NERVous Nelly

[JoeSchmuckatelli]

I've got my first big interplanetary planned.  Just dropping by Eve for a social call, but I thought I'd also leave them a present.  Lot's of folks over at Mission Control interested in Eve at the moment, so I'm trying to do a bunch of stuff in a single mission.  

I foolishly accepted a 'Build a 5 person Base' mission, which, sadly I did not read.  It has to have 4k liquid fuel to count as a base.  Which, seeing as I don't yet have a mining operation anywhere looks to be an expensive lift.  Plus, I have to send a Kerbal on a flyby (thankfully I don't have to land a Kerbal).

Plan is to launch the Base Lander (which has some retrorockets and parachutes... so I'm hoping it will land), and separately, Jeb with a return Mk2 capsule sitting on a NERV with a bunch of fuel.  They'll dock and then Jeb will push himself and the lander down to Eve, hopefully not die out there in space, de-orbit the base, fly home and get a parade.

So... the question:

Having never used a NERV - I understand they handle weight well... but need long burns.  Presuming I manage the heat correctly - do I keep the craft oriented toward the blue indicator the whole time or is it better to hold prograde and watch the map for the encounter?

(Not done any really long burns, yet  -- and I only recently learned of the Maneuver Mode feature, so...)

[bewing]

Gilly is a really great place to mine for fuel. You would be wise to send a mining setup to Gilly to provide fuel for the Eve system, rather than importing 4000 units.

But otherwise you have landed yourself in a mightily-debated KSP almost-flamewar! *gasp* Should you slavishly obey the Maneuver Node Target? No you should not!!!!

So, for really long burns, break them in two (sometimes even 3 or more, if your TWR is really bad). Do all your burns pure prograde. Do the first burn a month or two before you are really ready to leave. While you are burning, make certain your orbit will bring you back to your Pe on the day you want to actually leave. 

[N_Danger]

 I have done single burns to eject from  Kerbin SOI around 4-5 minutes long and that means 2.5 to 3 minutes ether side of the node which is doable in one go. Anything longer you will need to do multiple burns over a long time.

  It depends on the mass you are pushing.

 

[JoeSchmuckatelli]

1 hour ago, bewing said:

Gilly is a really great place to mine for fuel. You would be wise to send a mining setup to Gilly to provide fuel for the Eve system, rather than importing 4000 units.

But otherwise you have landed yourself in a mightily-debated KSP almost-flamewar! *gasp* Should you slavishly obey the Maneuver Node Target? No you should not!!!!

So, for really long burns, break them in two (sometimes even 3 or more, if your TWR is really bad). Do all your burns pure prograde. Do the first burn a month or two before you are really ready to leave. While you are burning, make certain your orbit will bring you back to your Pe on the day you want to actually leave. 

How... exactly... would one know how to do this?

I tried to picture me even doing 3 burns to Minimus' SOI just for practice... and my eyes crossed trying to figure out how to work that with a single maneuver node to ensure contact / perapsis.

(or is that the problem?)

Edited May 27, 2020 by JoeSchmuckatelli

[bewing]

There are two ways of knowing when your "window" is to leave for Eve. Either you can use one of the online transfer window planners -- or you can have a craft in orbit, and every day or two you create a prospective maneuver node for that craft and see how good the transfer looks. If you use the transfer planner, then you will obviously know years in advance exactly when you will be leaving. If you do it using the manual Maneuver Node method, then you will be able to see a few days in advance that your window is coming up soon. It is doable to make a Maneuver Node, and then put another Maneuver Node for a second burn onto your projected orbit from the first burn -- if you really want to be certain that it will work. Or, you can just start flying by the seat of your pants.

Getting back to your Pe on a particular day involves calculating the number of days and hours until you want to be back. Then you hover and right click on your Pe marker to pin it open. Then you burn until the Pe marker says the right number of days and hours for you to get back to it.

 

[Superfluous J]

4 hours ago, JoeSchmuckatelli said:

How... exactly... would one know how to do this?

Mun orbits Kerbin in about 6 days. Minmus orbits it in about 50. If you get your ship up to Mun's orbit with a low Pe, it'll have an orbit of about 3 days. If you do so at Minmus' orbit, you'll have a orbit of about 25 days. The higher you go, the longer it lasts.

If you do the burn past Pe (and with a NERV you'll at least END your burn that way because you burn for so long) your Pe will tell you how long it will take to get there. Presumably (either through math, a website, or a mod) you know when to eject. So, just make your Pe time equal to how long until you need to eject. If you started too early, make it exactly 1/2 that time.

But I don't suggest doing more than a single orbit. Mun loves to get in the way and screw up your plans (or your ship. BOOM.)

[JoeSchmuckatelli]

Thanks fellers - i am gonna have to mess around with it later. 

 

[Laie]

17 hours ago, JoeSchmuckatelli said:

How... exactly... would one know how to do this?

Be sure to turn on the subtitles.