Thinking about propeller safety will keep you and people around the model safe. Plus it will extend the lifetime of the model.
The propeller on an airplane or a drone is rotated at high speed, thus generating thrust. It also experiences a number of other complex forces that can place it under stress. As the propeller blades tend to be sharp to cut through the air they can also easily cut hands or worse. Therefore, however the propeller is being powered it needs to be treated with respect.
Here are some simple points to follow:
- Install the prop with the curved side of the blade facing forward and tighten the prop nut or bolt with the proper size wrench.
- Recheck the tightness of the nut or bolt often, especially on wood props which tend to compress and loosen more often.
- When starting the engine, keep spectators at least 20 feet clear of the model and out of the path of the propeller. The safest place to stand is behind the aircraft, except for pusher propeller installations .
- Keep hands away from the prop as much as possible. Use a chicken stick or and electic starter.
- Keep face and body out of prop arc as engine is started and run.
- Make all adjustments from behind the prop except on pusher prop installations.
- Never throw anything into the prop to stop the engine. Use a kill switch or pinch off the engine’s fuel supply.
- Discard any prop with nicks, scratches, splits, cracks or any other sign of damage. Never attempt to repair, alter or bend a prop.
- Don’t run an engine in areas of loose gravel or sand. The prop can throw such material into your face and eyes. It’s not a bad idea to wear eye protection.
- Keep loose clothing, shirt sleeves, and other such items away from the propeller. Also, avoid carrying objects that can fall into the prop such as pens, screwdrivers, etc.
- Be sure to keep the glow driver wire out of the prop path.
- If a spinner is used, be certain that it’s edges are not in contact with the propeller blades.
Propellers are one of the key components that need to be carefully designed and maintained. Propeller safety contributes significantly to overall flying safety.
Propeller Dynamics
All propeller blade airfoils have a certain angle of attack range, in which the flow around the airfoil remains attached to airfoil′s surface. While this is the case, the efficiency of the axial fan is satisfactory, but, when the angle of attack of the incoming free stream exceeds this angle of attack range, efficiency goes down and noise goes up.