Drag cubes setup (Solved)

[USB4]

 

Ive modeled that, and have animations for rotation, blade pitch and reverse, but I have no idea how to make the drag cube (what Im assuming is making this fly horribly) any better. 

 

What I have tried: Copying the parts config drag cube portion of another similar engine into the cfg file of this one, changing the collision model, setting the drag mode to none. 

 

I want the part to have drag however, I just want it not to be overkill Im assuming due to the large propellers.

 

Edit: So it seems despite trying with 2 different designs, it was more due to the design more than the drag model that the plane wouldnt fly correctly I guess. I feel silly. It was the most basic wings in the middle, weight infront of lift plane you ever could see. 

 

That being said, I would still love to know how youd go about changing drag cubes manually.

Edited December 18, 2017 by USB4

[SpannerMonkey(smce)]

Hi, this is what you need to do, 1 make sure there's no collider on the blur disc , continue as normal and export the part,  you will need to have it load at least once.   Once you've loaded it and checked that it does indeed have a drag equivalent to a small truck, close the game. Now in the main KSP folder find your PartDatabase.cfg Its here that all the drag cubes are stored.

  Also worth noting that should you change a model after first import, you should delete the PartDatabase.cfg as it has a tendency not to update and so all the old drag mass etc info is used on the new model.  

Open PartDatabase.cfg with notepad++  and search for you r part by name. you'll find something that looks like this

PART
{
	url = KAX/Parts/KAX_VintagePropelator/KAX_VintagePropelatorS/KAXVintagePropelatorS
	DRAG_CUBE
	{
		cube = Default, 0.01845,0.3367,0.5827, 0.01845,0.3367,0.624, 0.7261,0.4995,0.1486, 0.7261,0.4925,0.2677, 0.03583,0.2868,0.5827, 0.03583,0.269,0.5827, -1.013E-06,0.1083,-2.98E-08, 0.97,0.2163,0.97
	}
}

now open your internet browser and go here http://www.datainterlock.com/dragcubes.php

Copy this part of the drag cube from partDatabase.cfg

cube = Default, 0.01845,0.3367,0.5827, 0.01845,0.3367,0.624, 0.7261,0.4995,0.1486, 0.7261,0.4925,0.2677, 0.03583,0.2868,0.5827, 0.03583,0.269,0.5827, -1.013E-06,0.1083,-2.98E-08, 0.97,0.2163,0.97

and paste it into the box on that site marked Original Drag Cube

then in the drag modifier option box type 50 and press submit , this will reduce your drag by half, which i've found to be what small prop engines need if they're going to work at all. 

Then copy the newly written drag cube from the site to your PART CFG , NOT the partDatabase.cfg.  it will should look something like below when you;re done. ( a chunk from a KAX cfg)

// --- standard part parameters ---
mass = 0.11
dragModelType = default
maximum_drag = 0.2
minimum_drag = 0.3
angularDrag = 2
crashTolerance = 6
breakingForce = 50
breakingTorque = 50
maxTemp = 2900
fuelCrossFeed = True
DRAG_CUBE
{
     cube = Default,0.02641,0.29375,0.5892,0.02641,0.2864,0.5892,0.7452,0.49955,0.1486,0.7452,0.4964,0.2677,0.01955,0.3204,0.6402,0.01954,0.32615,0.5892, -1.013E-06,0.1083,-2.98E-08, 0.983,0.2163,0.983
}
RESOURCE
{
    name = IntakeAir
    amount = 5.0
    maxAmount = 5.0
}

MODULE
{
  name = ModuleResourceIntake
  resourceName = IntakeAir
  checkForOxygen = false
  area = 1
  intakeSpeed = 50
  intake

It's  a really bad idea to copy any drag cube, as you have no idea what the collider layout is that generating that cube, always generate a new one for your part and modify to suit , the drag cube does not only control drag but how your part is treated by game physics so it needs to fit your part.