Table 2: Selection criteria of different rotary AVS typologies [27] (1: bad, 10: very good).

Selection criteriaConventional (a)Ducted coaxial (b)Coaxial (c)

Compactness of folding1210
Reliability9108
Controllability557
Aerodynamic cleanliness828
Maturity of technology10810
Hover efficiency1088
Aerodynamic interaction777
Vibration121
Cruise efficiency768
Maneuverability533
Ease of payload packaging10810
Simplicity of structure8810
Simplicity of control system666

Selection criteriaSide by side (d)Tandem (f)Quad-rotor (g)

Compactness of folding228
Reliability889
Controllability5510
Aerodynamic cleanliness662
Maturity of technology9105
Hover efficiency10108
Aerodynamic interaction10107
Vibration222
Cruise efficiency665
Maneuverability449
Ease of payload packaging10108
Simplicity of structure887
Simplicity of control system6610