[1.2] Real Solar System v12.0 Dec 8

[NathanKell]

First, anyone is highly encouraged to tweak/change/buzzsaw the RealSolarSystem.cfg and change things however they want. I mean, it won't be the real solar system then, but as yet this mod doesn't make it entirely the real solar system yet either. :]

li7in6: Yes, MFS does thrust correction, from MFSC v1 onwards. On the other hand, MFSC (and the Stretchy SRB) are incompatible with KIDS entirely. However, if you want to scale Isps, just open MFT/RealFuels/RealSettings.cfg and scale the Isps yourself. All the MFSC-compatible engines pull from there.

Now, regarding curvature. Given the low resolution of the planet mesh (more noticeable with RSS since the planet is 11x as big but the mesh density is the same) you'll get straight lines instead of curves.

I have no reason to doubt your, KhaosCorp's, visual acuity in this matter, so let's say you can see it at somewhere between 166m and 1km. The reason you can't in KSP with RSS is because while the curve of the earth is essentially a polygon of infinite sides, the one in KSP is of quite finite sides. With the scaleup, the length of each side of that polygon increased, so stretches will look flatter (because they are flat, except at the corners) rather than constantly curving.

Now, regarding RSS and MFS...hoo boy, lot of posts.

First, yes, an overview of fuels would make sense. That's a good point, KhaosCorp.

iVG is pretty much spot on but here's my goto summary:

*LiquidFuel (aka kerosene aka RP-1) and LOx is the "standard" / "benchmark" fuel. It's what the early launchers used, and what many still do. It's non-toxic, quite dense, and the LOx is only mildly cryogenic, which means LOx boiloff is not a big issue except for weeks+ missions. For all these reasons, RP-1/LOx is the fuel of choice for lower stages.

*Liquid H2 and LOx is a high-performance fuel. It gives you more "bang for your buck" but it's less dense so you need more tanks (though the tanks are lighter). However, engines burning LH2/LOx generally have a lower TWR than other engines (in MFS, 75%). Also, it is generally less efficient at sea level (proportionally) than other fuel mixes. The main complication however is that LH2 must be kept extremely cold; boiloff is a serious issue even in insulated (cryogenic) tanks. You should always use cryogenic tanks with this mixture; they mass less for hydrolox than do regular tanks. Given these advantages and disadvantages, LH2/LOx is best for upper stages that are fired during the launch or a few days after; however, some lower-stage use has been done (Delta IV, Ariane 5, Shuttle / Ares / SLS) though often in combination with solid boosters.

*Liquid Methane and LOx is midway between RP-1/LOx and LH2/LOx: lower performance than hydrolox but denser, and less cryogenic.

*Various hypergolics. They are various nitrogen-based storable (but highly toxic) liquid fuels. They perform less well than RP-1/LOx (about 95% the specific impulse), but are slightly denser and non-cryogenic: they can be stored for months at a time. Given their advantage in density, in actual use they are better than 95% as efficient--tankage for them masses much less. Further, another key advatange is that they do not need ignition: hypergolic means that if the two substances are put in contact, they will burn with no outside trigger. N2O4 is the storable oxidizer used; the latest MFS will include four different fuels to go with it. UDMH is the most stable and least-high-performing fuel, and least dense; Hydrazine is the highest-performing and densest but is unstable and thus not often suitable for use. Aerozine-50 is a 50-50 blend of the two; it's what the Titan II-IV and Proton and Apollo SPS all use. It performs quite well, and has a density between the two. MMH is often used as the fuel for maneuvering systems (Gemini and Shuttle OMS for example); it is about the same performance in terms of specific impulse as AZ-50 but rather denser, leading to a better-performing stage all-around. Given their storability and hypergolic nature, hypergolics are the fuel of choice for upper stages, maneuverinig systems, and bipropellant RCS, though some hypergolic lower stages (Proton, Titan) have been used.

