# Performance Calculator

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

### Energy output over 1 minute

ohms ( ? )

Enter voltages

Time period (s) | Voltage ( ? ) | Voltage^{2} |
Voltage^{2} / Resistance |
Energy produced |
---|---|---|---|---|

0-4 |
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5-9 |
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10-14 |
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15-19 |
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20-24 |
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25-29 |
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30-34 |
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35-39 |
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40-44 |
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45-49 |
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50-54 |
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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

- Watts (W) = v
^{2}(voltage) / ohms (resistance) - Milliwatts (mW) = W (watts) * 1000

volts ( ? )

ohms ( ? )

Calculate### Turbine power results

Watts = _____ W

Milliwatts = _____ mW

## Calculate efficiency

- Available power = 0.5 * Ï€r(m)
^{2}(blade swept area) * 1.23 kg/m^{3}(air density) * v^{3}(velocity cubed) - Turbine efficiency = W (watts generated by turbine) / Available power * 100 (to get percentage)

cm^{2} ( ? )

m/s ( ? )

Calculate### Available power

Watts = _____ W

Milliwatts = _____ mW

### Turbine efficiency

Efficiency = _____%

### Weightlifting power

- Work (Energy Transferred) (J) = Force (N) x Distance (m)
- 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.

- Distance blade tip travels in one revolution (m) = 2Ï€r
- Revolutions per second = rpm / 60
- Blade tip velocity (m/s) = distance blade trip travels in 1 revolution * revolutions per second
- 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 = _____