Problem Problem with Periapsis and Apoapsis

[Battlestar]

Hello everybody :hello:,

today I've noticed some strange behavior of the Periapsis and Apoapsis i never noticed before.

I was using the new Deltaglider IV-2. I reached a stable low Orbit around earth approx 200 km with. Ecc approx. 0,0003. I wanted to "meet" the new Arrow Freighter in a higher orbit (Rinc approx 0,02). Acctually I wanted to raise my Apoapsis a little bit when reaching periapsis. Usually, when I'm in a stable orbit they are not moving. But in this case they are somehow oscillating and moving around. The same is happening for the Periapsis and Apoapsis of the Arrow Freighter. At the same time, as a result of this, the PeT and ApT are not changing in full second increments. To make a long story short, I cannot reach Periapsis. Can somebody explain what the reason might be for this behaviour? lease:


Thanks

 

[dgatsoulis]

Hi battlestar,

Which orbiter version are you using?

 

[Shadow Addict]

They will naturally vary in altitude a bit if you have non-spherical gravity turned on. Also, if i remember correctly, in a circular orbit, the PeA and ApA will shift around in the MFD because they're at the same altitude, so there's not really a lowest or highest point.

 

[Battlestar]

Thanks for your quick answers. :thumbup:

In the meantime I found the solution in another thread, describing a slightly different problem.

It was indeed the "non-spherical gravity"-switch, which I had turned on.
Everything goes smoothly right now and i hope to dock to Arrow Freighter One in about 7600 - 8000 seconds

But if this non-spherical gravity is something in the Real World, how the hack are they dealing with it in real spaceships?

Anyways, Thanks again

Happy Orbiting :tiphat:

 

[Shadow Addict]

Yeah, I've been playing Orbiter for four months and I still haven't gotten around to turning on non-spherical gravity.

 

[Tommy]

In an orbit with a bit of eccentricity, the PeA will tend to oscillate over about 1/3 of the orbit, but stay on the same side. You will get to it eventually, but timing that arrival accurately in advance is difficult. If your orbit is very circular, you may never catch your Pe, but it really doesn't matter since you're sort of always at Pe.

How do they deal with it in real life? Lots of preflight simulation, and an "approach by small steps" methodology. Each step brings you closer, but leaves a margin of error appropriate for the desired distance from target.

Once you get used to it, non-spherical gravity isn't hard to deal with. Docking with "Gravity Gradient Torque" is far more difficult, as you won't stay rotationally aligned for any length of time.