AS 350 hover question
Join Date: Feb 2004
Location: Just west of here
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Kinda like this.
"A fully articulated rotor system usually consists of three or more rotor blades. The blades are allowed to flap, feather, and lead or lag independently of each other. Each rotor blade is attached to the rotor hub by a horizontal hinge, called the flapping hinge (Starflex arm) , which permits the blades to flap up and down. Each blade can move up and down independently of the others. The flapping hinge may be located at varying distances from the rotor hub, and there may be more than one. The position is chosen by each manufacturer, primarily with regard to stability and control.
Each rotor blade is also attached to the hub by a vertical hinge (Thrust bearing), called a drag or lag hinge, that permits each blade, independently of the others, to move back and forth in the plane of the rotor disc. Dampers (Frequency adapters) are normally incorporated in the design of this type of rotor system to prevent excessive motion about the drag hinge. The purpose of the drag hinge and dampers is to absorb the acceleration and deceleration of the rotor blades.
The blades of a fully articulated rotor can also be feathered, or rotated about their span-wise axis. (Thrust bearing & self-aligning bearing mounted within the frequency adapter) To put it more simply, feathering means the changing of the pitch angle of the rotor blades."
WRL
"A fully articulated rotor system usually consists of three or more rotor blades. The blades are allowed to flap, feather, and lead or lag independently of each other. Each rotor blade is attached to the rotor hub by a horizontal hinge, called the flapping hinge (Starflex arm) , which permits the blades to flap up and down. Each blade can move up and down independently of the others. The flapping hinge may be located at varying distances from the rotor hub, and there may be more than one. The position is chosen by each manufacturer, primarily with regard to stability and control.
Each rotor blade is also attached to the hub by a vertical hinge (Thrust bearing), called a drag or lag hinge, that permits each blade, independently of the others, to move back and forth in the plane of the rotor disc. Dampers (Frequency adapters) are normally incorporated in the design of this type of rotor system to prevent excessive motion about the drag hinge. The purpose of the drag hinge and dampers is to absorb the acceleration and deceleration of the rotor blades.
The blades of a fully articulated rotor can also be feathered, or rotated about their span-wise axis. (Thrust bearing & self-aligning bearing mounted within the frequency adapter) To put it more simply, feathering means the changing of the pitch angle of the rotor blades."
WRL
Join Date: Dec 2001
Location: Philadelphia PA
Age: 73
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Having taught a lot of flight test classes on rotor heads, I'm inclined to say that an elastomeric head is not fully articulated, as the articulation part means that while the blades are free to move, the hinges do not allow moments to be passed across the hinge.
An elastomeric bearing will allow the blades some limited movement, but it will also allow moments to be transferred from the blade to the head. They probably deserve their own designation - all the advantages of the articulated head, with few of the maintenance headaches, and some of the benefits of the rigid head without the issues of exotic metals.
An elastomeric bearing will allow the blades some limited movement, but it will also allow moments to be transferred from the blade to the head. They probably deserve their own designation - all the advantages of the articulated head, with few of the maintenance headaches, and some of the benefits of the rigid head without the issues of exotic metals.
Really..........?
WRL,
The Starflex is the method used for the load path for the lead/lag damper (frequency adapter) to reference to the head. As you can see it is flexible in the flapping plane but NOT in the lead/lag plane or feathering plane. It is not the flapping hinge. That is in the spherical bearing.
There is no thrust bearing in the frequency adapter (lead/lag damper, the brown one on the lefthand end of the sleeves in the photo and vice versa in the images). There is a self aligning feathering bearing.
The thrust bearing for want of a word is the spherical bearing which is basically a pile of steel spherical cups separated by elastomer (rubber) elements. This bearing allows feather and flap and lead/lag. (The big black one on the righthand end of the sleeves in the photo and vice versa in the images .) The rubber elements are very thin so that failure of one will be not catastrophic as it would be if it were one big lump of rubber.
the flapping hinge (Starflex arm)
(Thrust bearing & self-aligning bearing mounted within the frequency adapter)
The thrust bearing for want of a word is the spherical bearing which is basically a pile of steel spherical cups separated by elastomer (rubber) elements. This bearing allows feather and flap and lead/lag. (The big black one on the righthand end of the sleeves in the photo and vice versa in the images .) The rubber elements are very thin so that failure of one will be not catastrophic as it would be if it were one big lump of rubber.
Join Date: Jun 2008
Location: Seattle
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Long Term...
I flew news down there for a while. It was an Astar B2, and I recall the longest I had to remain in one place was for the Scott Peterson trial. It was the day the verdict was coming down, so they had us fly over the couthouse in San Mateo. I left the Hayward airport, which is about 5 minutes away on the other side of the bay with a full tank of fuel. We stayed on site until I was out of gas and needed to return....which was almost 3 hours later.
