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Found 24 results

2. ## Orbital mechanics - Gravity Assist/Brake

I've been having trouble rapping my head around slingshot maneuvers. Enter Sphere of Influence (SoI) and exit SoI with changed velocity. It basically breaks down to four maneuvers. A and B are from a higher (faster) orbit, C and D are from a lower (slower) orbit. A and C are leading the object, B and D are trailing. There are some hints in https://wiki.kerbalspaceprogram.com/wiki/Tutorial:_Gravity_Assist It shows C and D. but what about A and B? Which ones will increase my exit velocity? C Which ones will decrease my exit velocity? D

4. ## Returning directly to the KSC from an inclined orbit?

This one has been nagging me for a while thanks to the STS challenge. In order to get the best rank, you need to land your shuttle back at the KSC (or other runway structure on Kerbin). When you're tooling around in an equatorial orbit, this is easy enough, since you're always more or less aligned with the position of the KSC. But when you get into the more advanced missions, you need to perform activities out-of-plane and still return to the KSC; I've been solving this by simply doing a plane change burn, but that'll be less viable as I head out to the Mun and beyond. I've tried to nail the KSC from an inclined orbit a few times, but I can never seem to get it. Thus, my question: how would I directly return to the KSC from an inclined orbit?
5. ## Descending Node or Ascending Node?

Hello dear reader Which is better and more fuel effecient? I remember hearing about the Dn and An but I don't know which one is more effecient.
6. ## Need help in calculating payload capacity to different orbits and inclination.

The title is pretty self explanatory. I want to find the general equation to calculate the payload capacity of a particular rocket (with a certain delta-v) to an orbit of x X y km with a Beta inclination around a planet of radius r and mass M. I hope to find a solution for an airless body before moving on to bodies with atmosphere. Thanks in advance!
7. ## Mun ejection angle

I'm trying to do as much as I can with KOS in this career, which means actually working out what's going on rather than just eyeballing it with the manoeuvre nodes. Calculating the dV and phase angle to get to the Mun is easy enough, but I can't get my head around coming back. I know from previous experience that 250ish m/s at an angle somewhere between pointing at Kerbin and Mun retrograde will get me the most efficient return to Kerbin atmosphere, but can't see how to work it out. For a given Ap altitude above Kerbin I can work out the velocity I need to achieve my required Kerbin Pe, and for a given ejection burn I should be able to calculate the velocity and altitude relative to Kerbin at the point it leaves the SOI (not done this yet but I think I know how), but as the required Kerbin velocity will change with Ap altitude I can't see how to link the two together. Any suggestions?
8. ## parabolic trajectories in KSP

Why KSP engine doesn't support parabolic trajectories? (You can try to put e = 1 into HyperEdit and see disappearing ship) What meaning of negative Apoapsis? I understand what it is about hyperbolic trajectories, but still, what its physical meaning? lim Ap = +∞ e → 1⁻ lim Ap = −∞ e → 1⁺ It is the reason why you get NaN if you put e = 1, but something wrong there. How it works in big science?

10. ## HELP NEEDED with Orbital Matching

Help me please, I think my game is glitching out. I'm playing with galileo's system replacer, using a station and a probe. I've put the station in the same orbit as Lili but shifted ahead (a large asteroid in the belt of a large planet) and want to use the probe to find ore deposits. the station is in a stable position - I've accelerated time and watched them orbit, they stay the same distance apart. The trouble begins when I actually go to use the probe. I get it into a capture of Lili, and then the station's orbit changes. it goes from stable and separate to falling straight down to the planet, and when I use Hyperedit to place it back in the same orbit as Lili, it starts Falling towards it. I've looked at the velocities, and they're the same. Lili is orbiting at 455,000m and 3578.5m/s, I'm orbiting at 449,000m and 3578.5m/s. When I switch to target mode, I'm moving towards Lili at around 200m/s. How can I be moving in the same orbit and same velocity as a celestial body AND be falling towards it? also, when I fall towards it my orbit doesn't show a transfer into Lili's SOI, I just crash and explode. Can anyone explain what is happening?
11. ## Nexus's Orbital Calculator

(Inspired by Interplanetary How-To Guide by Kosmo-Not) I proudly present to you the Nexus's Orbital Calculator It does a lot of calculations for you automatically. You only have to input the data. It has a: Orbit Calculator Hohmann Transfer Calculator Interplanetary Transfer Calculator And more... Works for both stock KSP and Real Solar System Download for free by clicking on the link below https://drive.google.com/file/d/0B0WLcnclj_TFSVBRUEExSWlmeW8/view?usp=sharing (I'm open to constructive criticism and suggestions)
12. ## Porkchop plots and Lambert's Problem

