On THE DECISIVE DUEL: SPITFIRE Vs 109 website, I have added a Soundtrack page linking text in the book to videos on You Tube. So on p. 436, reading about the Seafire 47, clicking on the link will bring up a video of its Griffon engine starting up and that amazing six-bladed contra-rotating propeller turning.
http://spitfirevsbf109.com/soundtrack/