Nachtengel

Hai, im an aerospace engineer so i might be able to help you here, first of all, both cases A and B are the same. you are increasing speed with a gravity assist, or swing-by. however, the common misconception here is that your speed on the instruments must increase, and it wont. your speed entering the planet encounter will equal the speed leaving the encounter if no thrusters were burned. gravity assists find no use in standard orbital mechanics within one body systems or systems with one moon. but they find many uses in systems with more bodies. like a solar system. gravity assists are used for interplanetary travel, to conserve time and fuel. first you need to understand that the speed we are considering here is not the speed of the orbit but the speed relative to the sun. start with a heliocentric reference frame. now, consider that your spacecraft and the planet pull on each other, its not just the planet pulling you, but also you pulling the planet, but the mass of planets is so large its negligible, but the principle is important. the idea is that the velocity vector of the planet and your spacecrafts entering velocity become an added vector Vin (you're in mathematics so i know you know how to add vectors, the arrow method will suffice.) now, the velocity vector of the planet and your spacecraft also form a resultant the moment you reach the escape node. construct the two resultants and observe the difference, in both cases A and B you will find the resultant Vout to be larger. meaning, you have assisted in increasing your speed relative to the sun, and thus are travelling to wherever youre going faster in terms of the solar system. gravity assists can also be used to slow down your craft if the planet is moving in the opposite direction of your spacecraft. and the manipulation of the encounter vectors Nin and Nout is what determines this, for example, case A is a large increase in velocity relative to the sun, while case B is a much smaller change. and depending on how exact the points i took from your drawing are, case B could also be a negative assist. regardless the understanding should be that you are trying to manipulate your vector, not your speed. because the resultant of the planets vector and your own will determine where and how fast your interplanetary travel will be. remember according to the planet, no matter the strength of the assist. the velocity on your screen will be the same at encounter point and escape unless any burns were made. so for quick analysis, arbitrary arrow lengths are acceptable, the spacecraft's and the planet's. find your encounter on the map, and work out your velocity vector and the planets and draw them on a sheet of paper for the resultant, if the assist does not benefit your flight, change early to minimize fuel usage. when the desired resultant is reached. enjoy the ride.

you have the logic a bit backwards, its actually the thrust to weight ratio that determines the G forces, change in acceleration causes the perceived effect of increased gravity, think of going up or down in an elevator. you do not get physically lighter or heavier, but for the moment the elevator starts, you feel it. just for a second. g and gravity are not the same thing, gravity is consistent (not constant, but its a function of distance nothing else) and your spacecraft will have the same acceleration exerted on it no matter what its doing. g is a designation for perceived weight, or the change in inertia. it is confusingly termed in amounts of gravities at earths surface. but nothing more. change in g force simply is a different method of saying you are accelerating faster. in much the same way that we dont use meters for space distances (AU instead) we use g for accelerations, because it gets silly when talking about such large numbers, so a new system was invented to describe it.

