Our retrieval aircraft has quite large landing gear to give enough clearance for the prop and allow it to take off from sandy or grassy terrain.
The retrieval aircraft will be landing at a very steep angle, and so the landing gear must be retracted during landing, and then deployed when it’s on the ground.
This requires a lot of torque from the servo-less retracts used to deploy the landing gear, which conventional servo-less retracts don’t have.
A servoless retract was opened up, and it was discovered that it consists of a geared motor driving a threaded rod which pulls a nut back and forth. There is a circuit board with limit switches on the bottom which is used to control the motor.
By coupling a modified servo directly to the threaded rod, the servo-less retract was able to provide a much higher torque, so the landing gear can be deployed when the aircraft is on the ground.
The servo motor was modified so it provides continuous rotation, and the control module was removed so the motor could be directly connected to the control module on the servo-less retract.
The original motor section of the servo-less retract is removed and the new servo can be attached.
The new retracts run a fair bit slower given the higher gearing ratio of the servo motors, but we can live with this. The video below shows them in action lifting up our retrieval aircraft.