I am going to Moho, what inclination should my Kerbin orbit be prior to the ejection?

[JacobJHC]

Hi, I have designed a big big ship to send 50 Kerbals to Moho and back. However, I want to be as efficient with possible with my ejection so I don't have to wait 1 hour for my ship to match Moho's inclination with a giant correction burn. What inclination should my Kerbin orbit be before I begin my escape burn? I plan to achieve this inclination by launching in that direction.

[Cunjo Carl]

@JacobJHC

I can't speak from personal experience, but @Turbo pumped was known for some insane optimizations along these lines, and has a Moho run which shows off the maneuver you're planning. I'll put the youtube video in the spoiler... looks like 15ish degrees. Also don't forget you can plane change at Eve if you happen to find a Kerbin->Eve arrival time near a Eve->Moho leaving time on a transfer calculator. Just at a glance, I'm finding

Place    yr x day
Kerbin   8x207
Eve       9x42
Moho    9x143

50 Kerbals to Moho!? Sounds like a heck of a trip.

Spoiler

 

 

Edited April 10, 2017 by Cunjo Carl

[Razorforce7]

Not sure what you have available. But I would first recommend THIS or alexmoon's planner online.

Two answers.

1: No inclination at all. You go to Eve first and use a gravity slingshot to both lower your 'Pe' and change inclination around Kerbol to match Moho's (this takes the least Delta V)
2: Based on earlier attempts I've directly send my craft on a east/southeast heading (starting at about 110degrees) That still required a inclination change though.

THIS can help you with gravity assist planning like that needed for Eve in case you've never done gravity assists before.

Edited April 10, 2017 by Razorforce7

[Cunjo Carl]

@Razorforce7 Jinx! ... Razorforce7.

Edited April 10, 2017 by Cunjo Carl

[FullMetalMachinist]

3 hours ago, JacobJHC said:

What inclination should my Kerbin orbit be before I begin my escape burn?

That depends on if you care what your final inclination around Moho will be when you get there. If you don't care too much about it being perfectly equatorial, then no inclination for your departure orbit is fine. 

The best way to Moho (disregarding an Eve assist) is to leave when Kerbin is lined up with Moho's An/Dn, which happen to be in the same spots as it's Ap/Pe. More info here:

Spoiler

Ignore traditional transfer windows and phase angles, don't use launch window planners, and just leave when Kerbin is at Moho's Ap.  

Since you left at one node, you'll intersect Moho's orbit at the other node half an orbit later, even though you don't have the same inclination. The problem is that Moho won't be there when you are (unless you're incredibly lucky). To fix that, use the "future orbit projection" trick. 

When you're in solar space between leaving Kerbin and getting to Moho's periapsis, place a node at the Pe. Make a slight retrograde adjustment (to the node, don't actually burn yet). Then click on the dashed-lined post-node orbit to place another node. Leave the second node alone, don't make it actually do anything, it's only a placeholder. 

Now go back to the first node and continue pulling the retrograde handle until you get a Moho encounter. If it takes a long time, right click on the second node and click the 'one orbit later button'. Then keep adjusting the prograde/retrograde handles of the first node until you get an encounter you're happy with. 

Then you execute the first node and wait for your encounter to happen. The only problem is that this leaves you with a fairly high inclination in your final orbit around Moho. If you want it closer to equatorial, you can combine an inclination adjustment to your Kerbin escape burn for only a few hundred m/s of dV. But it's still much easier to just launch equatorial around Kerbin first. 

 

Edited April 11, 2017 by FullMetalMachinist