How To Do Propeller Animations?

Using CFrames and welding would be the best way. This is untested, but should work

local prop = script.Parent.Propeller
local propw = Instance.new("Weld", script.Parent)
propw.Part0 = script.Parent.PropellerBase
propw.Part1 = prop
local rotv = 0
local on = true
while on == true do
    wait()
if rotv ~= 360 then
rotv = rotv +1
elseif rotv == 360 then
rotv = 0
end
propw.C1 = CFrame.new(0,0,0) * CFrame.Angles(0,math.rad(rotv),0)

end

Quick answer to this: CFrame.Angles

Let's say you have a part in workspace called Propel101 This is basically what you would do: (put this in a lonely script, without any other loops)

while wait() do
    workspace.Propel101.CFrame = workspace.Propel101.CFrame * CFrame.Angles(math.pi/100, 0, 0)
end

if the propel doesn't spin as it should, try moving the math.pi part into another axis. If it moves the opposite way of which you want it to, simply add a - to the pi, like this: -math.pi/100. If it moves too slowly, change the number after math.pi (the one that is being divided by), into something like math.pi/10

Hope this helped. Any questions/problems? Ask in the comments below