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Edax

Why does my rocket Instantly Explodes Mid-Flight?

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I've added a modification to my ore freighter by adding some girders on top to look like a comms relay, but apart from that, I've gotten 2 versions of this ship to Minmus already (before the patch that is), so I can't understand why it keep exploding. There's no pogo, just 90% of the rocket is instantly destroyed randomly about a minute from take off (there is no chain-reaction of failure), and according to the damage report, the comms relay is where the trouble starts, but I don't know how this can cause such a powerful insta-explosion.  Is it a bug of the new patch?  Is there an old part from the previous patch that is not reacting well to the update?

VTAVesEf.jpg

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And sometimes when I revert back to the pad, parts are missing, along with my astronaut.

Z4GFY4AI.jpg

Edited by Edax

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It is always the same linkage that fails? If so, try adding a strut. Or remove the girder.

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or try a clean reinstall. i've had some weird thing clear up with that. you can just copy your save folder over into the new install

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36 minutes ago, bewing said:

It is always the same linkage that fails? If so, try adding a strut. Or remove the girder.

I'm not sure what the linkage is, I have no girders connected to any nosecones, and I've removed all struts from nosecones, but that is the first linkage to fail.

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Hmmm. And it still gives you that same status report when it explodes, after removing the struts from the nosecones?

Edited by bewing

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5 minutes ago, bewing said:

Hmmm. And it still gives you that same status report when it explodes, after removing the struts from the nosecones?

Yeah.  It's always the first thing to fail.  I'm not even sure where the failure is happening because the whole rocket is instantly destroyed.

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Well, I can say for certain that the "parts missing after reverting to launch" thing is a new bug that I've never heard of before (and I keep close track of the bugtracker).

You do have one mod loaded (at least) -- and you really have no choice but to also try removing all the mods and launching the rocket again to look for differences.

One other thing I can say is that I know it is possible to slow down time. I'm not exactly sure how to do it, but I saw it done once on youtube. So you may want to figure out that trick, go 50 seconds into your launch, and slow down time so you can maybe see better. It's not an answer, of course, but we all need more info here.

Edited by bewing

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16 minutes ago, bewing said:

Well, I can say for certain that the "parts missing after reverting to launch" thing is a new bug that I've never heard of before (and I keep close track of the bugtracker).

You do have one mod loaded (at least) -- and you really have no choice but to also try removing all the mods and launching the rocket again to look for differences.

One other thing I can say is that I know it is possible to slow down time. I'm not exactly sure how to do it, but I saw it done once on youtube. So you may want to figure out that trick, go 50 seconds into your launch, and slow down time so you can maybe see better. It's not an answer, of course, but we all need more info here.

I do have some mods installed, the only part mod is Mechjeb.

I'm not exaggerating when I saying the destruction is instantaneous.  If I scroll down the whole damage report, they all happen at the exact same second, and you only hear one explosion soundeffect.  Some of the side boosters will survive, but it appears the entire rocket instantly collides with itself to delete itself from existence.  Although, sometimes the top half of the rocket will survive, so I suppose the problem part is in the body.  But again, I have no girders segments anywhere near the nose cones...

Maybe reinstalling the game will help...

Edited by Edax

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The destruction itself is, I'm sure. But a strut doesn't just fail for no reason. So there is either internal stress from a clipped part, or aerodynamic stress that will show up in the form of pieces of the craft starting to wobble. So any wobbling that shows up just before the explosion is interesting. But we beta testers were in fact seeing non-part mods causing in-flight issues. So don't rule them out completely.

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1 hour ago, bewing said:

The destruction itself is, I'm sure. But a strut doesn't just fail for no reason. So there is either internal stress from a clipped part, or aerodynamic stress that will show up in the form of pieces of the craft starting to wobble. So any wobbling that shows up just before the explosion is interesting. But we beta testers were in fact seeing non-part mods causing in-flight issues. So don't rule them out completely.

But is that a strut that's failing?  I removed all struts attached to the nose cones, but I still get a "linkage" failure between two parts that aren't even near each other, with nothing connecting the two.  There is no wobble leading up to the explosion (if parts were wobbling off, I know to add more struts).

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5 minutes ago, Edax said:

But is that a strut that's failing?  I removed all struts attached to the nose cones, but I still get a "linkage" failure between two parts that aren't even near each other, with nothing connecting the two.

