NathanKell

[1.2] Real Solar System v12.0 Dec 8

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I take it that sea level thrust is not always the listed number in your mod.

My understanding is that the thrust now varies with ISP, which KE and MJ don't appear to take into account, so far as I can tell.

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Yes, as the readme and OP for MFS say, thrust now (like real life) scales with Isp. Any MJ dev version released in the last month supports this (as the MFS thread OP says); just grab the latest dev version from http://jenkins.mumech.com/

Make sure, once you add a MFS-compliant engine to your rocket in the VAB, you click "all stats" in the dV window. That will make the SLT (Sea Level TWR) column appear.

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The meanAnomaly orbital parameter in the config file doesn't seem to work. I tried putting in different mean anomalies, but the planets in game are in the same places at the start of a new save. (Mean anomaly means where a planet is in its orbit at a specific time.)

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Yep. I probably should be setting Mean Anomaly at Epoch instead. I've fixed it on my end and PM'd you.

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I just realized that with this mod I can no longer use the existing launch window planners to get my interplanetary transits figured out.

OH GOD I'M GOING TO HAVE TO USE MATH, AREN'T I

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You can also ask NASA (or google) for the real life data :D

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I just realized that with this mod I can no longer use the existing launch window planners to get my interplanetary transits figured out.

OH GOD I'M GOING TO HAVE TO USE MATH, AREN'T I

Just guess like a real astronaut :P.

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Just guess like a real astronaut :P.

That... doesn't work real well when using a life support mod. Throw one of those in and suddenly you can't just wait several years for an intercept. :(

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jrandom: you can use real NASA porkchop plots. However, there was a bug with how mean anomaly was being set, so maybe not until next version will planets be properly aligned?

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jrandom: you can use real NASA porkchop plots. However, there was a bug with how mean anomaly was being set, so maybe not until next version will planets be properly aligned?

And it's the alignment that's getting me. I have other tools for getting my delta-v numbers, so it's the travel time I need. Travel to the planet, waiting for the next intercept burn, and travel back to Kerbin.

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Alright, how do I optimize for the best possible TWR to get the most out of each stage? I realize now that in this game you want to optimize for maximum performance/stage because each stage is the same number of parts - a tank + engine + struts and decouplers. (times however many you need for a reasonable amount of thrust)

Anyways, it's a math problem. Say you choose a TWR of 1.0. Then, you'll have to burn some fuel off to get anywhere, and once you do, you are carrying empty tank mass. So 1.0 can't be the optimum. The "1.2" that Nathan gave sounds like it is probably closer, since empty tank mass is fairly small, but how would I set up the equations to find out exactly what the right TWR is for a given tank : fuel mass ratio?

Another thing : is there any easy way to determine how much energy I lost from drag for a given rocket design? It occurs to me that I don't actually know if using asparagus staging or vertical staging is better in this game under these conditions. If you do vertical staging, you are carrying the dead weight for the engines of the upper stages, but you have less drag. With Asparagus, you don't carry that dead engine weight and you also carry less dead tank weight if you set it up for a lot of small asparagus stages.

If I could check a readout somewhere that would tell me how much delta-V was taken by aerodynamic drag, that would let me do a direct comparison.

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Alright, how do I optimize for the best possible TWR to get the most out of each stage? I realize now that in this game you want to optimize for maximum performance/stage because each stage is the same number of parts - a tank + engine + struts and decouplers. (times however many you need for a reasonable amount of thrust)

I usually design rockets based on what kind engines do I have (I use almost exclusively engines from BobCat's SovietEngines pack), carrying a mass-mock of a payload. Most of my lifters are 2 stage, or 2 stage + boosters (either SRBs or LRBs). Condition of TWR > 1 is only crucial for first stage (+ boosters where applicable), upper stages often have TWR less than 1 (as example consider Atlas-V rocket with it's underpowered Centaur upper stage). Upper stage design usually depends on destination orbit, for low orbits I usualy use KeroLOx RD-0124 or NK-43 (depending on the payload) since you have relatively short time for circularization, and as such it's preferred to have TWR or at least 0.7 at ignition with TWR crossing 1 somewhere mid-burn. For high orbits (KSO/KTO, escape) HydroLOx is preferred, while TWR is not as important for direct injection profiles. I use one or several of RD-0146s for low to mid-level payloads, and RD-0120 for heavy payloads.

