Hello everyone.I have 1 question about quadcopter.. can you help me on how to prove the quadcopter can lift up by using physic law... if you have any physic calculation can share with me..

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Yep, good advice all around. Momentum/actuator disk theory is the primary analysis model for rotorcraft lift and propulsion. Here's a bit more detail, with some basic calculations:

If you want a bit more calculus to chew on, the whole aggregate rotation of airflow theory is commonly known as Kutta-Joukowski, with the caveat that it is two-dimensional. Three dimensional analysis requires integrating KJ along the rotor span AKA blade element analysis. How detailed do you want to get?

Buy the book "Fascination Quadrocopter", from amazon. Or maybe you can download it for free from the internet. It is not an expensive book. The link I have given you is from google books. It is quite nice for mathematically/ via physics to understand how it 'really' functions. It will answer all your questions.

A multicopter in hover can be explained by Newton's First Law.

When in a hover there are two equal and opposite forces at work keeping the net force at zero and therefore the change in velocity at zero. One force (gravity) is pulling the copter downward. This force at 1G is equal to the mass of the copter. The opposing force is the cumulative thrust of the props. When the thrust in a upward direction and force of gravity in a downward direction are equal there is no change in velocity.

Any excess thrust will cause the copter to begin to accelerate upward according to Newton's second Law. Conversely if the thrust is lower than the force of gravity it will begin to accelerate downward.

At a high level this explains how a copter can lift up. Neglecting drag you can calculate the rate of acceleration upward or downward for a copter of a given weight and for a given differnce in thrust and gravitational forces on the copter..

If you want to calculate thrust from a rotating propeller from first principles this is a much more involved endeavor.

## Replies

For an interesting site on aerodynamics and flying take a peek at See how it flies

Newton is covered specifically in The laws of motion

/RS

Yep, good advice all around. Momentum/actuator disk theory is the primary analysis model for rotorcraft lift and propulsion. Here's a bit more detail, with some basic calculations:

http://diydrones.com/forum/topics/the-case-for-large-scale-electric...

If you want a bit more calculus to chew on, the whole aggregate rotation of airflow theory is commonly known as Kutta-Joukowski, with the caveat that it is two-dimensional. Three dimensional analysis requires integrating KJ along the rotor span AKA blade element analysis. How detailed do you want to get?

http://en.wikipedia.org/wiki/Kutta%E2%80%93Joukowski_theorem

Hey,

Buy the book "Fascination Quadrocopter", from amazon. Or maybe you can download it for free from the internet. It is not an expensive book. The link I have given you is from google books. It is quite nice for mathematically/ via physics to understand how it 'really' functions. It will answer all your questions.

All the best!

If you are talking about the third law then I think of wind.

Gravity no.

Thrust no.

Wind yes.

When

F_{2}= −F_{1}This means that

F_{1}andF_{2}are equal in magnitude and opposite in direction.Randy

thrust generated by propellers must be greater than weight of quadcopter

A multicopter in hover can be explained by Newton's First Law.

When in a hover there are two equal and opposite forces at work keeping the net force at zero and therefore the change in velocity at zero. One force (gravity) is pulling the copter downward. This force at 1G is equal to the mass of the copter. The opposing force is the cumulative thrust of the props. When the thrust in a upward direction and force of gravity in a downward direction are equal there is no change in velocity.

Any excess thrust will cause the copter to begin to accelerate upward according to Newton's second Law. Conversely if the thrust is lower than the force of gravity it will begin to accelerate downward.

At a high level this explains how a copter can lift up. Neglecting drag you can calculate the rate of acceleration upward or downward for a copter of a given weight and for a given differnce in thrust and gravitational forces on the copter..

If you want to calculate thrust from a rotating propeller from first principles this is a much more involved endeavor.