the Aviation Dictionary

blade dampener blanket method of recovering
hub. The airfoil shape of the cuff pulls cooling air into
the engine nacelle.
blade dampener - A shock absorbing mechanism
installed between a helicopter rotor blade and the hub
to diminish or dampen blade movement on the lead-lag
axis.
blade droop - The angle of the spa nwise axis of the
helicopter rotor at rest with only the : forces of gravity
acting on it.
blade face - The flat portion of a propeller blade,
resembling the bottom portion of an airfoil.
blade featherlfeathering - In rotorcraft, the rotation of
the blade around the spanwist: (pitch change) axis.
blade fillet -The portion of the blade closest to the base
or platform. Usually an area where the least damage is
allowed.
blade flap - In rotorcraft, the ability of the rotor blade to
move in a vertical direction. Blades may flap
independently or in unison.
blade flapping - The movement of helicopter rotor
blades, about a horizontal hinge, in which the blades
tend to rise and descend as they rotate. Blade flapping
tends to minimize asymmetrical lift by increasing the
angle of attack of the retreating blade while decreasing
the angle of attack of the advancing blade.
blade stall - A condition of the rotor blade in flight
when it is operating at an angle of attack greater than
the maximum angle of lift. This occurs at high forward
speed to the retreating blade and to all blades during
"settling with power."
blade station - Reference voints on the blade measured
in inches from the center of the propeller hub. Blade
station measurements are used to identify locations
along the blade of a propeller.
blade sweeping - An adjustment of the dynamic
chordwise balance in which one or both blades are
moved aft of the alignment point.
blade tabs - Fined tabs mounted on the trailing edge
helicopter rotor blades for track adjustment.
blade tip - In rotorcraft, the of the blade the
furthest from the hub of the rotor.
blade track - In rotorcraft, the relationship of the blade
tips in the plane of rotation. Blades that are in track
will move through the same plane of rotation.
blade tracking - 1. The process of determining the
position of the tips of the propeller blades relative to
each other. 2. The mechanical procedure used to bring
the blades of the rotor in satisfactory relationship with
each other under dynamic conditions so that all blades
rotate in a common plane.
blade grips - The part of a helicopter rotor hub into blade twist -The variation in the angle of incidence of a
which the blades are attached by a lead-lag hinge pin. blade between the root and the tip. The amount of
Blade grips are sometimes referred to as blade forks.
thrust that is produced by a propeller blade is
determined by the pitch angle of the blade at each
blade inspection method (BIM)- A system using an
blade station, and by the speed at which the blade is
indicator and inert gas to detect rotor blade cracking.
moving through the air. In order to maintain a constant
Used by Sikorsky Helicopter.
amount of thrust along the blade, the blade angle must
blade inspection system (BIS)- A method used by Bell be twisted; however, some degree of twist can also be
Helicopter to determine if rotor blades have cracked.
caused by aerodynamic forces.
blade lead or lag - In rotorcraft, the fore and aft
movement of the blade in the plane of rotation. It is
sometimes called hunting or dragging.
blade loading - In rotorcraft, the load imposed on rotor
blades, determined by dividing the total weight of the
helicopter by the combined area of all the rotor blades.
blade root - The portion of a propeller blade that fits
into the propeller hub. The blade root is also called the
blade butt.
blade section - A cross section of a propeller blade
made at any point by a plane parallel to the axis of
rotation of the propeller and tangent at the center of the
section to an arc drawn with the axis of rotat~on as its
center.
blade shank - The thick, rounded portion of a propeller
blade near the hub.
blade wrench - A paddle-shaped lever having a slot
shaped to fit the cross section of a propeller blade.
Used for manually turning propeller blades. Blade
beams are also referred to as blade wrenches.
blade-disk - A forged, one-piece compressor or turbine
blade and disk as opposed to separate blades fitted into
a disk.
blank - To cut out the surplus material from a part, prior
to finishing.
blank blade - The identification of one blade of a
helicopter during electronic balancing. It is the blade
with the single interrupter. The target blade will have
the double interrupter.
blanket - 1. A sheet of insulation material in the cabin
and passenger compartments used to aid in suppressing
noise. 2. A shroud covering for airplane heat ducts.
blade span - In rotorcraft, the length of a blade from its blanket method of recovering - The method of
tip to its root.
applying fabric to an aircraft structure so that the fabric
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