A plank driver here (though just starting helo training)...
I've been reading helicopter aerodynamics books for a while now and came accross one, which is more for engineers than pilots (quite a lot of maths there etc.) In the chapter on autorotation, the author states that for a typical helicopter, the glide angle in an auto for min sink rate is about 16.6 degrees IRRESPECTIVE OF MASS AND HELICOPTER SIZE/TYPE
The math behind this are the two following formulae:
Vy=0.14*omega*R
wmin=0.04*omega*R,
where:
Vy - autorotation speed for minimum sink rate
wmin - minimum sink rate
omega - rotor angular velocity
R - rotor radius
The author claims that they hold true for ALL conventional helicopters... Simple conversion of these formulae allows to obtain the aforementioned glide angle of 16.6 degrees.
Is that really like that? I buy the "mass" part, as the planks have the same best glide ratio for any mass (though at different speeds), but can't quite understand why it would be the same for different helicopter types
(have flown fixed-wings with best glide ratio ranging from 4 to 50)
I'm sorry if this question is too "nerdy", but I'm trying hard to understand why and how the helos fly...
