Flight Question Almost there........nevermind

[MJR]

This is my scenario. I launched the Shuttle to the ISS. My RInc is about 0.5 degrees. My CVEL is increasing, but then it starts to decrease. No matter if I burn at the -V[ISS] or +V[ISS] it does not increase. What do I do in this case. I never had a problem with this and I am only 7km away and the ISS keeps getting further away.

 

[eveningsky339]

Ensure that your relative inclination is as close to 0 as possible. A high rel. inc. can cause this sort of drift.

The most likely culprit would be gravity-gradient torque. This can be enabled/disabled in the Orbiter launchpad. If it isn't disabled, do so and see if the problem persists.

 

[MJR]

Thanks for the tips. I will try it and get back to you on it.

 

[Arrowstar]

Try burning toward the station when you get that close. The V+/- vectors are for nulling translational rates, far as I can tell. (Someone correct me if I'm wrong.)

 

[IthyStPete]

The V +/- vectors just show where you're going; pointing towards the +V[ISS] and burning should increase your CVEL.
Nonspherical gravity might well be the problem, but if it isn't, you'll just need to be more precise when aligning planes and setting up your rendezvous in Sync MFD. (assuming you use that) I can usually get a closest approach within a kilometer. With the relatively weak Shuttle OMS, you'll just have to start burning from a ways away.

 

[MJR]

The V +/- vectors just show where you're going; pointing towards the +V[ISS] and burning should increase your CVEL.
Nonspherical gravity might well be the problem, but if it isn't, you'll just need to be more precise when aligning planes and setting up your rendezvous in Sync MFD. (assuming you use that) I can usually get a closest approach within a kilometer. With the relatively weak Shuttle OMS, you'll just have to start burning from a ways away.

I guess I'll start the scenario back and start the burn to gain CVEL. I also shouild have aligned my plane better as I had thought that as long as it is below 1 that it is fine. I guess not. Thanks.

 

[Kaito]

Yeah, what I do is I just burn directly towards it if something starts to go bad. Are you sure your DTMin is 0.00?

 

[MJR]

I think I forgot to do that. Since I obviously can't reach my periapsis at the moment to lower my DTMin, what do I do?

 

[astrosammy]

Just lower your DTMin with linear RCS. Should be possible.

 

[Kaito]

well at 7km, DTmin should'nt matter terribly much. Although with the shuttle, its a different story...Yeah, just watch your DTMin