Why am I having so many structural failures?

[rpayne88]

So I'm trying to launch a heavy lift rocket. According to mechjeb, it can reach orbit. The issue is, the payload fairing base keeps breaking off the rest of the rocket. I've got KJR AND 32 HEAVY KW struts between the two parts. It launched an "inert" 100 ton payload, so I should already have the structural issues sorted out.

Rocket launching the inert payload:

F3 report after failure:

[Traches]

What's your TWR? Looks pretty high.

[SSSPutnik]

Suggest struts to the fairing.

The hidden 32 struts may be making things worse.

Edited December 15, 2013 by SSSPutnik

[astropapi1]

There's never enough struts.

[Taki117]

with KWR you shouldnt need 32 of the heavy struts. heres how I strut my things: 8x symmetry to the payload, (depending on what I'm launching) 8x to the fairing ring, then 4x to the fairing itself. That's all you should need.

[Traches]

with KWR you shouldnt need 32 of the heavy struts. heres how I strut my things: 8x symmetry to the payload, (depending on what I'm launching) 8x to the fairing ring, then 4x to the fairing itself. That's all you should need.

That's not very many struts? Woah...

Anyway if your launch TWR is more than about 2, you're putting a lot of stress on your rocket and might want to back it off a bit.

[SRV Ron]

Big rockets are difficult to brace properly. I had tip over issues with this one until I added some cross bracing between the boosters and the core section.

After the bracing redesign, a stable flight to orbit.

Over 100 tons into orbit and on its way to Jool with three Kerbals and eight probes.

[Beachernaut]

273 ms at 5400 meters. Looks like you've got some great thrust to weight. Seems a bit fast at that height to me, though I could be completely wrong. Maybe a combination of high thrust and high speed.

[rpayne88]

I got it solved. The payload was so high it was not staying on the rocket. I also didn't know you could strut to proc. fairings. Instead of two -64 tanks it now uses four -32 tanks.

[rpayne88]

273 ms at 5400 meters. Looks like you've got some great thrust to weight. Seems a bit fast at that height to me, though I could be completely wrong. Maybe a combination of high thrust and high speed.

I used FAR, that is likely the reason. Anyway, my TWR is something like 1.7.

[Taki117]

I got it solved. The payload was so high it was not staying on the rocket. I also didn't know you could strut to proc. fairings. Instead of two -64 tanks it now uses four -32 tanks.

I quite discovered this fact by accident. I don't remember what I was trying to strut to (Pretty sure I was trying to go through the fairing though) and it just happened.

[rpayne88]

And, its back again. Rebuilding it in .23, now with 50 heavy struts, KJR, 5m stacks, and struts to the fairings. Its not even surviving long enough to get of the ground. What is annoying me though is that it did get off the ground before I added fuel lines between the boasters and the core on the first stage.

[ferram4]

Well, what is the connection between the payload and the rocket? If you're trying to get a tiny docking port to support a huge payload under high loads it's going to break.

[rpayne88]

Well, what is the connection between the payload and the rocket? If you're trying to get a tiny docking port to support a huge payload under high loads it's going to break.

5m proc fairing base to 5m NP fairing ring.