Hg-5's not working together

[gtschmidty]

Hey guys, quick questions. I recently launched my first interplanetary probe, but I can't stay connected to KSC. I'm only going to Duna, and there isn't any other stellar bodies blocking communications. The probe consists of multiple probes, 12 in total, but the 12 Hg-5's on board aren't working to establish a connection to ksc. is it just a matter of range, and I've missed something, or what? Any help is appreciated. Pictures attached.

 

https://imgur.com/a/6Ba8o

Edited October 24, 2017 by gtschmidty

[Spricigo]

Reaching Duna with only Hg-5 will take a obscene amount of antennas even at the shortest distance.  So unless are you planning to have a relay with 100 antennas or so you need stronger ones.

there some useful links

https://wiki.kerbalspaceprogram.com/wiki/CommNet

 

[Aegolius13]

You quickly hit diminishing returns using multiple antennas.   Upgrading to a better antenna gets way better results,  both in terms of mass and range. So you may need to research the next tier of antennas (which are almost 1000x more powerful) before you can reach Duna.

[renhanxue]

The HG-5 is pretty much a toy antenna. There are some rather contrived use cases for it, like Apollo-style missions to the far side of the Mun with the HG-5 in a low orbit above a lander, but really, there's no real reason to ever use it. It's just too weak. A command pod using its built-in antenna will lose contact with a HG-5 relay at the impressive distance of 158 km (one hundred and fifty-eight kilometers, not a typo). If you put on a Communotron 16 (the humble red-and-white extendable whip antenna), you can now reach the HG-5 from an absolutely jaw-dropping distance of 1581 km, or about half the altitude of a keosynchronous orbit.

If you're going to Duna, bring a RA-15. It should be able to reach even a level 2 tracking station at the KSC (unless Duna and Kerbin are very far away from each other), and a Communotron 16 can reach it from anywhere within Duna's SOI.

Here's a handy cheat sheet for max ranges (in meters) between two craft with a single antenna each (and between a craft with a single antenna and a fully upgraded tracking station at the KSC):

Edited October 24, 2017 by renhanxue

[Spricigo]

1 hour ago, renhanxue said:

The HG-5 is pretty much a toy antenna.

...there's no real reason to ever use it.

Of there is reasons to use the HG-5. In fact you described very well one use: put it in orbit so it reach the craft in the surface. 

You may need a stronger relay to get in contact with Kerbin, but after that there's little reason to use anything but HG-5s to fill the gaps.

 

[renhanxue]

13 hours ago, Spricigo said:

Of there is reasons to use the HG-5. In fact you described very well one use: put it in orbit so it reach the craft in the surface. 

You may need a stronger relay to get in contact with Kerbin, but after that there's little reason to use anything but HG-5s to fill the gaps.

 

Well, as I said: the practical use cases where that would actually be meaningful are rather contrived. You have to try pretty hard to find a spot where a HG-5 in low orbit (and you can't really put it in high orbits because it's so weak) can reach a stronger relay but the lander on the surface can't, and even if you do have such a spot, why not use a RA-2 instead? Sure it weighs twice as much (a whopping 80 kg more) but it's also four hundred times more powerful, so you can leave it in a much higher orbit where it's over the horizon for longer and easily reusable by other missions in the same system, and it's much less likely to drop connections or devalue your science transmissions.

[Spricigo]

2 hours ago, renhanxue said:

and even if you do have such a spot, why not use a RA-2 instead? Sure it weighs twice as much

Answer is obvious. I can instead launch 2 satellites with HG-5s and double my surface coverage.

 

And no, it's not difficult to find a good orbit for the HG-5 operate. e.g. In my save more than half of the relays have a single HG-5 In it.

 

[renhanxue]

2 hours ago, Spricigo said:

Answer is obvious. I can instead launch 2 satellites with HG-5s and double my surface coverage.

 

And no, it's not difficult to find a good orbit for the HG-5 operate. e.g. In my save more than half of the relays have a single HG-5 In it.

 

How does that figure? A probe core weighs about as much as a HG-5 does. In general you never really gain anything by getting more relays with smaller antennas. The limiting factor for relays isn't really delta V or weight anyway, it's how much effort you can be bothered to expend getting them in place.

I really wonder how on earth you're setting up your relays though if you have that many HG-5's. I mean, KSP is pretty much a sandbox even in career mode so if you want to need HG-5's of course you can create a need for them, and it's not like using them is "wrong" in any way, but still. If all you want is a "good enough" relay network, you only need two relays per planet (highly eccentric polar orbits around the primary with apoapsis near the edge of the SOI, 180 degrees out of phase with each other) plus maybe a few to let you bounce around the sun. That only leaves very small blind spots near the equator of the primary and on the far sides of the moons, and while you can go to the effort of putting three evenly spaced HG-5 relays in a low circular orbit around every moon in the entire Kerbin system to get perfect surface coverage everywhere, I personally really can't be bothered. Just slap a RA-2 on the transfer stage and leave it in whatever orbit you end up in around the moon you're visiting and there you go, good enough.

