Oskar
Member
- Joined
- Mar 10, 2007
- Messages
- 251
- Location
- Auckland, New Zealand
- Aircraft
- R22, MTO Sport, GyroBee, Mosquito Air
This thread is about an electric tail rotor conversion on a Mosquito helicopter.
Measurements on the conventional tail rotor showed that it was very power hungry, and calculations indicated that drone motors driving fixed pitch props would use a lot less power. The mechanically driven tail rotor was thus removed and replaced with a few battery powered electric motors. The design ended up with seven motors arranged like this, the large circle is the old tail rotor and the thick dark line the main rotor.

The obvious place to put the battery is close to the motors, thus at the end of the tail boom. That’s what I did, the battery shown gives about 30 minutes of endurance.

For tail rotor control the existing foot pedals are used. At some point pedal movement needs to be converted into an electric signal, this is done using a potentiometer which is then fed into a microprocessor.

The micro decides what signal should be sent to the tail (more about that later) and that then goes all the way to the back with a single twisted pair.

The control signal is sent to each motor controller. The motors and their controllers are standard off the shelf drone stuff, nothing fancy there.
The battery management system in the first picture keeps an eye on the battery and is used to accurately measure the tail rotor power. A comms wire still needs to be installed so that the tail rotor battery can be monitored while flying.
So far I’ve had the heli in the air with only 4 motors, it works but they are working reasonably hard. The last 3 motors have since arrived and been installed, so testing with 7 motors will happen soon.
Measurements on the conventional tail rotor showed that it was very power hungry, and calculations indicated that drone motors driving fixed pitch props would use a lot less power. The mechanically driven tail rotor was thus removed and replaced with a few battery powered electric motors. The design ended up with seven motors arranged like this, the large circle is the old tail rotor and the thick dark line the main rotor.

The obvious place to put the battery is close to the motors, thus at the end of the tail boom. That’s what I did, the battery shown gives about 30 minutes of endurance.

For tail rotor control the existing foot pedals are used. At some point pedal movement needs to be converted into an electric signal, this is done using a potentiometer which is then fed into a microprocessor.

The micro decides what signal should be sent to the tail (more about that later) and that then goes all the way to the back with a single twisted pair.

The control signal is sent to each motor controller. The motors and their controllers are standard off the shelf drone stuff, nothing fancy there.
The battery management system in the first picture keeps an eye on the battery and is used to accurately measure the tail rotor power. A comms wire still needs to be installed so that the tail rotor battery can be monitored while flying.
So far I’ve had the heli in the air with only 4 motors, it works but they are working reasonably hard. The last 3 motors have since arrived and been installed, so testing with 7 motors will happen soon.