Exam 3 Flashcards
(149 cards)
Tandem Rotor Helicopters
aircraft with two main rotors and no tail rotor
on Tandem Rotor Helicopters the tandem rotors spin in the ______ direction
opposite
Tandem rotor eliminate the need for _____ and counteracts _______
a tail rotor
torque
on a tandem rotor the collective, cyclic, and anti-torque work the _____ as far as the pilot is concerned
same
Tandem Rotor collective stick
when using the collective all blades move up on both rotors. They all work together
Tandem Rotor cyclic stick
when using the cyclic stick the rotors also move together. the rotor disks will move together
Tandem Rotor yawing the helicopter
the pilot hits the foot pedals and the aircraft was. this happens by the rotors tilting in opposite directions. front disk and rotor will tilt in the direction that you want to turn.
Feathering
increasing and decreasing the pitch in the rotor blades
does the tip or the root of the rotor blade go faster
the tip.
three problems that come with flying helicopters
dissymmetry of lift and gyroscopic recession
coriolis effect
lead-lag movement caused massive vibration
dissymmetry of lift and gyroscopic precession fix
install flapping hinges
Coriolis effect fix
lead-lag hinges
lead-lag movement caused massive vibration fix
install lead-lag dampners
if you have flapping hinges and lead-lag hinges is called a
fully articulated rotor head
Flapping hinges
because the amount of lift was not the same on each side of the helicopter due to relative wind the rotors were allowed to move up and down and therefore could change how much lift is produced where.
Lead Lag hinges
allows the blade to move back and forth
Lead Lag dampners
the horizontal movement of rotor blades
Semi-Rigid Rotor
helicopter has lead-lag but no flapping hinge
works like a seesaw
Semi-Rigid Rotor limits the number of blades to
2, which limits the wing area of the aircraft
Rigid Rotors
no flapping and lead-lag but instead have flexible attach points
gyroscopic precession in helicopters
any force put into a spinning object takes effect 90 degrees later
Aluminum Alloys
commonly used all around the aircraft.
other elements added to pure aluminum
other elements make up 15%
AlClad Aluminum
cladding an aluminum alloy core with surface layers of pure aluminum
Grain in Sheetmetal
metal’s strength is related to its grain size
grains align themselves to the rolling process to become a sheet