Jason Patterson

TWR in orbit - This becomes important because orbital maneuvers need to be predictable. If you want to go from Kerbin to Duna, you need to make a particular burn to get there. Assuming you're in a parking orbit around Kerbin, the most efficient burn is going to happen at one instant in your orbit. With a real rocket, it is spread out over time. If that time is relatively brief compared to your orbital period, it is a good enough approximation of instantaneous that only very minor fudging is required to fix the burn from its idealized version. With a very long burn time (TWR<<1) the burn is spread out over a significant fraction of the orbit. This results in a very messy, difficult to predict burn. Further, it wastes much of the Oberth effect's ability to optimize your burn. By burning while slowing down you're losing out on maximum energy per delta-v. You can minimize that by making several small burns and gradually kicking yourself into higher and higher orbits, but in the end you'll have to commit and make a transfer burn, and if nothing else, your real life time is worth something here... In order to get into orbit your ship must accelerate to some velocity and ascend above the atmosphere (or at least the top of the mountains.) That change in velocity and the delta-v associated with the altitude change are the most basic parts of delta-v for ascending to orbit. If you're familiar with the impulse-momentum theorem, you can consider all forces acting in the rockets direction of motion as applying an impulse to it (F dt) and that impulse creating an associated change in momentum (m dv). That's where things like wind resistance can translate into a delta-v. The constant backward impulse from wind resistance equates to a loss in momentum that your rocket engines have to compensate for. The component of gravity that is in the direction that the rocket is traveling does the same (thus the concept of gravity drag and why we make gravity turns while burning.) I can only assume you meant TWR<=1 rather than TWR>=1. If that is the case, then yes, you're right. TWR = 1 is the case for thrust balancing weight. Anything higher and it is (at least theoretically) possible to go arbitrarily high/fast. For ascents you're typically looking for a TWR = 2. That seems to be a good balance of upward thrust and economy of scale. On planets with atmospheres it also is the most efficient way to ascend - always moving upward at terminal velocity. Once you start a gravity turn it becomes less important. For planets without an atmosphere bringing along a smaller engine (lower TWR but less total mass and greater delta-v as a result) is often a better option, but you don't want to go much below 1.8 or so for an ascent or you'll lose a bunch of delta-v to gravity drag. TWR = 2 includes drag. Isp is lower in an atmosphere because the gases being ejected from the rocket nozzle are blocked by the air outside the nozzle. They can't exit freely, at full speed, so the rocket is less effective.

Those are the units of that particular constant. meters cubed per (kilogram second squared). It's not a variable, it's just units, in just the same way that light goes 300M m/s <-- meters per second

The Oberth Effect isn't something that needs to be simulated. It's a consequence of conservation of momentum, conservation of energy, and gravity. As long as those are part of the simulation, Oberth will be as well.

Awesome, congrats!

I built a very simply ship in the demo to see what I could see. I'm a pretty experienced pilot, so I wouldn't expect a new player to do as well as I can with it, but I can fly the linked craft from Kerbin to the Mun's surface and back into Munar orbit before running out of fuel. http://www./view/2cbqt5zktftmwg6/Munar_Voyager.craft Part of getting better at this game is learning to make minimal craft - just enough to do the job and not much extra.

The fuel lines would start at the boosters and run toward the center. The idea is to drain the boosters' fuel while also making use of the central rocket engine's power. The boosters will run out slightly sooner, but the net effect is a significant increase in delta-v.

It is definitely possible to get very very large rockets into orbit in the demo (though it's much easier in the full game since you have larger components at your disposal.) As part of a challenge I managed to get to the surface of Eve and back (the hardest single destination return mission in the game) using only demo parts, but that required a ridiculous number of parts and was impractical for anyone with any kind of sense. From what I'm seeing it looks like you should have more than enough delta-v to reach orbit with the design you've got (in the OP, not the exploding monster.) I would be surprised if it couldn't get to Munar orbit, if not the surface, with good flying. One thing that I see is that your upper pair of boosters should be connected to the central rocket via fuel lines. You would activate all three engines at the same time and jettison the boosters when they are out of fuel. A second thing involves the pair of RCS tanks at the top. What are they for, and do you really need two of them? It's not much mass, but every bit you put at the top requires fuel to lift, and that fuel requires further fuel to lift, and so on. Cutting even a very small amount of mass from your uppermost stage can cut the total mass of the rocket dramatically (or extend your fuel significantly.) If you post your .craft file I would be happy to check it out to see if there is something obviously messed up or if there are easy things you could correct. Other than mechanical issues, it seems likely that it's your ascent profile that is the problem. Perhaps the ship is unwieldy, but starting a gravity turn at 21km means that you're spending far too long burning upward against gravity. Getting into space is far less about getting high above the surface and far more about getting going fast enough that you're able to fall around the planet instead of crashing back into it. Even a slight turn that begins earlier will save you fuel.

