# Campaign 137: Harness the Wind

## The Complete Windmill Construction, Wind Power, and Mechanical Wind Energy Guide

### A Sovereignty Module of the Practitioner Community

## Preamble

Wind is free, perpetual, and available everywhere on Earth. For over 2,000 years, windmills have ground grain, pumped water, sawed lumber, and powered workshops. A single windmill can pump thousands of gallons of water per day from deep wells, grind enough grain to feed a village, or generate electricity for an off-grid homestead. Wind power requires no fuel, produces no emissions, and operates day and night when the wind blows. This campaign covers the complete design, construction, and operation of wind-powered machines from simple water pumpers to grain mills to electricity generators.

## Part I: Wind Fundamentals

### Chapter 1: Wind Power Physics

| Concept | Formula/Value | Practical Meaning |
|---|---|---|
| Power in wind | P = ½ρAV³ | Power increases with the CUBE of wind speed. Double the wind = 8x the power. |
| Swept area | A = πr² | Doubling blade length = 4x the swept area = 4x the power |
| Air density (ρ) | 1.225 kg/m³ at sea level | Higher altitude = lower density = less power |
| Betz limit | 59.3% maximum efficiency | No wind turbine can capture more than 59.3% of wind energy |
| Practical efficiency | 25-45% for well-designed turbines | Real-world losses from friction, generator, and blade design |
| Cut-in speed | 7-10 mph typical | Minimum wind speed to start generating useful power |
| Rated speed | 25-35 mph typical | Wind speed at which turbine reaches maximum rated output |
| Survival speed | 60-100 mph | Maximum wind speed the structure can withstand |

### Chapter 2: Site Assessment

| Factor | Ideal | Measurement Method |
|---|---|---|
| Average wind speed | 10+ mph annual average | Anemometer for 1 year, or check wind maps |
| Prevailing direction | Consistent from one direction | Wind vane observation over months |
| Obstructions | None within 500 ft upwind | Trees, buildings, hills create turbulence |
| Tower height | 30+ ft above any obstruction within 500 ft | Higher = stronger, smoother wind |
| Ground conditions | Solid for tower foundation | Must support tower + wind loads |

### Chapter 3: Wind Speed and Power Output

| Wind Speed (mph) | Wind Speed (m/s) | Power Available (watts per m² of swept area) | Practical Output (6 ft diameter rotor) |
|---|---|---|---|
| 5 | 2.2 | 6.5 | ~5 watts |
| 10 | 4.5 | 52 | ~40 watts |
| 15 | 6.7 | 176 | ~135 watts |
| 20 | 8.9 | 417 | ~320 watts |
| 25 | 11.2 | 815 | ~625 watts |
| 30 | 13.4 | 1,407 | ~1,080 watts |

## Part II: Windmill Types

### Chapter 4: Windmill Design Comparison

| Type | Complexity | Efficiency | Best For | Materials |
|---|---|---|---|---|
| Savonius (vertical axis, drag) | Very simple | 10-15% | Water pumping, low-speed applications | Oil drums, sheet metal |
| American farm windmill (multi-blade) | Moderate | 15-20% | Water pumping from wells | Steel, wood, or aluminum |
| Dutch-style post mill | Complex | 20-30% | Grain grinding, sawmill | Heavy timber, canvas sails |
| Horizontal axis (3-blade, modern) | Moderate-complex | 30-45% | Electricity generation | Wood, PVC, fiberglass, or metal blades |
| Cretan sail windmill | Simple | 15-25% | Grain grinding, water pumping | Wood frame, cloth sails |

### Chapter 5: Building a Savonius Rotor (Simplest Design)

| Step | Action | Details |
|---|---|---|
| 1. Cut drums | Cut two 55-gallon drums in half lengthwise | Creates 4 half-cylinders |
| 2. Weld/bolt to shaft | Attach two half-drums to central vertical shaft, offset 90° | S-shape when viewed from top |
| 3. Mount shaft | Shaft in bearings at top and bottom | Vertical axis — works from any wind direction |
| 4. Connect to pump or generator | Belt, chain, or direct drive to load | Low RPM, high torque — ideal for pumping |

**ADVANTAGE:** Savonius rotors work from any wind direction (no yaw mechanism needed), start in very low winds, and are extremely simple to build. **DISADVANTAGE:** Low efficiency (10-15%), limited to low-speed applications.

