KTO node position for specific positioning

[federicoaa]

Hi,

Suppose we part from a 100km equatorial parking orbit and want to transfer to KEO so that the craft stays exactly on top of the KSC.

Where should we place the KTO node so that the resulting AP coincides with the KSC location?

Thanks.

[Alshain]

Well, that one is a little hard to answer because we don't know the location of KSC at any given moment in someone elses game play.  The best way to accomplish this is extend your Ap out to KEO,  Then if KSC is 'behind' you then make your Pe a little bigger than KEO so KSC will catch up.  If KSC is 'in front' of you, make your orbit a little lower than KEO so you will be traveling faster than the rotation of the planet.  Once you are in position, circularize your orbit at 6 hour orbital period.

Of course 'in front' and 'behind' are relative since KSC will always be both in front of and behind, but of course I mean where it is closer.

Remember, if your orbit is larger than KEO you are traveling slower than the rotation of the planet.

Edited May 13, 2016 by Alshain

[Venusgate]

I would see what your orbit time/2 is between Pe and Ap with a maneuvering node; take that number, over 6 hours; take that number * 360 degrees, and that is how many degrees removed from KSC you should start your place your burn.

[federicoaa]

@Alshain I know that way. I was wondering about a mathematical approach. I don't know enough orbital mechanics to calculate the answer.

My thinking is that taking into consideration the travel time for the Hohmann transfer from 100km to 2863km  and the rotation of Kerbin, we could find the timing to place the node.

 

Lets see, using wikipedia I get that

the fly time from 100km to 2863km is 10040 seconds (2 hours 47 min 21 sec)

Since kerbin rotation is 6 hours, we should depart almost oposite to KSC (167 degrees if KSC is at 0)

Am I right?

Edited May 13, 2016 by federicoaa