LV-N atomic engine question

[magnemoe]

hey RoboRay, i installed the protractor mod, and it works great. but i do have a question, when going to moho which has a somewhat elliptical orbit i notice that the protractor doesn't seem to compensate for it and my maneuver seems way off the mark. how do you get around this, do you wait for the next launch window when moho isn't in a particularly "elliptical" point in its orbit?

I always use Protractor as an guide, then to launch and estimated angle, then I make an node and burn after it. Trying to burn blind with low TWR is likely to be expensive to fix.

The important thing with moho is to get the intercept at the pe of the solar orbit to reduce the speed as much as possible. Going to Eve its not so important as you will aerobrake, for Dres and Eeloo you move pretty slowly anyway but putting your orbit inside Moho's give you an serious speed.

My first attempt came in in over 6000m/s, no chance of getting into orbit so I tried to land

[tavert]

None of the current mods or calculators for KSP transfer injections account for orbital eccentricity or inclination, AFAIK.

MechJeb2's interplanetary maneuver planner gets closest. It does the transfer burn in the ecliptic, but it chooses how much delta-V to use for that burn by minimizing the actual closest approach distance taking the eccentricity and inclination of the target's orbit into account. If you don't happen to get closest your destination when it is at its AN or DN, then you will miss it. However the "fine-tune closest approach" option in the MechJeb2 maneuver planner uses a real Lambert solver. It fixes the time of closest approach to be the same as the time of closest approach of the current orbit (kind of an arbitrary decision, but done so the minimization of delta-V is over a single variable) -- the in-ecliptic transfer, then chooses when to place a correction maneuver to minimize the delta-V that achieves an intercept.

Edited May 9, 2013 by tavert

[creator1629]

im comparing the phase angles the protractor mod gives to the phase angles recommended via ksp.olex.biz/mechjeb and i notice that they seem to be different by more than 10 degrees, does anyone know what accounts for this difference?

[John FX]

I find by the time you have an orange tank on a single nuclear engine it sort of hits the point of negative returns as far as functionality goes.