Snark

So, point it up more, then. If you don't want it to nose-dive, then just pitch up, right? Is the problem that you can't point it up? i.e. you're holding down the S key to try to pitch up, and it just won't pitch up enough? If that's the case, then it likely means you've designed your craft without enough pitch authority on its control surfaces, which in turn indicates a design issue (with their size, placement, and settings). Could you post a screenshot of your craft while it's re-entering?

Things to check: Is your bottom stage still under thrust (i.e. still has fuel in it, throttle set > 0)? Which part on your craft is the root part? Specifically, is the root part on the lander, or on the bottom stage? Also, a side note in passing, unrelated to your question. Any particular reason you've got a Mainsail on your lander stage? That seems like massive overkill for the Mun, unless your lander is well over 300 tons or something, which it doesn't look like in your screenshot. Looks more like you're in the 40-50 ton range, in which case a Poodle would be plenty for the Mun. The combination of saving several tons of engine weight and getting a significantly higher Isp would mean the lander would pack a fair bit more dV, which in turn would mean that the bottom stage wouldn't have to be as hefty.

As folks have observed, a lot depends on your preferred play style and design types. There are many different "right" (i.e. efficient, effective) ways to get to orbit. Unfortunately, there are many times that number of wrong ones. So here's what I do in my own gameplay-- not saying that this is any more "right" than any other means, just that it works well for me and is totally consistent with minimal guesswork. I never do this, myself. If engines are ever running at under 100%, that means wasted efficiency. If I don't need the full power of my engines, it means I'm carrying too much engine and am wasting dV due to hauling too much engine mass as dead weight. And as long as your launchpad TWR is no higher than 2 and you're reasonably streamlined, it's always most efficient to go at max throttle, because gravity losses far outweigh aero losses. The only time I ever launch at under 100% is if I have the rare occasional "freak" vessel that's ludicrously un-streamlined due to needing to lift a really awkward payload, or something. However, since you were mainly asking about repeatability rather than efficiency per se, I'll say this: I've found that it really, really helps to have a rigidly consistent launchpad TWR. Rationale: As long as all of my spacecraft have the exact same TWR on the launchpad, that means that my initial pitch-angle for the gravity turn will be the same. So holding the TWR constant means that I take the guesswork out of the pitch angle. Myself, I like a launchpad TWR of 2. No particular reason, that's just how I like to fly. That's about the highest that's practical; anywhere from 1.3 to 2.0 can work (though that would entail a different design strategy, and the lower your TWR the less initial pitch angle you'd want). Yes, the TWR will change as the rocket ascends (i.e. it climbs during each stage, then drops when I move to the next stage), but I've found that in practice that matters very little. I just design my rockets so that they have a consistent launchpad TWR, launch at 100% throttle, and stay at 100% during the entire boost phase until Ap gets where I want it. I don't do any of this. There's no wait, there's no unlocking of steering, and there's no "gravity turn speed" as a variable. And "angle" isn't a variable either, because I always pitch by the same angle because I always launch at the same TWR. What I do is this: Launch Immediately pitch east. I mean, the instant it lifts off the pad. The angle is fairly small, and depends on the TWR. It takes a little bit of trial and error to find the right angle initially... but if you always launch with the same TWR, then once you find the right angle, you just use it all the time. Also immediately, set SAS to hold . That's it. That's all there is. No steering, that's why it's called a "gravity turn", because gravity is doing the steering for me. I just hands-off the controls except for staging. Yup. Exactly what I do too, no differences there. Well, I don't do that, mainly because I don't use kOS or any autopilot mods. What I do is just wait until the craft leaves atmosphere, then go to map mode and drop a maneuver node right at my Ap point, with enough dV to circularize. Then the burn timer on the navball takes the guesswork out of when to burn. If you're using an automated tool that needs to run on a script, I understand that that might not work well for you. However, I think you can take the guesswork out of step 7. If the script knows the apoapsis, and knows the current and desired periapsis, then it's a fairly simple bit of math to calculate the amount of dV you'll need. A bit more simple math (based on your TWR) will tell you how many burn seconds you need. Start the burn half of that time before Ap, and there you go. So, to summarize: You mention the following variables in your OP: Target Ap and Pe Target TWR Pitch angle Gravity turn speed Seconds before apoapsis #1 will obviously be different on every launch, since that's your target orbit and will depend on the mission. But the above technique eliminates basically all the other variables. TWR goes away, because it's always the same, and throttle is always at 100%. Ditto pitch angle. "Gravity turn speed" simply isn't a thing, and "seconds before apoapsis" is a trivial bit of math based on Ap, initial and desired Pe, and TWR. Does that help?

