couldn't control the ratio.

I think I figured out my problem with the fuels. I was using RP-1(LiquidFuel)/LOX. So that might explain it. Also, the fuel values in the cfg are rounded up, which sadly makes them weigh more.

LH2: 0.00035425

LOX: 0.005705

It's not much, mind you, but at such high numbers it's probably close to a couple of tons difference.

Edited November 13, 2013 by Razorcane

[NathanKell]

okayfine. I set rounding to 8 places for the next MFS. And fixed LH2's density in g/cc (was 0.071; now 0.07085). Hope that's better.

[Captain_Party]

Have a lookie at the new realistic parachutes mod, very helpful for the new and improved CSS

[Nobody_1707]

It rounds up? I would have expected Banker's rounding. Especially as it's the default rounding mode for IEEE floating point.

[NathanKell]

I'm doing all this in excel first, then exporting to confignodes, so I use the built-in round(). Which always rounds up on 0.5, rather than banker's rounding.

[Guest]

OK, I'm nearly done with the Proton, but Luna is causing me problems. So it's a change of plans. I'm doing MIR first, and after that, Luna 17. You'll also get Zarya as a bonus, and an APAS docking port to go with all this.

Also, there's been a huge change in how I'm doing this. Thanks to BobCat's recent changes to Soviet Pack, the mod is now a ModuleManager file, which allows me to append necessary modules as needed instead of remaking the configs. This is the reason this update is taking so long, I needed to test if everything's working. It seems like my past issues with MM are fixed in 1.5, though, so I hope it'll be out soon.

NathanKell: While I was at it, I re-made your FASA modification to use MM. It's much neater that way. I still need to fix a few things (most notably, disable modifications MFT makes to FASA parts config-side), but it's pretty much working. Can I release it along with the Soviet Pack?

[NathanKell]

Dragon01: I'm 99% fine with that, but can you leave the cfgs for the engines as duplicates? As MFS desperately needs engine variety, it'd be good to still be able to use the engines as generics.

Also you'll probably want to rework the TACLS resources to ECLSS ones

[Guest]

Yeah, I'll be implementing ECLSS on Gemini. AFAIK, MM can't really add stuff, so the "main" engines will have to be changed. I think that I can make additional "backup" configs for MFS that would add those engines under a different name, much like you added a bunch of rescaled stock engines.

[MedievalNerd]

For those interested I just finished the layout of the Solar System Tech tree, in the Realistic Tech Tree overhaul thread! It's a massive beast! But it fits! Max zoom out I get only 11 fps, but hey,

We'll have to send NathanKell some energy and positive vibes so that he can muster the strength to code the integration of tech levels to nodes, and a few other things. I'm not good enough to do any of that!

Cheers,

[NathanKell]

Heh. Thanks. On the list it goes. :]

In other news: Dragon01, do you think people will mind if the Titan II is 2 inches narrower than it should be? (and Gemini 1.5 inches). That way it's precisely 3m.

Why does 3m matter?

Because I'm finally going back and doing what I was planning to do: Undo the Great Rescale in KSP, so sizes are now 0.5m, 1m, 2m, 3m, 4m, 5m, 6m, etc.

I've placed roughly a third the 1.25m engines in 1m (along with a few .625s), and the rest in 2m; the 2.5ms go in 3m; and the rest get distributed appropriately.

I'm liking the result, because--except for a few 2.5m diamater rockets (Thor/Delta, R-7 derivatives) most things fit pretty well. Oh, and the 6.6m S-IVB/S-I stuff. But that would fit just as badly under the old system.

I've also gone and allowed arbitrary fuel combinations at arbitrary mix ratios in my MFS excel spreadsheet.

[Guest]

You can try scaling it to 3m. I'll release the MM config, so you could try editing that and see how it works. Try replicating Agena and docking it, it's about the only time when Gemini would be seen next to another rocket stage (besides Titans).

[NathanKell]

Yeah, 2 inches off 10 feet is not going to be visually apparent. You just use 1.2, not 1.22...