On the basis of conservation of angular momentum, discuss why a helicopter must have more than one rotor.?

Clemmie Burkleo: Given a single rotor providing lift, the helicopter drive train must apply torque to keep the rotor spinning against air drag. This results in an equal and opposite reaction torque applied to the helicopter body. Without the application of a torque opposing this reaction torque the helicopter would spin helplessly and eventually go out of control. The opposing torque can come from a tail rotor or from a second lift rotor the rotates in the opposite direction to the first rotor.Tying this to conservation of angular momentum is a bit tricky. You cannot say that with only the single lift rotor the sum of the helicopter plus rotor angular momenta remains constant because that isn't true; as the helicopter continues to apply torque to the rotor the body spins up even if the rotor maintains a constant angular velocity. But you can say that the total angular momentum, including that which the rotor imparts to the air, is constant. The ang. mom. of the air is con! tinually increasing in a direction opposite to the increase of the body angular momentum. Of course a tail or second lift rotor nulls out the angular momentum of both the body and the air....Show more

Myron Leftwich: i aggree . it is not count fo friction is has to do regularly with regulations of conservation. we nust be taught the helicopter as a closed equipment. the great rotor is usinge the conservation of momentum thought so a ways as air-helicopter equipment is worried. many molecules of air pass at a undeniable direction the helicopter physique strikes on the different. oush right down to enhance up. now because of this action that the helicopter is utilising simply by fact the great propeller is transferring in one direction then the helicopter ought to cancel out this result so as avert it for spinning around .consequently the back rotor comes ot play...Show more

Collin Barter: According to the principle, helicopter will have a momentum which is the pr! oduct of its moment of inertia and angular momentum. so in ord! er to follow the conservative property it can to keep any of these values constant so as there is a inertia all the time the only thing to do is on the velocity factor so it can be done by regulating the helicopter's propeller on the back of the tail to have more stability. equation = L=IW [Where L= ang.momentum I=Moment of inertia. W=ang.velocity]...Show more