Best place for a sun-orbit relay?

[Jestersage]

Where is the best place to put a sun-orbit relay, and what is the launch window and launch vehicle required for it?

Edited October 24, 2016 by Jestersage

[Aegolius13]

I don't think there would be a specific launch window to go around the Sun.  However, it is extremely expensive to do something like a polar orbit around the Sun, so it might be worth it to do a gravity assist / plane change maneuver by Eve or Jool.  In that case, you'd want the launch window for that planet.

As far as launch vehicle, depends heavily on where you're going.  But one general principle for solar orbit stuff is that TWR is not very important.  So nukes, ions or smaller LF engines may be good ideas.

[Plusck]

Sun orbit relay for what, exactly?

Unless you use a bunch (quite a few, really, like about 8, I think) of the highest-power antennae together, a relay in sun orbit is always going to be significantly less powerful than the Kerbin ground system.

So if it's distance you're looking for, you're almost always going to be better off putting a good relay at your destination, so that it can connect properly to Kerbin despite the weak signal. If the signal is still too weak at the destination, then you need to know why... which leads to the next point...

If you need a relay because the target is opposite the sun from you, then you need to get around the sun. Ship-borne relays being weaker than the Kerbin ground network unless you spam antennae, you want the relay to be close to the target. Therefore what you really want is a relay that is almost but not quite opposite Kerbin, but on the same orbit so it stays there.
And with spammed antennae, this will let you reach Jool, Eeloo etc. when they are opposite the sun.

The trouble is that to get there, you need to go up or down first - either burn towards Moho, then recircularise along Kerbin's orbit an orbit or two later when Kerbin is the other side of the system (quickest, but expensive - can be complete in just over half a year), or you burn up towards Duna and then recircularise along Kerbin's orbit just under a year-and-a-half later (cheaper, but necessarily slower).

 

Any other solution is only going be useful at specific times, not necessarily when you need it, unless you produce a constellation of the things. Either they shadow your target, or they have the same orbital period as Kerbin, or they need to be one of several doing the same job.

Which comes back to the question, sun orbit relay for what exactly?

Edited October 24, 2016 by Plusck

[Jestersage]

46 minutes ago, Plusck said:

Which comes back to the question, sun orbit relay for what exactly?

As of now, the reason I am doing a sun Orbit launch is to waste less of a launch and have less objects to track while doing a contract to test the TR-XL. If I am throwing something up there that involve a probe core, I may as well send a useful relay up.

That being said, I did planned to eventually put an actual Relay just in case I want to talk with something on the opposite end of Kerbin; this is about the only reason I see a sun orbit relay being useful.

[Plusck]

32 minutes ago, Jestersage said:

As of now, the reason I am doing a sun Orbit launch is to waste less of a launch and have less objects to track while doing a contract to test the TR-XL. If I am throwing something up there that involve a probe core, I may as well send a useful relay up.

That being said, I did planned to eventually put an actual Relay just in case I want to talk with something on the opposite end of Kerbin; this is about the only reason I see a sun orbit relay being useful.

Ah ok.

In that case, I'd forget about trying to make a relay unless you feel like making a serious commitment to it.

With a serious commitment, 6 to 8 strong antennae (88s basically) on a ship could be very useful later on. Just send out prograde and look at when you reach sun orbit Pe - you should burn until it reads 1 year 180 days or so. Then wait for Pe and make circularise to follow Kerbin's orbital period exactly.

But without that serious commitment, your sun orbit relay will be pretty useless. It might help once in a blue moon but everything would have to be perfectly aligned for that.

[Jestersage]

Ah okay then. I will just put a cheap Relay up. A contract is still a contract.