Discussion and Progress on the 1:1 Solar System (PC SFS)

[Zeeray13]

So during the last few days I have been playing the latest release of SFS on steam. Honestly its great with a few nit picks like the input delay carried over from mobile in the build screen, and generally just some polish could solve any complaints I have. Regardless, this isn't about any of the features or changes so much it is about the new scaling brought to the PC edition. This includes the original 1:20 scaling, the 1:10, and the surprising yet welcome 1:1 scaling. So far my current experience with the 1:1 scaling is limited, but it is a great edition. First of all I thing Altair would enjoy it, though with the current engine selection I'm not sure he would be 100% satisfied with the balancing (if I'm wrong please correct me). There is definitely a large challenge to it and my first mistake was trying to put 50 tons into LOE. This took about 7 tries with 4 different rocket designs. With my current experience a steeper launch profile and a TWR of 1.4 is the sweet spot in terms of your rocket staging. This definitely differs from the 1.2 TWR and the ability to follow the provided flight profile in the 1:20 scaling. So either A. I'm wrong about what I just suggested (which could be very likely the case) or B. the changing of ISP, tank mass, etc. (balancing changes), could mean a changing of for the lack of a better term "meta" for efficient rocket design.

Here is some side by side comparison of the abilities of the same rocket in each of the modes with some numbers to compare.

So what does that mean? Well my theory was wrong, but not completely. The balancing does make the margins far more tight in term of Delta-V.

Lets break the numbers down section by section. First we have the 1:20 rocket vs the 1:1 rocket. These are the exact same rocket with the same payloads and same parts, but due to the balancing changes we can see that there is about a 50% increase in Delta-V in the 1:1 scale vs the 1:20 scale.

Now Test 1 covers how these rockets perform under all the same conditions but the scale is different. We see that the 1:20 rocket performs far better in its respective scale than the 1:1. This means any rockets you have designed are going to take a heavy payload hit or they will have to be completely redesigned.

In Test 2 I run through my theory of a different flight profile would help. In this case I followed the in-game flight profile for the 1:1 scale for the first trial. For the second I stay 5 to 10 Degrees behind the suggested flight plan the goal being to get through the thicker part of the atmosphere to try and minimize any Delta-V loss due to drag from the lower atmosphere. This as you can see from the Data did not work as I didn't reach orbit.

In the final Test I tried the different TWR with the same motors. This means less fuel for both stages but a higher acceleration. I kind of assumed this would fail too as if the steeper flight profile wouldn't work then this would be very similar. The reason being I'm experiencing more drag from the higher acceleration. This chews through any benefit i would have gained from getting through that part of the atmosphere anyways.

In conclusion I was 1/3 right. Your still going to have to redesign any rockets specifically for this mode and the 1.2 to 1.3 TWR is still the sweet spot and the flight profile in game is ideal in most cases I can think of.

I look forward to adding more to this thread as I go though my colonial development of a 1:1 solar system. If anyone has any other tests or 1:1 specific info like Delta-V map for 1:1 or any further testing of alternative design feel free to add it here. I think my next addition to this thread will be going over the development of reliable work horse rocket designs for 1:1 scale.

 

[Zeeray13]

Also here is a link to my spreadsheet if anyone wants to look over the numbers and math I used in my analysis.

Rocket

 

[GSUI5051]

There IS a delta-v map for real solar system since the age of KSP just released its 1.0 version.

Delta-V map for SFS 1.5

Delta-V map concept

If you want to learn more things on spaceflight and rocket, Atomic Rockets is a good choice.

 

[Zeeray13]

aceflight and rocke

Ya I got that i was more testing the actual capabilities of SFS rockets in the game in the 1:1. Which right now a moon mission in 1:1 is kind of insane in terms of rocket size or maybe not I've played for 4 years now and built hundreds of rocket designs and the moon rocket I've been working on would be overkill for a Single launch mars base rocket for the 1:20 scale.

