Example Drag Calculation

[Right]

Could someone do an example drag calculation for me? I'm close... I can taste it. I've read through the Overhauls for 1.0 thread a few times.

Using this example: http://i.imgur.com/DBQUGvH.png

Which is a lone FL-T800 Fuel Tank.

PART

{

name = fuelTank_long

module = Part

author = NovaSilisko

mesh = model.mu

scale = 0.1

node_stack_top = 0.0, 15, 0.0, 0.0, 1.0, 0.0

node_stack_bottom = 0.0, -15.1, 0.0, 0.0, -1.0, 0.0

node_attach = 5.01, 0.0, 0.0, 1.0, 0.0, 0.0, 1

TechRequired = fuelSystems

entryCost = 4800

cost = 800

category = FuelTank

subcategory = 0

title = FL-T800 Fuel Tank

manufacturer = Jebediah Kerman's Junkyard and Spacecraft Parts Co

description = A stretched variant of the FL-T400, the FL-T800 holds twice the fuel in a slightly stronger container. The black stripes along the side make the rocket go faster, our engineers tell us.

attachRules = 1,1,1,1,0

mass = 0.5

dragModelType = default

maximum_drag = 0.2

minimum_drag = 0.3

angularDrag = 2

crashTolerance = 6

breakingForce = 50

breakingTorque = 50

maxTemp = 2000 // = 2900

bulkheadProfiles = size1, srf

RESOURCE

{

name = LiquidFuel

amount = 360

maxAmount = 360

}

RESOURCE

{

name = Oxidizer

amount = 440

maxAmount = 440

}

}

url = Squad/Parts/FuelTank/fuelTankT800/fuelTankT800/fuelTank_long

DRAG_CUBE

{

cube = Default, 4.421483,0.7854716,0.6937256, 4.421483,0.7857229,0.6937256, 1.213026,0.9634836,0.1404351, 1.213026,0.9634838,0.1716429, 4.421483,0.7849605,0.6937259, 4.421483,0.7850149,0.6937259, -1.376047E-16,-0.01320377,-3.882692E-08, 1.25,3.778993,1.250001

DRAG_TIP

{

key = 0 1 0 0

key = 25 1 0 0

}

DRAG_SURFACE

{

key = 0 0.02 0 0

key = 0.85 0.02 0 0

key = 0.9 0.0152439 -0.07942077 -0.07942077

key = 1.1 0.0025 -0.005279571 -0.001936768

key = 2 0.002083333 -2.314833E-05 -2.314833E-05

key = 5 0.003333333 -0.000180556 -0.000180556

key = 25 0.001428571 -7.14286E-05 0

}

DRAG_TAIL

{

key = 0 1 0 0

key = 0.85 1 0 0

key = 1.1 0.25 -0.02215106 -0.02487721

key = 1.4 0.22 -0.03391732 -0.03391732

key = 5 0.15 -0.001198566 -0.001198566

key = 25 0.14 0 0

}

DRAG_MULTIPLIER

{

key = 0 0.5 0 0

key = 0.85 0.5 0 0

key = 1.1 1.3 0 -0.008100224

key = 2 0.7 -0.1104858 -0.1104858

key = 5 0.6 0 0

key = 10 0.85 0.02198264 0.02198264

key = 14 0.9 0.007694946 0.007694946

key = 25 0.95 0 0

}

DRAG_CD

{

key = 0.05 0.0025 0.15 0.15

key = 0.15 0.0225 0.3 0.3

key = 0.25 0.0625 0.5 0.5

key = 0.35 0.1225 0.7 0.7

key = 0.45 0.2025 0.9 0.9

key = 0.55 0.3025 1.1 1.1

key = 0.65 0.4225 1.3 1.3

key = 0.75 0.5625 1.5 1.5

key = 0.8 0.66 2.3775 2.3775

key = 0.85 0.8 2.733777 2.733777

key = 0.9 0.89 1.1 1.1

key = 1 1 1 1

}

So..

Lets assume AoA = 0°

Coefficient = 0.9634836

Density = 1.117653 kg/m3

Velocity = 100.025 m/s

Area = 1.213026 m2

Running these figures through the drag equation, we get 5.847 kN. However, our reported drag (By AeroGUI) is 5.714 kN.

I'm wondering what the game's calculation is, including tail drag, surface drag, and anything else I'm missing.

And if anyone is feeling more ambitious, I'd also be curious to see the calculation for this:

http://i.imgur.com/blRA6QT.png

AoA is 30°, sideslip is 0°

Denisty = 1.12298 kg/m3

Velocity = 100 m/s

EDIT: Okay its probably a little different in 1.05 now... there is another drag coefficient multiplier - pseudo-Reynolds number. Loving the new descriptions in the Physics.cfg.

Edited November 10, 2015 by Right