Indeed there is. That mod is designed specifically to support exactly this type of scenario (i.e. spaceplane-style reentry where you want to hold a slightly-nose-up attitude). Not only does it allow you to use action groups to switch control points, but it also implements a "Pitched" control point whose angle you can control with a menu slider or axis binding. So, if you choose to use the mod, you don't need to add any extra parts rotated 15 degrees or whatever-- you can just use the stock parts mounted pointing you can toggle between and nose-up with an action group you can use a right-click menu slider, or axis binding keys, to adjust the nose-up angle you want, in flight (anywhere from 0 to 90 degrees) you can patch it with ModuleManager to adjust the limits of the sliders, if you don't like the default choices Sorry, don't mean to plug the mod, just that it may be helpful since it's designed for exactly this. It's very lightweight and doesn't add any UI other than new part actions and a new right-click menu slider when the "pitched" control point is active. (And yeah, it would be nice if the stock game had something like this, no argument there!) [EDIT] Pinging @slaintemaith, since that's the person who asked the original question and may be interested.

Hi @Wjolcz, Congratulations on producing your first mod! By the way: per the add-on posting rules, you need to provide a link to your mod's source code (e.g. on github or wherever). Could you please add one to your OP? Thanks! ^ Very much this! If you learned something, and if you plan on ever making any more mods in the future... then that's a win. Given the scattered paucity of documentation, an awful lot of modding is trial-and-error. My own experience as a modder the last few years is that a lot of wrong trees must unavoidably be barked up, especially when starting out. There's a steep learning curve. One time I spent an entire week coding up something that I then realized was the wrong approach and had to throw the whole thing out... and it was not a waste of my time. The lessons learned really helped me on my subsequent mods. So I hope you take encouragement that you actually figured out how to make it work (I always get a rush from that, don't you?), and bring what you've learned to the next mod you make.

Hello, and welcome to the forums! The usual mitigation is to put two propellers on, spinning in opposite directions. There's basically no way to make a single prop not torque your plane around-- perhaps other folks may have some suggestions for how to compensate, but speaking for myself, I just always use props in counter-rotating pairs.

Photons carry momentum, even though they have zero rest mass. Each photon has an effective mass given by its energy, as given by Einstein's famous equation E = mc2. So, the laser (which is attached to the ship) imparts momentum to all those photons that it's spraying out the back end of the ship, thus imparting momentum to the ship in the opposite direction. It's not any different than a regular rocket, really, and still governed by the rocket equation-- just with a really ridiculously insanely high Isp. If you ask "but where is the reaction mass coming from?", it's from the ship. Energy has mass. The ship is generating the energy to create those photons, which means the ship is losing the energy that it's emitting, which means the ship is losing mass. In the particular case of the nuclear-powered ship, the mass loss happens when the nuclear reactions convert a tiny fraction of their atoms' masses to energy.

It just now occurs to me that, in the same way that "rapid unplanned disassembly" is great kerbal-speak for "explosion"... ...the phrase "rapid unplanned momentum transfer" would be great kerbal-speak for "collision".

Not correct. It's trading the momentum of the fuel (its mass times its velocity) for the momentum of the ship (its mass times its velocity). The ship is giving velocity to the fuel's mass (i.e. giving it momentum). The result is that the ship's mass also gains velocity (i.e. giving it momentum), in the opposite direction. Thus moving the ship.

Correct. p = mv. However, do realize that momentum is a vector quantity (it's a direction, not just an amount), because velocity is also a vector. This means differing momentums can cancel each other out (by being in opposite directions). By transferring momentum. You can't store momentum, or create it. But you can transfer it from one thing to another. In this case, the rocket is transferring momentum to its spent reaction mass. Let's suppose you have a 1000 kg ship (dry mass), that contains 1 kg of reaction mass. Let's say that the ship is pointed in the +X direction, and has zero velocity. So, the net momentum of this system is zero. Right? The ship then hurls its 1 kg of reaction mass out the back of the ship (i.e. in the -X direction), at a speed of 1000 m/s. Result? You have 1 kg of gas moving in the -X direction at 1000 m/s, and you also have a 1000 kg ship that's moving in the +X direction at 1 m/s. And... the net momentum of the system is still zero. They're equal and opposite. Measured on the X axis, the empty rocket has a momentum of +1000 kg m/s, and the momentum of the spent gas is -1000 kg m/s. So when you add +1000 to -1000, you get zero. Which is what you started with. And propels the spent reaction mass backwards. Equal and opposite.

