# Calculating Power & Torque for Flywheel Drives

• Bassam Salman
In summary, to calculate the power output from a flywheel, you need to account for the losses in the system.
Bassam Salman
Hi
I have a personal project, In link bellow in figure A I need to calculate appropriate power motor (HP) and torque (N.M) to drive flywheel at maximum speed 2000 rpm and what is value of resulting power on 750 rpm pulley.
In figure B if we use two flywheel the weight for each half weight of flywheel in figure A do motor power and resulting power equal to figure A

At steady state, in an ideal (lossless) system, the power out at 750 rpm will be equal to the power in at 3000 rpm.

Since no real system can be built without losses, you will need to account for the losses in the system to see how much power can be drawn out. Much depends on the quality of your bearings, the alignment of shafting, and the windage of the several elements.

With zero friction it takes zero power to maintain a rotation at constant speed.

Are you sure that the question is related to constant speed rather than acceleration?

Real life flywheels have friction and thus power loss.

Dr.D said:
At steady state, in an ideal (lossless) system, the power out at 750 rpm will be equal to the power in at 3000 rpm.

Since no real system can be built without losses, you will need to account for the losses in the system to see how much power can be drawn out. Much depends on the quality of your bearings, the alignment of shafting, and the windage of the several elements.
Is that mean no power loss on flywheel

anorlunda said:

With zero friction it takes zero power to maintain a rotation at constant speed.

Are you sure that the question is related to constant speed rather than acceleration?

Now I need calculate without friction and at constant speed

An ideal flywheel requires no power to run at constant rotational speed. Real flywheels (and every other machine part as well) always involve friction at bearings and windage. How much these friction losses are depends upon the shapes, the speeds involved, and the surrounding fluid medium.

Bassam Salman said:
Now I need calculate without friction and at constant speed

anorlunda said:
With zero friction it takes zero power to maintain a rotation at constant speed.

@Dr.D is telling you the same thing I am.

Edit: rearranged the above.

Ok thank you Dr. D and anorlunda
I need value of motor size (calculation) and also calculate out power

Bassam Salman said:
I need value of motor size (calculation) and also calculate out power
If there is no friction, the output power is equal to the input power; the flywheel doesn't change that.

You aren't thinking that the flywheel let's you get more power out than you put in, are you? That would violate the laws of physics and therefore the rules of this forum...

## 1. How do you calculate the power of a flywheel drive?

To calculate the power of a flywheel drive, you need to know the rotational speed of the flywheel and the torque it produces. The formula for power is P = T * ω, where P is power in watts, T is torque in Newton-meters, and ω is angular velocity in radians per second.

## 2. What is the role of a flywheel in a drive system?

A flywheel in a drive system acts as a kinetic energy storage device, storing energy in the form of rotational motion. It helps to maintain a constant speed and provide smooth power output by absorbing and releasing energy as needed.

## 3. How do you calculate the torque of a flywheel drive?

The torque of a flywheel drive can be calculated by multiplying the moment of inertia of the flywheel by its angular acceleration. The formula for torque is T = I * α, where T is torque in Newton-meters, I is moment of inertia in kg*m^2, and α is angular acceleration in radians per second squared.

## 4. What factors affect the power and torque of a flywheel drive?

The power and torque of a flywheel drive depend on several factors, including the size and weight of the flywheel, the rotational speed, and the amount of energy stored. Additionally, the design and efficiency of the drive system can also affect the power and torque output.

## 5. How can you increase the power and torque of a flywheel drive?

To increase the power and torque of a flywheel drive, you can either increase the size and weight of the flywheel or increase the rotational speed. However, it is important to note that there are limitations to how much power and torque a flywheel drive can produce, and exceeding these limits can result in damage or failure of the system.

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