E-PROPS : Blade pitch adjustment
What makes the plane take off is not the engine rpm, but the traction of the propeller..
When trying to reduce the take-off distance of an airplane, traction between 40 and 80 km/h is much more important than between 0 and 40 km/h :
✗ While the plane goes from 0 to 40 km/h, its average speed is only 20 km/h, so the distance traveled remains low (ex: 16 m in 3 sec).
✗ Between 40 and 80km/h, the average speed is 60 km/h: this is where you "consume" the length of the track (ex: 60 m in 3.5 sec).
For E-PROPS propellers, which have a strong ESR effect, the static traction measurement is not a significant factor, as they are designed to achieve full traction while moving, not in static. In statics, the blades of E-Props propellers are slightly stalled.
The ideal engine speed is measured in flight and not on the ground.
The adjustment of the blade pitch depends on the type of aircraft engine.
1 - E-Props adjustment on Rotax 4 stroke series 9xx engines
2 - E-Props adjustment on Rotax 2 stroke 582 engines
3 - E-Props adjustment on Jabiru 2.2 engines
On Rotax 9xx series 4-stroke engines (912, 912S, 912iS, 914, 915iS), the pitch at which the E-PROPS propeller will give the best performance over the whole speed range of the aircraft is obtained at 5500 rpm.
So it is strongly recommended to adjust your E-PROPS propeller to obtain this value when you put full throttle (horizontal flight).
Of course, this does not mean that you have to fly cruising at 5.500 rpm: this is only the right value to have the best pitch.
So, on a Rotax series 9, here is the method to obtain the best pitch of your E-PROPS propeller, which will give the best possible performance over the whole speed range of the aircraft:
✗ Adjust the pitch as recommended on your E-Props Propeller Identification Sheet
✗ Then, on the ground, put full power on brakes or chocks: if you have between 5.100 and 5.800 rpm, you can go flying. If it is not the case, adjust the blade pitch to have a minimum of 5.100 and a maximum of 5.800 rpm on the ground.
✗ In flight, fly horizontally and measure the rpm when you put full power: if you get about 5.500 rpm (+/- 50 rpm), it's perfect. If not, adjust the pitch to get 5.500 rpm at full power in horizontal flight.
On Rotax 9xx series engines, the 0.6° increase in engine timing reduces full throttle engine speed by 100 rpm.
Example: in full throttle, the engine is running at 5,700 rpm, while the target is 5,500 rpm. The difference is 2 x 100 rpm, so the pitch must be increased by 2 x 0.6° = 1.2°.
If you don't get this value of 5,500 rpm in full throttle, then your propeller is not optimally set for the full speed range of your aircraft.
On Rotax 2-stroke 582 engines, the propeller pitch for which the E-PROPS propeller will give the best performance over the whole range of speed is obtained at:
So it is strongly recommended to adjust your E-PROPS propeller to obtain this value when you put full throttle (horizontal flight).
Of course, this does not mean that you have to fly cruising at 6.800 rpm: this is only the right value to get the best pitch of your propeller blade pitch.
So on a Rotax 582, here is the method to obtain the ideal pitch of your E-PROPS propeller, which will give the best possible performance over the entire speed range of the aircraft:
✗ Adjust the pitch as recommended on your E-Props Propeller Identification Sheet
✗ Then, on the ground, put full power on brakes or chocks: if you have between 6.000 and 6.800 rpm, you can go flying. If it is not the case, adjust the blade pitch to have a minimum of 6.000 and a maximum of 6.800 rpm on the ground.
✗ In flight, fly horizontally and measure the rpm when you put full power: if you get about 6.800 rpm (+/- 50 rpm), it's perfect. If not, adjust the pitch to get 6.800 rpm at full power in horizontal flight.
On Rotax 582 engines, the increase of the pitch reduces the engine speed in full throttle by a value that depends on the reduction ratio of the engine:
Example: in full throttle, the engine is running at 6,600 rpm, while the target is 6,800 rpm. The difference is 2 x 100 rpm, so the pitch must be decreased by 2 x 0.7° = 1.4°.
If you don't get this value of 6,800 rpm in full throttle, then your propeller is not optimally set for the full speed range of your aircraft.
information coming soon
When trying to reduce the take-off distance of an airplane, traction between 40 and 80 km/h is much more important than between 0 and 40 km/h :
✗ While the plane goes from 0 to 40 km/h, its average speed is only 20 km/h, so the distance traveled remains low (ex: 16 m in 3 sec).