=================

Now, regarding masses.

STATS DON'T MATTER WITHOUT USE CASES.

In isolation it is true that MFS with realistic masses will give you much lighter rockets for a given amount of delta V. That's because KSP engines mass about 3.2x what they would in real life for their thrust, and KSP tanks mass on the order of 2-10x what they would in real life. RM exists to correct that. (Though I'm constantly refining it; RM tank mass is a little low in 3.2, and a lot low in 3.0).

If your rocket, with RM, is 100 tons lighter, then RM is doing its job. The point of RM is to make rocket performance in KSP closely parallel real life rocket performance. Why? Because the solar system is no longer shrunken and thus flight also now parallels real life requirements. If you don't want the planets resized, then you really shouldn't be using RM mode; that's why I made it toggleable, and that's what I say explicitly in the MFS readme.

Finally, you mention terminal velocity...um, you are using FAR right? There's really little point in using RSS (or MFS RFRM) if you're not using FAR too.

[KhaosCorp]

This. ^^^^^^^^^^

you just invalidated everything else you've said and you really have nothing meaningful to contribute.

Are you just here to troll? I can see no other purpose to your being here at this time.

I am so very sorry you're not enjoying the mod but please leave the rest of us alone until you're actually wanting to participate.

Read my original post...I think going to the Mun is a more valid test than orbit anyway...

And no, Im not trolling, would not..I was actually enjoying the convo till diablos jumped in

[NathanKell]

Yes, I saw that you went to the moon; I just want to reaffirm (in my post above--we're now ninjaing each other so you may have missed it) that RM is working by design. Realistic doesn't always mean harder, or rather, it does in toto in KSP, but not for each individual thing.

[diablos]

When did I 'invent' any facts at all?? I have expressed opinions and given data directly from MJ2...nothing was invented.

No, what you're giving are anecdotes, not data. I've seen people testifying on their heart of hearts to the most stupendous claims you could ever imagine. But they, like you, are probably forgetting the first rule of honest discourse: the easiest person to fool is yourself.

And if your wondering where I got the 500ft figure it wasnt from math (and btw, math dont lie, but nor does it always tell the whole story) but rather from the 160+ jumps Ive done, I used to be a certified jumpmaster till I got put on full disability.

Reminds of this part: http://youtu.be/NSJElZwEI8o?t=8m44s

Also, what part of this story doesn't math tell? What hidden variables have I missed?

Just curious how often/many times youve been up in small craft, how many jumps have you done, that you can argue the point so much?

Sorry, but I trust my eyes alot more than your math....

I've stared my fair share of times right at the horizon from flight altitude and never had the confidence to declare with bold certainty what you claim. As Richard Feynman famously said: "The first principle is that you must not fool yourself and you are the easiest person to fool."

http://www.brainyquote.com/quotes/quotes/r/richardpf137642.html

Now, if anyone is actually interested in continuing this convo in a civilized manner Id be happy for it...

That you would perceive me challenging your claim to be "uncivilized" or "hostile" clearly tells me that you believe it for other than rational reasons. Frankly I couldn't give a damn either way - maybe you did see it, or maybe you didn't. All I'm saying is that based on the math, the odds are highly stacked against your claim.

[NathanKell]

So, I don't claim to know when one can see the curvature of the earth. But I do know that this tangent no longer belongs in this thread. Please take it elsewhere. Thanks.

[diablos]

Read my original post...I think going to the Mun is a more valid test than orbit anyway...

And no, Im not trolling, would not..I was actually enjoying the convo till diablos jumped in

My apologies for sinking my teeth too deep in this. I really don't mean any animosity towards you. I'm strictly trying to debate the issue, not the person.

[asmi]

Things seemed to get a little too hot over here. Everybody please calm down.