I've taken on the project of writing an interplanetary trajectory optimization tool and a comparison of algorithm efficiency for the problem at arbitrary starting points. Looking further into the problem, however, I have a question that I can't seem to answer. When you optimize an interplanetary trajectory in a patched-conics approximation like KSP, how do initial and target orbit influence the problem? Specifically, I understand how the 'interplanetary' part works. Given the position of two planets, you can calculate the orbit that will intersect one position at one time (the departure date) and the position of the other at another time (the arrival date) easily by cranking through Lambert's Problem for the solar orbit case. However, how do you account for leaving the orbit of the start planet and arriving in orbit of the destination planet? Put another way, how do you calculate ejection angle or the optimum burn to leave/enter the patched conic gravity well?
13. ## Calculate periapsis velocity based on known values on apoapsis, perapsis and apoapsis velocity *without* the standard gravitational parameter

I'd like kOS to calculate the velocity at periapsis for me with the apoapsis height, periapsis height and apoapsis velocity as variables. However, if one is using the specific orbital energy v2/2 - µ/r = constant, you must know the standard gravitational parameter. I could hardcode the values into my script for every celestial body, but I want it to be as general as possible (if you decide to alter the default masses with mods etc). How do I get rid of the dependency of µ in my formula?
14. ## Hellion [videogame]

https://www.playhellion.com/ Incredible new space sim/survival/orbital mechanics/multiplayer game. Early access is coming out next week. Looks absolutely fantastic! Any KSP players dream come true. Check it out, and spread the word!
15. ## Jovian Warfare

Suppose two countries with all of the technologies we expect to have by the year 2150 exist on Ganymede and Europa. They cover the whole of their moons. They have giant vertical underground farms to sustain themselves and huge solar fields with almost 100% efficiency (virtually no energy (light, heat, vibration, etc.) is missed or wasted). They have mining running down to the cores. They have big cities like on Earth, mostly underground. And they go to war with eatchother. No prisoners. No survivors. No slaves. Total annihilation. How is it fought? What are the advantages of Europa over Ganymede?
16. ## Mun rendezvous issue

I'm a newbie in career mode and have hit a roadblock in attempting to fly by and gather scientific data near the Mun - I've followed Scott Manley's tutorials on how to do this, but I'm doing something stupid because I can't succeed - after achieving a stable orbit around Kerwin, I place a manuever node 90 degrees ahead of my target (Mun) - no matter how I try, I cannot get a projected orbit to get closer to the Mun than 2429.6 km - no matter how many ways I try to do it (ahead of it, behind it, near it), the closest approach miraculously stops at 2429.6 km - also, the application is so sensitive as I increase the projected orbit near the Mun that I instantly "pop" into a totally different orbital arrangement (is that the effect of the Mun's sphere of influence?), but still keeps me 2429.6 km away from it - and finally, is there a way to zoom in on the projected near encounter of the Mun in map view? Mine remains centered on my spacecraft and when I try to zoom in the "spaghetti" of orbits near the Mun I only zoom in on my spacecraft so it is impossible to analyze what my projected path(s) are doing very easily. Sorry for all the questions - I love the application but I'm up against a "wall" that's preventing me from advancing - the issues are exactly the same in sandbox as well as career mode. Thanks in advance for anyone's assistance/suggestions.
17. ## how do you manually calculate a trajectory with out map mode

how does mission control calculate where you will end up and how map calculates this. like for translunar injection how do you know how your orbit is by not using map mode
18. ## Placing satellites in a geostationary orbit

Hello! This may sound silly but with all my years playing ksp, having bought it several years ago, when the game was just about the extent of the demo now, ive never acquired a true geostationary orbit, is there any way to place a ship or satellite in such an orbit without the use of mods, does KSP have a feature or something else to help a craft into such unique orbits, thanks!
19. ## Orbital Mechanics Questions; Help

Hey guys, understand this is a bit of an ask but I've come to the end of my tether with trying to calculate these. If any of you are nerdy enough to give these a go I'd greatly appreciate it. http://prntscr.com/d52ktz?
20. ## To Oberth, or not to Oberth?

Let's keep it simple: Arrive at Minmus SOI from Kerbin. Hyperbolic orbit with perigee at 150km, generally equatorial. Desired orbit is 15km x 15km, equatorial. I can play this two ways: 1) Immediately burn retro, dropping Pe to 15km. Then burn retro at Pe to lower Ap to 15km. 2) immediately burn nadir to tighten Pe down to 15km. Then burn retro at Pe to lower Ap to 15km. What at is the difference? What is the trade off between the two methods? Would (1) actually effect entry speed in a meaningful way, if it were Duna and not Minmus? Would (2) provide more of a boost if I was only using the encounter for a slingshot? These are my suspicions, but I find it hard to quantify any F5/F9 results. When should I be employing which method?
21. ## Calculating Δv -- where am I going wrong?

