63 inch 2- blade carbon fiber propeller for mega UAV Drone Airplane paramotor paraglider

For a paramotor use, the propeller must :

- be exactly adapted to the engine and the RPM

- give the best thrust

- be ultra-light to be as reactive as possible, and to guarantee a long life to the engine

The freerchobby propellers are very different from the other propellers. They have special profiles, patented designs, and special position of the blades to reduce the blades drag, so to obtain the best thrust.

1- Propeller efficiency

Propulsion efficiency factor is calculated from propeller diameter and engine power. This efficiency factor is the max achievable propeller efficiency. Then, it is up to the propeller designer to come closer to this limit.

This software allows the team to imagine new propellers concepts, by using particular geometries and profiles developed inhouse. That is why propellers are very different from other propellers proposed at present on the market.

When we speak of efficiency, we obviously speak of thrust and also of fuel consumption.

A propeller which has a better efficiency allows to reduce the fuel consumption of the engine.

2- Blades number

For a paramotor use (it means low speed), for the same diameter, more blades = more efficiency.

A 3-blades has a best efficiency (= a best thrust) than a 2-blades.

=> Please note :

This is true if the blade form is exactly adapted to the configuration : a blade of a 2-blades propeller mounted on a 3-blades or 4-blades hub would not give the best performances.

The "universal" blade for any configuration does not exist. Every propeller has a dedicated blade geometry, or the efficiency would not be the best.

3- Propeller diameters

The increase of the diameter is better for the efficiency, because of the improvement of the pusher efficiency.

More thrust is obtained with a propeller with a diameter of 150 cm than with a propeller with a diameter of 125 cm.

With the same number of blades, the thrust gap depends on the diameters and on the engine reducer.

4- Propellers : 2-blade / 3-blade

Some people are saying that the wake of the third blade of a 3-blade propeller is crossing the wake of the 2 other blades, and this phenomenon decreases the efficiency of the propeller.

That's wrong. The wakes of the different blades cannot crossed themselves. It is physically impossible, because the blade's wake is sweeped away by the wind.