# Comment on Flywheel energy storage experiment video

Electrical tests! | 2 Mechanical Battery by Black Sahara at https://www.youtube.com/watch?v=uiOf_-0aFP8

I like what you are doing or I would not comment. Please get a stand for your camera. Learn to solder. Learn to use sound card oscilloscopes and spreadsheets. Keep up the great work!! Thanks for the videos!!

Put a “support” “donate” button somewhere.

https://en.wikipedia.org/wiki/Flywheel has the equations you need to calculate how much energy this will store.

The energy in Joules for a rotating cylinder (yes it is a short cylinder) with radius R in meters is

EnergyJoules= (1/2) MomentOfInertia * (2 pi Frequency_Hertz)^2

MomentOfInertia = (1/2) * MassCylinderKilograms * RadiusCylinderMeters^2

You need know the CurrentAmperes and the VoltageVolts of what you want to power. And how long you are going to provide energy. You can use a sound card oscilloscope with your computer/laptop to measure and record the voltage over time. Take the readings each second and add them up.

EnergyJoulesForOneSecond = PowerWattsForOneSecond * 1 second

PowerWatts = CurrentAmperes * VoltageVolts

EnergyJoules = PowerWatts* TimeSeconds

VoltageVolts = CurrentAmperes * ResistanceOhms

PowerWatts = ResistanceOhms * CurrentAmperes^2

PowerWatts = VoltageVolts^2/ResistanceOhms

I think that is 66 foot electrical tape at 3/4 inch wide and weight 90.7 grams or 0.0907 Kilograms. The radius is something close to 2.5 centimeters or 0.025 meters.

The MomentOfInertia is close to (1/2)*(0.0907 kg) * (0.025 meters)^2 = 0.00002834375 KilogramMeterSquared

EnergyJoules = (1/2) * (2 pi)^2 * MomentOfInertia * FrequencyHertz^2

EnergyJoules = EnergyWattSeconds = 5.59483*10^-4 WattSecondsPerHertzSquared * FrequencyHertz^2

EnergyWattSeconds = 0.5595 * F^2 in milliWattSeconds

1000 RevolutionsPerMinute = 1000/60 RevolutionsPerSecond = 16.667 Rps = 16.667 Hertz

EnergyWattSeconds = 0.5595 * (16.667 Hertz)^2 = 155.4 milliWatt seconds.

If you power something that need 1 milliWatt, it will last about 155 seconds, except the power drops off fast and it will only work for a shorter time at that power level.

It seems like a lot to remember, but put it into a spreadsheet and you don’t have to remember all the details, just get them right when you set it up. There are going to be flywheel groups all over the Internet, and many many many calculators, models, equations and estimates.

Here is something more specific to storing energy at https://en.wikipedia.org/wiki/Flywheel_energy_storage

While electrical energy is useful, you might want to consider its use for storing angular momentum that can be used directly — https://en.wikipedia.org/wiki/Control_moment_gyroscope

Sincerely,
Richard Collins, Director, The Internet Foundation