# Circular motion of airplane

#### denian

what provide the centripetal force?

the lifting force on the airplane? or the weight of the airplane? or both?
i read from the book, it says both, but since weight [mg] is always acting downward, how can it provide the centripetal force?

my teacher seems cant help me a lot.

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#### denian

and is there any webpage that give a good explaination on circular motion of the airplane?

#### KLscilevothma

Originally posted by denian
what provide the centripetal force?

the lifting force on the airplane? or the weight of the airplane? or both?
i read from the book, it says both, but since weight [mg] is always acting downward, how can it provide the centripetal force?
I think it is the horizontal component of lifting force which gives necessary centripetal force for banking. In other words, an airplane needs to bank so as to turn in a flight. I don't think weight provides necessary centripetal force as it only acts down as you've said.

#### enigma

Staff Emeritus
Gold Member
The lift is the only component unless the plane is flying in a downward spiral.

#### russ_watters

Mentor
HERE is a good explanation of the force components in a turn.
what provide the centripetal force?
Remember, when a plane is in a turn, its banking. The lift is always perpendicular to the wing, which means part of the force (vertical component) can be considered lift and part of the force (horizontal component) can be considered the turning force. Generally though the resultant force of a wing is not vertical, lift is always the vertical component and drag is the horizontal in one axis and turning force is horizontal in the other.

Also remember there is no force to balance the turning force - thats why the plane turns. A turn is an acceleration.

#### denian

thank you for the explaination.

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