TeeS, you mention you A level physics so just spoke to my daughter, doesn't usually help!!! albeit, she gave me a wonderful sum once about slope landings and how helicopters could land on excessive slopes by compounding the slope. Anyway, you dont have an equation without various weights, gravity, various accelerations, chords, washout/shape/taper types of head and a few other things I can't even spell she's a Dr MPhys (Hons) MSC AMinstP DIP IPEM, so far but not an aerodynamicist. Not sure I am disagreeing with Nick or he with me. Other than one of terminology.
Nick, nice animation and very graphical, a good learning lesson but cant see how it proves your point I believe it generalises, pity the max rates of descent are only half what you quoted hope you sort of agree with my my last sentance to TeeS. Enjoy