Let me guess, you kept drifting off to the left or right. Which then in turn caused you to put the prop in to the ground.
To take off in IL2 you need to apply rudder correction. As I said, easier with a twisty joystick but you can do it via the keyboard. IIRC, it's the , & . keys but you'll need to make sure by looking in the ingame control screen.
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