Articulated Rotors have less chance of mast bumping?

[Aviator168-aircraft]

Does an articulated rotor (even fixed pitch) have less chance of mast bumping? Even in a 2 blade rotor. Since the blades are not linked to each other, the rising of the advancing blade won't force the retrieving blade to go down, so the lowest point the retrieving blade can go is when it is normal with the mast. This will reduce the chance of mast bumping. If the RRPM is low relative to forward speed, the advancing blade will just rise higher.

 

[Mayfield]

I'm having difficulty envisioning how a fixed pitch, articulated rotor would work.

Jim

 

[WaspAir]

Me, too.

On the general topic, mast bumping isn't really an issue for fully articulated rotors, but there can be some risk of ground resonance. I consider that a good trade, because resonance can be avoided with just a bit of care.

 

[Aviator168-aircraft]

Me, too.

On the general topic, mast bumping isn't really an issue for fully articulated rotors, but there can be some risk of ground resonance. I consider that a good trade, because resonance can be avoided with just a bit of care.

Yeah. The FAA still wants us to use teetering blades

I'm having difficulty envisioning how a fixed pitch, articulated rotor would work.

Same as current rotors, but with flapping and lead-lag hinges.

 

[XXavier]

Yeah. The FAA still wants us to use teetering blades


Same as current rotors, but with flapping and lead-lag hinges.

I try to visualize the forward moving, fully-articulated rotor in flight as if the blades –seen from the autogyro– were moving across the surface of a cone, the axis of that cone tilted back forming an angle (the flapping angle) with the rotor shaft axis. However, a flapping hinge is not enough, because (due to the flapping, and as seen from the rotor shaft) the distance between the center of mass of a blade and the rotor shaft axis changes cyclically. That cyclical change creates an (also cyclical) acceleration of the blade. In order to give the blades freedom for the resulting leading and lagging movements, you need the lead-lag hinges…

I hope that my description is correct (and intelligible…)