An electric vertical take-off and landing (eVTOL) aircraft uses electric power to hover, take off, and land vertically. The eVTOL aircraft is modelled as shown with a total mass of M = 40m and radius of gyration about the centre of mass axis OX of d and includes four rotor blade systems, each of mass m and diameter d. The rotor blade systems can provide thrust in the z directions that increases with the magnitude of the spin rate p. The direction of the spin axis, z, can be tilted to be aligned with the vertical, Z, during takeoff as shown. Assume no friction between the aircraft body and each rotor. Assume OXYZ is aligned with the principal axes and the rotor blade (note there are two blades per rotor) may be modeled as a uniform thin rod with mass moment of inertia about its centre of mass Icom=m_r d^2/12. The rotors are spun up to speeds of p, p p and p-p (in rad/s) relative to the aircraft body in the directions as shown above using motor torques acting between the rotors and body. The aircraft body is initially on the ground during spinup. (b) Calculate the angular momentum