[KhaosCorp]

I am actually not using FAR Nathan...airplanes are a big part of my game, esp on Kerbin...and I cant seem to build anything that flys better than a wet brick with FAR(again, this is not a shortcoming of the mod, but rather in my understanding of advanced aerodynamics). My understanding was that it didn't change how rockets behave so much, though understandable that this may change with the increase in atmo height.

And FYI...I have always used nosecones..yes they do nothing without FAR, but they dont weigh much and they make your rocket look purdy...I like purdy rockets =)

[metaphor]

First, anyone is highly encouraged to tweak/change/buzzsaw the RealSolarSystem.cfg and change things however they want. I mean, it won't be the real solar system then, but as yet this mod doesn't make it entirely the real solar system yet either. :]

Haha, I was just playing around with this. Setting Kerbin's rotation rate to slightly higher than orbital velocity results in some very interesting behavior. (You will spontaneously fall up and around Kerbin and then touch down at another point on the planet at 0 m/s relative speed.) It's the next best thing to a custom planets mod. =)

[metaphor]

I am actually not using FAR Nathan...airplanes are a big part of my game, esp on Kerbin...and I cant seem to build anything that flys better than a wet brick with FAR(again, this is not a shortcoming of the mod, but rather in my understanding of advanced aerodynamics). My understanding was that it didn't change how rockets behave so much, though understandable that this may change with the increase in atmo height.

And FYI...I have always used nosecones..yes they do nothing without FAR, but they dont weigh much and they make your rocket look purdy...I like purdy rockets =)

I've tried playing RSS without FAR, it seems to take a little more delta-v to reach orbit, but it's not a huge difference (about 11 km/s versus 9.5 km/s) since most of the velocity you need is in the horizontal direction in near-vacuum anyway.

[diablos]

@KhaosCorp FAR changes the atmosphere and makes it a lot less soupy, so atmospheric drag is far less of a concern in rocket ascent. The practical upshot is that you can all but ignore terminal velocity on ascent.

[KhaosCorp]

@KhaosCorp FAR changes the atmosphere and makes it a lot less soupy, so atmospheric drag is far less of a concern in rocket ascent. The practical upshot is that you can all but ignore terminal velocity on ascent.

Ok...I was under the impression that going over terminal velocity on launch is basically wasting fuel..or Dv rather, either way. This part Im a bit fuzzy on...I know a bit about terminal velocity, but as it applies to stuff falling, not stuff going up.

So if my impression is wrong (as it seems like it may be) then whats the significance of it going up?

[metaphor]

Ok...I was under the impression that going over terminal velocity on launch is basically wasting fuel..or Dv rather, either way. This part Im a bit fuzzy on...I know a bit about terminal velocity, but as it applies to stuff falling, not stuff going up.

So if my impression is wrong (as it seems like it may be) then whats the significance of it going up?

You're right, if you go above terminal velocity you would be wasting fuel. What FAR does is it reduces atmospheric drag for most parts, which means that almost any rocket will have a much higher terminal velocity (something like 400 m/s instead of 100 m/s near the ground). So most rockets even accelerating at full throttle will never hit terminal velocity (because terminal velocity goes up fast as you go higher in the atmosphere).

[ferram4]

Going over terminal velocity means that you're going to waste fuel because while you're reducing gravity losses you're increasing drag losses by a much greater magnitude. It only really makes sense to worry about terminal velocity with stock aerodynamics since terminal velocity is so low.

If you install FAR, terminal velocity is much higher than you can easily reach. I've calculated an estimate of terminal velocity for rockets that ranges from ~400 m/s (for small rockets) to ~700 m/s for Saturn V / N1-like monsters. On the pad. If you actually went that fast at sea level you'd get the rocket to do exciting backflips, so with FAR installed nothing good comes of chasing it.