Back in the days of pre-0.17(?) there was a problem with the objects gaining random velocities when far from Kerbin. This was called the Space Kraken and it ate many a rocket. It was eliminated way back then, but it has been followed by a number of other physics bugs that can tear your ship apart. Many of these are also referred to as being due to the kraken, but they aren't.

2. Planes work on Laythe as well. Just sayin. 3.5 This sounds like a pretty darned "cheat-like" mod. If you're willing to simply jump an hour into the future without having to deal with possibly crashing during that hour, just use hyperedit and put yourself where you want to be. To answer your question directly though, it sounds like you're after a mod that gives an even higher version of physics warp without all of the chaos that would come with it. No, to the best of my knowledge there isn't such a thing.

Here's a video from January of my going IVA only from Kerbin to Duna and back. The only times I went to map view or EVA were to reload parachutes and to set the planets as targets. All three of these were done while landed. I also used the lander can as my crew module because at the time (and maybe still?) it had the worst instrumentation of any of the choices, a radar altimeter, navball, and vertical speed meter only.

I built a truck some time ago. I thought I had video of it, but I must have never posted it to youtube. The forum crash ate the thread that it was in. It's definitely possible to do this without a proper bearing though. If you put enough jet engines on your vessel's body it will move even with lots of friction. The only screenshot I can find of the thing is when I flew it to the moon to monkey around with it. And a blown up image showing how the two axles/crappy bearings were put together. As I recall, my top speed on Kerbin wasn't very high, maybe 10-20 m/s before pieces would start coming off and 40-ish m/s if I wanted to destroy it in testing.

But that's just it, this vessel will never reach apoapsis; it's on an escape trajectory from the solar system. It's entirely possible to go get it, of course. You'd need to get enough delta-v into orbit to catch up with it and then return home. It's quite an undertaking, but again, there's nothing particularly challenging about it in terms of the mechanics of the situation, only in the amount of delta-v required. Get an orange tank's worth of fuel (preferably in smaller containers you can jettison as you go) and an LV-N into orbit and you've probably got the delta-v you need. From there it's just a matter of timing and patience.

You definitely don't have to do the math. The best places for using ideas like delta-v and TWR are in making minimalist designs or in attempting very difficult maneuvers (Eeloo, Moho, Tylo, or Eve return missions, for instance.) You can always strap on more rockets and go for it, but you will eventually run into issues with part counts and the like on very large vehicles. If you're not interested in doing those things then you're already in good shape.

Your best bet is to post a picture and/or craft file for the vessel that you've already built. It's a lot easier to give advice based on something rather than just throwing things out randomly and hoping that one of them applies. I'm not sure how you're trying to fly your rocket, but it sounds like your ascent profile might be a bit off as well. If you aren't doing a gravity turn at around 10km altitude then it's likely that you're wasting lots of fuel trying to gain height instead of getting to orbit.

If you undock the first pair, the second should engage almost immediately (leaving the first uncoupled.) If this doesn't happen then there's some sort of alignment issue with your vessels, either in their construction or in the docking process. If they do engage then you can undock that pair, quickly switch to the Tracking Station then quickly switch back to either vessel. If you do this fast enough, neither vessel will have moved appreciably with respect to the other, and both ports should immediately couple.

Unless you're playing with mods that change air resistance, I think you're off by about 800 m/s. A very very clean launch to a very low orbit costs about 4400 m/s (it can be cheated somewhat by using parts with 0.1 resistance.) Anything from 4500-4800 is a reasonably clean launch.

They swim very very slowly, but they do indeed swim.

This. Though Harvester's updater might save the day. Honestly though, with the game in alpha you can and should expect persistence file breakage now and again. It's a good thing, because it means that they're making major updates to the game. When it gets to the point that everything is fine from update to update they're down to polishing things up, which is really kind of boring in my opinion.

Landing on Moho is one of the most challenging missions in the game. It's tiny, requires enormous delta-v, and its orbit is all kinds of messed up. What I've got listed below will get you there, but it's important to note that it is far from being the most energy efficient method. 1. Put your Moho rocket on the launchpad. 2. Find the orbital node between Kerbin and Moho. - Go to map view and double click the sun. - Move and zoom your camera so that you're about to see Kerbin's entire orbit on edge. - Without moving your camera up or down, move it around the sun (along Kerbin's orbit) until you also see Moho's orbit on edge. Both orbits should be lines on your screen now, or as close to lines as you can get them. - The points where the two orbits cross (which will also line up with the Sun) are the orbital nodes. 3. Time warp until Kerbin is at one of the two nodes. 4. Launch and burn so that your new orbit's periapsis will be at the altitude of Moho's orbit at the orbital node. (You do not need to match orbital inclinations at any point in this process, that's why we picked the orbital node.) 5. Time warp to periapsis and plan a retrograde burn to get your Moho encounter. If you are right at the orbital node you won't need anything other than retrograde, but that's very unlikely. Use the close approach markers to fix it (this will be a sizeable burn, but it will also be slowing you down partially for your landing, so it's not all wasted.) Moho's SOI is smaller than the distance from Kerbin to the Mun, and it's moving at an incredible pace, so you just have to be patient and keep trying until you get it.

