RocketPlumber
XCOR Rocket engine designer
Launch to docking in as little as 663 seconds!
Last weekend I finally figured out how to do a fast precision first orbit rendezvous. This of course requires that your launch site both be in-plane and have the correct phasing, which a rare thing for most space stations.
Therefore, I cheated some. I used the Location MFD to move Mir into a 300 km circular equatorial orbit, saved the scenario, and copied the state vector info. Next, I moved the DGIV to my best guess for the right longitude, zero latitude, heading 90 degrees to launch east.
Saved that scenario, started it, did a takeoff, climbout at 70 degrees gamma, once above 150 km, pitch down to level and watch the Orbit MFD apogee prediction climb to 300 km. Pitch down to about -6 degees to hold apogee altitude constant in the lofted trajectory (vertical velocity was as high as 1200 m/s at one point). On reaching 300 km, level again, use alt hold, and accelerate until insertion into a 300 km orbit. Note the distance to Mir, convert that to degees of longitude, adjust the scenario, try again.
This time I got within about 20 klicks, thought I was doing okay, then I figured out how to use Encounter with Arrive to end up _parked_ within 50 meters at zero relative velocity. It's kinda cute. My best time, Earth surface to docked on Mir, is 663 seconds.
To get everything set up, I start the sim in paused mode, take a deep breath, unpause, and "R" to go to 1/10th time. Numpad +, cltrl-+ slams the throttle on and we slowly start to move. While the ground roll starts, I can leisurely set up Arrive and Encounter with Mir as the target (Orbit MFD with Proj Ship, Frame Equator, Alt mode, Mir as target is in the scenario- I'm lazy). Also in the scenario, Nav/com 1 on the Mir XPDR freq, 2, 3, & 4 on the IDS freqs. Left MFD Surface, Right Orbit.
Long before 100 m/s, we're all set up, so "T" for 1x time, take off, gear up, accelerate to 250 m/s, pull up to 70 degrees, using aero controls only, and trim to hold it as long as possible. When you run out of air, enable RCS Rot mode. At 100 km, pitch down to 25 degrees. Yes, this gives a lot of steering loss, but hey, it's a direct ascent ot 300 km, that's just the way it is.
Bring up the Encounter MFD, the miss distance should drop rapidly toward zero as apogee goes up, and put the HUD in Dock mode- as Encounter get close to zero, put the nose on the relative velocity crosshair. (During this part of the ascent, your gravity loss is now negative- the lofting from early in the flight is being taken back.) Small pitch and yaw changes can be used to drive Encounter to zero- this will take some practice.
Before you get Encounter fully dialed in, bring up Arrive on the other MFD, shift-H to enable autothrottle on the main engine. You're now on course for a dynamic stop at Mir. Put a little offset on the Encounter MFD, maybe 40 meters if you're feeling sporty, Once you get the heading just right, you can trim the miss distance by going to Linear on the RCS, and just drive the aimpoint directly.
This technique gives a result like the arrival of the Motie embassy ship in _The Mote in God's Eye_ -backing down on a column of flame until it just... stops. If you lean on the numpad + key during the last 20-30 km of the approach, you can drive the Arrive MFD's acceleration down to reduce the workload- when you let off the + key, Arrive will throttle down as needed. At about 5 km out, bring up Attitude MFD instead of the Encounter (keeping Arrive on) and put Attitude in mode 3 for relative velocity. In the last 100 m, as the HUD velocity drops below 5 m/s, shift-5 to make Attitude kill your relative velocty, and shift-H on Arrive to turn its Main control off- then hit * to kill the main engine pronto!
Pitch down to bring Mir into view, bring up Dock MFD in place of Arrive, and do the RCS dance for docking from close in. Attitude in relative mode is very helpful for docking, since it can selectively kill transverse velocities once to get lined up.
If you tried this in real life, the space station crew would die of heart attacks, of course.