[diablos]

Terminal velocity, mathematically, is really just the velocity when two opposing force vectors cancel out. Obviously, when falling, your downward force is dictated by gravity, whereas the opposing vector is your drag (dictated by your surface area and shape). FAR doesn't change gravity, but it does change drag, rather significantly. Originally, KSP simply calculates drag as the lump sum of the drag of all of your components, regardless of whether they're exposed to the airflow or not. FAR does much better modeling here, and so by virtue of rockets being pointy at one end and having a much smaller surface area, their drag is far less in that direction. Therefore, your engines don't have to overcome nearly as much drag and so your terminal velocity on ascent is much higher, to the point where you almost don't have to worry about it at all. The overall tradeoff is that you should start doing your gravity turn much sooner, so that you minimize the amount of time you're burning against Kerbin's gravity. I typically start at around 400-600m, or about 20-30s after liftoff. Be careful about too aggressive maneuvers with FAR though - since FAR takes your relative angle to the airstream into account, any strong maneuvering while in the thick of the atmosphere at significant speeds (typical rocket Max-Q comes at around 400-500m/s at ~10-15km in altitude, ~1 minute after liftoff) can cause the dynamic pressures to overcome your thruster/fin control authority and tear your craft apart.

[SRFirefox]

You're right, if you go above terminal velocity you would be wasting fuel. What FAR does is it reduces atmospheric drag for most parts, which means that almost any rocket will have a much higher terminal velocity (something like 400 m/s instead of 100 m/s near the ground). So most rockets even accelerating at full throttle will never hit terminal velocity (because terminal velocity goes up fast as you go higher in the atmosphere).

More importantly, regular aerodynamic sensibilities apply when flying in FAR. It isn't that the drag of parts is lower (often, it isn't), but that the craft is treated as a whole and not the sum of it's parts. Therefore a strangely shaped payload will usually flip out in FAR due to drag, whereas adding a fairing around said payload will both significantly reduce drag and increase control. Nosecones on boosters are a must for the same reason. The parts inside/behind these parts then don't have drag from compressing the airflow before them, but simply whatever drag their surface adds as the air goes by. When the rocket is properly sleek, then the terminal velocity goes way up.

Ninja'd by Ferram himself! Awesome

Edited November 18, 2013 by SRFirefox

[KhaosCorp]

I'm thinking of installing FAR for further testing, but 2 things worry me.

Planes...I kinda suck at making planes with stock aerodynamics....I have tried FAR a couple times in the past, the end result was not good.

The other thing is I am really into the industrial aspects of the game, kethane and eplp are 2 of my favorites (i have even added oil and water to harvest to make reprocessing more complex)....this is something that may screw me using RSS anyway...but alot of my 'payload' craft are huge, bulky, and often misshapen industrial landers/bases....stuff that wouldnt fit in a fairing if your life depended on it....and its actually gotten worse since Ferram gave us KJR mod.

[SFJackBauer]

This mod is in its early days, I assume in time Kethane and EPLP will be made compatible.

As for the payloads well... sorry can't help you there. I am using this mod also with a project of industrial colonization of the solar system, but I intend to launch feasible things, not entire bases on one launch as I see people doing in KSP, and I hope to think my way around those limitations (in-orbit assembling, surface assembling etc).

[ferram4]

All you need to do to build rockets properly in FAR is to remember three things:

1. TWR ~1.4; higher than 1.8 leads to overspeeding and losing control.
   
2. Pitch over early and smoothly; 45 degree shifts in angle at 10km leads to a bad time.
   
3. Put fins at the bottom / flare the rocket at the bottom; this is less critical with MFS (since engines are lighter, so the rocket is more stable).

That's all you really need to worry about for launching a simple rocket.

As for crazy-shaped payloads, figure out how to divvy them up into multiple parts and launch them using smaller rockets. Use docking ports on bicouplers / tricouplers to make sure parts are oriented properly. Figure out what isn't necessary and remove it.

[diablos]

I'm thinking of installing FAR for further testing, but 2 things worry me.

Planes...I kinda suck at making planes with stock aerodynamics....I have tried FAR a couple times in the past, the end result was not good.