That's the thing -- a linkage between two distant parts sounds like a strut to me. So it sounds like you've got invisible struts. *shrugs*

So is it a problem with the craft file being incorrectly ported to a new version? Is a mod making invisible struts? Are you running KJR?

Have you tried taking the ship apart and putting it together again?

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As a honest-to-$DEITY aerospace engineer (no joke - it's my undergrad degree), your craft is pretty complex for a single launch. Yes, I know, #lolsokerbal ...  

Thing is, as KSP has matured over the last year or so, it's getting harder and harder to lob "unnatural looking rockets" like that from the ground in one piece. The error messages you're getting indicate - to me - that your .craft file is confusing the bejeezus out of the physics engine; parts are moving a tiny bit in relation to one another due to wobble or aerodynamic stress during ascent and at some point it just goes kablooey. 

First thing I'd try is installing Kerbal Joint Reinforcement - if that works, great. Problem solved. If not, I'd do what @bewingsuggests and rebuild the craft. I wouldn't take it apart, I'd just start completely over from scratch and see how it goes. it's possible the .craft file has gotten corrupted or confused over time.

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46 minutes ago, LameLefty said:

As a honest-to-$DEITY aerospace engineer (no joke - it's my undergrad degree), your craft is pretty complex for a single launch. Yes, I know, #lolsokerbal ...  

Thing is, as KSP has matured over the last year or so, it's getting harder and harder to lob "unnatural looking rockets" like that from the ground in one piece. The error messages you're getting indicate - to me - that your .craft file is confusing the bejeezus out of the physics engine; parts are moving a tiny bit in relation to one another due to wobble or aerodynamic stress during ascent and at some point it just goes kablooey. 

First thing I'd try is installing Kerbal Joint Reinforcement - if that works, great. Problem solved. If not, I'd do what @bewingsuggests and rebuild the craft. I wouldn't take it apart, I'd just start completely over from scratch and see how it goes. it's possible the .craft file has gotten corrupted or confused over time.

I managed to get this up in February, it seemed to go fine.  All I did now was remove the top 3 docking ports, and stick a science unit and 3 xl girders.  Although, I am aware that something happened during the patch, the bottom solid rocket boosters before would only lightly wobble around, but now they violently wobbled and ripped the landing apparatus off along with the bottom part of the payload.  I fixed that by tying a strut to the body of the payload, and that's when the flight lasted long enough that I encountered the explosion problem.

As for mods, I have Mechjeb, Planetshine, EnvironmentalVisualEnhancements, Distant Objects, and Stage Recovery (that doesn't work.)

I hesitate to rebuild it from scratch since it's been slowly modified of the course of 8 months and tested to perfection.  This is not the easiest thing to rebuild...

Spm9ugfB.jpg

Edited by Edax

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I realize it's not easy to rebuild from scratch, but the fundamental problem is, it's a beast that would never work in real life - it's far too complicated, with way too many parts, all of which cause tons of drag, lots of vibration and a lot of heat - both from engines burning and atmospheric drag. Earlier versions of KSP were more forgiving of a lot of stuff like that. As the game has evolved, it's less tolerant AND the change to Unity 5 as the game engine has changed some of the underlying physics calculations. 

tl;dr - it just may not work in current versions.

Install Kerbal Joint Reinforcement and try to launch again - KJR is a plug-in only mod that doesn't require adding any parts to your vessel. 

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48 minutes ago, Edax said:

I hesitate to rebuild it from scratch since it's been slowly modified of the course of 8 months and tested to perfection.  This is not the easiest thing to rebuild...

Understandable. However there appears to be quite a few things wrong with it as it is:

- those fuel lines parallel to the XL girders don't seem to touch the outer stacks but are instead attached to the docking ports. Is this deliberate?

- the struts appear not to have symmetry - especially what looks like a single strut connection to the top of the comms tower thing and between the tops of the outer stacks. Others are off-centre on the boosters (generally not disastrous, but it adds instability),

- the girders on the outer stacks, which connect to the decouplers on the main stack, look very much like they'll hit the nosecones just underneath them when you stage,

- the outer stacks aren't centred on those same girders,

- is that the M700 orbital scanner? If so, I don't know if it has a different aerodynamic model when opened or closed, but I would leave it closed just in case,

- I also don't know whether KSP considers gimbal angle when it determines whether your exhaust cone is hitting the ship and therefore gives zero thrust, but the girders holdng the bottom kickbacks on are within the scope of gimbal from the twin boars and therefore, if gimbal is active on them, will be hit by their exhaust cone.

