# Max RPM of a Flywheel: Calculating Friction & Drag-Free

• JakeMLaBonte
In summary, the fastest flywheel CTG manufactures has a rotational tip speed in excess of an incredible 1,000m/s!
JakeMLaBonte
Hey guys, new to the forum. I am wondering how to find what the maximum rpm of a flywheel could be. I was looking at stirling engines, and trying to compile all the equations that apply to calculate the rpm of the engine. I know the equation for the expansion of gas in the cylinders and the force applied to the pistons, however I know that as the flywheel starts turning, the energy carried with it and the continued force applied builds upon each other until it reaches its maximum rpm. Excluding the impact of friction and drag, I was wondering how you calculate the max rpm.

Welcome to PF!

I'm not sure you're asking the right question: excluding friction and drag, there is no maximum rpm for a flywheel. But why would you even care about that? Are you looking for the power output of the engine? It is a completely separate issue...

Wow, got to say, feeling pretty dumb right now, didnt even realize that until I wrote it out. And yes. I though if you were to hook stirling engine to sone type if generator, that the speed the motor rotates plays a factor.

The maximum revolutions per minute of a flywheel is the rpm when the flywheel flies apart.

Google found..
http://www.ctgltd.com/product/flywheels

The fastest flywheel CTG manufactures has a rotational tip speed in excess of an incredible 1,000m/s!

Not sure if this is out of date but...

http://www.guinnessworldrecords.com/world-records/fastest-rotating-flywheel/

The fastest rotational speed for a ring or disc-shaped object was achieved by scientists at Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA, on 9 December 1985. Using an air turbine, the Demo 1C flywheel was spun up to a tip speed of 1405 m/s (5,058 km/h 3142.9 mph), at which speed it failed due to the stress on the materials involved.

5000 km/h is about four times the speed of sound.

Not exactly a flywheel but...
http://www.cnet.com/uk/news/fastest-man-made-spinning-object-clocks-in-at-600m-rpm/

Scientists at the University of St. Andrews in Scotland spun a man-made sphere of calcium carbonate at 600 million revolutions per minute.

The sphere was only 4 micron in diameter so although it was doing 600,000,000 rpm the tip speed was only 125m/s.

Edit: I'll let someone work out the g-forces.

## 1. How do you calculate the maximum RPM of a flywheel?

The maximum RPM of a flywheel can be calculated by dividing the maximum angular velocity (measured in radians per second) by 2π, which gives the maximum revolutions per second. This can then be multiplied by 60 to get the maximum revolutions per minute (RPM).

## 2. What factors affect the maximum RPM of a flywheel?

The maximum RPM of a flywheel is affected by several factors, including the size and weight of the flywheel, the amount of friction and drag present, and the material the flywheel is made of. In addition, the power and torque of the engine or motor driving the flywheel can also impact its maximum RPM.

## 3. How does friction affect the maximum RPM of a flywheel?

Friction plays a significant role in determining the maximum RPM of a flywheel. The presence of friction between the flywheel and its bearings or other components can slow down its rotation and decrease the maximum RPM that it can reach. Reducing friction through proper lubrication and maintenance can help increase the maximum RPM of a flywheel.

## 4. What is drag-free and how does it impact the maximum RPM of a flywheel?

Drag-free refers to the absence of air resistance or drag on a flywheel. This can be achieved by enclosing the flywheel in a vacuum or by using a magnetic levitation system. Drag-free conditions allow the flywheel to spin at higher speeds, increasing its maximum RPM.

## 5. Can the maximum RPM of a flywheel be exceeded?

Yes, the maximum RPM of a flywheel can be exceeded in certain conditions. However, this can result in damage to the flywheel and other components. It is important to always operate a flywheel within its maximum RPM limit to ensure safe and efficient operation.

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