Maneuver Prograde Issues

[Cathix03]

 Hello, Fellow Kerbalnaughts!

 My 1st post! I have a station 120km in orbit above Kerbin with a 50-degree inclination. No problem waiting to have the station sailing above KSC and launching. My issue is with Mechjeb wasting my RSC propellent going back and forth a hundred times trying to dock a Progress or Capsule Vehicle to the station. What's with that?  (I use MJ for the launching, rolling and gravity turns. too much to key manually in a few seconds)

Thanks, Guys!

 

[Gargamel]

Hi @Cathix03, welcome to our little corner of the net!

MJ is notoriously inefficient when it comes to RCS usage for Docking.  You could try scouring the MJ release thread for info on changing the PID settings some to see if it helps, but I have found that if MJ get's stuck in a loop trying to dock, I just turn it off and dock manually.   Now, this might seem like it defeats the purpose of using an autopilot, but sometimes you just have to step in take over.  By the time you realize MJ isn't going to cut it this time, you are usually 95% of the way there, so you just have to pilot the end of the sequence.   There are a lot of mods out there that help you dock manually, and I strongly suggest having these on standby when using MJ. 

Check out this thread for some really good tips on learning to dock:

 

 

[GKSP]

6 hours ago, Cathix03 said:

 Hello, Fellow Kerbalnaughts!

 My 1st post! I have a station 120km in orbit above Kerbin with a 50-degree inclination. No problem waiting to have the station sailing above KSC and launching. My issue is with Mechjeb wasting my RSC propellent going back and forth a hundred times trying to dock a Progress or Capsule Vehicle to the station. What's with that?  (I use MJ for the launching, rolling and gravity turns. too much to key manually in a few seconds)

Thanks, Guys!

 

If you have time to spare for some testing on your ships, you can turn the autopilot off and on again, and see how it works.  Otherwise, if the notorious docking loop still persists, dock manually.  Having docked 100m away with 7 units of fuel and no SAS, you just have to make sure your prograde is on target if you want to waste minimal fuel.  If you still want to use MechJeb to dock, I have a tip I learned from an old Scott Manley video: point your docking ports normal.  When you do this, you do not have to readjust rotation along the orbit, and MJ likes to waste fuel rotating and readjusting.

[Vanamonde]

If you wanted to practice manual docking, I made a practice ship. 
https://kerbalx.com/Vanamonde/M131-Docking-Trainer

Launches as a single craft, 

then detaches smaller ships. 
 

[Cathix03]

On 3/30/2019 at 9:33 PM, GKSP said:

If you have time to spare for some testing on your ships, you can turn the autopilot off and on again, and see how it works.  Otherwise, if the notorious docking loop still persists, dock manually.  Having docked 100m away with 7 units of fuel and no SAS, you just have to make sure your prograde is on target if you want to waste minimal fuel.  If you still want to use MechJeb to dock, I have a tip I learned from an old Scott Manley video: point your docking ports normal.  When you do this, you do not have to readjust rotation along the orbit, and MJ likes to waste fuel rotating and readjusting.

Sometimes I can dock with no problem if my orbit in sync with the same velocity on a lucky rendezvous, but there are times I fight to get into that sweet spot not overdoing it and gets out of whack again...especially that 50-degree incline. Wish that target would stay in its prograde mode and not slowly tumbling.