Eeloo comnet

[bjerrang]

Got a launch window for eeloo in 22 days.

Going to send 2 ra-100 relays.

Im guessing the solar power aint enough to run the satellite without overdoing the panels.

How many PB-NUK Radioisotope Thermoelectric Generator are needed to run Ra-100 and a RC-001S Remote Guidance Unit , im guessing i dont need a extra battery with this layout.

or

How many 1X6 panels are needed to run it safely at the furthest distance combined with Z-1k Rechargeable Battery Bank

 

brg

 

Bjerrang

 

[Draalo]

Relayantennas need at least a positive amount of EC to operate but they dont consume EC while relaying.

So you just need enough EC replenish to operate the RC-001S - guess 1 PB-NUK will be enough.

Just test it on the launchpad, combine the probecore with one RTG, if the EC isnt decreasing, its enough.

If you want to send science directly from that sat you only need enough EC in batteries to send the biggest one, recharging with even a very small amount per minute is enough. Wait till batteries are full again, send next experiment, repeat.

Dont have the numbers at moment, but guess you are fine with 1k EC and one RTG - one RTG equals a 1x6 panel in Kerbin orbit.

Edited October 7, 2017 by Draalo
typos

[bjerrang]

so 1 PB-NUK Radioisotope Thermoelectric Generator is enough.

But how many solar panels so i need without the PB-NUK Radioisotope Thermoelectric Generator on eeloo

[Spricigo]

I don't know how much energy a solar panel will produce around Eeloo, but you can quickly find out using the cheat menu [set orbit].

Edited October 8, 2017 by Spricigo

[Geschosskopf]

9 hours ago, bjerrang said:

Im guessing the solar power aint enough to run the satellite without overdoing the panels.

How many PB-NUK Radioisotope Thermoelectric Generator are needed to run Ra-100 and a RC-001S Remote Guidance Unit , im guessing i dont need a extra battery with this layout.

Antennae only need power when transmitting Science!  For everything else, you only need power to run the probe core.  So if the CommSat has a large enough battery (a few thousand EC storage usually does it), all you need is enough EC/sec to keep the probe core from dying.  You can trickle-charge the batteries between the occasional instances of needing them to power Science! transmissions.

IIRC, a Gigantor solar panel produces about 0.9 EC/sec at Jool.  In any case, it averages somewhat less at Eeloo, although it briefly does a bit more when Eeloo is inside Jool's orbit.  An RTG always does 0.8 EC/sec unless you have a mod that makes them die off.  So you need however many of those to keep the probe alive, plus some extra to trickle-charge the batteries.

[Spricigo]

Btw, you don't even need a buffer for science transmission, just let you antenna [allow partial]. OTOH Reaction Wheels may require a bit during maneuvers. 

[Geschosskopf]

44 minutes ago, Spricigo said:

Btw, you don't even need a buffer for science transmission, just let you antenna [allow partial]. OTOH Reaction Wheels may require a bit during maneuvers. 

But you still need more EC/sec than what the probe core and anything else you're always running on it need.  Otherwise, the transmission will never complete.

[bjerrang]

No science on the relays.

Did a test launch. Had to little delta v to catch the orbit.

The map says 2000dV to get a encounter ,  1370dV to orbit. 

I would guess i need 2300dV based on the nodes. 

Why is the delta V map wrong or is it my bad encounter ? 

[Draalo]

Eeloos orbit is not only inclined but also eliptical. I use this dV map:

https://wiki.kerbal7spaceprogram.com/wiki/Cheat_sheet

In worst case the dV are 1140m/s for the encounter and 1330 m/s to match inclination, so 2470m/s in total.

 

If Kerbin is at the Eeloo AN/DN the transfer will be cheaper.

[bjerrang]

Thats the sheet i use. I got a 2000dV (lowest possible dV from kerbin) from kerbin. 

Then to make a orbit i used 2300dV .

I dont understand cause the dV map says kerbin -> eeloo 950+1140+1370 = 3460dV and i used ~ 4300dV .

Might have to try get the inclination better at kerbin launch 

[Geschosskopf]

8 hours ago, bjerrang said:

Why is the delta V map wrong or is it my bad encounter ? 

I would say it's probably a bad encounter.  The standard dV map is based on the best-case scenario of leaving Kerbin when the planets are aligned so that when your ship gets out to Eeloo, Eeloo is at whichever of its AN/DN that's closer to Kerbin, AND that your ship encounters Eeloo with as little angle as possible between their trajectories. 

The size of the transfer burn (or Hohmann 2-step burn) from Kerbin depends on:

• How far away in the horizontal plane Eeloo is at the time, which varies because the orbit is elliptical
• How far above or below the ecliptic Eeloo is when you get there, which determines how much of an inclination change you have to make

The size of the capture burn at Eeloo depends mostly on the angle between your trajectory and Eeloo's orbital path, which is determined by the transfer burn.  Ideally, after the transfer burn, your Ap should be right on the orbit of the target planet.  The further your Ap is out beyond the target orbit, the more radial velocity your ship has to kill off when it arrives, and the less circumferential velocity it already has in the same direction as the target, so the more of that you have to create.

Getting the Ap right on the target orbit becomes more and more critical the further away the target is.  This is because the greater the distance between your Pe (at Kerbin) and Ap (at the target), the more eccentric  your transfer orbit is (as in longer and skinnier).  So at Duna and Eve, the precision of the transfer burn isn't very critical because your Ap and Pe aren't far off from being circular.  But at Eeloo, your transfer orbit is a very skinny ellipse, so even with the Ap only "relatively" out beyond Eeloo, you'll still intercept it on nearly a perpendicular path, which causes a large capture burn.

[bjerrang]

Good info. Tried to match the inclination as best as possible now on my 2nd try.  The capture angle on eeloo is a bit extreeme. 

[Palaceviking]

A gravity assist from Jool solves nearly all eeloo based problems (except for questioning why you bothered).