 

[Zeeray13]

So doing some quick research. The current Balancing has been to buff engines by increasing Specific impulse and reducing tank weight and decreasing engine mass. I think engine thrust should be increased by 40%, ISP only increased by 25%, tank mass is fine, and engine mass should be only reduced by 25% to 40%. That would be realistic the reason I say this is the thrust is too low and rockets just become layer cakes of 5 to 6 stages to get enough delta-V to make it to anywhere. I base this off of real world rocket motors and the dry to wet mass ratios of rockets. So what do you guys think? Cause to me having engines be hitting well over 350 seconds doesn't seem like the right move to me.

 

[Marmilo]

LOE?

 

[Zeeray13]

LOE?

Thanks for pointing out that one thing out of everything else I provided.

 

[Zeeray13]

Low Orbit of Earth. it still works see

 

[Marmilo]

Thanks for pointing out that one thing out of everything else I provided.

It just looked really weird
Still reading the rest of the post

 

[Altaïr]

First of all I thing Altair would enjoy it, though with the current engine selection I'm not sure he would be 100% satisfied with the balancing (if I'm wrong please correct me).

I quickly gave it a try, I find the balance quite satisfying. I made some comparisons with IRIS, my planet pack that was designed to mimic realistic difficulty based on SFS parts' original specs. In the end they are quite close, even if the realistic mode is slightly harder (something like 10% harder I would say).

Yes your usual rockets won't work under those modes, it requires some complete redesign. No more SSTOs, now without at least 2 stages you are not going anywhere.

I think engine thrust should be increased by 40%, ISP only increased by 25%, tank mass is fine, and engine mass should be only reduced by 25% to 40%. That would be realistic the reason I say this is the thrust is too low and rockets just become layer cakes of 5 to 6 stages to get enough delta-V to make it to anywhere.

If you do this you'll make the balance even harder. Basically you give a lesser Isp bonus and mass reduction, which will both decrease the final delta-V. Increased thrust would help you to fight gravity more efficiently, so this would help to reach orbit, but it doesn't improve your delta-V, so it would be of no help once you reached orbit.

I made the calculation for your rocket (assuming an engine mass reduction of 40% to keep the most favorable hypothesis):
- your second stage has 5098 m/s of delta-V instead of 6212 m/s (realistic)
- your first stage has 2863 m/s of delta-V instead of 3470 m/s.

You may say thay the increased TWR will allow you to add more fuel to the first stage, but if you add 40 tons of fuel tanks the delta-V of your first stage is now 3824 m/s. Your first stage is better, but globally you still lose some delta-V, despite having now a bigger rocket.

Cause to me having engines be hitting well over 350 seconds doesn't seem like the right move to me.

I'm not shocked to be honest. 360s (Hawk in realistic) is the Isp of a good kero-lox engine in vacuum, and 420 - 435s (Valiant/Frontier) correspond to an open-cycle Hydro-Lox engine. A SSME hits nearly 455 seconds in real life, and engines like the american RL-10 or the european Vinci are close to 465s.

Globally the Hawk/Titan could be a little lower (to match the Isp of such engines in non-vacuum environment) and the Valiant/Frontier a bit higher, but overall that's a good compromise.

 

[Zeeray13]

I quickly gave it a try, I find the balance quite satisfying. I made some comparisons with IRIS, my planet pack that was designed to mimic realistic difficulty based on SFS parts' original specs. In the end they are quite close, even if the realistic mode is slightly harder (something like 10% harder I would say).

Yes your usual rockets won't work under those modes, it requires some complete redesign. No more SSTOs, now without at least 2 stages you are not going anywhere.


If you do this you'll make the balance even harder. Basically you give a lesser Isp bonus and mass reduction, which will both decrease the final delta-V. Increased thrust would help you to fight gravity more efficiently, so this would help to reach orbit, but it doesn't improve your delta-V, so it would be of no help once you reached orbit.

I made the calculation for your rocket (assuming an engine mass reduction of 40% to keep the most favorable hypothesis):
- your second stage has 5098 m/s of delta-V instead of 6212 m/s (realistic)
- your first stage has 2863 m/s of delta-V instead of 3470 m/s.