✗ Between 40 and 80km/h, the average speed is 60 km/h: this is where you "consume" the length of the track (ex: 60 m in 3.5 sec).
For E-PROPS propellers, which have a strong ESR effect, the static traction measurement is not a significant factor, as they are designed to achieve full traction while moving, not in static. In statics, the blades of E-Props propellers are slightly stalled.
The ideal engine speed is measured in flight and not on the ground.
The adjustment of the blade pitch depends on the type of aircraft engine.
1 - E-Props adjustment on Rotax 4 stroke series 9xx engines
2 - E-Props adjustment on Rotax 2 stroke 582 engines
3 - E-Props adjustment on Jabiru 2.2 engines
1 - E-Props adjustment on Rotax 4 stroke series 9xx engines
On Rotax 9xx series 4-stroke engines (912, 912S, 912iS, 914, 915iS), the pitch at which the E-PROPS propeller will give the best performance over the whole speed range of the aircraft is obtained at 5500 rpm.
5.500 rpm at full throttle
So it is strongly recommended to adjust your E-PROPS propeller to obtain this value when you put full throttle (horizontal flight).
Of course, this does not mean that you have to fly cruising at 5.500 rpm: this is only the right value to have the best pitch.
So, on a Rotax series 9, here is the method to obtain the best pitch of your E-PROPS propeller, which will give the best possible performance over the whole speed range of the aircraft:
✗ Adjust the pitch as recommended on your E-Props Propeller Identification Sheet
✗ Then, on the ground, put full power on brakes or chocks: if you have between 5.100 and 5.800 rpm, you can go flying. If it is not the case, adjust the blade pitch to have a minimum of 5.100 and a maximum of 5.800 rpm on the ground.
✗ In flight, fly horizontally and measure the rpm when you put full power: if you get about 5.500 rpm (+/- 50 rpm), it's perfect. If not, adjust the pitch to get 5.500 rpm at full power in horizontal flight.
On Rotax 9xx series engines, the 0.6° increase in engine timing reduces full throttle engine speed by 100 rpm.
Example: in full throttle, the engine is running at 5,700 rpm, while the target is 5,500 rpm. The difference is 2 x 100 rpm, so the pitch must be increased by 2 x 0.6° = 1.2°.
If you don't get this value of 5,500 rpm in full throttle, then your propeller is not optimally set for the full speed range of your aircraft.
2 - E-Props adjustment on Rotax 2 stroke 582 engines
On Rotax 2-stroke 582 engines, the propeller pitch for which the E-PROPS propeller will give the best performance over the whole range of speed is obtained at:
6.800 rpm at full throttle
So it is strongly recommended to adjust your E-PROPS propeller to obtain this value when you put full throttle (horizontal flight).
Of course, this does not mean that you have to fly cruising at 6.800 rpm: this is only the right value to get the best pitch of your propeller blade pitch.
So on a Rotax 582, here is the method to obtain the ideal pitch of your E-PROPS propeller, which will give the best possible performance over the entire speed range of the aircraft:
✗ Adjust the pitch as recommended on your E-Props Propeller Identification Sheet
✗ Then, on the ground, put full power on brakes or chocks: if you have between 6.000 and 6.800 rpm, you can go flying. If it is not the case, adjust the blade pitch to have a minimum of 6.000 and a maximum of 6.800 rpm on the ground.
✗ In flight, fly horizontally and measure the rpm when you put full power: if you get about 6.800 rpm (+/- 50 rpm), it's perfect. If not, adjust the pitch to get 6.800 rpm at full power in horizontal flight.
On Rotax 582 engines, the increase of the pitch reduces the engine speed in full throttle by a value that depends on the reduction ratio of the engine:
Example: in full throttle, the engine is running at 6,600 rpm, while the target is 6,800 rpm. The difference is 2 x 100 rpm, so the pitch must be decreased by 2 x 0.7° = 1.4°.
If you don't get this value of 6,800 rpm in full throttle, then your propeller is not optimally set for the full speed range of your aircraft.
3 - E-Props adjustment on Jabiru 2.2 engines
information coming soon