Assuming that you're talking about the engine driving the object's orientation rather than the servo-- i.e. you're just trying to react passively to the angle the servo happens to be at-- then no, that's not a thing. The stock game doesn't have any "angle sensors" that you can use to control something like that. Perhaps there's some mod that might help, though I don't know of any myself. Maybe go ask in Add-on Discussions?

Hello everyone, A huge amount of material (many pages' worth) has been split off into this thread from a discussion of the Rosatom rocket failure, due to being off-topic in the original location. Unfortunately this has scrambled this thread a bit, since the split material predates Cheif Operation Director's original post for this thread. We apologize for the confusion; can't be helped. Here's the central idea of this thread: @Cheif Operations Director, we appreciate that you're earnestly trying to figure out a working system, due to your love of rockets and spaceflight. Thumbs up for that. However, you do need to realize that your idea cannot possibly work. At all, in any permutation, no matter how cleverly you try to arrange things, even if it uses magnets. This is because your basic concept is trying to violate the laws of physics-- specifically, the law of conservation of momentum. We've known about for over 300 years, Newton got it right from the start. I've been reading through the many pages of people trying to explain why your idea won't work. They're all correct, please listen to them. If I may, I notice a general source of confusion in your responses: You are consistently confusing "energy" with "momentum". Don't. Energy and momentum are completely different things. They both have conservation laws, but they're different things being conserved. Nobody is suggesting that you're proposing a "perpetual energy machine", because you're not-- you're explicit about that, there's a nuclear reactor providing energy. That's not why your idea won't work. The problem is that you are proposing a "perpetual momentum machine", which won't work because momentum is conserved. Here are some important ways that momentum differs from energy: Energy can be stored. Momentum can't. Energy can be converted to different forms. There's only one "kind" of momentum, so that's not a thing. Energy can be moved from place to place without any inherent "cost" other than losses to inefficiencies. It can be "redirected", in that sense. Momentum can't. You can't "redirect" momentum. The only way to change the momentum of one object is to transfer momentum to another object. Momentum is a vector quantity; it has a direction. (Unlike energy, which is a scalar and has no direction associated with it.)I If you have a body that's in a vacuum with no external forces acting on it-- e.g. a rocket-- then the only way it can accelerate in one direction is to expend reaction mass in the opposite direction. If you want your rocket to go north, it has to throw reaction mass south. And the only way for the rocket to keep going north is if the spent reaction mass keeps going south. If you stop the one, you stop the other. We appreciate that this thread has been so civil and articulate, so a thank you from us to everyone here-- both Cheif, and the folks debating with him-- by keeping this on friendly collegial terms and not resorting to personal comments. Well done, everyone. And encouragement to @Cheif Operations Director, who's working to better understand the physics of these things. Yes, it's hard. It's literally rocket science. Hope the discussion goes well and that you can gain more understanding of how things work, which after all is pretty much the point of the Science & Spaceflight forum. We now return you to your lively debate about Newton's laws of motion. Thank you again for everyone's patience and grim determination to be helpful.

Hi folks, A gigantic amount of completely off-topic speculation about how to make a magic, physically impossible rocket that's a perpetual momentum machine has been split off into a separate thread. The topic of this thread is the Rosatom engine explosion. Please try to stay on topic, everyone. Thank you for your understanding.

If you say so, will just have to trust your judgment. Effectiveness of Tylo reverse assist and/or Oberth maneuver depends a lot on the geometry, e.g. what direction you're coming from, etc. How thermal-resistant is your craft? Any chance of doing an aerobrake at Laythe to capture to Jool?

Set it up properly and there's no burn needed at Tylo. That depends on how fast you're going, though. What's your excess hyperbolic velocity with which you're entering the Jool system?

Yes, and your explanation was a really good one-- my bad for not noticing the staging comments later on. A few thoughts on the nature of explanations in spoiler, since I'm starting to wander afield from the topic of the thread, which is the OP's question.

