Building issue with a docking port

[gc1ceo]

All of my design so far that have used docking ports have largely placed them towards the top of a craft, however i am currently working on attaching my version of Apollo to a lifter. My Kapollo design mimics the Apollo design where the lunar lander is placed below the service module (and its engine) and the CSM will flip around once in orbit to get a hold of it before heading for TLI. The lunar lander itself has a docking port on the top and it rests right below the service module's engine. Try as I might I haven't been able to make the connection stable enough for any real flight, it either fails immediately at launch or anywhere up to 10k up. I have tried placing another docking port, a seperator, etc and nothing seems to worked and I have used so many struts i can't use any more but it still doesn't work.

Any suggestions?

[sweetpezak]

can you post a pic of the launch vehicle? And are you using jr. docking ports, regular, or senior for the connection between the modules? Not sure if that makes a difference in stability but maybe a larger docking port would help, idk...

[sal_vager]

It sounds like you need struts, I also have made an Apollo style craft and it has four struts from the CSM to the third stage, passing the lander on the way.

Depending on the size of your lander you may need to run struts from the CSM to the LM, then from the LM down to the rest of the rocket

[gc1ceo]

[gc1ceo]

I have plenty of struts but enough thrust or enough time just it all to fail, I run into the same problem if the connection is two docking ports and I'm using the standard Clamp O' Tron. The only mod I have is MechJeb2 for stats.

[Commander Zoom]

For a rocket as tall and thin as that, you're going to need (even) more struts. Struts everywhere.

[Dkmdlb]

struts struts struts.

Also, use this configuration for the connection between your lander and command module: docking port on the lander connected to upside down decoupler connected to a right side up decoupler connected to the engine on the command module. When it comes time to dock the two, first decouple the upside down decoupler (the one nearest to the lander), then rotate the command module and dock with the lander, and then decouple the other decoupler which still should be connected to the command module engine. This will keep it out of your way when docking.