Performance Calculator

If you're new and need guidance, this document will be your friend.

Select an option to get started
Electrical Output
Weightlifting Output
Tip Speed Ratio
energy output over 1 minute
turbine power and efficiency

Energy output over 1 minute

As your wind turbine operates, measure the voltage at 5 second intervals, for 60 seconds. Record the average voltage you see on your meter. This can be challenging (that's the reason why we love data collecting tools from Vernier). For this calculation to work, you will need to measure the voltage across a known resistor and enter that into data into the spreadsheet.

ohms ( ? )

Enter voltages

Time period (s) Voltage ( ? ) Voltage2 Voltage2 / Resistance Energy produced
0-4
5-9
10-14
15-19
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-60
Calculate

Millijoules over 1 minute = _____

Turbine power and efficiency

The turbine power calculator outputs the power output of your small turbine in watts and milliwatts. All you need to do is measure your voltage across a known resistor.

If you know how much power you are generating, the wind speed, and how long your blades are, you can calculate the efficiency of your turbine. Based on the Betz Limit, the highest this can be is 59%.

Please note: the efficiency calculator is only useful for horizontal axis machines. We're working on a vertical axis calculator.

Calculate power

Equations used →

  1. Watts (W) = v2 (voltage) / ohms (resistance)
  2. Milliwatts (mW) = W (watts) * 1000

volts ( ? )

ohms ( ? )

Calculate

Turbine power results

Watts = _____ W

Milliwatts = _____ mW

Calculate efficiency

Equations used →

  1. Available power = 0.5 * πr(m)2 (blade swept area) * 1.23 kg/m3 (air density) * v3 (velocity cubed)
  2. Turbine efficiency = W (watts generated by turbine) / Available power * 100 (to get percentage)

cm2 ( ? )

m/s ( ? )

Calculate

Available power

Watts = _____ W

Milliwatts = _____ mW

Turbine efficiency

Efficiency = _____%

Weightlifting power

This calculator can be used to help quantify the amount of energy your turbine transferred from the wind to lifting weights. You can also use this data to calculate the average power output of your turbine.

Equations used

  1. Work (Energy Transferred) (J) = Force (N) x Distance (m)
  2. Average Power (w) = Energy Transferred (J) / Time (s)

washers (REcharge kit washers are 13g each)

cm

s

Calculate

Weightlifting power results

Millijoules = _____ mJ

Milliwatts = _____ mW

Tip speed ratio

If you know the diameter of your wind turbine rotor, the velocity of the wind, and your RPM, you can calculate tip speed ratio (TSR). Generally the higher your TSR, the more electricity you are going to be able to generate on a three bladed turbine.

This calculator uses your rotor diameter to determine the distance your blades travel in one revolution. Using RPM it then determines how many revolutions your blades make in one second. With these numbers it can then calculate the velocity of the blades in m/s and compares that to the velocity of the oncoming wind.

Show equations used

  1. Distance blade tip travels in one revolution (m) = 2Ï€r
  2. Revolutions per second = rpm / 60
  3. Blade tip velocity (m/s) = distance blade trip travels in 1 revolution * revolutions per second
  4. Tip speed ratio = Blade tip velocity / Wind speed (m/s)

cm (rotor diameter)

rpm

m/s

Calculate

Tip speed ratio results

Distance blade tip travels in 1 revolution = _____ m

Revolutions per second = _____

Velocity of the blade tip = _____ m/s

Tip speed ratio = _____