If I could check a readout somewhere that would tell me how much delta-V was taken by aerodynamic drag, that would let me do a direct comparison.

MechJeb shows total dV expended, gravity losses and steering losses. Everything else is basically aerodynamic losses. But unless your LV and/or payload is particularily non-aerodynamic, aero losses are usually very small (<200 m/s).

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MechJeb shows total dV expended, gravity losses and steering losses. Everything else is basically aerodynamic losses. But unless your LV and/or payload is particularily non-aerodynamic, aero losses are usually very small (<200 m/s).

Where? I wouldn't have asked if this was obvious. Every screen available to me does not show this, so far as I can see.

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I just realized that with this mod I can no longer use the existing launch window planners to get my interplanetary transits figured out.

OH GOD I'M GOING TO HAVE TO USE MATH, AREN'T I

Yes, and may I be so bold as to recommend using one of the early Pentium models to handle your math coprocessing needs? Guaranteed to make all your rocketry calculations more memorable.

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As of some version of MJ2, they stopped bundling the prebuilt Ascent Stats window. You need to go to custom window editor, create a new window, and add the various ascent stats to it.

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As of some version of MJ2, they stopped bundling the prebuilt Ascent Stats window. You need to go to custom window editor, create a new window, and add the various ascent stats to it.

I've noticed even just adding a dev .dll kills your custom window setups...

Edit: not necessarily all the time and maybe not all of them but I've had some go missing and havent had a chance to try to figure out why...

Edited by Starwaster

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maybe someone mentioned it before in this thread but it's tedious to read back 110 pages lol

Is there any tool or webpage or something that can help you calculate transfers and other trajectories, like launch window planner and sort, but with the rescaled data for this mod?

or is it safe to assume that real world data can be used here accurately?

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Is there any tool or webpage or something that can help you calculate transfers and other trajectories, like launch window planner and sort, but with the rescaled data for this mod?

The Alex Moon's Launch Window Planner tool has source code on github, and a quick glance through the code tells me it shouldn't be too tricky to get it set up for RSS -- I just don't quite know all the new numbers to input for the orbits. Do that and set the epoch to Jan 1st, 2000 and it should work with RSS 5.3 (where the mean anomaly was corrected, I believe).

It's going to be a little while before I'm ready for my first interplanetary journey, so I haven't actually tried to figure out how to get the right orbital/epoch numbers into the code, so if someone else already knows the right ones... there's our tool right there. Just fork and update!

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I wish I knew how to edit this stuff lol

I'm probably gonna have to study the right calculations for this flightplanning, but the goal would be to find accurate launch windows for, currently, the Mun, and plan the launches accurately so that you arrive at the appropriate time, and you have the appropriate lighting and all, etc. Basically, tools to allow you to plan your trips, rather than fiddling with maneuver nodes in-flight.

I'm researching, but the amount of information to consider at all times is so great that is overwhelming me lol.

I'm sure there are people here who are trying to do the same (or maybe have already achieved it).

I'm looking at Orbiter's tools available, as they're probably similar to what KSP+RSS is.

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The launch window planner I linked to above is the perfect tool and already does the math, which is why I think our best option is to fork the code and just plug in the new orbit and epoch numbers. Trouble is I don't fully understand how to do that exactly right -- but if I'm correct we only have to modify... two files I think. Doesn't look that hard from a code perspective. I'll continue to investigate.

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When ever i launch rocket in space// about after 100km it starts to spin like crazy.. and i cant stop it.. even with sas and rcs it spins out of control... any ideas what is causing the problem?

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