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.

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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.

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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.

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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.

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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.

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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.

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