Edited October 25, 2017 by renhanxue

[Snark]

21 hours ago, renhanxue said:

The HG-5 is pretty much a toy antenna. There are some rather contrived use cases for it

Not at all.  It's a highly useful antenna, and I use it all the time, for a variety of purposes.

What it isn't, even slightly, is an interplanetary antenna.  It's for building planetary networks, not interplanetary ones.  Some examples:

• It's useful as a relay around Mun or Minmus, to talk to craft that are on the "back side" and can't see Kerbin.
• It's useful as a local relay antenna on other planets, as long as the planet's comm network has at least one long-range satellite that can talk to Kerbin.  For example, building a relay network around Duna to blanket the surface.
• For players who like to play with the "no extra ground stations" option, it's also very useful for building LKO comm networks around Kerbin itself.

 

23 minutes ago, renhanxue said:

In general you never really gain anything by getting more relays with smaller antennas.

Sure you do.  You get better coverage, which can be pretty important.

Any given satellite can only "see", at most, half of a planet.  Less, if it's not in a really high orbit.  Having multiple satellites spread out, which can see each other, gives better coverage.  It's why we have networks.

6 hours ago, renhanxue said:

why not use a RA-2 instead

Because there are circumstances where LOS is more important than range, and the RA-2's extra power simply isn't needed.  And the HG-5 is a much more convenient form factor-- attach it radially anywhere, doesn't break up the lines of the ship, don't need to put a fairing around it.

Are there a lot of cases where the RA-2 would be a better choice?  Sure.  But there are other circumstances where the HG-5 works better, too.  It all comes down to ship design and play style.  Personally, I tend to use the HG-5 a lot more than the RA-2.  I use the HG-5 through the entire game, even after I've unlocked all the antennas-- whereas I only use the RA-2 in a brief window until I've got the tech to unlock the RA-15.

[renhanxue]

49 minutes ago, Snark said:

Not at all.  It's a highly useful antenna, and I use it all the time, for a variety of purposes.

What it isn't, even slightly, is an interplanetary antenna.  It's for building planetary networks, not interplanetary ones.  Some examples:

• It's useful as a relay around Mun or Minmus, to talk to craft that are on the "back side" and can't see Kerbin.
• It's useful as a local relay antenna on other planets, as long as the planet's comm network has at least one long-range satellite that can talk to Kerbin.  For example, building a relay network around Duna to blanket the surface.
• For players who like to play with the "no extra ground stations" option, it's also very useful for building LKO comm networks around Kerbin itself.

 

Sure you do.  You get better coverage, which can be pretty important.

Any given satellite can only "see", at most, half of a planet.  Less, if it's not in a really high orbit.  Having multiple satellites spread out, which can see each other, gives better coverage.  It's why we have networks.

Because there are circumstances where LOS is more important than range, and the RA-2's extra power simply isn't needed.  And the HG-5 is a much more convenient form factor-- attach it radially anywhere, doesn't break up the lines of the ship, don't need to put a fairing around it.

Are there a lot of cases where the RA-2 would be a better choice?  Sure.  But there are other circumstances where the HG-5 works better, too.  It all comes down to ship design and play style.  Personally, I tend to use the HG-5 a lot more than the RA-2.  I use the HG-5 through the entire game, even after I've unlocked all the antennas-- whereas I only use the RA-2 in a brief window until I've got the tech to unlock the RA-15.

I don't get it. Like, at all. I play with no extra ground stations once I've unlocked the RA-2 because I can't be arsed to set up three sats with HG-5's only to scrap them five minutes later when I get the RA-2, but I don't get it anyway. With two sats in modestly high orbits (which the HG-5 of course isn't useful for) you get coverage of like 95% of the surface of a body like 95% of the time (actually it's probably very close to 100% in practice with the default occlusion settings, but that's beside the point). Adding a bunch of HG-5's in impractically low orbits around everything is just busywork for no meaningful practical gain. I mean, I guess if building relay networks for 100% coverage is what you enjoy doing in KSP, go right ahead, but you really don't need much of a network in the stock game. A lot of people I've seen overbuild theirs to an incredible degree. I put relays around the Mun and Minmus in one game and then I got tired of all the busywork and never bothered again. Once the network for bouncing around the sun is in place and I have a few random RA-2's on scansats and other various spacejunk the blind spots never really become an issue again.

I mean, the thing here is that powerful relay antennas are so cheap and so light that it's much more practical to get good coverage with a few high power general-purpose relays very far away than it is to have a whole bunch of specialized low power relays close by.

[Spricigo]

1 hour ago, Snark said:

Are there a lot of cases where the RA-2 would be a better choice?  Sure.  But there are other circumstances where the HG-5 works better, too.  It all comes down to ship design and play style.

^This.

@renhanxue you talk about other people options being 'unnecessary' and without 'real advantage'. The fact is: your options are also just a preference and may be as 'unnecessary' and 'impractical' from their perspective.

2 hours ago, renhanxue said:

How does that figure? A probe core weighs about as much as a HG-5 does.

Simple,  already have a bunch of stuff orbiting low(ish) every planet. Add a HG-5 and now it is a relay.