Single launch Commnet

[grimlock14]

Caveat:  I  admit that it is entirely possible that I was being too cute for my own good. 

I've launched my first fleet for Duna, and it includes a ship with a stack of  HECS cores each with as battery, a pair of OX-4L solar panels, and an RA-2, with decouplers to separate them.  The plan is to arrive at Duna with plenty  of delta V, park myself in nice wide orbit, say 4-5 Mm, pop off the first relay.

And this is where I've hit a rough patch.  What sequence of maneuvers will put me back in the same orbit, but X degrees ahead(or behind) the first relay?

[The Aziz]

Technically, you could just raise the apoapsis a bit, that way when you reach peri again you'll be behind your probe, then just burn back to desired orbit. But there goes the math, how far you'll get after maneuver of your choice, and that I do not know, but probably there is a way to tell for sure.

[4x4cheesecake]

There is nice web app to calculate resonant orbits: https://meyerweb.com/eric/ksp/resonant-orbits/

Set it to Duna, the number of relays you want to release, the orbital altitude you want for your relays and the app will tell you, which Pe and Ap you will need to place your relays evenly spaced. Put your ship in the orbit calculated by this app and release a relay every time you pass the Ap (Dive orbit setting enabled) or Pe (Dive orbit setting disabled). Basically, relase one each time you reach the desired orbital altitude.Then switch to your relay and perform a circularisation burn.

Done

[LordFerret]

34 minutes ago, 4x4cheesecake said:

switch to your relay and perform a circularisation burn.

The problem is, these relay probes the OP is describing have no propulsion system onboard.

This will present a future problem; Unless the probes are placed in very precise orbits (MechJeb), they'll change position (in relationship to each other) over time. I put Ion propulsion systems on my relay probes, because I don't use MechJeb, and tease them into their orbits. Being able to set the Ion drive thrust limit to 1% makes orbit circularization tweaks easy. Also, over the course of 50 or 100 years or whatever, should probes drift out of the desired constellation, they can be easily put back in place.

[4x4cheesecake]

33 minutes ago, LordFerret said:

The problem is, these relay probes the OP is describing have no propulsion system onboard.

Uh, you are right. Well...if the relays don't need to be perfectly spaced, it is still possible to use the resonant orbit:

-> resonant orbit -> circularization burn -> release relay -> burn retrograde back into resonant orbit -> repeat

It will not be very acurate, but actually you will never be acurate with any kind of low thrust propulsion (I'm using RCS thruster with a thrust limit of 0.5%)

33 minutes ago, LordFerret said:

This will present a future problem; Unless the probes are placed in very precise orbits (MechJeb), they'll change position (in relationship to each other) over time.

Unfortunately, yes, they will drift away. Have to disagree on the mechjeb part though, you can achive very precise orbits with less then 1m difference between Pe and Ap without this mod (but I'm sure you know this ). Might be easier though...

Edited July 15, 2018 by 4x4cheesecake

[MR L A]

29 minutes ago, 4x4cheesecake said:

56 minutes ago, LordFerret said:

This will present a future problem; Unless the probes are placed in very precise orbits (MechJeb), they'll change position (in relationship to each other) over time.

Unfortunately, yes, they will drift away. Have to disagree on the mechjeb part though, you can achive very precise orbits with less then 1m difference between Pe and Ap without this mod (but I'm sure you know this ). Might be easier though...

You're both wrong here.

1) MechJeb, afaik, is not capable of ultra precise orbits with comsats

2) Less than 1m difference between Pe and Ap is completely irrelevant - you need to install KER and set exactly matching orbital periods i.e. time of orbit. You can fairly easily have an orbital period that matches your other sats to within one THOUSANDTH of a second - this is the smallest unit of time KER will display. I don't know if the game actually deals with units of time smaller than this, so assuming you match all sats within your network with the chose OP, they will never drift. 

[4x4cheesecake]

@MR L A Correct me if I'm wrong but identical relays, orbiting at an identical orbital altitude will result in an identical orbital periode, right? So where is the difference between 'try to match orbital periode' and 'try to match Ap & Pe'? The result (matching orbital periode) should be the same.
Of course, you don't need to match Ap & Pe to get an identical orbital periode, but if you want the relays in the same orbit (like the OP), I don't see any difference.

 

edit: Oh, I guess it's just a lack in my english skills to be more precise in my explanation...let me try again: If you match the Ap of relay 1 with the Ap of relay 2 and the same for their Pe, you should end with the same orbital periode.

Edited July 15, 2018 by 4x4cheesecake

[LordFerret]

37 minutes ago, MR L A said:

1) MechJeb, afaik, is not capable of ultra precise orbits with comsats

That was just a guess on my part. I don't know zip about MechJeb, I've never used it.

 

38 minutes ago, MR L A said:

2) Less than 1m difference between Pe and Ap is completely irrelevant

This is true. But we're not talking about that, or using KER, and we're not even sure the OP has MechJeb. The OP wanted to know what kind of maneuvers could be used to accomplish the task, and that was defined (The Aziz & 4x4cheesecake). What I was pointing out, was the potential that this manner of (imprecise) placement will likely lead to drift over time, and that the OP's probes have no propulsion system to compensate.

 

I'm sure the OP's efforts at this point will suffice for a good few years (depending on the care and precision of their initial placement), but I'm also pretty sure that in the future they'll find those probes out of alignment.

[Vanamonde]

This question about how to play the game has been moved to Gameplay Questions. 

[MR L A]

6 hours ago, 4x4cheesecake said:

identical orbital periode, right

It could do, but it is the most difficult way of doing so and is very inaccurate compared to simply synchronising the orbital period.

5 hours ago, LordFerret said:

What I was pointing out, was the potential that this manner of (imprecise) placement will likely lead to drift over time, and that the OP's probes have no propulsion system to compensate.

and I'm pointing out that they needed drift if they're set up properly in the first place and that if OP would like to do so, KER can help them out. In other words, you're pointing out to the OP that drift can be a problem without propulsive compensation, I'm pointing out that drift can be virtually negated and that propulsive compensation is not required.

I fail to see how my post is somehow not part of the same conversation as you suggest? 

[Superfluous J]

Hint: If you have enough satellites, you don't NEED to account for drift. Or set up any particular orbit except wide (to miss Ike) and polar.

I'd use the decoupler's fairly strong (for the case of your tiny hecssats) power and not change the orbit of the mothership at all. I'd just get into an orbit, and at Pe or Ap eject a satellite retrograde or prograde. Do that 10 times - in 10 orbits - and your satellites will be spaced out fairly well. If you quicksave first and adjust your orbit on a reload, you can even space them out perfectly. Though they'll naturally drift over time as their orbits will each be slightly different, because each time you toss one the mothership's orbit will change slightly. You can correct for this by burning it back down to the same speed each time, but I don't bother.

I strongly suggest a polar orbit, because most of what you do will "see" satellites north and south of you, and not be blocked by Duna or Ike. If you can afford the dV, rotate that polar orbit 90 degrees halfway through tossing the satellites, and you'll likely never ever lose coverage.

I've found that 100% coverage is a lofty but impractical goal, and just accepting 90+% coverage for 1% of the work is fine.

[Kryxal]

My personal preference is for eccentric orbits for multiple commsats (probably inclined as well), it means you're spending a lot of your orbit in roughly the same place.