Aerodynamics Flashcards
Absolute altitude
The altitude above ground level (AGL)
True Altitude
Average altitude above sea level or MSL
Indicated altitude
Altitude on an altimeter that has been calibrated to sea level performance
Pressure altitude
Altitude on an altimeter that has been set to reference sea level conditions
Describe why an airfoil stalls and recovery procedures
An airfoil stalls when the critical AOA is exceeded. There are two types of stalls:power off and power on
To recover Max-smoothly add power Relax-relax our of critical angle of attack Roll-roll our of asymmetric attitude DO NOT RAISE FLAPS
Describe Bernoulli’s Law
Total pressure equals static pressure plus dynamic pressure
As velocity increases dynamic pressure causing a drop in static pressure, assuming density remains constant
What is Density altitude?
Pressure altitude corrected for nonstandard temperature
Most important factor in aircraft performance
As density altitude increases performance decreases due to less air molecules for propellers to generate thrust and lift from
Describe the effect of temperature on performance
Higher temperatures make the aircraft fly higher and equal a lower altimeter setting
Lower temperature makes the aircraft fly lower and equals a higher altimeter setting
Cold weather corrections must be applied when temperature is 0 def C or less (table found in FIH)
Describe the effects of the Fowler flaps
Fowler flaps move aft and down producing significant modifications in camber and wing surface area. Deflection increases the chord and wing area and if AOA is not changed the coefficient Of lift will increase with flaps extended
Understand fin stalls and recovery procedures
Fin stalls are produced from very violent uncomfortable maneuvers
High AOA, low airspeed and high rudder deflection
To recover smoothly reduce rudder deflection and recenter the ball. DO NOT ABRUPTLY APPLY FULL OPPOSITE RUDDER
Define Parasitic and Induced Drag
Parasitic drag increases with Velocity, consists of
- interference drag (surface abnormalities)
- profile drag (skin friction)
Induced drag is a function of AOA
Critical field length
Is the distance an aircraft can accelerate, experience engine failure (Vcef) and either continue the takeoff or abort in the same distance
Critical Engine Failure speed
Is the speed at which an aircraft can accelerate, experience engine failure, and either continue the takeoff or abort the takeoff
Refusal speed
Maximum speed an aircraft can accelerate on 4 engines and then stop within runway available
If Vref > Vr then use Vr
If Vref < Vr then you have split markers, use accel time check
Vmca Minimum aircraft control speed
Minimum speed to maintain directional control
MFLMETO
Minimum field length for Max effort Takeoff
Runway required to accelerate to Vr (decision speed) experience engine failure and either stop or continue to 1.05 Vmu4 (engine unstick speed)
DOES NOT GUARANTEE Vmca3
What are two instances one would fly below Vmca?
HAAR and max effort takeoffs
What is service ceiling?
Altitude at which MCP is 100 ft/min
Describe best rate of climb and best angle of climb
Rate of climb- best climb performance over time
Angle of climb-used for obstacle clearance, most altitude gained over shortest distance
Does a heavier aircraft descend faster than a lighter aircraft?
No. Lighter aircraft descend faster and are more maneuverable
Understand the implications of low altitude threat reactions
At 0G maneuver you will lose 32ft/ s which is egregious at low altitudes
Negative G bunt maneuver recovery will not be instantaneous, account for lag at low altitudes
Wings are not level with airfoil, therefore at 10deg bank angle one must climb 10 feet for 10 more deg AoB to satisfy ground clearance
Discuss Load limits
Load limits assumed that Weight and fuel weights are within limitations
Load limits also assume smooth application of force on flight controls
If not, these may occur
Torsion moments-twisting of a body by the exertion of forces (aileron roll)
Bending moment- transverse deflection of a body perpendicular to its longitudinal axis (wing relieving fuel can help this)
Shearing moment-abrupt forces applied to a surface may cause damage by deformation of a plane from slippage
What maneuvers are prohibted?
Spins, nose high attitudes, hard rudder deflections, steel dives
Describe basic aerodynamic forces
Lift = 1/2(to)Cl(V^2)S
Drag=1/2(ro)Cd(V^2)S
To increase lift, increase Cl through AOA or S at constant density and velocity
AOA increases with wing tilt relative to the wind
