launch window

[startrekmaniac]

Can someone on post a picture of lunch window to the ISS? Thanks!!!!

 

[garyw]

a lunch window is when the crew breaks for lunch. NASA TV has pictures of them eating.

A LAUNCH window is when the path of the ISS passes over the launch site.

 

[pandadude]

Use map MFD. When the ISS' orbit goes over your launch site, that's when you launch. You could also open up Align MFD, target the ISS and wait until Relative Inclination is at a minimum. Alternatively, you could use the launch heading MFD (is that its name, I can't remember?).

 

[garyw]

It's Enjo's launch MFD. You can also use the align planes MFD.

 

[startrekmaniac]

Can someone show me a picture? Im trying to get to the ISS but I think my window is bad. Just something to go off of.

 

[Master of Blades]

It would be easier if you'd describe exactly what you do when you are trying to get to the ISS, so we can identify your problem. There might be other faults than just the launch window.

For seeing the launch window though, just target the ISS in Map MFD, and when the yellow line passes over your location (or very close), it would be a good time to launch.

 

[startrekmaniac]

It probley is not the window. I have been trying to get to the iss for a while and havent been able to. I havent played for a while. I just want to see a picture from the mfd. Please!!!

 

[Urwumpe]

Do you know how to fly a rendezvous?

 

[TSPenguin]

The first two pictures on this polish site feature perfectly good examples of launch windows.
http://www.elwico.pl/~ender-sz/orbiter-pdf/instrukcje/azymut.htm

Although I strongly recomend following the advice of previous posters!

 

[startrekmaniac]

No I dont know how to fly a rendezvou. I thought I was needed to take off when the ISS was over me.

 

[pandadude]

Basically, take off on a 90degree heading when the ISS' orbit is over you. Once you have achieved oribt, use Align MFD to align your plane with that of the ISS and to reduce relative inclination to zero. Once you've done this, sync your orbits so that in a few orbits time, you and the ISS are at the same place (within about 500km of each other). This can be done using Sync MFD. Once you are close to the ISS reduce your relative speed to zero. Then slowly move towards the ISS and use the dock MFD to dock with it.

This is just a very basic set of steps for docking with the ISS. If you need more info than that, I recommend reading the Go Play In Space tutorial. It is very useful.

 

[Urwumpe]

90° is already damn wrong. For KSC, the typical launch heading is 42°, when the ISS ground track is pointing north (south is not allowed - it disturbs Cuba)

 

[darian]

The best time to launch is when the ISS orbital plane (its orbit) is about 310 seconds from passing right over your launch site. Align Planes MFD gives this value, its the Tn (time to node.) Launch MFD also gives this value which is "time to intersection." So in essence when either of these values are approaching 310sec then get ready to launch.

However I'm speaking for realistic vehicles like the Space Shuttle, in which its "time to reach half orbital vel is 310sec."

 

[pandadude]

90° is already damn wrong. For KSC, the typical launch heading is 42°, when the ISS ground track is pointing north (south is not allowed - it disturbs Cuba)

I don't know about how it's done in real life, but in my Orbiter, if I launch to the ISS and launch on a heading of 90degrees, RInc is pretty much zero when I reach orbit. I think I may have changed the ISS' inclination for all my scenarios though....what is the ISS' inclination by default? Isn't it close to 70? I changed mine to about 50, or whatever it was in real life when I changed it. Oh, and in Orbiter I tend not to worry too much about disturbing Cuba.

 

[Urwumpe]

I don't know about how it's done in real life, but in my Orbiter, if I launch to the ISS and launch on a heading of 90degrees, RInc is pretty much zero when I reach orbit. I think I may have changed the ISS' inclination for all my scenarios though....what is the ISS' inclination by default? Isn't it close to 70? I changed mine to about 50, or whatever it was in real life when I changed it. Oh, and in Orbiter I tend not to worry too much about disturbing Cuba.

51.6° equatorial.

And if you are able to get to the ISS, by cheating and putting it into a 28.8° orbit, you should maybe tell startrekmaniac about it. :dry:

 

[pandadude]

Yea I changed my ISS orbit to 51.6. That way, when I launch on a 90degree heading from KSC, I'm pretty much perfectly aligned with the ISS. I didn't do that to make it easier, I just wanted it to be more realistic. I can rendezvous with pretty much anything in orbit by now (I think, although the only things I've ever really tried docking with are the ISS and Mir).

 

[Urwumpe]

Yea I changed my ISS orbit to 51.6. That way, when I launch on a 90degree heading from KSC, I'm pretty much perfectly aligned with the ISS. I didn't do that to make it easier, I just wanted it to be more realistic. I can rendezvous with pretty much anything in orbit by now (I think, although the only things I've ever really tried docking with are the ISS and Mir).

You likely changed it to 51.6° in the ecliptic frame. This should not give you perfect alignment, but in some occasions (combinations of LAN and Inc), bring you within 3° of it, when you launch from KSC.

But in reality, it is 51.6° in the equatorial frame.

 

[pandadude]

You likely changed it to 51.6° in the ecliptic frame. This should not give you perfect alignment, but in some occasions (combinations of LAN and Inc), bring you within 3° of it, when you launch from KSC.

But in reality, it is 51.6° in the equatorial frame.

Ah OK my mistake. I shall have to make the necessary changes to my scenarios!

 

[garyw]

What Urmupe said. When I fly shuttle missions to the ISS I launch at 42 degress from KSC. If I get the timing spot on then I'm normally within 0.5 degress of the ISS inclination.

All you have to do is launch when the yellow line (the ISS orbit) passes over your launch site. Launch MFD will give you a count down for this. Note that its the ISS ORBITAL PATH and not the ISS itself that's important. If you wait until the ISS is overhead you will have to wait a long time for the perfect launch window.

There are two launch windows per day. One when the yellow line goes south - You don't want this as Urwumpe already stated - Cuba gets a bit upset so you launch when the yellow line is over KSC and is pointing to the North. This is an ascending node trajectory.

Once in orbit your oribtal path should be identical to that of the ISS. The actual position of the ISS doesn't matter as you should be in a lower, faster orbit to start the chase.

 

[pete.dakota]

Also, use Align Plane MFD during the insertion. After I reach 100km, I open up align planes, check the numbers, and yaw to bring my close rate up. As the closing rate moves toward zero, I yaw back to hold the rate at 0.000/s. Simply holding a given heading isn't going to be perfectly accurate. With the DGIV, I can usually get within 0.05 every time.