Why do my fuel tanks/rocket engines keep breaking off?

[davel23]

I built a Kethane refinery ship, it uses four radially-mounted FL-T800 tanks each with an LV-T30 engine on the bottom for propulsion. I can get it into Kerbal orbit, I can transfer it to Munar orbit, I can land it on the Mun and drill and convert Kethane. But whenever I try to lift off from the Mun, it gets several km up, then one of the engines loses thrust and it goes into an uncontrolled spin. Checking the post-flight log it seems that the tank loses structural connection with the rest of the ship. I've tried reinforcing them with quantum struts at four separate points, but it still happens. Anyone have any suggestions?

[allmhuran]

Reading your post, it sounds like you believe the failure of the structure is causing the spin.

However, you also said that one of the engines loses thrust. Perhaps the engine has simply run out of fuel due to erroneous fuel lines. This then causes the craft to spin so violently that the structure fails.

When watching the events take place, does it look like the engine is losing power before or after the structural failure?

Do you have fuel lines on the craft? (Post a picture or craft file to make things easier)

[davel23]

Of course, when I try to reproduce it just now, it works fine...

Anyway, I don't think it's a fuel issue, there's a central tank with lines leading out to all four radial tanks, and they work fin at all other times. If you'd like to have a look at the .craft and see if it does the same for you it's here, needed addons are Kethane, Quantum Struts and Mechjeb. I have B9 installed but I don't think I used any of its parts on this ship. (edit: just remembered I used some lights from B9)

Also, for reference custom actions are:

1: Toggle solar panels on engine section

2: Toggle lights on engine section

5: Toggle solar panels on lander

6: Toggle kethane detectors on lander

7: Toggle kethane drills on lander

8: Toggle kethane converter on lander (liquid, oxidizer and monoprop only)

9: Toggle lights on lander

Thanks!

Edited July 30, 2013 by davel23