Resonant Orbit Calculator v1.4

[Wkf Kerman]

I've been using the calculator site recently. Really want to express my appreciation to your work. Thanks!

[Ithendyr]

@linuxgurugamer The mod (KSP Resonant Orbit Calculator) on CKAN is on version 0.0.6.2 and the maximum compatible KSP version is 1.10.1 so for the KSP version 1.11 it doesn't show if you doesn't show other compatible version.

I've installed this mod, is compatible with the KSP version 1.11.1 . (https://imgur.com/a/msQ5GAa)

Maybe you can just update the compatible version on CKAN, that's will great.

 

Thanks.

[linuxgurugamer]

11 hours ago, Ithendyr said:

@linuxgurugamer The mod (KSP Resonant Orbit Calculator) on CKAN is on version 0.0.6.2 and the maximum compatible KSP version is 1.10.1 so for the KSP version 1.11 it doesn't show if you doesn't show other compatible version.

I've installed this mod, is compatible with the KSP version 1.11.1 . (https://imgur.com/a/msQ5GAa)

Maybe you can just update the compatible version on CKAN, that's will great.

 

Thanks.

Just tell CKAN to allow compatible mos from 1.9.  I support over 240 mods, I dont have time to do updates formthat formall of them.

[Maurizio Kerman]

On 2/5/2017 at 5:17 AM, meyerweb said:

Not 100% sure this is the right place to post this, but I created a single-use widget for calculating resonant orbits to deploy satellites into a circular orbit at regular intervals along that orbit.  It’s at http://meyerweb.com/eric/ksp/resonant-orbits/.

In case you’re wondering “what the heck is this?”, a resonant orbit is most commonly used to set up CommNet constellations around non-Kerbin bodies.  Suppose you want to put three relay satellites into circular polar orbit around Minmus.  You could launch them one at a time from Kerbin and do all kinds of shenanigans to get them into a common orbit (say, 100,000 km above Minmus) at 120-degree intervals along that shared orbit.  Which requires matching inclination and LAN and all manner of stuff, and then trying to jostle them into the right places along the circle.

Or, you could build a carrier craft that hauls three satellites to Minmus, then release them one at a time.  That solves inclination and LAN problems, but what about timing?  The easiest thing is to put the carrier craft into an eccentric orbit with its periapsis at the altitude the satellites should share, and an orbital period 4/3rds the length the satellites will have in their circular orbit.  In this example, the satellites’ final orbits at 100,000m above Minmus will have a period of 2 hours, 39 minutes, 29.5 seconds.  So you put the carrier into an orbit with a periapsis of 100,000m and an apoapsis of 167,652.4m.  That has an orbital period of 3 hours, 32 minutes, 39.3 seconds—exactly 133% the orbital period of the circular orbit.

Having done that, you just release one satellite from the carrier as it passes periapsis on each of three successive orbits.  Hey presto!  You now have three satellites in a polar triangle, sufficient to cover the entirety of Minmus and maintain a network back to Kerbin.  Quick, deorbit or otherwise move the carrier’s orbit so it won’t smack into the first satellite you released on its next periapsis.

I built some spreadsheets to manage the necessary calculations for myself, but it seemed more fun to build a web-based tool that could draw a diagram of the orbits and all that while also spitting out exact Ap and Pe altitudes.  And, while I was at it, show the minimum altitude for a functioning three-satellite setup as well as the edge of the SOI for whatever body I was trying to put satellites around if my orbits were large enough to be a problem, show atmospheres (where applicable), tell me the dV I’d need to inject each satellite into its final circular orbit, and stuff like that.  It looks like this:

It’s of fairly limited use, but it was fun to make and it supports stock as well as RSS and GPP.  I figured if someone out there could make use of it, that was good enough for me to release it.  Share and enjoy!

 

(P.S. If anyone has feature requests, I’m happy to hear them, though I may not get around to actually doing them.  I mean, I might do them, but I have a tendency to toss these little projects into the wild and then get distracted by some new project and never go back to update the old ones.  So fair warning and all that.)

I believe there is an error in the Apoapsis calculation.
I tried the calculation on a synchronous kerbin orbit with 4 satellites.
Apoapsis from the calculation results an Apoapsis of 3,974,352.2 m
but this value is incorrect, since if I check the period with T = (2 * Pi / SQRT (u)) * a ^ 3/2 (https://en.wikipedia.org/wiki/Elliptic_orbit)
where a is the Apoapsis, and result T <> Tcalc.
The corrected Apoapsis is 3,418,843 m.
Is my reasoning correct?
I'm sorry for my english

[GabeTeuton]

On 2/8/2022 at 11:50 AM, Maurizio Kerman said:

I believe there is an error in the Apoapsis calculation.
I tried the calculation on a synchronous kerbin orbit with 4 satellites.
Apoapsis from the calculation results an Apoapsis of 3,974,352.2 m
but this value is incorrect, since if I check the period with T = (2 * Pi / SQRT (u)) * a ^ 3/2 (https://en.wikipedia.org/wiki/Elliptic_orbit)
where a is the Apoapsis, and result T <> Tcalc.
The corrected Apoapsis is 3,418,843 m.
Is my reasoning correct?
I'm sorry for my english

I just used it to create a 3 satellite network, i checked for your request and to me it seems to be working correctly

a synchronous orbit should have a 6 hours period (more or less...) you get 5h:59m:9.4s when clicking the synchronous button, according to the wiki that's (exactly) the sideral rotation period, if you want to deploy your sats behind the "lastest" one you need to have a period 5/4 longer, you are suggested by the app 7h:28m:56.8s => 6 * (5/4) is 7.5, i can't be bothered to get the exact numbers but it seems honestly 100% accurate.

 

this may be resolved by now, but maybe someone else may need clarification regarding your question, let's save someone else's time i guess, at least in part

[NewtSoup]

I still find this very useful.  I have worked out that often the orbital period is more important than precise AP and PE when you want satellites to stay in roughly the same positions relative to each other.   Resonant orbits are very handy if you have stack that you can place in one go to get the positions roughly correct ( it's NEVER perfect) after that it's Orbital Period that keeps them looking tidy.

Also when deploying sats - have some engines on them to adjust the orbits and set your separator force to almost nothing.

[Zhetaan]

1 hour ago, NewtSoup said:

I have worked out that often the orbital period is more important than precise AP and PE when you want satellites to stay in roughly the same positions relative to each other.   Resonant orbits are very handy if you have stack that you can place in one go to get the positions roughly correct ( it's NEVER perfect) after that it's Orbital Period that keeps them looking tidy.

That's because orbital period defines the resonance implicitly.  Resonance occurs when the two orbital periods are in a ratio that can be reduced to low integer terms, such as 1/2, 2/3, 5/4, and so on.  For satellite networks, you generally want 1/1 because that keeps the spacing, and manoeuvres for that are more a matter of relative positioning rather than resonance.

The reason that specific values for the apsides don't matter is because orbital period, in turn, is dependent on the semi-major axis, and only on the semi-major axis.  The eccentricity doesn't matter; only the semi-major axis does.

That said, for a comm system, having the satellites in high-eccentricity orbits will change their relative positioning on a cycle even though the average is constant.  This can be a feature rather than a bug:  satellites in Molniya orbits exploit this in combination with inclination to spend a long time above the northern hemisphere in resonance with the Earth's rotation, thus repeatably giving better satellite coverage to certain longitudes in the northern hemisphere.  There are other important features of Molniya orbits, as well, but the point is that the resonance works because of the semi-major axis and its relationship to orbital period, not because of any other factor, which means that there's a lot of room to modify those other factors and thus many potential applications for different types of resonant orbit.