Last weekend I finally figured out how to do a fast precision first orbit rendezvous. This of course requires that your launch site both be in-plane and have the correct phasing, which a rare thing for most space stations.
Therefore, I cheated some. I used the Location MFD to move Mir into a 300 km circular equatorial orbit, saved the scenario, and copied the state vector info. Next, I moved the DGIV to my best guess for the right longitude, zero latitude, heading 90 degrees to launch east.
Saved that scenario, started it, did a takeoff, climbout at 70 degrees gamma, once above 150 km, pitch down to level and watch the Orbit MFD apogee prediction climb to 300 km. Pitch down to about -6 degees to hold apogee altitude constant in the lofted trajectory (vertical velocity was as high as 1200 m/s at one point). On reaching 300 km, level again, use alt hold, and accelerate until insertion into a 300 km orbit. Note the distance to Mir, convert that to degees of longitude, adjust the scenario, try again.
This time I got within about 20 klicks, thought I was doing okay, then I figured out how to use Encounter with Arrive to end up _parked_ within 50 meters at zero relative velocity. It's kinda cute. My best time, Earth surface to docked on Mir, is 663 seconds.
To get everything set up, I start the sim in paused mode, take a deep breath, unpause, and "R" to go to 1/10th time. Numpad +, cltrl-+ slams the throttle on and we slowly start to move. While the ground roll starts, I can leisurely set up Arrive and Encounter with Mir as the target (Orbit MFD with Proj Ship, Frame Equator, Alt mode, Mir as target is in the scenario- I'm lazy). Also in the scenario, Nav/com 1 on the Mir XPDR freq, 2, 3, & 4 on the IDS freqs. Left MFD Surface, Right Orbit.
Long before 100 m/s, we're all set up, so "T" for 1x time, take off, gear up, accelerate to 250 m/s, pull up to 70 degrees, using aero controls only, and trim to hold it as long as possible. When you run out of air, enable RCS Rot mode. At 100 km, pitch down to 25 degrees. Yes, this gives a lot of steering loss, but hey, it's a direct ascent ot 300 km, that's just the way it is.
Bring up the Encounter MFD, the miss distance should drop rapidly toward zero as apogee goes up, and put the HUD in Dock mode- as Encounter get close to zero, put the nose on the relative velocity crosshair. (During this part of the ascent, your gravity loss is now negative- the lofting from early in the flight is being taken back.) Small pitch and yaw changes can be used to drive Encounter to zero- this will take some practice.
Before you get Encounter fully dialed in, bring up Arrive on the other MFD, shift-H to enable autothrottle on the main engine. You're now on course for a dynamic stop at Mir. Put a little offset on the Encounter MFD, maybe 40 meters if you're feeling sporty, Once you get the heading just right, you can trim the miss distance by going to Linear on the RCS, and just drive the aimpoint directly.
This technique gives a result like the arrival of the Motie embassy ship in _The Mote in God's Eye_ -backing down on a column of flame until it just... stops. If you lean on the numpad + key during the last 20-30 km of the approach, you can drive the Arrive MFD's acceleration down to reduce the workload- when you let off the + key, Arrive will throttle down as needed. At about 5 km out, bring up Attitude MFD instead of the Encounter (keeping Arrive on) and put Attitude in mode 3 for relative velocity. In the last 100 m, as the HUD velocity drops below 5 m/s, shift-5 to make Attitude kill your relative velocty, and shift-H on Arrive to turn its Main control off- then hit * to kill the main engine pronto!
Pitch down to bring Mir into view, bring up Dock MFD in place of Arrive, and do the RCS dance for docking from close in. Attitude in relative mode is very helpful for docking, since it can selectively kill transverse velocities once to get lined up.
If you tried this in real life, the space station crew would die of heart attacks, of course.
Every time I have a dillema whether to tell about something I wrote and risk that it would be perceived as shameless autopromotion, or stay silent, somebody pops up and brings many new things to my programs 