A maneuver node has two parts, one that indicates the delta-v you requested (X m/s at Y heading) and the second part that provides a projected route following that burn. While the second part is calculated from the first, the first doesn't know that the second exists. The game calculates a projected orbit based on an instantaneous burn at the node. For short burns t = 0 is a good approximation, but for longer burns things like the direction of gravity and your heading will change markedly before you finish. The game doesn't compensate for that in any way. Instead it tells you to keep burning to finish the original [X,Y] burn. The difficulty is that you, the pilot, don't want an [X,Y] burn. You want to get to destination Z, which is described by the second part of the maneuver node, but that spot on the navball just doesn't care. You have to watch your map and try to compensate so that your actual final orbit matches the projected orbit. It should be close, but the longer your burn is, the worse the agreement between projection and reality will be. For escape orbits it can be fairly easy, particularly for fast escapes (non-Hohmann transfers or going to Eeloo or Moho, for instance.) You just look along the two orbital paths and pitch up or down (toward the zenith or nadir, I mean, I'm assuming the ship to be upright and facing in the direction it's heading) to make them match. In most cases you'll wind up pitching up above the maneuver node toward the end. Could you wait and do all of the adjustments later? Of course. But if you're going to be burning, you might as well burn in the right direction in the first place to save some fuel.

It's a fuel line issue though, so you know. You've got fuel going from a central tank to multiple separate branches and then back to a different central tank, a loop in the fuel line which the game doesn't handle properly. This can be done intentionally using fuel lines but it also happens occasionally with fuel crossfeed parts that activate on their own. In short, this is fine: (sticks are fuel lines, v shows fuel flow direction - downward) | | / \ | | | | v v And this is fine: | | | | \ / | | v But a combination is not: | | / \ | | | | | | | | \ / | | v

Are you spinning like a top (rolling) or flipping end over end? If it's the former, I don't know what the problem might be. You could have a keybind messed up or if you have a joystick it might be active at the wrong time (check your roll axis instrument to see if it is pegged to one side or the other.) More likely it's the latter, and it's due to a lack of control in the rocket you've built. You've got a very small probe module for your command module. Without additional help in the form of thrust vectoring, RCS, or control surfaces, it just doesn't have the power to keep the rocket on track. As a result your angle of attack for maneuvering is very limited (or you'll spin out.) You might try using an LV-T45 engine, as that will give you thrust vectoring and much much better control over your rocket. You could also replace the probe (or augment it) with a manned capsule, as those have far greater turning power. ETA: I'm assuming you built this rocket yourself, rather than it being supplied by the game. I don't have any tutorials that feature a rocket of the type you describe.

I understand that it's a single launch, but just to be clear, does that also mean a single kerbal flying the mission (until the pickup, anyway?)

If you are going to be captured into a retrograde orbit, you can burn to change it into a prograde capture. You just have to lower your periapsis through the planet and out the other side. If you do it early enough it costs very very little delta-v. If you're having trouble seeing whether your encounter will be prograde or retrograde, you can try changing the value of CONIC_PATCH_DRAW_MODE in your settings.cfg file. It defaults to 3 (the loopy, end to end version of orbits you normally see, that shows your actual path around the parent body. I can't recall which it is (1?) but one of them draws the orbits with respect to the object being orbited. That is, it would put the Minmus encounter at Minmus and you'd be able to see whether you were pro- or retrograde right away. Best of luck.

You'd either need to calculate the right launch window to make it happen in one go, or you could launch and get your gravity brake at Eve and set your solar periapsis to the correct altitude. You'd then need to make an adjustment burn at periapsis to get your Moho encounter. It's that last bit that can be problematic, since the burn is going to be costly at those speeds. I haven't done the math or anything, but I would be surprised if you could save much delta-v with a multiple burn approach. I've got no good idea for how to calculate the launch window times for a one shot mission. In any case, if you want to play with it, you'd just need to set up an Eve encounter and play around with the maneuver node until you get an orbit (post Eve encounter) that is sufficiently low. If you do it early enough in the process there shouldn't be much difference between a gravity brake and gravity assist as far as your initial launch goes.