Constructing A Swashplate-less Helicoper Rotor

A helicopter blade makes use of a swash plate and a set of linkages to alter the angle of the blades. Not solely does it fluctuate the collective pitch to extend or lower thrust, nevertheless it varies every blade’s pitch all through every rotation, letting it produce extra elevate on one facet of the rotor. This offered an issue to [worked in theory] — he’s constructing an RC helicopter from scratch, and this mechanism added each complexity and weight. Instead, he started looking for a way to get around the problem.

There have been two choices to get rid of the linkages: a linkage-less swashplate design utilized in Black Hornet drones, and an under-actuated design utilizing angled hinges to regulate the blade angle. [worked in theory] began with the Black Hornet design, which has the top of every blade run alongside the swashplate on wheels, whereas a central spring presses them down. Friction within the hinge and wheels proved too excessive, and it stopped responding at greater speeds. A second, lower-friction design appeared promising, nevertheless it nonetheless required actuators, and thus weight, to regulate the swashplate. [worked in theory] subsequently moved on to the under-actuated method. In this design, the blades are mounted on angled hinges — by various the motor’s pace all through every rotation, inertia causes the blades to swing backwards or forwards, altering their pitch.

[worked in theory] examined two such rotor designs: one with one hinge per rotor, and one with one hinge for each rotors. The design utilizing a single hinge appeared much less delicate to friction, was extra responsive in testing, and had a extra linear management response, so he used that. To really make the blades, [worked in theory] 3D printed them as flat blanks, then thermoformed them utilizing printed molds. During testing, the blades wanted weights added to tug them again towards the usual angle below fixed rotation; fortuitously, although, this had the facet impact of damping out undesirable vibrations.

There’s nonetheless a protracted technique to go earlier than the helicopter’s completed, however that is fairly a powerful begin. This is the second under-actuated propeller we’ve seen not too long ago, each impressed by [Tom Stanton]’s original design.