Creating Rocket Engine: Falls Off At Max Thrust Issue

[starius]

So I was remaking the LV-T30 config file (A separate copy from the original) so I could have an engine that could launch my super large rockets without an issue, however there is an issue! Everything works fine enough except it breaks off after I hit half thrust! Below is the code. Only things I really changed were thrust, fuel consumption and crash tolerance (so I could use the rocket as a lander as well).

PART
{
// Kerbal Space Program - Part Config
// LV-T30 Liquid Fuel Engine
// 

// --- general parameters ---
name = StariusLiquidEngine
module = Part
author = Starius

// --- asset parameters ---
mesh = model.mu
scale = 0.1


// --- node definitions ---
node_stack_top = 0.0, 7.21461, 0.0, 0.0, 1.0, 0.0
node_stack_bottom = 0.0, -7.27403, 0.0, 0.0, 1.0, 0.0


// --- FX definitions ---

fx_exhaustFlame_blue = 0.0, -10.3, 0.0, 0.0, 1.0, 0.0, running
fx_exhaustLight_blue = 0.0, -10.3, 0.0, 0.0, 0.0, 1.0, running
fx_smokeTrail_light = 0.0, -10.3, 0.0, 0.0, 1.0, 0.0, running
fx_exhaustSparks_flameout = 0.0, -10.3, 0.0, 0.0, 1.0, 0.0, flameout

// --- Sound FX definition ---

sound_vent_medium = engage
sound_rocket_hard = running
sound_vent_soft = disengage
sound_explosion_low = flameout

// --- editor parameters ---
TechRequired = start
entryCost = 0
cost = 850
category = Propulsion
subcategory = 0
title = LV-T30 Starius Made
manufacturer = Starius' Backyard and Spaceship Parts Co.
description = Starius tested Starius Approved

// attachment rules: stack, srfAttach, allowStack, allowSrfAttach, allowCollision
attachRules = 1,0,1,0,0

// --- standard part parameters ---
mass = 1.25
dragModelType = default
maximum_drag = 0.2
minimum_drag = 0.2
angularDrag = 2
crashTolerance = 70
maxTemp = 3600

stagingIcon = LIQUID_ENGINE

MODULE
{
	name = ModuleEngines
	thrustVectorTransformName = thrustTransform
	exhaustDamage = True
	ignitionThreshold = 0.1
	minThrust = 0
	maxThrust = 2000
	heatProduction = 400
	fxOffset = 0, 0, 0.8
	PROPELLANT
	{
		name = LiquidFuel
       	        ratio = 0.000001
		DrawGauge = True
	}
	PROPELLANT
	{
		name = Oxidizer
		ratio = 0.000001
	}
	atmosphereCurve
 	{
   	 key = 0 370
  	 key = 1 320
 	}

}

MODULE
{
       name = ModuleJettison
       jettisonName = fairing
       bottomNodeName = bottom
       isFairing = True
       jettisonedObjectMass = 0.1
       jettisonForce = 5
       jettisonDirection = 0 0 1

}

MODULE
{
      name = ModuleAnimateHeat
}

MODULE
{
	name = ModuleAlternator	
	RESOURCE
	{
		name = ElectricCharge
		rate = 7
	}
}
RESOURCE
{
	name = ElectricCharge
	amount = 0
	maxAmount = 0
  	isTweakable = false
	hideFlow = true
}
}

[Diazo]

I see you've set thrust max to 2000.

The Mainsail has a thrust max of 1500 and I have problems with those staying attached sometimes if I stage at 100% thrust.

Combined with the smaller radius of the LV-T30 for less surface area on the joint, it's maybe simply too much force for the physics engine on the joint?

If so, maybe Kerbal Joint Reinforcement (a mod) would help?

D.

[kellven]

Been a really long time since I looked at it, might want to also check if the part was overheating/exploding also, if you haven't resolved the problem.

[Raptor831]

First thing you should try is increasing the attach node size. Mainsail has a node size of 2 (2.5m) I believe. Try adding the node size to the end of your node_stack lines, like this:

node_stack_top = 0.0, 7.21461, 0.0, 0.0, 1.0, 0.0, 2
node_stack_bottom = 0.0, -7.27403, 0.0, 0.0, 1.0, 0.0, 2

[Starwaster]

So I was remaking the LV-T30 config file (A separate copy from the original) so I could have an engine that could launch my super large rockets without an issue, however there is an issue! Everything works fine enough except it breaks off after I hit half thrust! Below is the code. Only things I really changed were thrust, fuel consumption and crash tolerance (so I could use the rocket as a lander as well).

Add the following lines to your PART{}

breakingForce = 200

breakingTorque = 200

You might even bump those values up a bit since they're engines.

Additionally for your own personal use you should have the following config if you use ModuleManager. Why? Because missing breakingForce / breakingTorque properties is a major cause of structural failure at times when you would think the part should have held. There is a default value if the properties are not present but it is woefully too low for large parts. And most of Squad's parts are affected. I first devised this when my nuclear engines kept falling off in solar orbit when I was doing nothing more stressful than floating in space.

Has nothing to do with attachnode size or space cephalopods.

// Adds breakingForce / breakingTorque with value 200 to every part that lacks these properties. That's it!
@PART[*]:HAS[~breakingForce[]]
{
	breakingForce = 200
}
@PART[*]:HAS[~breakingTorque[]]
{
	breakingTorque = 200
}