How to maneuver big, slow ships effectively

[jeti140973]

Suppose you have a big, clumsy and slow ship (TWR < 0.25) in orbit around Kerbin, and plan to fly to, say, Duna.

You make a maneuver node, and the burn duration is estimated to about 10 minutes (or longer). Your ship will move a lot during that time.

So my question is: how do you executive such a maneuver effectively?

- Should I split the burn 50/50 between the burn point, starting the burn five minutes early?

- Or, should I perhaps execute multiple smaller burns over several orbits?

- And should the ship point towards the maneuver node indicator on the navball the entire time, or is it better to point prograde during the entire burn?

In my experience the end result is never aligned with the planned trajectory, and it makes my flights a bit... troubling. Help appreciated.

[rryy]

To be the most efficient, I would suggest you perform smaller burns over several orbits at periapsis. Also, if your periapsis rises significantly in the prograde burns, burn retrograde at apoapsis to lower your periapsis to get the most effect out of the Oberth Effect.

[Shrike42]

You're at maximum fuel efficiency when you burn prograde at periapsis; I'd suggest multiple smaller burns on multiple orbits, even though it's more tedious, because you can improve fuel economy that way, and have plenty of opportunities to correct your orbital inclination.

Mechjeb does a 50/50 burn split around a manuver node (Note: I don't use MJ myself, this is just what I've heard here). If you do that with your periapsis, you'll likely have a much saner piloting experience doing 10 1 minute burns than 1 ten minute burn.

[NovaSilisko]

Do an initial burn to about 75% escape velocity incrementally then do the final kick with your manuever node. Don't do multiple burns for the same manuever node, it breaks if you burn at the node on different orbits (dV indicator going upward if you do it one orbit around for example)

[RoboRay]

Yes, just use the maneuver node for your first burn, to establish your Pe at the proper ejection angle. Just burn prograde as you pass Pe for the rest of your "Pe kicks" until you are ready to make the final injection burn. Then, set up a new maneuver planning node at your Pe for the last burn.

[Tank Buddy]

Well, if you want to get as close to the maneuver node's result as possible, you should start the burn five (5) minutes early, and burn five minutes after. This means starting at burn

-5:00 and ending at +5:00. You should hit "burn in 0:00" as you pass over the node. You will want to burn towards the horizon the whole time, but I'm not sure. It probably won't kill you so don't worry about it. Also, be sure to make corrective burns while escaping Kerbin or in Kerbol orbit. Remember, your burns will have a greater effect the further you are from the encounter, so don't hesitate to make corrections, as you will have to use more fuel if you save for the last minute. Fiddling with the maneuver nodes will also guide you. Try Dying To Live posted a video with the "hidden" KSP options, one of which lets you better see how you will encounter the target. This will help with precision insertion. I hope this helps, and feel free to contact me if you need further assistance. Good luck, fellow Kerbonaught!

P.S.: If push comes to shove, I would recommend making a smaller ship or adding more powerful engines, as this will cut your burn time.

[Markus Reese]

I do a rough staging just to capture orbit then a second burn to catch atmosphere and make adjustments to allow an aerobrake. Without mods, it is very tough to get perfect intercepts manually on massive ships. Better to do it in steps even if less efficient.

[dronkit]

With either method the question is how do you time the maneuver (s) for an encounter ? Specially in the case of several burns over several orbits, you need to know how long will it take you to achieve the transfer orbit, to start the maneuvers in advance to catch the planet (ie the phase angle should be the transfer time plus the maneuver time (?))

[zekes]

I have found USE TONS OF RCS. And when you are in line for a maneuver, warp so the ship stops rotating.