flatten out vs touch down

flatten out

verb
  • To become more even. 

  • To win a fight, usually by punching someone until they are knocked over 

  • To make flat (something rough, folded or bumpy). 

touch down

verb
  • To score a try. 

  • To land an aircraft or spacecraft. 

  • To score a touchdown 

How often have the words flatten out and touch down occurred in a corpus of books? (source: Google Ngram Viewer )