# What is pitch angle of gear?

The addendum is the height by which a tooth of a gear projects beyond (outside for external, or inside for internal) the standard pitch circle or pitch line; also, the radial distance between the pitch diameter and the outside diameter.
A.

### What is meant by pitch angle in wind turbine?

Blade pitch or simply pitch refers to turning the angle of attack of the blades of a propeller or helicopter rotor into or out of the wind to control the production or absorption of power. Wind turbines use this to adjust the rotation speed and the generated power.
• #### Why do wind turbines have curved blades?

Just like an aeroplane wing, wind turbine blades work by generating lift due to their curved shape. The side with the most curve generates low air pressure while high pressure air beneath pushes on the other side of the blade shaped aerofoil.
• #### What is the prop pitch?

When it's time to buy a new propeller, diameter and pitch are the watchwords. Pitch is defined as "the distance a propeller would move in one revolution if it were moving through a soft solid, like a screw through wood." For example, a 21-pitch propeller would move forward 21 inches in one revolution.
• #### What is feathering in aviation?

On some variable-pitch propellers, the blades can be rotated parallel to the airflow to reduce drag in case of an engine failure. This is called feathering, a term borrowed from rowing. On single-engined aircraft, whether a powered glider or turbine-powered aircraft, the effect is to increase the gliding distance.
B.

### What is pitch attitude?

Angle of attack (AOA) is the angle between the oncoming air or relative wind and a reference line on the airplane or wing. Pitch angle (attitude) is the angle between the longitudinal axis (where the airplane is pointed) and the horizon. This angle is dis- played on the attitude indicator or artificial horizon.
• #### What causes stall?

A stall is a condition in aerodynamics and aviation wherein the angle of attack increases beyond a certain point such that lift begins to decrease. The angle at which this occurs is called the critical angle of attack.
• #### Why is angle of attack important?

Angle of attack is the angle at which the relative airflow meets the wing. This is what determines when a wing will stall. It's important to understand relative wind – this is the way the air flows over the wing – when this is disrupted, air can no longer flow the way it's designed to over the wing, and lift decreases.
• #### What is the difference between wind speed and airspeed?

Airspeed is the vector difference between the ground speed and the wind speed. On a perfectly still day, the airspeed is equal to the ground speed. But if the wind is blowing in the same direction that the aircraft is moving, the airspeed will be less than the ground speed.

Updated: 2nd October 2019