You may say thay the increased TWR will allow you to add more fuel to the first stage, but if you add 40 tons of fuel tanks the delta-V of your first stage is now 3824 m/s. Your first stage is better, but globally you still lose some delta-V, despite having now a bigger rocket.


I'm not shocked to be honest. 360s (Hawk in realistic) is the Isp of a good kero-lox engine in vacuum, and 420 - 435s (Valiant/Frontier) correspond to an open-cycle Hydro-Lox engine. A SSME hits nearly 455 seconds in real life, and engines like the american RL-10 or the european Vinci are close to 465s.

Globally the Hawk/Titan could be a little lower (to match the Isp of such engines in non-vacuum environment) and the Valiant/Frontier a bit higher, but overall that's a good compromise.

The only thing I say is if stef wants to add a career mode in the realistic scale, we need a true heavy lift engine for larger rockets. I say that because otherwise any large constructions or colonization your gonna run into build limitations not in height but in width.

 

[Altaïr]

The only thing I say is if stef wants to add a career mode in the realistic scale, we need a true heavy lift engine for larger rockets. I say that because otherwise any large constructions or colonization your gonna run into build limitations not in height but in width.

In need of this launcher?


Seriously, I would say yes and no.
Yes because if you want to build big good-looking rockets, you don't really have solutions now. Before heat was added it was possible to stack engines like I did, now it's a guaranteed instant fireworks. Or you have to disable heat through bp-edit, but that would probably be forbidden in a no-cheat mode. So there's a real topic there.

And no because... Well, that's realistic precisely. In such a mode you really need a Saturn V to perform a Moon mission, no less. And that's assuming you optimized your upper stages. You can't just go all over the place by going bigger and bigger and bigger. You have to be efficient, and if you really need a big ship you'll need several launches and to assemble it in orbit.

And to be honest I prefer to play that way. With more powerful engines you can lift more mass, but with more efficient engines you can afford using less mass.

Also remember you still have access to ion engines (especially that their ISP is 1800s in realistic). I know they are a pain to play with, but that's still the ultimate mass killer.

 

[Zeeray13]

T

In need of this launcher?
View attachment 79250

Seriously, I would say yes and no.
Yes because if you want to build big good-looking rockets, you don't really have solutions now. Before heat was added it was possible to stack engines like I did, now it's a guaranteed instant fireworks. Or you have to disable heat through bp-edit, but that would probably be forbidden in a no-cheat mode. So there's a real topic there.

And no because... Well, that's realistic precisely. In such a mode you really need a Saturn V to perform a Moon mission, no less. And that's assuming you optimized your upper stages. You can't just go all over the place by going bigger and bigger and bigger. You have to be efficient, and if you really need a big ship you'll need several launches and to assemble it in orbit.

And to be honest I prefer to play that way. With more powerful engines you can lift more mass, but with more efficient engines you can afford using less mass.

Also remember you still have access to ion engines (especially that their ISP is 1800s in realistic). I know they are a pain to play with, but that's still the ultimate mass killer.

ya I'm sure new engines will be added in the feature and probably one will alleviate this. A true low efficiency high thrust engine would be the best move forward. Rather than the hybrid titan engine we have right now.

 

[Zeeray13]

Soooo after a couple days of planning and prepping (and in general just getting used to the challenge that is 1:1) I am back! So things I have learned rockets have to be much MUCH bigger. This makes sense for obvious reasons but I was surprised on what it took to get to the moon and back and as well as getting 100 tons into LEO (yes LEO this time and not LOE, I'm looking at you Marmilo). So what now since I've landed on the moon and gotten into orbit. Well Mars of course. So I decided to take a very mathematical approach to this mission (i.e. actually planning it out). So first we got the delta-V requirements which my math came out to over 24km/s.

This is definitely a high figure as I can shed some delta-V using aerobraking. Also a cheeky moon assist could provide a small save as well. With the requirements in now I moved over to design and I work my way from top to bottom, so first is the payload. In this case I designed one that would be able do a curiosity/perseverance style landing. Where by there would be a capsule/heatshield cover, then parachutes, then a propulsive landing. So I came up with this single stage lander that weighs in at 67 tons:

Also I created a little table stacking up the engines so I can visualize engine choice quite easily, which helped with my selection of engines on my stages.

