How to Dock
Jun. 26th, 2018 03:48 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
the_sky_callsGerbert Kerman was still trapped in orbit. But on the previous mission, a Clamp-O-Tron Docking Port Jr. was attached to his PTD-6 “Star” Module so that, when this next craft met it in orbit, the two craft could dock and Gerbert could transfer to the Mk2 Command Pod and return home.
Mission Designation : CV-2
Rocket Model : Chiravot C-II
Mission Objectives : Rescue Gerbert Kerman from Kerbin orbit
Total Mass (Mass to Orbit) : 45.5 tons (6.9 tons)
Total Delta-V (dV to Orbit) : 5,288 m/s (1,596 m/s)
Surface TWR : 1.3
Contract for Construction : Year 1, Day 42
Launch Site : KSC
Launch Date/Time : Year 2, Day 42 05:56
Engineer : Bob Kerman
Before docking, the two craft must rendezvous. The craft trapped in orbit is usually in fairly circular orbit of around 85 km altitude. Launching from KSC when the target craft is over the Great Desert, where the new Dessert Launch Site is located, will allow you to get into orbit ahead of the target craft. When you make the circularizing node at apoapsis, you “swing wide” to a higher orbit to slow down and rendezvous with the target craft.
On this flight, I waited almost too long. I was able to have a 5 km intercept with the target craft on the ascent. In that case, with only 5km, difference, I set to target retrograde at the closest approach marker and reduced the relative velocity to zero. After that, it was using the main engines at a low throttle to approach the target.
Docking can be quite the challenge. Having a sense of 3D spacial relations is vital.
Use RCS or the main engines at low throttle to move your primary craft in front of the target craft. It can take a lot of getting used to how to interpret the target icon on the NavBall and where to point your level indicator to get where you want relative to the target.
Next, is lining up the ports. Start by right-clicking on the target port and “set as target.” Then you right click on your own port and “control from here.” This will give you more accurate data on distances between the craft because otherwise the information is relative to center of mass. You can use the “]” key to switch over to control of the target and see where the level indicator is pointing relative. Then, when you return to your craft, you can point your craft 180 degrees to that so that a straight line from your port and the target port are parallel.
When you do this, you will probably not be pointing directly at the target prograde marker on the navball. You are going to use “I, J, K, L” to line those up. This is called translation. If you pitch or yaw using the “W, A, S, D” keys you will be pointing straight at the target port but they will no longer be parallel. You will come in on the port at an angle.
Once that's all lined up, Use the “H” key to move forward and dock.
Or, do what I do and get the Docking Port Alignment Indicator mod. It's not automated docking but what it does do is present a display that shows all the information directly. Parallel docking ports are represented by a target prograde circle. Rotate so that is in the center of the screen and your ports are lined up. There are two green lines that represent the movement vector between the ports. Move your prograde marker to where those green lines cross and you will push them towards the center. When it all lines up, move in to dock.
I can help make dockings almost routine. I don't consider it cheating much at all because you are still doing the dock, you just have a graphical representation of all the vectors instead of having to just eyeball it.
And so, Bob's craft was able to dock with the PTD-6 “Star” Module and Gerbert was able to transfer over. Because the docking port had been attached on the previous mission there was really no specific reason for Bob to be there except as an engineer should something go wrong. Of course, at this point his skill level wasn't high enough to do much so, if something DID go wrong, there was a good chance Bob couldn't fix it anyway.
The two craft remained attached until the reentry burn. After which the PTD-6 “Star” Module was undocked and would thus be on a trajectory to fall to the ground. If you don't do something like this, all those craft from which Kerbals have been rescued will remain in orbit, cluttering up the space around 85 km altitude. Space is still pretty big so the odds of running into that debris is pretty low but it is not zero and if you can reduce it to zero by deorbiting the module, all the better.
