Blade Angle
Blade Angle is the tilt of a windmill blade, which changes how much wind it catches and how much power it makes.
Hold a flat spatula and tilt it under a running faucet. At a small tilt, water hits the flat side and pushes hard. You can feel the force in your hand. Tilt it more and water still pushes, but it starts to slide off the edge. Tilt it straight up and water just splits around it with no push at all. A windmill blade works the same way. The right tilt catches the most wind and turns it into spin.
Explaining blade angle by grade level
A windmill has flat parts that spin in the wind. If you tilt them too much, the wind slips past. If you tilt them too little, they just block the wind. A tilt near the middle works best.
Projects that explore blade angle
Blade angle controls how much wind a blade catches. Tilt the blade too flat and it slides through the air without pushing. Tilt it too far and it blocks the wind like a wall. In one test, blades set at 75 degrees produced the highest current. At 90 degrees the blades sat flat against the wind and made no power at all.
A small tilt barely deflects airflow, so the blades spin weakly. As the angle increases, each blade catches more wind and the turbine spins harder — up to a point. Zinc-sheet blades mounted in wooden blocks at seven angles, from 0 to 90 degrees, showed voltage rising steadily as the angle increased. Output peaked at 75 degrees, reaching 0.95 volts on a digital voltmeter. Beyond that angle the blades stalled and voltage dropped back to zero.