System, assemblies and methods for mechanical-thrust power conversion multifans
A multi-rotor system for providing air thrust is disclosed comprising at least one multi-rotor assembly. The multi-rotor assembly comprising at least two rotors rotatable about a common axis wherein the outer radius of a first rotor is substantially similar to the inner radius of the second rotor. An airborne vehicle is also disclosed that is adapted to perform vertical takeoff and landing (VTOL). The airborne vehicle comprising at least two multi-rotor system disposed substantially symmetrically around the center of gravity of the vehicle.
1 . A multi-rotor system comprising:
at least two concentric rotors rotatable about a common axis and disposed axially with respect to each other;
wherein blades of different rotors of the at least two concentric rotors have the same inner radius and different outer radiuses;
wherein the at least two concentric rotors are rotatable at different angular speeds with respect to each other; and
wherein the angular speeds of the at least two concentric rotors are set so as to rotate blade tips of the at least two rotor rotors at substantially the same tangential speed.
2 . The multi-rotor system of claim 1 , wherein the tangential speed of the rotor blade tips of the at least two concentric rotors is a maximal practical tangential speed for an operational profile of the multi-rotor system.
3 . The multi-rotor system of claim 1 , wherein the tangential speed of the blade tips of the at least two rotor rotors relative to the air is 0.2 Mach or less.
4 . The multi-rotor system of claim 1 , wherein the at least two concentric rotors are rotatable in the same direction.
5 . An airborne vehicle adapted to perform vertical takeoff and landing (VTOL), the airborne vehicle comprising at least two multi-rotor systems, each of the at least two multi-rotor systems is according to claim 4 .
6 . The airborne vehicle of claim 5 , wherein at least one multi-rotor system of the at least two multi-rotor systems is adapted to be tilted between a first position in which the at least one multi-rotor system provides mainly horizontal thrust and a second position in which the at least one multi-rotor system provides mainly vertical thrust.
7 . The airborne vehicle of claim 5 , wherein at least one of the at least two multi-rotor systems is adapted to provide mainly horizontal thrust when in flight maneuvering.