OhioBob

I've thought about that. I haven't studied in detail the atmospheres of the OPM planets/moons, but I'm planning to take a closer look at them. If it looks like there is anything there that I can make improvements on, I'll probably contact @CaptRobau first to see if he's willing to consider some suggestions. I think it makes more sense to incorporate any changes directly into OPM, rather than writing a mod to a mod. In the time I spent looking at OPM, I didn't see any red flags. The temperature curves looked really good to me, so there's no need to do anything there. What I'm curious to see is how the pressure curves stack up. All I have to do is put the temperature-height profile and surface conditions into my spreadsheet, and it will compute a lifelike pressure curve. When I did this for the stock planets, I saw disparities, which is what prompted me to write Realistic Atmospheres. If I see any big disparities with OPM, I'll bring them the CaptRobau's attention.

Realistic Atmospheres version 1.1.0 is now available. Realistic Atmospheres has been updated to use Bodyloader 0.2.0.0, thus making it compatible with KSP 1.1.0. Special thanks to @NathanKell for his prompt work on Bodyloader. I also took this opportunity to rework the each planet's atmospheric model. In the first release of Realistic Atmospheres, each atmosphere was extended until the atmospheric pressure fell to a set value. Although this made sense from a physics standpoint, in terms of gameplay, it produced some undesirable situations. For instance, consider the atmosphere of Duna. Because of its low gravity, Duna's thin atmosphere extended all the way to an altitude of 90 km. Couple this with the fact that entry velocities at Duna are low, an approaching spacecraft would have to pass through tens of thousands of meters of atmosphere where the air was too thin to produce significant aerodynamic effects. This resulted in a relatively long wait time, without high-speed time warp, until we got to see any significant and interesting drag and heating effects. With the new release, hopefully this situation has been remedied. I've revised the upper boundaries to be based on the aerodynamic effects the atmosphere has on an incoming body traveling at escape velocity. Within the first several seconds of an encounter, an incoming body should experience similar initial drag and heat conditions regardless of the planet. Of course this similarity changes quickly as the body dives deeper into each planet's unique atmosphere. Although this revision focused on the upper atmospheres, in some case small changes to the lower atmospheres resulted (probably not even noticeable). The new atmosphere heights are: Eve 55 km Kerbin 70 km Duna 70 km Jool 400 km Laythe 60 km

WE ARE EXPERIENCING TECHNICAL DIFFICULTIES - PLEASE STAND BY Regrettably, Realistic Atmospheres/Bodyloader does not work with KSP version 1.1.0. I'm aware of the problem and will try to get it fixed as soon as I can. Please check back later.

I thought that I was the admin.

Hallelujah! That did it. You're the man. +1 rep.

I looked in KSP_Data, KSP_x64_Data, and Launcher_Data. I can't find a log in any of them. I had no problem finding the log in my old installation. I'm just going to download the file again and start over.

I did do that. I renamed my old KSP folder, created a new folder (using the old name), and extracted the files into it without any mods, old saves, etc. Thanks, that's helpful. Unfortunately I don't think the game progress far enough to even create a log. I could find the log in my old installation, but there is no output log in the new (apparently corrupted) installation.

I'm going to try redownloading it. But if that doesn't work, where do I find the logs?

I downloaded the Windows version of the game from the KSP store. Now I can't even get the game to run. When I try to run Launcher.exe, the "Play" button is grayed out and I can't proceed past the opening screen. When I try to start the game directly from either KSP.exe or KSP_x64.exe, the game tries to start but it gets hung up and never loads. The progress bar says "Loading Asset Bundle Definitions" and it freezes there and never progresses any further. The progress bar never shows more than a few percent complete. Help, please!

That Mk1-2 command pod is pretty massive to be at the back end of you vehicle (the pod weighs more then the MPL). I think it's likely that your CoM is just too far aft. You need to either find a way to distribute the mass closer to the heat shield, or find a way to add drag at the aft end.

I agree. A very non-aerodynamic payload probably doesn't cost more than about 100-200 m/s over a very streamlined payload. What I find to be the biggest problem with draggy payloads is aerodynamic stability. Increasing drag at the front end of the rocket will often cause the CP to move ahead of the CM, causing the rocket to flip.

Duna's air is thin enough that you might not have to worry about streamlining your lander. (The density of Duna air at the 0km elevation is like being at an altitude of about 14 km m on Kerbin.) Therefore, you could probably eliminate the nosecone and tapered adapter, which will save you some mass, and then just enclose the whole thing in a fairing for your initial launch. (I also recommend switching to a 1.25m decoupler.) Not streamlining the will cost you some drag losses when you launch from Duna, but in that thin air the losses should be tolerable. The extra drag losses will likely be offset by not having to carry as much mass during your ejection and orbit insertion burns. you might actually come out ahead.

