Sync Orbit MFD problem

[vchamp]

It looks like a bug in the Sync Orbit MFD. If you run the attached scenario, you will see that MFD shows a wrong time to the reference for the target vessel. Is this really a bug or I misunderstand something?

View attachment test.scn

 

[flytandem]

I wish I could help you. I saw that this post sat here with no response for a while. I am not very familiar with sync anymore since I started using transx a couple years ago. But running it I agree that it appears to be giving the wrong time for the GL-01 to get to the reference point, no matter which reference point you use or even if you switch ships and target back to the PB.

 

[Gorn]

Rinc between the ships is 0, so no problem there. Check out the difference in TrLs in Orbit MFD, then look at the DLng number in Sync Orbit MFD. For some reason Sync Orbit thinks the ships are a lot further apart than they really are.

I've been using Orbiter for a while now, and I found that Sync Orbit MFD is flaky; sometimes it works, sometimes it doesn't. I'll usually try to check it against something else. Orbit MFD is reliable, and if it disagrees with Sync Orbit's numbers, I'll go with it.

This will give some of the purists a hemorrhage, but since the target craft in your scenario (GL-01) has a very low eccentricity (0.0001), you can just treat its orbit as circular and assume that its angular velocity is constant. Its orbital period is 5245s, your orbits are aligned and it's 0.18 degrees TrL behind you, so it needs to go one full orbit + 0.18 degrees to get to where you are now. Which means if you set your orbital period to 5245s * (360.18/360) = 5248 seconds, you'll get to that point in the orbit at the same time GL-01 does the next time around ... and looking at your Orbit MFD numbers, I see you've already done that ...

Danny

 

[vchamp]

Thank you for your replies. It's a pity that such useful and necessary MFD is not very reliable. Since the bug is obvious I would like to post the report and hope that it will be fixed soon. Can someone please give me the right place where to post bug reports. Is the corresponding section of this forum the only place to do this?

Until the bug is fixed I must find ways to sync orbit using other methods. The orbit in scenario is not random. It lies perfectly in ecliptic plane. I use it for interplanetary ship assembly and will do many delivery flights, so I need the most convenient way of orbit syncing. Your, Gorn, method seems to be good. I didn't know about it and set the correct PB's orbital period accidentally. It will be interesting to know if there are other ways to sync orbits. TransX doesn't allow to select vessels as targets. I am not very familiar with IMFD. Maybe this or some other MFD could be used.

 

[flytandem]

TransX targets vessels and works very well to make either slow (several orbits) or fast (less than 1 orbit) approaches to ships.

Open your scenario and bring up TransX in the left MFD.
click...to get
VW Setup
VAR Select Target
ADJ Ships
++ enter your ship name, in this case, GL-01

You might want to choose a future orbit, comes in multiples of half orbits.
click VAR to get "Orbits to Icept"

You can either make planned maneuver burns or just burn on the fly. To burn on the fly, test with a bit of Lin in each direction to see which will reduce the Closest Approach the most efficiently.

 

[vchamp]

:speakcool:

I used TransX many times for Earth-Moon flights, but this MFD turns out to be even more helpful. It should be a good alternative for orbit syncing. Thanks for the help.

 

[garyw]

I've never used TransX - Always IMFD but this bug with SyncMFD could explain why some of my ISS rendevous are a bit off. Thanks flytandem for the little tutorial!

 

[martins]

It looks like a bug in the Sync Orbit MFD. If you run the attached scenario, you will see that MFD shows a wrong time to the reference for the target vessel. Is this really a bug or I misunderstand something?

Thanks for the bug report. I have tried to address the problem in the latest public beta (081007, can be found at http://orbitervis.wiki.sourceforge.net/OrbiterPublicBeta). Could you (and anybody else who found problems with sync orbit) please test this version and report back? Thanks!

 

[vchamp]

Hello, Martin. The Sync Orbit MFD works perfectly in 081007beta, at least in the test.scn. I couldn't hope to have this bug fixed so quickly! Thank you very much for this and for the Orbiter itself!