RemoteTech math

[deeirl]

After discovering the RemoteTech mod, I started searching for resources which would help me choose good communication constellations. I didn't really find anything I liked, so I went about doing the analysis myself.

My findings are at https://github.com/deirdreobyrne/KSP/blob/master/RemoteTechMath.pdf

One thing I've noticed is that, when it comes to eclipses, most analysis only talks about eclipses by Kerbin. It turns out that the Mun and Minmus can generate far longer eclipses.

WARNING: math. Lots of math  

[Starhawk]

This discussion relating to an add-on has been moved to the Add-on Discussions section of the forum.

[RizzoTheRat]

Interesting.  Not read it all yet but I've never got as far as looking at eclipses.

A couple of things I've found useful with RemoteTech

• Always match the period of the individual satellites in a constellation, if their Ap/Pe varies a little between them it doesn't matter so long as the period is the same.
• Resonant orbits make life a lot easier.  If you have 3 satellites in a constellation with a period of 90 mins, you want them spaced at 0, 30 and 60 minutes.  Setting up the launch vehicle with one apsis at the required satellite orbit altitude and a period of 60 minutes allows you to drop of a satellite each orbit and they only need enough fuel to circularise their orbit.

[DStaal]

I haven't played with RemoteTech, though I do play with CommNet it's lighter-weight sibling.  How well do highly eccentric polar orbits work with RemoteTech?    Those are usually my first step towards a network: a pair of relays in highly eccentric orbits around Kerbin, which are intended to be the last stop on any relay chain, and rarely in eclipse because of their orbit.

[Drew Kerman]

here's a nice RT planner that is still available: http://ryohpops.github.io/kspRemoteTechPlanner/

[deeirl]

Thanks for the feedback. I think I've cracked the math of how much of Kerbin's surface will receive coverage, so I hope to update the document in the next few days. And for good measure I'll see about doing the math for the resonant orbits - that's a pretty good idea!

DStaal - the problem with RemoteTech and highly elliptical orbits is that the RemoteTech omni-directional antennas don't have a massive reach (the best one is 5Mm). The directional antennas, obviously, have much better reach, but then you end up with too many antennas on too many relay satellites.

Drew - yes I saw that page. I believe it gets one quite significant thing wrong - it doesn't account for eclipses by the Mun and Minmus which occur when the satellite is above Kerbin's terminator. I believe those eclipses tend to last far longer than eclipses by Kerbin. Also, I like to specify my orbits by period and not altitude, as it's vital to match the period between all the satellites in a constellation.

What I do is put 3 satellites in equatorial orbit with Communotron 32's in a period of about 1h30m (I think that gives best coverage for the surface of Kerbin when paired against Communotron 16-S's - I'll know for sure when I've checked the math). I also put the Mun and Minmus antennas (HG-5 and DTS-M1) on those 3 satellites. That's the Kerbin system covered.

For further afield, I use a pair of relay satellites in highly elliptical polar orbits, and put an RA-2 on them pointed at Kerbin. I tend to aim for a period of 38 days - it's easily achievable, and works well. I then put 2 (for redundancy) satellites in Keostationary orbits a bit ahead of and behind KSC with RA-2's pointed at the two polar satellites, and a Communotron-32 to reach KSC.

[RizzoTheRat]

As an alternative to Geostationary satellites once you have the LKO network in place....

 

Bit boring flying them a third of the way around the planet though, and I had to do rocket assisted takeoff and land them by parachute as I couldn't get the range with engines powerful enough for VTOL.  

[deeirl]

OK - new version of the document is up with the math for how much of Kerbin is covered by a constellation.

Rizzo - I see two problems with placing relays around Kerbin. The first is that if you are looking for constant coverage, you need to provide enough battery to survive the Kerbin night. (Either that or risk contaminating large parts of Kerbin with radioactivity after crashing something with an RTG  ). The second problem is that the Mun and Minmus can pass between your relay and what you are trying to communicate with.

[RizzoTheRat]

Dunno if it's still the case, but on older versions of KSP unloaded vessels didn't use power, so it's a bit of an exploit. 

 

[deeirl]

Well if my math is right my LKO relay will reach to 77 degrees latitude north and south. So I think instead of Keostationary relay satellites with RA-2's on them to reach the highly elliptical polar relay satellites, I'll park some drones with RTK's on them as close to the 77 degrees limit as reasonable. I've practice landing a drone a couple of times, and no crashes, so the Kerbin Nuclear Safety Authority has given me the go ahead