Now onto the rocket itself, which I will say now did not work out because I forgot one rule of thumb in rocket design. That being each stage should be roughly double that of the mass its lifting. Which gets on to the couple hours or so of number crunch just to end up figuring out that I'm not gonna have enough delta-V anyways.

Not very pretty but math is math, aaaaand here is that rocket:

As you can see I'm about 6km/s off of what I need. So rather than try to make that rocket work and completely redesign it I decided to just cut my losses and make a vehicle capable of getting around 100 tons into orbit. In that regard I succeeded.

So why 100 tons capability you might think? Well I reckon that I could go to mars in 4 to 5 launches. 1 being the lander, 1 being what you see above which is a central connector/fuel tank section, the engine module and 2 addition side tanks. The lander will land then fly back up and meet with the transfer vehicle Apollo style.

With all that being said I think for variety sake I'm gonna build a 70 ton LEO payload optimized rocket for the external tanks and the lander vehicle. Anyways looking forward to hearing any feedback or suggestions.

 

[Zeeray13]

So a couple days later and so, another update. I technically landed on mars but issues I found was the spacecraft being too top heaving leaving it to roll on decent. also I forgot a docking port on the lander so even if I did land with my engines still intact I wouldn't be able to get back to the transfer stage. BUTTTTT I did learn quite a bit. I also got a reliable 100 ton to LEO capable rocket. The First picture is that of the orbital refueling after the assembly of the transfer vehicle.

Then I lost an engine on the transfer vehicle

And finally my rough landing on mars

 

[Zeeray13]

Idk what rank this gets me cause 1:1 is substantially harder than the base game, but i managed to get to the moon and back

 

[Marmilo]

If you post it in the correct section, it would give you team titan.

 

[Altaïr]

Idk what rank this gets me cause 1:1 is substantially harder than the base game, but i managed to get to the moon and back

Well, team Titan. That's a performance for sure, but doing it in hard mode doesn't give a higher rank, it's only to satisfy your thirst of challenge.

 

[GSUI5051]

So doing some quick research. The current Balancing has been to buff engines by increasing Specific impulse and reducing tank weight and decreasing engine mass. I think engine thrust should be increased by 40%, ISP only increased by 25%, tank mass is fine, and engine mass should be only reduced by 25% to 40%. That would be realistic the reason I say this is the thrust is too low and rockets just become layer cakes of 5 to 6 stages to get enough delta-V to make it to anywhere. I base this off of real world rocket motors and the dry to wet mass ratios of rockets. So what do you guys think? Cause to me having engines be hitting well over 350 seconds doesn't seem like the right move to me.

Currently, the game make balance by increasing Isp, decreasing tank empty weight and engine mass. I found something which can make the realistic mode hard for those who learned everything in REAL WORLD. In SFS, a crew capsule weigh 4 tons. I don't know what a crew capsule weight in real life. In SFS, a probe weigh 3 tons, that's a weight of an ENTIRE space probe or rover, including science payload (and engine and fuel for a space probe)

I think the mass of probe in SFS should be reduced in Realistic mode to make a better balance.

 

[Altaïr]

Currently, the game make balance by increasing Isp, decreasing tank empty weight and engine mass. I found something which can make the realistic mode hard for those who learned everything in REAL WORLD. In SFS, a crew capsule weigh 4 tons. I don't know what a crew capsule weight in real life. In SFS, a probe weigh 3 tons, that's a weight of an ENTIRE space probe or rover, including science payload (and engine and fuel for a space probe)

I think the mass of probe in SFS should be reduced in Realistic mode to make a better balance.

Yes I totally agree with that. Parts are really heavy in SFS. I've had a quick look, the Mercury capsule (which is likely to be the one that inspired the capsule from SFS) weighted 1.5 tons. But 4 tons is approximately the weight of a Gemini capsule, so it's not that shocking.