landing comes in two shapes, ambiguous landing and targeted, first you must figure out what your landing speed MUST be, F = ma so take the total weight of your lander and consider it the mass, now the speed of your lander at the point of impact will actually be your acceleration, because the celestial body will not move. so your speed at that moment is reduced to 0 and therefore we can say that is your acceleration. now the legs you put on the lander have a certain compressive strength, place that in the F position of the formula, so say i have a leg with compressive strength (or shear depending on orientation, shear means sideways) of 200, and the mass of my lander is 5 tonnes. then 200=(5000 kg)(final velocity). This will be enough to tell you for your lander at what speed you must be under to land safely. as a benchmark you would want to land at around 5 m/s or less usually is a good rule of thumb if you don't enjoy doing the calcs. now that you have the speed you can adjust your plan. Ambiguous landing: you have no target, the game is simple, once you are in orbit around the target celestial body, retrograde burn to deorbit, and keep pointing retrograde the entire time. after your short deorbit burn warp to about 10k altitude and turn your engine on very low, you should be within, this will largely depend on the planet, you may need to start higher than 10k, but do some gravity math or just trial and error and you'll get a feel for when, but you burn the engines low. gradually losing speed, you will watch two things, your altitude and your engine thrust. the idea is to steadily decrease the speed as you are coming down. the ideal case you are aiming for is that you reach 0 m/s at altitude 0, if you keep pointed retrograde the entire time, eventually your arch will be straight down, the side angle is enough to cancel your lateral translation, so dont overdo it. near the ground you may have to increase engines to get your speed down, dont overdo that either, keep a steady increase or decrease no matter what you do. no sharp movements in either direction. if you overshoot , you will overshoot a lot and its difficult to correct. Targeted: same as before except the deorbit burn will occur about 45 degrees from the target, now execute your deorbit burn and watch the map view until your arch is beyond your target by about 5 km. once this is complete, goto 10k again and continue as normal. your target should be close by if you are slow and consistent in your burns. the key is subtlety, no large burns anywhere, just low constant velocity loss. with practice you will get the hang of it. Rendezvous: rendezvous requires one extra step if you are trying to reach an inclined orbit. For 0 degree inclination orbits you can proceed directly to the next step. for inclined orbits you must first go into map view, and wait until the orbit of the target is directly over your launch pad. then launch. this will save you fuel and time trying to correct your orbit otherwise apart being very hard to do so. the next step is to figure out of the target is behind or in front of you (do this as you increase your apoapsis to orbit height. to get a better idea of where the target will be at the moment you reach orbit.) now this is key, if the target is ahead of you, you must move faster, and therefore require a lower orbit. the opposite is also true, if the target must catch up with you, take a higher orbit. lower orbits have higher speeds due to the required lead for the gravity force vector to keep it in perpetual free fall (a simple way to think of it is a ball on a string you are swinging around, the closer the ball is to your hand, the faster you must spin it to keep it in the air.) don't make the altitude difference too great, remember you need to join orbits eventually. match the orbit eccentricity as you normally would at the apoapsis. now you wait for the target to get as close to you as possible, warp if necessary. at this point, your target should be nearly above or below you burn at an angle nadir or retro-nadir (toward or away from the earth) in the direction of the target, and then reestablish your orbit. once complete, burn the main thruster very low (you should be within a few km at this point, you are getting to a couple hundred meters) again gentle movements. be slow, careful. do not go 200 m/s, try 20-40. once close lose your relative velocity with the target and engage RCS. now you are a hundred or so meters away from target, RCS only from now on. use the keys to gently inch yourself closer to the target, like landing you want to make contact at less than 2 m/s or so, you will get close, kill your relative velocity, align with target and readjust, then continue. do this until you are aligned and within a few meters. then the magnetic force should take over and pull you together, now you turn off ASAS to allow it to turn slowly into position, and it will dock. GL!

good im glad i have something i can offer. debris is kind of an art form for the field. methods are only beginning to get sophisticated according to the danger, but in KSP there are problems we don't have to worry about, and that helps open our options immensely. example: a mission to Ganymede or Callisto, cannot jettison anything it can afford to keep for the sake of polluting the untouched environment. However in ksp debris that reenter are simply destroyed. as the mechanics change i will have to keep watch. but for now ill make a few posts or vids. starting with the basics, and moving on to the advanced techniques for interplanetary, fun things like pre planned jettison retro-boosted gravity-assisted collision with an asteroid (my favorite). That, is awesome this excites me, to think that we are entering an age where even the types of games you play can create connections between companies and new engineers. imagine, getting into a debate with the head of a company about which launcher they should use on the forums for fun, and he offered you an interview. that's the kind of thing i hope this world is heading for. the internet is a more powerful tool for helping the world than i think even most ppl realize. thanks to the rest, looking forward to seeing everyone's creativity

Hey all, just joined the group. A few of us here are really interested in this game, we study at the aerospace engineering faculty and it was really fun to mess around with this game, i heard about it from a friend who thought i would like it, hes the kind of guy who tells you things you don't care about most of the time because hes not in aerospace and thinks everything you can link to it must fascinate you haha, but in this case he was quite right. i torrented it to see what it was all about, and before i knew it i was planning moon bases. when i get moments like that its my cue to buy it, so i did, and here i am. its really interesting to apply the knowledge gained in the study to this game to see the outcome. for a game, it is surprisingly well made. obviously i thought it was strange a kerbel could reenter atmosphere in nothing but his suit and survive until the ground, but its alpha stage, i don't expect everything to be perfect yet. i think i may make a tutorial on how the industry keeps debris down, i see a lot of peoples mission view screen and there is tons of garbage, with only a few missions in the mix, you guys are in trouble. my mission window has 0 debris that isn't on the ground or on trajectory for reentry, and maybe this is something i can share. i expect there will be a few other aerospace ppl in here so i look forward to the conversations. currently i like mods like ISA, that's my field, earth and planetary observation. so it was fun to make mapping satellites to select proper grounds for bases and outposts. if i have time i would enjoy expanding on that mod to include instruments currently being used. im a fan of the sentinel program so i might start there current project: moon base is dark in eclipse, need battery and solar array bank to store enough power for complete eclipse cycle. working out how many batteries in need and gonna store up power during day and discharge so the base is lit while dark on the mun