OHM Tutorial: DG to ISS

[OrbitHangar]

Author: ar81

[FONT=Arial, Helvetica, sans-serif]With this tutorial you will understand how to take off from Cape Cañaveral to reach ISS.
This is not really a tutorial about how to understand MFDs (that's what's the Orbiter manual for).
This will explain graphically what you are doing when you pass through the different actions to reach ISS.[/FONT]

[FONT=Arial, Helvetica, sans-serif]This will not explain the controls you need to pilot the craft, not basic concepts on how to pilot a plane.[/FONT]

[FONT=Arial, Helvetica, sans-serif]This tutorial is not intended to be very basic.
It is more a tutorial to help people to understand graphically what is the general logic of going to ISS using a Delta Glider.
It provides awareness about how to understand things.
So you may excuse why this tutorial is not explaining basics of atmospheric flight.[/FONT]

[FONT=Arial, Helvetica, sans-serif]The main focus was to understand what happens once you are in orbit, and why you do things and not only what to do.[/FONT]



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[WelshGit]

Thanks for this tutorial.. I found it well written and easy to understand..I'm now performing alignments and orbit syncs like an old hand..My only problem now is docking. BUT.. Think I have finally got that part licked! I'm now 800 meters away with 0 relative velocity. Looking good.. Guess thats the secret matching speed before trying to do the fine stuff. But anyway great tutorial. helped me no end.

 

[ADSWNJ]

Think I have finally got that part licked! I'm now 800 meters away with 0 relative velocity. Looking good.. Guess thats the secret matching speed before trying to do the fine stuff.

Yup definitely. You need to align planes first, so you have 0.00 relative inclination. Then you need to sync your orbit to arrive at the same place in the orbit as the ISS. Think of this like reeling in a fish on a line ... target say the ISS periapsis and come up from beneath to match your orbit's apoapsis and periapsis to match the target as closely as you want. The lower you get your closing speed at the RV point, the better matched your orbit is and the less you will drift on final approach. Once within say 10km, null out your relative velocity on the docking MFD, and look for the docking corridor (hit HUD to see this). Roll your nose onto the end of the docking corridor and fly gently towards it. Once you are within say 50m of the last rectangle on the corridor, you are ready for final alignment and approach.

For this last phase, you need to align in 5 degrees of freedom (pitch, yaw, roll, left-right, up-down), and then approach in the 6th degree (forward-back). Work on each degree at a time until you are quite tight on track.

One thing that can help you is to switch to the target (F3, select ISS), and set an autopilot (e.g. PROGRADE), to hold alignment, (then F3 and switch back to your ship). Or do a Scenario Editor (sh-F4), select ISS, then select angular rotations and kill them. Of course you can still dock with the target wobbling around, but it's way harder!

If you want, have a look at my Rendezvous MFD (in Orbit-Hangar.com). The autopilot is not stable yet, but the HUD and tracking is accurate for manual flight. You also need to install the HUD hooking code too.

 

[WelshGit]

I'm managing to align planes on ascent now (within 5 degrees) Pretty pleased with myself over that! I found out my biggest problem with docking..I had no keys set forward forward/reverse thrusters, I assumed that would be on joystick forward/backward.. Kinda difficult to dock without those! Still haven't quite licked it but with your excellent advice to switch vessel and engage autopilot.. I thought the damn thing was moving as I approached (ever so gingerly!) That just might make the difference. Thank you! Can't get my head round rendezvous MFD yet..Its my next thing to learn. I'll admit since I picked this software up a week ago I've spent as much time researching as I have flying but that is part of the joy for me. Oh hang on do I need another package to link the MFD to the HUD?

 

[ADSWNJ]

yeah - it needs HUDDrawer SDK v0.3 to do the hooking. unzip this on top of the Orbiter directory, then you should be fine.

(Also the usual note about VC runtimes ... any missing MSVC*100*.DLL means you need to install the MV VC runtimes (2010 SP1) from Microsoft.com.)

Oh - and fly the approach on your numpad keys for much more precise accuracy than joystick. It takes a few goes until the keys are natural, but you will be highly rewarded.

 

[WelshGit]

Thank you. Your right it is easier with the keypad.. Might have to break out my hacksaw, super glue and soldering iron and see what I can make with my spares pile :hmm: But either way I finally got docked! happiest day of my week! Anyhow this is a bit strange.. I searched for HUDDrawer SDK v0.3 with the forum search button and got no matches.. Not even this thread where I cut and pasted from! It seems the orbiter website is down at the mo so couldnt search there. Could you give me a link please?
Oh cancel that request.. Found it. Good old ****** (Unmentionable tax dodging search engine)

 

[Astro Tom]

I am managing to get aligned with the docking port but whenever I begin approaching for final docking (with the fore and aft translation) I start to drift around on the roll and yaw axis, HELP...

 

[Tenmu-101]

Thanks! it worked for me!

 

[johan]

I am managing to get aligned with the docking port but whenever I begin approaching for final docking (with the fore and aft translation) I start to drift around on the roll and yaw axis, HELP...

What I've found sometimes, is that in some scenarios the ISS has (or develops?) a small amount of spin, and this causes it to be VERY difficult to dock unless you can do it very quickly - ram it home and shoot the bolts.

The solution for me was to change the ship view to the ISS, and hit the "killrot" autopilot (keypad "5", is the shortcut, IIRC). I was surprised that this worked, because I didn't think the ISS in Orbiter was supposed to have RCS thrusters or fuel on board... but hey.

 

[Enjo]

Mir doesn't have, if it helps you somehow

 

[sorindafabico]

What I've found sometimes, is that in some scenarios the ISS has (or develops?) a small amount of spin, and this causes it to be VERY difficult to dock unless you can do it very quickly - ram it home and shoot the bolts.

The solution for me was to change the ship view to the ISS, and hit the "killrot" autopilot (keypad "5", is the shortcut, IIRC). I was surprised that this worked, because I didn't think the ISS in Orbiter was supposed to have RCS thrusters or fuel on board... but hey.

You can also use Scenario Editor >> Edit >> Angular velocity >> Kill without leaving your ship.