Hi, I noticed that the breakingForce & breakingTorque are not set in the cfg's for the mk3 parts. As a result these craft are very fragile. For example the following craft with almost no fuel and no payload needs to land with a vertical velocity of about 1m/s other wise it will fall apart. Copying the breakingForce & breakingTorque for 3m parts into the cfg's for equivalently sized mk3 parts appears to make the craft behave more consistently. Example ---------------------------------------------------------------- cfg from the large mk3 LFO fuel tank PART { name = mk3FuselageLFO_100 module = Part author = Porkjet rescaleFactor = 1.0 node_stack_top = 0.0, 5.0, 0.0, 0.0, 1.0, 0.0, 3 node_stack_bottom = 0.0, -5.0, 0.0, 0.0, -1.0, 0.0, 3 node_attach = 1.63, 0.0, 0.0, 1.0, 0.0, 0.0, 1 TechRequired = experimentalAerodynamics entryCost = 84000 cost = 10000 category = FuelTank subcategory = 0 title = Mk3 Rocket Fuel Fuselage Long manufacturer = C7 Aerospace Division description = Filled to the brim with Rocket Fuel, C7 Aerospace's supplier Ekson-Kobil have assured us that this tank is absolutely airtight. attachRules = 1,1,1,1,0 mass = 7.14 dragModelType = default maximum_drag = 0.2 minimum_drag = 0.3 angularDrag = 1 crashTolerance = 50 maxTemp = 2300 // = 3000 emissiveConstant = 0.87 fuelCrossFeed = True bulkheadProfiles = srf, mk3 MODEL { model = Squad/Parts/FuelTank/mk3Fuselage/LFO_100 } RESOURCE { name = LiquidFuel amount = 4500 maxAmount = 4500 } RESOURCE { name = Oxidizer amount = 5500 maxAmount = 5500 } } ---------------------------------------------------------------- cfg from the equivalent 3m part PART { name = Size3LargeTank module = Part author = Squad mesh = Size3LargeTank.mu rescaleFactor = 1 node_stack_top = 0.0, 3.74, 0.0, 0.0, 1.0, 0.0, 3 node_stack_bottom = 0.0, -3.74, 0.0, 0.0, -1.0, 0.0, 3 node_attach = 0.0, 0.0, -1.89, 0.0, 0.0, 1.0 TechRequired = highPerformanceFuelSystems entryCost = 46600 cost = 13000 category = Propulsion subcategory = 0 title = Kerbodyne S3-14400 Tank manufacturer = Kerbodyne description = When nobody believed in (or even asked for) an even larger fuel tank than the already enormous S3-7200, Kerbodyne stepped up with the sanity-defying S3-14400 model. Carrying fully twice as much fuel as before, this fuel tank may just pack enough propellant to justify its proportionately enormous cost. attachRules = 1,1,1,1,0 mass = 9 dragModelType = default maximum_drag = 0.2 minimum_drag = 0.3 angularDrag = 2 crashTolerance = 6 breakingForce = 400 breakingTorque = 400 maxTemp = 2000 // = 2900 bulkheadProfiles = size3, srf RESOURCE { name = LiquidFuel amount = 6480 maxAmount = 6480 } RESOURCE { name = Oxidizer amount = 7920 maxAmount = 7920 } }