Hitting a wall at ~11k meters that rips my rocket apart...

[DanGovier]

This is my first post so... hi!

I've recently just achieved my first 3-Crew Mun landing using only stock parts in 0.16 (without mods, yay!) but my lander didn't have enough fuel left to break Munar orbit and get home. So, bigger rocket needed!

However, now I can't seem to actually get into orbit without my rocket tearing itself apart, even with loads of structural bracing.

It's like I hit a shockwave of some kind at about 11km up, which causes my first stage boosters to tear free. I tried throttling down to pass over the bump, which does actually work, but then it just happens further up once I throttle to full power again.

Is this a sound barrier kind of thing? I've only just upgraded from 0.13 so it's all new and different

[J_Man_X_663]

Maybe you are building your rockets to big, maybe with to much power :0. But the only way i can think of to overcome this problem is to do a few test with many different types of these three man rockets. and come to a conclusion through trial and error.

[EndlessWaves]

It's almost certainly the aero-kraken. Ships get reset every 6km travelled which imposes additional forces and can snap apart ships close to the breaking point (especially if they're bending a lot).

You could try rearranging your bracing to prevent bending specifically but otherwise it's a case of redesigning to a different plan more capable of carrying the weight.

[Tommygun]

Build a rocket that is wider and shorter.

Try using four strap on liquid boosters and place fuel pumps on two of them to the center stage.

[simplemunrockets]

Never run the big parts at full throttle. When the G's hit 2 or 3, the decouplers will fail and your rocket will implode. It's best to keep throttle at about 2/3 for most of the trip.

[bsalis]

I've only just upgraded from 0.13 so it's all new and different

Your not alone. everyone had some troubles with the new parts.

Can you post a pic of your craft? Easier to help that way.

[The Destroyer]

Not to be rude, but am i the only one here who didnt have problems with the new parts?

[willitstimothy]

What you're describing sounds like your ship is top heavy (the Cm is too far forward) and does not have enough stabilizers in the form of RCS. Try adding a bunch of RCS thrusters to the top and bottom of your rockets and you might be able to coax them into orbit. Better still would be to redesign your rockets so that the Cm is further back. If it is too far back then your rocket will be super sensitive to inputs (it would be difficult to fly even with SAS), too far forward and it will be unstable and difficult to control in a bad way.

[Rickenbacker]

More struts, especially between stages. The new decouplers break very easily, but 4-6 struts shoring them up fixes it. And keep an eye on your G meter, you want to throttle back if the forces get too high.

[sal_vager]

Never run the big parts at full throttle. When the G's hit 2 or 3, the decouplers will fail and your rocket will implode. It's best to keep throttle at about 2/3 for most of the trip.

simplemunrockets is dead on with this, your craft are now more sensitive to G forces, especially the new parts as they have a great deal more mass.

Keep an eye on your G force meter on the left of the Navball, you definitely want to keep it out of the red, and ideally in the green

[RoboRay]

Never run the big parts at full throttle. When the G's hit 2 or 3, the decouplers will fail and your rocket will implode. It's best to keep throttle at about 2/3 for most of the trip.

If you are forced to run your engines at greatly reduced throttle all the way up to prevent dangerously excessive acceleration, your engines are simply too big for the mass they are pushing. Use smaller engines, or fewer engines, or boost a bigger payload!

Or, you may be able to keep the LV the way it is and change your launch-profile a bit for the best of both worlds...

On a couple of my really big launchers that experienced some structural failures at the "6km resets", I've started throttling back as I approach 6k and 12k, much like the space shuttle throttled back when passing Max Q, then throttling back up after passing the danger point.

Edited September 13, 2012 by RoboRay

[UNSC]

I never have problems running the new parts on full throttle. Just don't let the acceleration get out of hand.

[Ziff]

It's like I hit a shockwave of some kind at about 11km up, which causes my first stage boosters to tear free. I tried throttling down to pass over the bump, which does actually work, but then it just happens further up once I throttle to full power again.

Pay close attention to where the failure occurs, or check the flight log at the end. Does it, by any chance, appear that the large decoupler is failing and the rocket engine is pushing straight up through the rest of the parts? There is a small, albeit catastrophically dangerous, bug within the large stack decoupler. If you look at the stats on the large decoupler you will notice it has a 10x increase in mass and no increase in strength over the stock 1 meter decoupler. This causes them to fail when under increased G forces. I recommend modifying the part.cfg file and increasing the strength. You can find a post in the Bugs section about this issue.

[jenskerman]

Sound barrier has nothing to do with your altitude. It's the G force, and at this special point it brakes your ship. I know that feel, bro. Happend to me way to often.