Ideal Interplanetary Departure Orbit, Oberth vs Time Warp

[footman04]

I've been thinking about interplanetary transfer orbits lately. A low orbit, let's say 100 km circularized, would enable you to gain much more usable velocity from a smaller amount of propellant due to the oberth effect. However, a higher orbit, let's say 600 km circularized, would allow you to utilize the maximum amount of time warp, giving you more freedom to wait for a transfer window without utilizing a second craft.

What I am wondering, is how much delta v do you then sacrifice in utilizing the higher orbit for a Duna or Jool departure?

Edited August 29, 2013 by footman04

[Johnno]

1. Find out how much extra delta-v you need to get to 600km orbit from 100km orbit.

2. Use http://alexmoon.github.io/ksp/

3. Math

4. ???

5. Profit

[Mr Shifty]

Higher orbits also have lower escape velocities.

[bsalis]

If you don't want to time-warp using a different craft you can just time-warp on the pad before launch. Theres no time-warp limit when pre-launch (or landed for that matter).

If you time it right you can launch directly into the transfer and not bother with an orbit at all. My understanding is that is actually the most efficient way to do it.

[SRV Ron]

Just because some of the bigger ships are spin unstable, they work best by directly launching them to escape velocity. The best timetable for launch is from midnight to dawn for the outer planets and noon to dusk for the inner ones. Just be sure that you shut down the instant you hit escape velocity as an elliptical orbit can be far less efficient for planning the capture burn then a nice circular one.

Of course, if timed right, you can go from launch to transfer burn all in one step.

[Tank Buddy]

Your best bet is going for a lower orbit so you use less of your Delta-v on circularizing some silly orbit that will not matter for the majority of your trip. You can switch to another craft to time warp faster, but fist try to launch a day or so before your window for flexibility.

[MrPopcup]

I'd say you put your craft in lower orbits, dock if you have to, then send them to 600 km orbit, send a refueling missions to refuel, then head interplanetary, as others said, more delta-v to reach higher orbits but LOWER delta-v to escape, also lower gravity and all that stuff, everything is related to each other. it's only up to you. I'd do what I said, I find it perfect!

[Guest]

I find that a 200km parking orbit is about right for interplanetary burns. I have the boost stage circularize me up there and then jettison it, leaving me with a full load of interplanetary transfer fuel. Time warping isn't my concern since I have a rover parked at KSC for advancing launch dates, the real reason I go to 200km is that long burns (8 min+) at around 100km tend to dip you into Kerbin atmosphere.

YMMV and everyone has their favorite way of doing things.