I just installed the Outer Planets Mod and am trying to figure out what kinds of Δv's I'll need to reach those planets. I began setting up a spreadsheet to calculate the required orbital velocities, but something's not right. The standard equations are giving me a reasonably accurate orbital velocity of 2,295 m/s at 70 km above Kerbin, escape velocity of 950.7 m/s and orbital velocity around Kerbol of 9,282 m/s. However, when I plug in the average orbital distance of Duna (2.07 × 1010 m) and try to calculate the Δv necessary to raise myself from periapsis at Kerbin orbit to apoapsis at Duna orbit, no matter which variation of the equation I use (I've found three), I keep coming up with a Δv of about 918 m/s, rather than the 130 m/s listed on the KSP Δv map. I'm getting similarly inflated Δv's for every planet in the Kerbolar system. What on earth am I doing wrong? The initial formula I used, provided by Scott Manley in one of his tutorial videos, is v2 = GM(2 / r - 1 / a). For M, I'm using the mass of Kerbol; for r, the orbital radius of Kerbin; and for a, the semimajor axis between the orbital radii of Kerbin and Duna. Variations found on Wikipedia provide the same result as the initial formula.
22. ## Transfer Energy

Last week there was a thread created that discussed the basic requirements of deltaV required to get into various positions of the moon. Other than the launch variables the statement was made or asked if deltaV tables was the best way to handle this. I looked at the from an energy perspective, first off I need to add that the classic formula for calculating delta-V between two circular orbits is - SQRT(u/r0) for the first burn (r is r0 in this case in the wiki image, ignore the v = ) r can either be an apoapse or periapsis and SQRT(u/r1) - (r is r1 in this case in the wiki image) for the second burn. r can either be an periapsis or apoapse The perfect energy requirement equal to the is close to this at in the case of the lowest and highest eccentricities (e = 1) but in the middle ranges it is considerably different. The basic problem is that elevation of a circular orbit neccesarily requires two burns. During small burns the change of velocity is small and as a consequence little momentum is lost. In changing to very eccentric orbit much momentum is lost, but the dV required to establish the second orbit is small fractional to the energy required to create the transfer orbit. At minimum escape velocity its zero. In eccentricities (e) of transfer orbits around 0.7 (e.g a geosynchronoous from LEO transfer) have substantial inefficiency because considerable momentum is lost as the satellite slows to its apoapse at which it needs to burn. So for example a station keeping burn is perfectly efficient, and also a escape orbit (minimal) is perfectly efficient (but because of N-body problems more or less a theoretical exercise) The energy requirement works within tolerances if the correction factor for eccentricity is provided dV (total)/((1-e)+LN(1+e^1.9)), up to about e=0.75 but becomes inaccurate after this. Its not perfect. I tested this with a number of orbits, a is irrelevant the error is a function of e. This means without using a table one has a minimum requirement for a single step energy plot of knowing e as well as initial radius and final radius. Its not hard to calculate e but in creates also a two step operation. Ergo the OP is correct, the two step dV plots are as simple as any other means of plotting the dV requirements of an orbital change.
23. ## Celestial Command

FYI found a very early access indy game on steam called Celestial Command, which is a space game which uses Newtonian orbital mechanics and the Unity engine, reminds me of early KSP quite a bit, though it is not the same kind of play, being top down 2D/3D. It is a resourcing / crafting / trading / pew 'em up game and looks like it is being built with multiplayer in mind though I have only tried single player so far. Gameplay is, like KSP, engaging for mechanical types. You mine asteroids/moons/planetismals in orbit to trade the ores, make fuel and also build your ship out of the same ores. The structure of the ship and thruster placement etc all matter for the flight physics as does mass distribution including cargo. Its very early days, so is cheap, thought some might enjoy. http://celestialcommand.com/ It occurred to me this game owes a lot to KSP and probably wouldnt even exist if KSP had not made it possible for gamers to engage with orbits and, in that sense, Squad would probably be justified in considering it a sincere form of flattery! Gameplay screeny to give some flavour. http://imgur.com/XldxJrZ
24. ## Looking for Orbital Mechanics resources

Can anyone recommend some good resources on the mathematics of orbital mechanics? I'm comfortable calculating Hohmann transfers (including alignment angle, dV budget, etc.), I can calculate dV for stages and total craft, but I'm having a hard time figuring it out past there. I'd love to be able to calculate the dV required for plane changes the new trajectory from a gravity assist the launch window for non-Hohmann transfers porkchop plots map out a spiral transfer for low thrust engines and plan re-entry trajectories. I expect some of these problems have known simple solutions, and some will require numerical integration. I'm comfortable setting up and solving either method. My background: I'm a chemical engineer. I'm comfortable solving ODEs (ordinary differential equations) and PDE (partial differential equations). I don't usually work in multi-dimensional calculus, but I do understand the basics of dot and cross products. There was a point in time in college where I was better with those. My trig is pretty good, but my calculus in cylindrical or polar coordinates isn't great. I usually use MathCAD for complex problem solving but don't have access to it right now. So I usually set up Eularian integrators in excel when I can't work out exact solutions. With a little work I could make it run Runge-Kutta instead. I've read the wikibooks articles on orbital mechanics, as well as these links http://hyperphysics.phy-astr.gsu.edu/hbase/kepler.html http://www.braeunig.us/space/orbmech.htm http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-07-dynamics-fall-2009/lecture-notes/MIT16_07F09_Lec14.pdf http://www.bogan.ca/orbits/kepler/orbteqtn.html
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