The other thing is I am really into the industrial aspects of the game, kethane and eplp are 2 of my favorites (i have even added oil and water to harvest to make reprocessing more complex)....this is something that may screw me using RSS anyway...but alot of my 'payload' craft are huge, bulky, and often misshapen industrial landers/bases....stuff that wouldnt fit in a fairing if your life depended on it....and its actually gotten worse since Ferram gave us KJR mod.

As long as you stick to relatively cigar-shaped objects, you should be able to fit them inside of the largest fairings (3.75m expanded etc.). The Procedural Fairings mod might also help. Also keep in mind that since the delta-v budget requirements with RSS are much higher, the resulting payload-to-launcher mass ratios are much greater (i.e. larger launchers, smaller payloads), so you're probably gonna have to do a whole lot of on-orbit or post-landing assembly anyway. That's how in real life the MIR the ISS and everything else larger in space was built, and that's also how all long-term Lunar and Martian outposts are planned to be constructed. There's no launcher in the world that will bring several hundred tons of payload into orbit in one go, much less send it to the Moon or Mars and land them there. The biggest, most capable thing that we ever built was the Saturn V, and even that maxed out at 120t. And it was the size and mass of a freakin' skyscraper.

[KhaosCorp]

So whats ideal FAR setting for RSS+MFS with the real masses folder added?

[diablos]

So whats ideal FAR setting for RSS+MFS with the real masses folder added?

Don't understand what you mean by "FAR setting". You don't need to tune FAR itself, it's already awesome As for your rocket designs, it really depends on the parts you have available, the mission profile, the spacecraft, delta-v budget and tons more variables. For sensible designs, I'd recommend having a look at real launch vehicles. With FAR+RSS+MFS you've already got mostly realistic physics and proportions going, and real rocket engineers have optimized the heck out of their launchers and spacecraft, so learning by imitation is a good start.

[NathanKell]

KhaosCorp, I (and a number of others) have found making planes in FAR _much_ easier than in stock. I can't make and fly planes for stock, whereas I have yet to make a plane that wouldn't fly in FAR. The simple rule is, in FAR, it'll fly like it looks. Other than the dynamically-unstable planes that in real life require computer assistance, most planes are designed to fly well, so if you clone them you should be fine. And the FAR thread has a ton of guidance and helpful mentors if you get stuck.

Regarding large bulky payloads: they actually will fit, because remember how much larger rockets you require. That means you'll need, say, 8m diameter cores to lift your 100ton payloads. And I bet your 100 ton drill + transfer stage will fit in an 8m-diameter fairing!

Also, AFAIK, there's nothing about RSS that should break Kethane. Try it and see! Same with EPLP. I'm just rescaling, it's not like I'm changing how planets are made!

Oh, speaking of 8m cores...I'm putting the finishing touches on RftS-Engines, the successor to KATO engines. In combination with the rest of my realism tweaks you'll have realistic rocket sizes and support for large cores (the old NovaPunch 1.5 M-50, aka F-1-alike, in its 5x version, is rescaled 10m part).

and regarding FAR settings: diablos has it, there are no settings. It's all automatic. Just, and THIS IS IMPORTANT, you have to change your ascent profile.

As other others have said, you need to start your gravity turn EARLY, like, at about 100m/s. You should be horizontal by maybe 80-150km, depending on your TWR (lower TWR upper stage = pitch down slower; trying to SSTO, with a 12G burnout TWR, pitch down fast!)

[li7in6]

redacted...

Edited November 18, 2013 by li7in6

[KhaosCorp]

I never had an issue getting planes to fly stock..maybe not fly well...but put CoL just behind CoM and it gets off the ground.

Also I just tested, Kethane works just fine with RSS, map and drilling (though I didnt scan, had a debug save going already to test).

Im thinking of scaling the KW parts up in size.....I need bigger fairings for this to continue.