Hi, this problem is bugging me for several days now. In ”200 Puzzling Physics Problems”, Gnadik, Honyek, Riley there is this Problem 59: The solution to this is an ingenious resort to dimensional analysis, as follows: Now, I don't have a problem with this. I wonder however, what if we express, instead of the power needed to hover, the rotor speed, or frequency, that has the dimension s-1. this would lead to α=1/2, β=-1/2 and γ=-δ=k. So, we'll get for the rotor speed s, needed for the helicopter to hoover: http://www.educatiarutiera.ro/wp-content/uploads/2017/03/sol591.png [Broken] Please let me know wether my reasoning is correct. I'm not familiar with dimensional analysis and I'd really want to introduce this problem to some of my students. Thank you.