The distance traveled by the propeller plane when the propeller rotates in the air.
Assuming that the propeller rotates in a medium that cannot flow, then each time the propeller rotates, it will move forward a distance, and continuous rotation forms a spiral. The same blade rotates once to form a spiral. The distance of the spiral is called the pitch.
Because it is difficult to actually measure the pitch, generally fixed-pitch propellers (simple propeller aircraft and propellers used on ships) will have the pitch size marked (mostly in inches). , so as to be provided for engine supporting use.
Extended information:
Geometric parameters
1. Blade angle (β)
The blade angle changes with the radius. Regularity is the most important factor affecting the working performance of the paddle. It is customary to use the blade angle value at 70% of the diameter as the named value of the blade angle. Pitch: It is another way of expressing the blade angle.
2. Geometric pitch (H)
The distance traveled by the blade in one rotation when the angle of attack of the blade profile is zero. It reflects the size of the blade angle and more directly indicates the working characteristics of the propeller. The geometric pitch of each blade section may be unequal. It is customary to use the geometric pitch at 70% of the diameter as the nominal value. Propellers can be ordered abroad according to diameter and pitch. For example, 64/34 means that the diameter of the propeller is 60 inches and the geometric pitch is 34 inches.
3. Actual pitch (Hg)
The distance the aircraft travels when the blades rotate once. Hg=v/n can be used to calculate the actual pitch value of the propeller. The value of the geometric pitch of the propeller used in the aircraft can be roughly estimated based on H=1.1~1.3Hg.
4. Theoretical pitch (HT)
When designing a propeller, the speed of air flowing through the propeller must be considered to increase. The airflow speed flowing through the rotating plane of the propeller is greater than the flight speed. Therefore, the distance the propeller advances relative to the air - the theoretical pitch - will be greater than the actual pitch.
Baidu Encyclopedia-Propeller
Baidu Encyclopedia-Pitch