You can reduce drag quite a bit by using 2.5x1.25m tapered adapters to form smooth size transitions. In your case, placing an adapter on the bottom of the top stage won't work because it messes up your lander. But you can certainly place a tapered adapter on the top of the bottom stage. You can also reduce drag and mass by using a 1.25m decoupler instead of a 2.5m. I also agree that struts across the stages will make the connection a lot stronger.

Real Plume version 0.10.6 now supports Eve Optimized Engines.

I have not used that mod, so I can't verify. If I get a chance, I'll run some experiments. I have no idea how that mod works, but if it performs its computations using atmospheric properties pulled from the configuration files, then it will likely work. I see from the Trajectories thread that there is some dispute as to whether or not it works with Real Solar System. If is works with Real Solar System, then I think it should work with Realistic Atmospheres. The only problem I've noticed so far using Realistic Atmospheres is that there may be incompatibilities with some of the orbit contracts. I recently accepted a contract to put a satellite in orbit around Duna that had a periapsis altitude of something like 65 km. I forgot that the mod atmosphere goes to 90 km. What I ended up having to do was to insert into an orbit that matched in every characteristic except the periapsis altitude. Then, when I got to apoapsis, I performed a small burn to drop the periapsis, got credit for completing the contract, and then immediately raise the periapsis back to a safe altitude.

This mod changes Eve's atmosphere quite a bit. The surface conditions are the same, but the atmosphere thins out much quicker and is only 50 km deep. In the stock game, the scale heights of the atmospheres of Eve and Duna are far off from what they should be, which is the main reason I was motivated me to write this mod. In Realistic Atmospheres the scale heights are correctly computed for each planet's physical and atmospheric characteristics. Eve's atmosphere works out to be much shallower and Duna's much deeper. I experimented a bit with launches from the surface of Eve, comparing the difference between the stock atmosphere and the mod atmosphere. I don't remember now what the results were, but I'm thinking it was about 500-1000 m/s easier with the mod atmosphere. It also helps if you use,

Sure, you have my permission to include if you want to. You might want to wait until I can verify that it works with version 1.1. I don't use Steam, so I don't have access to the pre-release. We'll have to wait for the official 1.1 release. I'm not very familiar with that. I'll have to study it an get back to you.

From the KSP Wikipedia... Maneuver node

Yes.

For a liquid fueled rocket, my basic rules of thumb are, The second stage (i.e. upper stage) should have a propellant mass equal to the payload mass*. The second stage should have a TWR at ignition of 1.1 to 1.3. The first stage (i.e. lower stage) should have a propellant mass equal to twice the payload mass (or twice the second stage propellant mass). The first stage should have a TWR at liftoff of 1.3 to 1.5. Using these guidelines, the second stage will have a mass ratio of about 1.8, and the first stage will have a mass ratio of about 1.7. The launch vehicle's total Δv will be equal to about 11 times the specific impulse. Of course, because of the finite number of parts we have to work with, it's not always possible to hit the target numbers precisely. There is usually some massaging that has to be done, but the above rules are a good starting place. * In this case, "payload mass" refers to the total mass that mounts to the second stage, which includes decoupler, fairing, etc. This mass is often greater than the useful payload.

Real Solar System Using the same method as described in the opening post, I was curious to see how the ratios worked out when launching from an earth-sized planet. I don't use Realism Overhaul, but I do use Real Solar System with ROMini and stock aerodynamics. I don't know how the size and mass scaling in ROMini compares to full-blown RO, but I assume it is the same or similar. By playing around with the numbers and launching some test rockets, I've come up with the following: Second stage propellant mass ≈ 6 × payload mass Second stage dry mass ≈ 0.05 × propellant mass Second stage TWR ≈ 0.8 to 1.0 First stage propellant mass ≈ 24 × payload mass First stage dry mass ≈ 0.05 × propellant mass First stage TWR ≈ 1.2 to 1.5 These numbers seem to work pretty well. As before, it's just a starting point and the figures need to be fined tuned to the specific situation. No example is needed here because the method is identical to the OP, just with different ratios. I'm sure that other players have their own preferences and guidelines, which may differ from mine. If anybody wants to post their own numbers, I'm interested in seeing what you use.