 

So it looks great in its bewildering complexity, but it isn't all that surprising that it's blowing up... :wink:

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35 minutes ago, Plusck said:

Understandable. However there appears to be quite a few things wrong with it as it is:

- those fuel lines parallel to the XL girders don't seem to touch the outer stacks but are instead attached to the docking ports. Is this deliberate?

- the struts appear not to have symmetry - especially what looks like a single strut connection to the top of the comms tower thing and between the tops of the outer stacks. Others are off-centre on the boosters (generally not disastrous, but it adds instability),

- the girders on the outer stacks, which connect to the decouplers on the main stack, look very much like they'll hit the nosecones just underneath them when you stage,

- the outer stacks aren't centred on those same girders,

- is that the M700 orbital scanner? If so, I don't know if it has a different aerodynamic model when opened or closed, but I would leave it closed just in case,

- I also don't know whether KSP considers gimbal angle when it determines whether your exhaust cone is hitting the ship and therefore gives zero thrust, but the girders holdng the bottom kickbacks on are within the scope of gimbal from the twin boars and therefore, if gimbal is active on them, will be hit by their exhaust cone.

 

So it looks great in its bewildering complexity, but it isn't all that surprising that it's blowing up... :wink:

The fuel lines that run parallel in the XL girders aren't functional, they are aesthetic, to provide a logical reason as to why craft docked to the port can be refueled.

The strut attached the comms tower I removed because it was a connection between a nosecone and girder, which I thought was the original problem, but that didn't fix anything.

The giant LFO boosters decouple when in orbit, so there is no risk of hitting the nosecone during staging.  The payload is launched mostly empty, it's designed to carry on a minimal amount of fuel, and drain leftover fuel from the boosters once in orbit.

True, it's really difficult to center things like that in the VAB, for once, when I'm attaching the boosters, I can't see the alignment.

I've tried launching it opened or closed, doesn't help with exploding.

Gimballed thrust hasn't been a problem before.

 

Here's a video of the launch of the earlier "lighter" variant so you can see that the launch isn't all that complicated, it's merely the payload that complex.

Basically there's 2 stages.  Ignition, then decouple solid rocket boosters.  The rest will go all the way to orbit.  It's just with the heavier variant, I've added a few extra solid rocket boosters.

 

Edited by Edax

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Just finished reinstalling KSP.  Looks like I will indeed have to rebuild this thing from scratch, I can't even get this thing on the pad anymore:


oyib6m7b.jpg

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59 minutes ago, Edax said:

The fuel lines that run parallel in the XL girders aren't functional, they are aesthetic, to provide a logical reason as to why craft docked to the port can be refueled.

The strut attached the comms tower I removed because it was a connection between a nosecone and girder, which I thought was the original problem, but that didn't fix anything.

The giant LFO boosters decouple when in orbit, so there is no risk of hitting the nosecone during staging.  The payload is launched mostly empty, it's designed to carry on a minimal amount of fuel, and drain leftover fuel from the boosters once in orbit.

True, it's really difficult to center things like that in the VAB, for once, when I'm attaching the boosters, I can't see the alignment.

I've tried launching it opened or closed, doesn't help with exploding.

Gimballed thrust hasn't been a problem before.

 

Here's a video of the launch of the earlier "lighter" variant so you can see that the launch isn't all that complicated, it's merely the payload that complex.

Basically there's 2 stages.  Ignition, then decouple solid rocket boosters.  The rest will go all the way to orbit.  It's just with the heavier variant, I've added a few extra solid rocket boosters.

OK, well you seem to have all that covered.

After having seen the video (nicely done btw), that question of gimbal clearly doesn't apply - the girders are far too close and therefore at too much of an angle to be hit by the exhaust cone. I thought they were lower from the pics.

So that leaves me at a loss to suggest anything.

One last thing - multiple docking port connections have some severe problems in 1.1 - so the original explosion could have been because of that, maybe?

Edited by Plusck

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Actually, this started happening since the new reinstall when I tried to get the thing to the launch pad.  I don't even know what to think...Anyone see this before?

 

Edited by Edax

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Looks like a support issue rather than a gameplay question. And so, moved. 

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