All answers are songs that contain a mode of transport (not all are song titles)
3) Ups-a-daisy (1,7,4,3,3)
10) Because I'm not that rich (2,4,4,3,3,2,1,8,4)
13) If they don't, we stay where we are (3,6,2,3,3,2,5,3,5)
15) I might come back ( 2,7,2,1,3,5)
21) This will make your arms ache(3,3,3,4,4)