aerodynamics basic Flashcards
coefficient of lift is determined by…
camber
AoA
where does the point of maximum camber occur
where the distance between the camber line and chord line is greatest
what makes a coupled moment
two opposite forces separated by a horizontal distance
define the separation point
the point where airflow cant follow the streamline and acts in spastic directions
as we get closer to the stall, what happens to the separation and transition point
get closer and closer to the leading edge
the tendency to overbank in a climb is a result of…
the puter wing experiencing
greater velocity
greater AoA
the tendency to underbank in a descending turn is a result of
the inner wing
lower velocity
higher AoA
what are the three types of ailerons
frise ailerons
differential ailerons
coupling of ailerons ams rudder
describe frise ailerons
offset hinges deflect aileron upward to create drag on that side
describe differential ailerons
the up going aileron is deflected more than the down-going aileron
describe what coupling the ailerons and rudders does
rudder automatically deflects with aileron movement to counteract adverse yaw
what defines a spin
aggravated stall that results in a wing drop
during a spin, one rotation + recovery =
800ft
in a spin, one rotation =
300 ft
why does a flat spin occur as opposed to a normal spin
aircraft centre of mass is further away from the spin axis
why is the use of ailerons bad in the incipient (and all stages) of a spin
aileron creates higher AoA, thus creating drag on specific wing, thus dropping that wing (that was intended to go up) even more.
what does IAS represent
dynamic pressure
1/2 x pv^2
what is calibrated airspeed
IAS corrected for position error (position of pitot tube) and instrument error
what is equivalent airpseed
CAS corrected for compressibility error
what is TAS
true airspeed corrected for air density error (most likely due to temperature)
at what speed and altitude is CAS EAS considered negligible
UP TO 200 kts and 10,000 ft
how does a turn at low speed differ to turns at high speed
smaller turn radius
GREATER rate of turn
what dictates a standard rate turn (rate 1)
3 degrees a second
180 degrees a minute
how does am increase in altitude affect turn performance
decreases it (as a result of higher speed)
turn rate=
AoB/TAS
turn radius is proportional to
TAS^2/AoB
for maximum range, what speed do we fly at
the speed with minimum drag (68 kts)
range =
TAS/fuel flow. = distance/fuel flow
drag =
power/TAS
a headwind does what to glide distance
decreases it
a tailwind does what to glide distance
increases it
what affects rate of descent
weight
does wind have an affect on rate of descent
no
when is maximum endurance achieved
at minimum power for a given airspeed
endurance =
flight time/amount of fuel
what is the region of reverse command
and area of the power vs IAS graphs where more power is needed to stop airspeed dropping (rather than the point of max endurance where min power is needed to maintain airspeed)
longitudinal STABILITY occurs on which axis
lateral axis
later STABILITY occurs on which axis
longitudinal axis
directional STABILITY occurs in which axis
normal axis
what are the three types of stability
stable
neutral
unstable
describe stable
object returns to original point
describe neutral
object stays displaced until moved back
describe unstable
object continues to become more and more displaced from the origin
why are dihedral wings good
they improve lateral stability
more stable role
why are sweepback wings good for lateral stability
because in a turn, there is less effective span on the higher wing, resulting in a more stable turn.
is lateral stability of or directional stability stronger
directional
what are the three types of balance tabs
aerodynamic
automatic balance
fixed
describe aerodynamic tabs
–> horn balance, a horn protrudes in the opposite direction of the control surface deflected (on outer edge of c172 elevator)
describe automatic balance
automatically moves in the opposite direction of surface deflection
(c172 does this slightly)
describe fixed tabs
tab that stays fixed
on the 172, is the rudder balance tab
what are anti-balance tabs and what are their benifits
makes it harder to deflect surfaces, thus reducing airframe stress
describe mass balance
mass placed inside control surfaces to move CoG closer to hinge line, thus reducing flutter
what is ground looping and why is it dangerous
the weather-coking of tailwheel aircraft
if not corrected is almost impossible to recover from
what is wheelbarrowing
high speed and excessive forward pressure resulting in the main wheels leaving the ground before the nose wheel
what gyroscopic characteristic causes the aircraft to yaw to the left
precession
force displaced by 90 degrees (yaw to left)
what variables are involved in the gyroscopic effect
blade mass
rpm
rate at which tail is lifted
what is the p factor
more thrust is produced on the downgoing half of the propellor disc than the upgoing half
p factor is strongest when
high power settings
high AoA
low airspeed