Mission Statistics
Total Mission Time : 42 min
Landing : 179 km east of KSC
Forty-two minutes. With the lucky 5 km intercept on the ascent, the mission was accomplished in one orbit. It could have been even shorter had I not cared about landing close to KSC to get a better craft recovery return.
Mission Designation : CV-2Rocket Model : Chiravot C-II
Mission Objectives : Rescue Gerbert Kerman from Kerbin orbit
Total Mass (Mass to Orbit) : 45.5 tons (6.9 tons)
Total Delta-V (dV to Orbit) : 5,288 m/s (1,596 m/s)
Surface TWR : 1.3
Contract for Construction : Year 1, Day 42
Launch Site : KSC
Launch Date/Time : Year 2, Day 42 05:56
Engineer : Bob Kerman
Before docking, the two craft must rendezvous. The craft trapped in orbit is usually in fairly circular orbit of around 85 km altitude. Launching from KSC when the target craft is over the Great Desert, where the new Dessert Launch Site is located, will allow you to get into orbit ahead of the target craft. When you make the circularizing node at apoapsis, you “swing wide” to a higher orbit to slow down and rendezvous with the target craft.
On this flight, I waited almost too long. I was able to have a 5 km intercept with the target craft on the ascent. In that case, with only 5km, difference, I set to target retrograde at the closest approach marker and reduced the relative velocity to zero. After that, it was using the main engines at a low throttle to approach the target.
Docking can be quite the challenge. Having a sense of 3D spacial relations is vital.
Use RCS or the main engines at low throttle to move your primary craft in front of the target craft. It can take a lot of getting used to how to interpret the target icon on the NavBall and where to point your level indicator to get where you want relative to the target.
Next, is lining up the ports. Start by right-clicking on the target port and “set as target.” Then you right click on your own port and “control from here.” This will give you more accurate data on distances between the craft because otherwise the information is relative to center of mass. You can use the “]” key to switch over to control of the target and see where the level indicator is pointing relative. Then, when you return to your craft, you can point your craft 180 degrees to that so that a straight line from your port and the target port are parallel.
When you do this, you will probably not be pointing directly at the target prograde marker on the navball. You are going to use “I, J, K, L” to line those up. This is called translation. If you pitch or yaw using the “W, A, S, D” keys you will be pointing straight at the target port but they will no longer be parallel. You will come in on the port at an angle.
Once that's all lined up, Use the “H” key to move forward and dock.
Or, do what I do and get the Docking Port Alignment Indicator mod. It's not automated docking but what it does do is present a display that shows all the information directly. Parallel docking ports are represented by a target prograde circle. Rotate so that is in the center of the screen and your ports are lined up. There are two green lines that represent the movement vector between the ports. Move your prograde marker to where those green lines cross and you will push them towards the center. When it all lines up, move in to dock.I can help make dockings almost routine. I don't consider it cheating much at all because you are still doing the dock, you just have a graphical representation of all the vectors instead of having to just eyeball it.
And so, Bob's craft was able to dock with the PTD-6 “Star” Module and Gerbert was able to transfer over. Because the docking port had been attached on the previous mission there was really no specific reason for Bob to be there except as an engineer should something go wrong. Of course, at this point his skill level wasn't high enough to do much so, if something DID go wrong, there was a good chance Bob couldn't fix it anyway.
The two craft remained attached until the reentry burn. After which the PTD-6 “Star” Module was undocked and would thus be on a trajectory to fall to the ground. If you don't do something like this, all those craft from which Kerbals have been rescued will remain in orbit, cluttering up the space around 85 km altitude. Space is still pretty big so the odds of running into that debris is pretty low but it is not zero and if you can reduce it to zero by deorbiting the module, all the better.
Mission Statistics
Total Mission Time : 42 min
Landing : 179 km east of KSC
Forty-two minutes. With the lucky 5 km intercept on the ascent, the mission was accomplished in one orbit. It could have been even shorter had I not cared about landing close to KSC to get a better craft recovery return.
