SIFT Exam Prep with 100% Complete
Solutions
Lift generated by an airfoil depends on such factors as: - ANS-1. Speed of the airflow
2. Density of air
3. Total area of segment or airfoil
4. Angle of attack (AOA) between air and airfoil
A symmetric airfoil must have ---- AOA to generate positive lift - ANS-positive
Flow forced under the object is rapidly slowed or stagnated causing an area of ---
pressure. This also causes the flow to --- along the upper surface of the object - ANS-1.
high
2. accelerate
If the weight of a helicopter is 1600 lbs, the weight supported by the rotor disk in a 30
degree bank at constant altitude would be --- . In a 60 degree bank, it would be ----. In a
80 degree bank, it would be around ---- - ANS-1. 1856 (1600*1.16) *if two bladed
system - each blade = 928 lbs
2. 3200
3. 8000
--- ratio is the ratio of the total blade area, which is the combined area of all the main
rotor blades, to the total rotor disk area - ANS-solidity
--- drag develops from the frictional resistance of the blades passing through the air.
Increases moderately when airspeed increases. Composed of form drag and skin
friction. - ANS-profile
--- drag is generated by the airflow circulation around eh rotor blade as it creates lift.
High-presssure area beneath the blade joins the low pressure area above the blade at
the trailing edge and at the rotor tips. Air pressure differential increases with an increase
in AOA, stronger vortices form, and induced drag increases. (AOA lower at higher
speeds, induced drag decreases) - ANS-induced
--- drag is present any time the helicopter is moving through the air. Increases with
airspeed. Non lifting components of the helicopter contribute - major. cause of drag at
higher airspeeds - varies with the square of the velocity - ANS-parasite
As airspeed increases, --- drag increases, while --- drag decreases - ANS-parasite
induced
, The low point on the total drag curve shows the airspeed at which drag is --- - ANS-
minimized
L/DMAX - ANS-greatest lift-to-drag ratio
(total lift capacity, compared to total drag, is most favorable)
The --- is used to make changes to the pitch angle of the main rotor blades - ANS-
collective pitch control
Pitch angle increases, angle of incidence ---, drag ---, and rotor rpm ---- - ANS-increases
increases
decreases
the function of the --- is to regulate engine rpm - ANS-throttle
Twisting throttle to the left --- rpm, twisting the throttle to the right --- rpm - ANS-
increases
decreases
Governor function: - ANS-once the rotor rpm is set, the governor keeps the rpm
constant and there is no need to make any throttle adjustments
Correlator - ANS-Mechanical connection between the collective lever and the engine
throttle (still requires adjustment of the throttle)
Cyclic pitch control - ANS-Allows the pilot to fly the helicopter in any direction of travel
The ---- tilts in the same direction the ---- is moved - ANS-rotor disk
cyclic pitch control
The antitorque pedals, located on the cabin floor by the pilot's feet, control the ___ and
therefore, the ___ of the tail rotor blades or other antitorque system. (Applies to
Newton's Third Law) - ANS-pitch
thrust
The primary purpose of the tail rotor - ANS-Counteract the torque of the main rotor
density altitude - ANS-Density altitude is pressure altitude corrected for nonstandard
temperature. As temperature and altitude increase, air density decreases. In a sense,
it's the altitude at which the airplane "feels" its flying.
higher density altitude
--- air density
--- aircraft performance - ANS-lower
lower
Solutions
Lift generated by an airfoil depends on such factors as: - ANS-1. Speed of the airflow
2. Density of air
3. Total area of segment or airfoil
4. Angle of attack (AOA) between air and airfoil
A symmetric airfoil must have ---- AOA to generate positive lift - ANS-positive
Flow forced under the object is rapidly slowed or stagnated causing an area of ---
pressure. This also causes the flow to --- along the upper surface of the object - ANS-1.
high
2. accelerate
If the weight of a helicopter is 1600 lbs, the weight supported by the rotor disk in a 30
degree bank at constant altitude would be --- . In a 60 degree bank, it would be ----. In a
80 degree bank, it would be around ---- - ANS-1. 1856 (1600*1.16) *if two bladed
system - each blade = 928 lbs
2. 3200
3. 8000
--- ratio is the ratio of the total blade area, which is the combined area of all the main
rotor blades, to the total rotor disk area - ANS-solidity
--- drag develops from the frictional resistance of the blades passing through the air.
Increases moderately when airspeed increases. Composed of form drag and skin
friction. - ANS-profile
--- drag is generated by the airflow circulation around eh rotor blade as it creates lift.
High-presssure area beneath the blade joins the low pressure area above the blade at
the trailing edge and at the rotor tips. Air pressure differential increases with an increase
in AOA, stronger vortices form, and induced drag increases. (AOA lower at higher
speeds, induced drag decreases) - ANS-induced
--- drag is present any time the helicopter is moving through the air. Increases with
airspeed. Non lifting components of the helicopter contribute - major. cause of drag at
higher airspeeds - varies with the square of the velocity - ANS-parasite
As airspeed increases, --- drag increases, while --- drag decreases - ANS-parasite
induced
, The low point on the total drag curve shows the airspeed at which drag is --- - ANS-
minimized
L/DMAX - ANS-greatest lift-to-drag ratio
(total lift capacity, compared to total drag, is most favorable)
The --- is used to make changes to the pitch angle of the main rotor blades - ANS-
collective pitch control
Pitch angle increases, angle of incidence ---, drag ---, and rotor rpm ---- - ANS-increases
increases
decreases
the function of the --- is to regulate engine rpm - ANS-throttle
Twisting throttle to the left --- rpm, twisting the throttle to the right --- rpm - ANS-
increases
decreases
Governor function: - ANS-once the rotor rpm is set, the governor keeps the rpm
constant and there is no need to make any throttle adjustments
Correlator - ANS-Mechanical connection between the collective lever and the engine
throttle (still requires adjustment of the throttle)
Cyclic pitch control - ANS-Allows the pilot to fly the helicopter in any direction of travel
The ---- tilts in the same direction the ---- is moved - ANS-rotor disk
cyclic pitch control
The antitorque pedals, located on the cabin floor by the pilot's feet, control the ___ and
therefore, the ___ of the tail rotor blades or other antitorque system. (Applies to
Newton's Third Law) - ANS-pitch
thrust
The primary purpose of the tail rotor - ANS-Counteract the torque of the main rotor
density altitude - ANS-Density altitude is pressure altitude corrected for nonstandard
temperature. As temperature and altitude increase, air density decreases. In a sense,
it's the altitude at which the airplane "feels" its flying.
higher density altitude
--- air density
--- aircraft performance - ANS-lower
lower
