Decoupler destroying my ship

[grimper12341]

I have some TT-38k Radial Decouplers on my small Munar lander, but when I activate them, they explode with such force that it destroys my ship and sends parts flying everywhere. I havn't played in about 4months, but the last time I did I don't remember radial decouplers being so powerful...

This is my ship, the drop tanks are attached by TT-38k Radial Decouplers. When the tanks are empty I decouple them, with the resulting force destroying my ship (it doesn't always destroy it, but it's more common when I'm throttled up)

This is a test I did on the launchpad with full tanks:

This is a test with empty tanks:

The config file for the part says ejection force is 250, and none of my mods (I only have Mechjeb and Kerbal Attachment System) overwrite it.

So is this amount of force normal? If so, how do I decouple drop tanks safely?

Edited November 2, 2014 by grimper12341

[SRV Ron]

Going to have to test this one out. Meanwhile, try using three tanks instead of four. I have had no issues with that design with either radical decoupler prior to 0.25.

[Pondafarr]

you *could* try going into the part file and changing it to a less powerful ejection force:

Look for

MODULE

{

name = ModuleAnchoredDecoupler

anchorName = anchor

ejectionForce = 250 <--------------------change to something lower(but remember the number to put it back if it doesn't work)

explosiveNodeID = srf

}

[grimper12341]

Yeh I know I can change it, it's just that I don't remember ever running into this problem before. I've made plenty of ships with drop tanks, which by design are dropped when they are empty and light, but they didn't eject with such force as to tear my ship apart or send it spinning around.

[Starman4308]

Yeh I know I can change it, it's just that I don't remember ever running into this problem before. I've made plenty of ships with drop tanks, which by design are dropped when they are empty and light, but they didn't eject with such force as to tear my ship apart or send it spinning around.

It's a known bug with the decoupling physics: something causes decoupled parts to scythe viciously inwards, destroying rocket parts. If you don't mind using mods, I would use Claw's stock bug fix for this. Otherwise, you can either edit the config as mentioned above, use Tweakable Everything to set decoupling force to zero, or use a bajillion Sepratrons to ensure they all fly away.

EDIT: I can't keep my modders straight.

Edited November 2, 2014 by Starman4308

[iFlyAllTheTime]

... I would use NathanKell's stock bug fix for this.

I could be wrong on this one, but I thought Claw brought that fix.

either way, OP, highly recommend getting that fix.

[grimper12341]

Yeh I'll give that and Tweakable Everything a try. Thanks guys.

[Claw]

From the looks of your on-orbit picture, I would say you're running into the stock decoupler bug that my fix is aimed at. Tweakable Everything should also work, but as was stated you'll have to put sepratrons (or do something else) to ensure the parts are safely out of your way.

If you end up using both my fix AND tweakable everything, it's been reported that they are compatible but the numbers tweakable everything shows in-flight will look weird. Just wanted to throw that out here in case you see that and come back here asking. If you only want to fix this problem, then you can pick either my fix or tweakable everything and don't have to use both.

Cheers,

~Claw

[LethalDose]

you *could* try going into the part file and changing it to a less powerful ejection force:

Look for

MODULE

{

name = ModuleAnchoredDecoupler

anchorName = anchor

ejectionForce = 250 <--------------------change to something lower(but remember the number to put it back if it doesn't work)

explosiveNodeID = srf

}

Instead of remembering the number, you can comment out the original line like this:

//ejectionForce = 250

ejectionForce = 25

The "//" tells the program to ignore anything after that on the same line, so this code sets the ejection force to 25, but leaves the original line of code in place for easy reverting.

[SRV Ron]

Did some flight test with both braces and fuel line, no braces and fuel line, and no fuel line. Found that how the fuel line is connected affects the ejection as well as the weight of the tanks.

Ejection force is less severe under mostly full tanks but quite violent with empty ones. Just leave a clear path as they sure fly upwards with extreme force when empty and in space.

[SRV Ron]

I have some TT-38k Radial Decouplers on my small Munar lander, but when I activate them, they explode with such force that it destroys my ship and sends parts flying everywhere.

Try moving your drop tanks 45* in relation to the Goo Canisters directly above two of them. Testing has shown that they are being hit by the drop tanks flying upwards which is what is destroying your ship. Testing also shows sideways tumbling of full tanks at launch while empty ones fly almost straight up when near space. Seems all the radical decouplers are suffering from the upward force bug.

[DrMonte]

Try moving your drop tanks 45* in relation to the Goo Canisters directly above two of them. Testing has shown that they are being hit by the drop tanks flying upwards which is what is destroying your ship. Testing also shows sideways tumbling of full tanks at launch while empty ones fly almost straight up when near space. Seems all the radical decouplers are suffering from the upward force bug.

Why not 90º?

[SRV Ron]

Why not 90º?

Because the next set of drop tanks will then be under them. The rotation along the vertical axis, Q or E key if you disconnect the section under the Material Bay, places the drop tanks between the Goo Canters when they fly up vertically.