Tilt object x degrees, smoothly

Dear knights of Unity Answers.

For the last couple of days, i have been struggling with this scripting issue. Imagine a propeller flying by itself, being controlled by a remote. To fly left, it would have to tilt 10 degrees left, to fly right it would have to tilt 10 degrees right, et cetera. This is what i am trying to simulate.

Everything is working fine, except that i can't figure out how to tilt it 10 degrees smoothly. I've been punishing Unity Answers and google for the last couple of days, and just can't seem to figure it out.

I am very new to scripting in unity, so if you would comment your script that would be greatly appreciated!

Thanks a ton in advance.