Aerodynamics Flashcards
Questions and statements for the PPL Aerodynamics syllabus (40 cards)
A typical recovery action to address either retreating blade stall or settling with power is to …
decrease the angle of attack by lowering the collective
In the conventional helicopter, the percentage of total available power used for torque control (tail rotor) is approximately …
10% -15%
Negative G tends to effect blood pressure by …
increasing it
The pedal controls of the coventional helicopter give the pilot …
yaw control
The collective control on a helicopter …
changes the pitch of each blade an equal amount (relative to the hub)
In a ‘stick-fixed’ condition, a helicopter has
static stability in pitch
If you were flying with a significant tail wind component, the greatest ground distance travelled will be achieved by flying at …
an airspeed slower than the manufacturer’s recommended maximum range airspeed for nil wind
Compressibility is most likely to occur …
at the tip of the advancing blade when RRPM is high
You are yawing the helicopter to the right with right pedal input. If you suddenly apply a strong left pedal input, the helicopter will …
not respond right away, but will start to yaw left after a brief delay.
When flapback occurs during flight it is compensated for by …
cyclic feathering of the main rotor blades
In a still air hover the forces acting on a helicopter are balanced as follows …
total rotor thrust = weight, torque = rotor drag
lDuring takeoff, when the tail rotor achieves effective translational lift, the nose of a conventional helicopter will begin to …
Yaw to the left
The instrument which will read incorrectly in a descent if the pitot tube becomes blocked is …
the airspeed indicator (ASI)
To account for the differences in lift produced across different parts of the rotor disc during horizontal flight, most rotor systems enable the blades to flap. Flapping is described as …
the angular movement of the rotor blades above and below the plane of rotation
For powered forward flight in a helicopter, the never exceed speed (VNE) is an indicated airspeed which …
may vary with any change in weight, altitude, temperature or RRPM
VNE is a term usually related to …
IAS and retreating blade stall
During a hovering right turn you will experience …
an increase in main rotor RPM
Reasons for specifying a maximum rearwards airspeed for a helicopter include …
to preserve longitudinal stability and prevent exhaust ingestion
Vortex ring state (VRS) is likely to occur duiring a…
high rate of desent with slow forward moving airspeed such as a vertical approach at high power into a hollow surrounded by trees
Ref: Principals of Helicopter Flight, Chapter 19, pg. 157
Effective Translational Lift is experienced with…
wind or forward airspeed between 10-12kts
Gyroscopic Precession is when…
any force applied to a rotating disc is felt 90° in the direction of rotation.
Overpitching could be rectified by …
Lowering collective and opening throttle
When studying the behaviour of air we can cosdider it to be fluid. This means …
it has viscosity, which is a measure of a fluid’s resistance to flow or deformation
Refer to rotor blade diagram
The station on the blade which produces the greatset amount of lift is …
B, because it is not influenced by the rotor tip vortex which reduces efficiency at A
