Aerodynamics Flashcards
Define dynamic rollover and the three conditions that must be present?
The susceptibility of the helicopter to a lateral-rolling tendency.
The three conditions required are pivot point, rolling motion, and exceedance of the critical angle.
TC 3-04.4 1-219, pg1-61
What are the physical factors of dynamic rollover?
Main Rotor Thrust
Center of Gravity
Tail Rotor Thrust
Crosswind
Ground Surface
Low Fuel
Slopes
TC 3-04.4 1-229 pg1-63
What are the human factors for dynamic rollover?
Failure to make timely corrective action
Inattention
Inexperience
Inappropriate control input
Loss of visual reference
TC 3-04.4 1-229 pg1-63
What are the three no lift areas along the blade in forward flight, starting at the hub and working out?
Reverse Flow
Negative Stall
Negative Lift
(Positive Lift)
(Positive Stall)
TC 3-04.4 1-115 pg1-37
Define Ground Effect
Increased efficiency of the rotor system caused by interference of the airflow when near the ground.
TC 3-04.4 1-105 pg1-33
Define dissymmetry of lift
Difference in air flow over the advancing half of the blade and the retreating half of the blade due to forward flight.
TC 3-04.4 1-120 pg1-38
How is dissymmetry of lift compensated for?
Blade flapping
Cyclic feathering
TC 3-04.4 1-121 pg1-38
Define Translational Lift
Improved rotor efficiency resulting from directional flight.
TC 3-04.4 1-129 pg1-40
Define Transverse Flow Effect
Difference in lift between the fore and aft portions of the rotor disk between 10 and 20 knots.
TC 3-04.4 1-132 pg1-41
Define Effective Translational Lift
Occurs between 16 and 24 knots, the helicopter completely outruns vortexes and begins to work in relatively undisturbed air.
TC 3-04.4 1-133 pg1-42
Define Translating Tendency
A single rotor helicopter has the tendency to drift laterally in the direction of tail rotor thrust.
TC 3-04.4 1-111 pg1-35
Define Settling with Power
A condition in powered flight at which the helicopter settles in its own downwash.
TC 3-04.4 1-211 pg1-59
What three conditions must exist simultaneously for settling with power to occur?
Vertical or near-vertical descent of at least 300 FPM
Slow forward airspeed (less than ETL)
20-100% of available engine power
TC 3-04.4 1-215 pg1-60
Define Loss of Tail Rotor Effectiveness or Authority?
In helicopters, loss of Tail Rotor Effectiveness, for unanticipated yaw, is an uncommanded rapid yaw that does not subside on its own accord and which, if not quickly reacted to, can result in loss of aircraft control. LTE can occur in all tail rotor equipped helicopters at airspeeds lower than 30 knots.
