This kinda expands off of my last post. So basically I have this script that automatically sets the Position of a part and its orientation after doing some calculations, but for some reason setting the Rotation of the part would also deal collateral damage and mess up the Position-al component.

Version 1 (commented)

Code:

local runService = game:GetService("RunService")

local parachute = script.Parent
local base = parachute:WaitForChild("Base").Value
local dragBF = base:WaitForChild("Drag")

local resistanceCoefficient = 10
local parachuteDistance = 10

runService.Heartbeat:Connect(function(step)

    -- Compute the parachute's drag force
    local drag = -base.Velocity * resistanceCoefficient

    -- Compute position and rotation of parachute
    local chutePos = base.Position + base.Velocity.Unit * parachuteDistance
    local d = base.Position - parachute.Position        -- Delta X Y Z
    local hXY = math.sqrt(d.X^2 + d.Y^2)                -- Hypotenuse of triangle with dX and dY as legs
    local hXZ = math.sqrt(d.X^2 + d.Z^2) 
    local hYZ = math.sqrt(d.Y^2 + d.Z^2)

    local rotZ = math.asin(d.X/hXY)
    local rotY = math.asin(d.Z/hXZ)
    local rotX = math.asin(d.Y/hYZ)

    parachute.Position = chutePos
    --parachute.Rotation = Vector3.new(rotX, rotY, rotZ)    -- rotation commented out

    print(tostring(chutePos))
    print(tostring(parachute.CFrame.p).." "..tostring(parachute.Rotation))

    dragBF.Force = drag
end)

BTW I did try setting the rotation by multiplying by CFrame.Angles but that didn't yield any better results

Output:

0, 54.5970306, 0
0, 54.5970306, 0 0, 0, 0
0, 54.7103844, 0
0, 54.7103844, 0 0, 0, 0
0, 54.7820587, 0
0, 54.7820587, 0 0, 0, 0
...

Version 2 (uncommented)

Code:

local runService = game:GetService("RunService")

local parachute = script.Parent
local base = parachute:WaitForChild("Base").Value
local dragBF = base:WaitForChild("Drag")

local resistanceCoefficient = 10
local parachuteDistance = 10

runService.Heartbeat:Connect(function(step)

    -- Compute the parachute's drag force
    local drag = -base.Velocity * resistanceCoefficient

    -- Compute position and rotation of parachute
    local chutePos = base.Position + base.Velocity.Unit * parachuteDistance
    local d = base.Position - parachute.Position        -- Delta X Y Z
    local hXY = math.sqrt(d.X^2 + d.Y^2)                -- Hypotenuse of triangle with dX and dY as legs
    local hXZ = math.sqrt(d.X^2 + d.Z^2) 
    local hYZ = math.sqrt(d.Y^2 + d.Z^2)

    local rotZ = math.asin(d.X/hXY)
    local rotY = math.asin(d.Z/hXZ)
    local rotX = math.asin(d.Y/hYZ)

    parachute.CFrame = CFrame.new(chutePos)
    parachute.Rotation = Vector3.new(rotX, rotY, rotZ)

    print(tostring(chutePos))
    print(tostring(parachute.CFrame.p).." "..tostring(parachute.Rotation))

    dragBF.Force = drag
end)

Output:

0, 54.5970306, 0
0, -3.40282347e+38, 0 0, 0, 0
0, 54.6886597, 0
0, -3.40282347e+38, 0 0, 0, 0
0, 54.7569809, 0
0, -3.40282347e+38, 0 0, 0, 0
...

So what's happening here? How is the Rotation of the part adversely affecting the Position??