(d)direct that any aircraft or class of aircraft, or any aerodrome, aircraft factory, flying school or club, or place where aircraft are manufactured, repaired or kept, together with any machinery, plant, material or things used for the operation, manufacture, repair or maintenance of aircraft shall be delivered, either forthwith or within a specified time, to such authority and in such manner as it may specify in the order, to be at the disposal of Government for the public service.