Sovereignty Module: Catch the Wind
Complete Windmill Construction: From Breeze to Power
Wind power has driven civilization for millennia. This campaign covers windmill types, blade design, tower construction, mechanical power transmission, and applications.
Chapter 1: Windmill Types
| Type | Complexity | Power Output | Wind Speed Needed | Best For |
|---|---|---|---|---|
| Savonius (vertical axis) | Very low | Low (5-15% efficient) | Low (5+ mph) | Water pumping, small tasks |
| American farm windmill | Moderate | Moderate | Moderate (8+ mph) | Water pumping |
| Post mill (traditional) | High | Moderate-high | Moderate (10+ mph) | Grain milling |
| Dutch-style tower mill | Very high | High | Moderate (10+ mph) | Grain milling, sawing |
| Small horizontal axis | Moderate | Low-moderate | Moderate (8+ mph) | Electricity generation |
Chapter 2: Savonius Rotor (Simplest Build)
| Component | Material | Size | Function |
|---|---|---|---|
| Rotor blades | Split barrel, sheet metal, or plywood | 2-4 feet tall | Catch wind |
| Central shaft | Steel pipe (1-1.5 inch) | Height of rotor + bearings | Rotation axis |
| End plates | Plywood or metal | Diameter of rotor | Hold blades, structural |
| Bearings | Pillow block bearings | Standard | Low friction rotation |
| Frame/tower | Wood or steel | 6-20 feet | Elevate rotor |
Savonius construction: 1) Cut barrel or drum in half lengthwise (two half-cylinders). 2) Mount half-cylinders on central shaft with offset (S-shape when viewed from top). 3) Gap between halves: 10-15% of diameter (allows air to flow through). 4) Attach end plates top and bottom (structural rigidity). 5) Mount shaft in bearings on frame. 6) Rotor catches wind on concave side, deflects on convex side. 7) Net force causes rotation. 8) Savonius works in any wind direction (no yaw mechanism needed). 9) Low efficiency but extremely simple and reliable.
Chapter 3: Blade Design (Horizontal Axis)
| Blade Count | Speed | Torque | Best For | Efficiency |
|---|---|---|---|---|
| 2 blades | Very fast | Low | Electricity generation | Good |
| 3 blades | Fast | Moderate | Electricity, general | Very good |
| 4-6 blades | Moderate | High | Water pumping | Good |
| 12-24 blades (fan mill) | Slow | Very high | Water pumping | Moderate |
Blade principles: 1) Blades must be airfoil-shaped (curved on one side, flat on other). 2) Twist blades from root to tip (angle decreases toward tip). 3) Root angle: 20-30 degrees from plane of rotation. 4) Tip angle: 5-10 degrees from plane of rotation. 5) Blade length determines swept area (power). 6) Power increases with cube of wind speed (double wind = 8x power). 7) Power increases with square of blade length (double length = 4x power). 8) Material: wood (carved), sheet metal, or PVC pipe (split lengthwise).
Chapter 4: Tower Construction
| Tower Type | Height | Difficulty | Cost | Durability |
|---|---|---|---|---|
| Wooden pole | 10-20 feet | Low | Very low | Moderate |
| Wooden lattice | 15-30 feet | Moderate | Low | Good |
| Steel pipe | 15-40 feet | Moderate | Moderate | Very good |
| Steel lattice | 20-60 feet | High | Moderate-high | Excellent |
| Tilt-up (hinged base) | 15-40 feet | Moderate | Moderate | Good (easy maintenance) |
Tower principles: 1) Height matters enormously (wind speed increases with height). 2) Tower should be at least 30 feet above any obstacle within 300 feet. 3) Guy wires provide stability (3-4 wires at 120-90 degree intervals). 4) Guy wire anchor points: distance from base = 50-80% of tower height. 5) Foundation: concrete pad or deep post holes. 6) Tilt-up towers allow ground-level maintenance (highly recommended).
Chapter 5: Applications
| Application | Power Needed | Mechanism | Complexity |
|---|---|---|---|
| Water pumping | Low-moderate | Crank and piston pump | Low |
| Grain milling | Moderate-high | Gears to millstones | Moderate-high |
| Electricity (small) | Low-moderate | Generator/alternator | Moderate |
| Sawing wood | High | Crank to saw frame | High |
| Bellows (forge) | Low | Crank to bellows | Low-moderate |
| Washing machine | Low | Agitator mechanism | Low |
Water pumping system: 1) Windmill drives rotary motion. 2) Crank converts rotation to reciprocating (up-down) motion. 3) Pump rod connects crank to piston pump at ground level. 4) Piston pump draws water from well on downstroke. 5) Check valves prevent backflow. 6) Water delivered to tank or trough. 7) American farm windmill: 18-24 blade fan, 6-10 foot diameter. 8) Can pump 500-2,000 gallons per day in moderate wind.
Reference Card
- Height is everything (wind speed increases dramatically with height; every additional 10 feet of tower height significantly increases power output). 2. Power increases with the cube of wind speed (doubling wind speed produces eight times the power; site selection and tower height are critical). 3. The Savonius is the simplest windmill (a split barrel on a vertical shaft; it works in any wind direction and can be built in a day). 4. More blades means more torque (multi-blade fan mills start in lighter winds and produce high torque for pumping; fewer blades spin faster for electricity). 5. Twist the blades (blades must twist from root to tip because the tip moves faster than the root; without twist, the inner portion stalls). 6. Guy wires prevent collapse (a tall tower without guy wires will eventually fall; use 3-4 guy wires anchored at 50-80% of tower height distance). 7. Tilt-up towers save lives (a hinged tower that lowers to the ground allows safe maintenance; climbing a windmill tower is dangerous). 8. Wind plus water storage equals reliability (wind is intermittent; pump water into an elevated tank during windy periods and gravity-feed it when calm).