^ This. I make it a habit never to launch anything to orbit without sticking some HG-5 antennas on there (it's available really early in the tech tree, so I have it by the time I'm going to orbit). Given the number of miscellaneous launches I do, pretty soon there's a motley assortment of junk in random orbits all carrying around 14M of antenna power (i.e. what you get from a quartet of HG-5s), which is plenty to extend all around Kerbin out as far as the Mun, and gives reasonably high (random) coverage of the planet's surface.

Well, not quite-- be careful not to over-generalize. The analysis you give in the spoiler's a nice one ... but that's the effective upper limit of an Isp 350 engine in a single stage. Multi-stage rockets can and do get better than that total amount of dV; it's why multi-stage rockets are a thing. You can always add dV to your rocket by adding another, bigger stage under it. It's just that because of the rocket equation, adding dV this way is going to require each successive stage to be exponentially bigger, which makes things less and less practical the more dV you add. It's technically possible to build an Isp 350 rocket that gets 25 km/s of dV, for example. It would just be stupendously, inconveniently gigantic for a tiny payload, is all. So there's not any one hard-and-fast cutoff for the maximum dV that a particular set of parts can get, just exponentially diminishing returns the farther you go. So the observation stated in the OP is correct in essence... but be careful about trying to hand out one specific number, since it's a bit messier than that.

There's a large measure of truth in that. "How far can you go" is roughly equivalent to "how much dV do you have". And the logarithmic nature of the rocket equation means that simply piling on more mass (additional fuel) gives very rapidly diminishing returns in terms of additional dV. So if you're designing to try to pack more dV into your rocket... yeah, you gotta build smart. Building smart will yield far more reward than just throwing more mass at it. This is true IRL too, not just in KSP, because of the way the math works. So yeah, you've pretty much hit the nail on the head. Welcome to KSP, and the "tyranny of the rocket equation".

I confess I was having a bit of trouble following, myself. "Code mixing"? My impression from looking at the github repo is that this isn't bundling any code from other mods-- looks like it is its own DLL. @whale_2, can you confirm that what you're releasing here is just your own code, not borrowed from elsewhere? If that's the case, you should be good to go-- it's your stuff, so you can put whatever license you want on it.

Well, it depends how carefully you match the periods. The stock game makes it tricky to get an exact match because it doesn't have a high precision readout for orbital periods, but mods can provide that. For example, BetterBurnTime will display a precision orbital-period delta display if you target another orbiting vessel and your period is somewhat close; this lets you match periods within a millisecond, without too much trouble. At that level of precision, it takes thousands of Kerbin years to drift significantly out of formation. ... but yeah, pretty much this, too. Just saying that it's not too hard to make a long-term stable formation, if that's what someone wants. But yes, you make a good point that one can have a perfectly serviceable, practical comms network without needing fancy synchronization. It's all a matter of what the player wants out of their network.

https://wiki.kerbalspaceprogram.com/wiki/Mun#Terrain If you're equatorial, then the highest point is just under 6 km. It's the cliffs flanking the big equatorial canyon that extends from the eastern edge of East Farside Crater. The reason I remember the minimum possible orbital height being lower than 10 km was that one time (quite a while ago) I wanted to see how low I could put something in a stable long-term orbit. So I got it perfectly equatorial and threaded the needle on that canyon. I don't remember exactly (it's been a few years), but I believe I had my orbital height down so that it was about at the level of those cliff tops.

That completely depends on what you're trying to do. "Satellite network" is a vague term-- there are lots of different situations that need different kinds of networks. It's hard to offer specific advice without knowing what you're trying to accomplish. So... could you explain a little? For example, why do you want a "satellite network"? What do you want to do with it? What is your goal? What is the problem that you're trying to solve?

Depending on how you're EVAing and getting back in... it can make a difference. Each time a kerbal bumps your vessel, it alters the orbit slightly. In particular, if your kerbal has a significant orbital or component relative to the ship, it'll raise or lower the opposite side of the orbit very slightly. Usually it's not something that matters much, but if you're in a very low orbit to start with, even just a kilometer or two of difference can be critical. Unless they've changed it recently, I'm pretty sure it's lower than that-- I'm just about positive that I've managed to create stable circular Mun orbits at altitudes a fair bit lower than that. I think you can get down to about 6K if you're careful. But yes, there's certainly a limit.

Since this question was asked (and answered) nearly three years ago, everyone involved has presumably long since moved on. Accordingly, locking the thread to prevent further confusion. If anyone has further questions or comments about this subject, please feel free to spin up a new thread.