### Chapter 6: Building a 3-Blade Wind Turbine for Electricity

| Component | Material | Details |
|---|---|---|
| Blades (3) | Carved wood, PVC pipe, or fiberglass | 3-6 ft long each. Airfoil shape critical for efficiency. |
| Hub | Steel plate or flange | Connects blades to generator shaft at correct pitch angle |
| Generator | Permanent magnet DC motor (treadmill motor) or car alternator | Treadmill motors are ideal: low RPM, high output |
| Tail/vane | Sheet metal or plywood on boom | Keeps rotor facing into wind |
| Tower | Steel pipe, wood poles, or lattice | 20-40 ft minimum. Guy-wired for stability. |
| Charge controller | Electronic (purchased or built) | Prevents battery overcharge |
| Batteries | Deep-cycle lead-acid or lithium | Store energy for calm periods |
| Inverter | DC to AC converter | If powering AC appliances |

### Chapter 7: Blade Design (Airfoil)

| Parameter | Value | Why |
|---|---|---|
| Number of blades | 3 (optimal for electricity) | Balance of efficiency, smoothness, and structural balance |
| Tip speed ratio (TSR) | 5-7 for 3-blade | Blade tips move 5-7x faster than wind speed |
| Blade width (root) | 8-12% of blade length | Wider at root for strength |
| Blade width (tip) | 4-6% of blade length | Narrower at tip for speed |
| Twist angle (root) | 20-25° | Steeper angle at root (slower section) |
| Twist angle (tip) | 5-8° | Shallower angle at tip (faster section) |
| Airfoil profile | Flat bottom, curved top (like airplane wing) | Creates lift that drives rotation |

## Part III: Water Pumping Windmills

### Chapter 8: American Farm Windmill Design

| Component | Function | Details |
|---|---|---|
| Multi-blade rotor (12-18 blades) | Captures wind energy | Many blades = high torque at low speed (ideal for pumping) |
| Tail vane | Points rotor into wind | Also serves as overspeed protection (folds in high wind) |
| Gearbox | Converts rotary to reciprocating motion | Crank mechanism drives pump rod up and down |
| Pump rod | Transfers motion to well pump | Steel rod runs down inside well casing |
| Cylinder pump (at bottom of well) | Pumps water | Piston pump with check valves |
| Tower | Elevates rotor above obstructions | 20-40 ft steel lattice or wood |

### Chapter 9: Pumping Capacity

| Rotor Diameter | Well Depth | Wind Speed | Approximate Output |
|---|---|---|---|
| 6 ft | 50 ft | 15 mph | 200-400 gallons/day |
| 8 ft | 100 ft | 15 mph | 300-600 gallons/day |
| 10 ft | 150 ft | 15 mph | 400-800 gallons/day |
| 12 ft | 200 ft | 15 mph | 500-1,000 gallons/day |
| 14 ft | 250 ft | 15 mph | 600-1,200 gallons/day |

## Part IV: Grain Grinding Windmills

### Chapter 10: Windmill-Powered Grain Mill

| Component | Function | Details |
|---|---|---|
| Sails/blades | Capture wind energy | 4 sails with canvas covering (adjustable for wind speed) |
| Main shaft | Transfers rotation from sails | Heavy timber or steel |
| Great spur gear | Changes rotation axis from horizontal to vertical | Large wooden or cast gear |
| Stone spindle | Drives upper millstone | Vertical shaft from gear to stone |
| Millstones (2) | Grind grain between surfaces | Lower stone fixed (bedstone), upper rotates (runner stone) |
| Hopper | Feeds grain to center of stones | Vibrating feed mechanism |
| Meal spout | Collects ground flour | Flour exits at edge of stones |

### Chapter 11: Grinding Capacity

| Wind Speed | Sail Span | Approximate Output |
|---|---|---|
| 15 mph | 20 ft | 50-100 lbs flour/hour |
| 20 mph | 20 ft | 100-200 lbs flour/hour |
| 15 mph | 30 ft | 150-300 lbs flour/hour |
| 20 mph | 30 ft | 300-500 lbs flour/hour |

## Part V: The Practitioner Wind Power Reference Card

**WIND CUBES:** Power in wind increases with the cube of wind speed. 10 mph wind has 8x more power than 5 mph wind. Site selection and tower height are the most important factors — get into stronger, smoother wind.

**HEIGHT MATTERS:** Every 10 feet of additional tower height increases wind speed by approximately 10-20%. A 40-foot tower captures significantly more energy than a 20-foot tower at the same location.

**3 BLADES FOR ELECTRICITY, MANY BLADES FOR PUMPING:** Three-blade rotors spin fast with low torque (good for generators). Multi-blade rotors (12-18 blades) spin slowly with high torque (good for pumps). Match the rotor to the task.

**SAVONIUS FOR SIMPLICITY:** If you need a wind-powered water pump and have access to 55-gallon drums, a Savonius rotor can be built in a day. It works from any wind direction and starts in the lightest breeze.

**TREADMILL MOTORS ARE IDEAL GENERATORS:** Permanent magnet DC motors from treadmills generate useful voltage at low RPM (200-500 RPM), making them perfect for direct-drive wind turbines without gearboxes.

**REMEMBER:** Wind is the most accessible renewable energy source. It requires no fuel, no grid connection, and no ongoing cost. A Practitioner with a wind turbine has water from deep wells, ground grain, and electricity — all from thin air. Wind power built civilizations before fossil fuels existed, and it will power them long after fossil fuels are gone.

## Council Approval

**Council Result: 12/12 APPROVED.**