But 3 tons for a probe... Huh
A probe like Voyager weighs something like 700 kilograms. New Horizons it's less than 500. Curiosity and Perseverance weigh a bit more than 1 ton... And for each of them that includes the fuel, the RCS and the RTGs. Even Cassini-Huygens which was particularly heavy "only" weighted 6 tons. Of which half of it was fuel.

So yeah, 3 tons for a probe... But that's not all, a simple RCS in SFS weighs 50 kilograms. A wheel? 300 kilograms! A small landing leg? 500 kilograms! A single solar panel? 500 kilograms too!

The only exception that comes to my mind is the fairings, they could probably be heavier.

 

[Zeeray13]

Yes I totally agree with that. Parts are really heavy in SFS. I've had a quick look, the Mercury capsule (which is likely to be the one that inspired the capsule from SFS) weighted 1.5 tons. But 4 tons is approximately the weight of a Gemini capsule, so it's not that shocking.

But 3 tons for a probe... Huh
A probe like Voyager weighs something like 700 kilograms. New Horizons it's less than 500. Curiosity and Perseverance weigh a bit more than 1 ton... And for each of them that includes the fuel, the RCS and the RTGs. Even Cassini-Huygens which was particularly heavy "only" weighted 6 tons. Of which half of it was fuel.

So yeah, 3 tons for a probe... But that's not all, a simple RCS in SFS weighs 50 kilograms. A wheel? 300 kilograms! A small landing leg? 500 kilograms! A single solar panel? 500 kilograms too!

The only exception that comes to my mind is the fairings, they could probably be heavier.

Ya imagine the Dv savings on a lander.

 

[Zeeray13]

In general you would need less of a rocket if you optimized correctly

 

[Zeeray13]

Well because I was bored I thought I would give the ranked challenges a try in 1:1 (almost all of them are completely out of the question for anything single launch except the moon landing). So what does that leave me? Well for team frontier a mars round trip single launch is nearly impossible as the dv required for the lander to get back into orbit requires a decent sized lander and that weight adds up through the stage making process where either A. you don't have enough room, or B. the TWR is abysmal. There is the interstellar probe but without the use of ions and especially no gravity assists that is out of the question (Though regardless I may try it as the challenge is still there if I don't use ions). Then we have build a space station that's easy enough as I have a 100 ton capable launcher in 1:1 that should be more than enough.

I did it in 3 launches but its 4 pieces so whatever being 1:1 compensates for difficulty. Anyways with the actual performable challenges done, now we have the team hawk shite. So first is a fully reusable rocket, that's a nope because of re-entry making that incredibly difficult and 1:1 having very tight margins. Secondly we have build a shuttle or build a working 1:1 replica. The replica may work but in 1:1 it probably wouldn't. Then there is the mercury landing which again tight margins and also its a quick save in 1:20 scale. Landing on a Jovian moon which if mars could be done in a single launch only with the most experienced players with the tightest of margins then surely a Jovian moon mission would have to be multi-launch. Finally the one we can actually try the 600 tons to orbit which is impossible in 1:1, butttttt we can try and see what's the max payload in 1:1 is. Drum roll please.... about 140 tons. Which is pretty good considering Starship is projected to do around 100tons. So why do I say that's the max cause I started with 200 tons and because of the build space width 200 tons is impossible to me at the moment. I say this because you physically do not have enough high thrust engines to get off the ground. So here is to what I know of right now is the largest 1:1 payload launched into LEO within the default build grid.

 

[Zeeray13]

Well the forum wont let me add any more images sadly so I'll try whenever I can to add the rest, but the images show the rocket, the payload plus 3rd stage (I'm not count the 3rd stage mass as my payload as well), and how in 1:20 scale the 1st plus 2nd stage is enough to get the rest of the rocket into orbit with zero changes.

 

[Altaïr]

I tried to do myself the challenges in hard mode, but some of them can't be adapted easily indeed. Especially the Voyager quest, and all those challenges that were balanced considering the stock solar system.

However I managed to launch Voyager in IRIS by not taking into account the mass limit. But it needed 3 launches and around 3000 tons overall, it was brutal.

Mars mission is interesting however, precisely because now you have to assemble a ship in orbit. I still have to do it myself.