Alternative Design Method - Parallel Staging Another common design method is to use parallel staging instead of serial staging. It turns our that we can use the same ratios here as well, it's just that the first stage mass is now distributed between the two outboard stages. I've found that it works very nicely to use three identical stages, such as the real-life Delta-IV Heavy. In this case the rule is very simple: Propellant mass per each common stage ≈ 1 × payload mass (3 stages total) The plan here is to ignite all three engines at liftoff and feed propellant from the outboard propellant tanks to the center propellant tank using external fuel ducts (onion staging). I've found that, rather than designing from the payload down, it is usually easiest to select an engine and then design a launch vehicle around it. For example, Use Mainsail engine (sea level thrust = 1379 kN, vacuum thrust = 1500, vacuum Isp = 310 s) If we assume a liftoff TWR of 1.4, then our total launch mass will be approximately, Estimated launch mass = (1379 × 3) / (9.81 × 1.4) = 301 t We learned from the previous example that we should have a payload fraction of about 0.21, therefore Estimated payload mass = 301 × 0.21 = 63 t We want to put a mass of propellant in each of our three common stages that is equal to the payload mass. Let's call it 64 tons and go with, Use (2) Jumbo-64 Fuel Tanks per stage Let's now determine the actual mass of each of our stages. For the two outboard stages we must add for a decoupler, nosecone, fuel duct, and struts. Let's say all of those extras come to 0.8 t/each. Mass of center stage = 78 t Mass of outboard stages = 78.8 t × 2 each = 157.6 t total If we slap on a 64-t payload, our total launch mass and our mass at staging (i.e. outboard jettison) becomes, Total launch mass = 78 + 157.6 + 64 = 299.6 t Total mass at staging = 78 + 64 = 142 t Let's now check our TWR, TWR at liftoff = (1379 × 3) / (9.81 × 299.6) = 1.41 TWR at staging = 1500 / (9.81 × 142) = 1.08 Our staging TWR is on the low side, but it's still OK. Let's now compute the Δv, Δv before staging = 310 × 9.80665 × LN(299.6 / (299.6-128)) = 1694 m/s Δv after staging = 310 × 9.80665 × LN(142 / (142-64)) = 1821 m/s Total Δv = 1694 + 1821 = 3515 m/s (vacuum) So we see that we have plenty of Δv to get our 64-ton payload to orbit. If you need to adjust the amount of propellant that you're carrying (for instance, to match a slightly lighter or heavier payload) then, generally, you should do so as follows: ● If you need to add propellant, do so to the outboard stages. ● If you need to subtract propellant, do so from the center stage. The reason for this is because of the high TWR of the outboard stages in comparison to the center stage.

Helix Nebula

I've found that dividing the propellant up on an approximate 1:2 ratio works our pretty well. This generally gives a little more delta-v to the second stage. Here's a thread in which I've broken down my design method based on a few simple ratios. http://forum.kerbalspaceprogram.com/index.php?/topic/136666-a-quick-method-for-designing-liquid-fueled-launchers/

When dealing with very small payloads, the stage dry masses are often a little higher than the "0.25 x propellant mass." The small parts tend to be less mass efficient. I based my ratios mainly on 2.5m parts. Something doesn't sound right here. You say the payload is 1t, the fuel tank is 1.125t, and the engine is 0.145t. That adds up to, 1 + 1.125 + 0.145 = 2.27t. Typically for this step I use the actual mass of the second stage. The estimated mass is used to select the second stage engine, but now that we know what the second stage's actual mass is, we should use it to compute the first stage thrust. You don't say what the mass of the first stage engine is but, based on what you've told me, I'm estimating 0.44t. Adding up the masses of all the parts, I get Payload = 1 Stage 2 propellant = 1 Stage 2 tank = 0.125 Stage 2 engine = 0.145 Decoupler = 0.05 Stage 1 propellant = 2 Stage 1 tank = 0.25 Stage 1 engine = 0.44 TOTAL = 5.01 With a stage 1 TWR of 1.44, the thrust is 5.01 x 1.44 x 9.81 = 70.8 kN. This is about 4.4 times the sea level thrust of the Spark, which is why I estimate the scaled up mass to be 0.44t. If these numbers are correct, then the delta-v should be, Δv = 300*9.80665*LN(2.27/1.27) + 300*9.80665*LN(5.01/3.01) = 3208 m/s That's a little lower than the target 3400 m/s for a couple reasons. First, as I already said, the small parts are less mass efficient, leading to slightly higher dry masses. The other reason is that the Spark is not a very good engine in terms of specific impulse. Most other second stage engines have an ISP of 320 s or greater. This part I don't understand. Based on the numbers you've given me, I don't see how the Δv can be that low. Even if I use your mass of 2.472t for the second stage (rather than 2.27t), I still manage to compute a vacuum Δv of about 2950 m/s.