Flight Mechanics + Threats Flashcards
Frost contamination on A/C
Parked A/C at night
Below freezing/high humidity
Crystalline
10mm to 5mm thick
Rime Ice on AC
Accumulate at LE
Brittle
SCWD freeze on impact
Easy to remove
Clear Ice on AC
SCWD that flow back
Most dangerous due to mass and surface area
Risks of contamination
Drag increase
Reduced lifting ability
James controls
CG out of limit
Propellers in balance structural failure
Stall warning become unreliable
Sharp vs thick wing for icing
Sharper LE more ice accumulator than thick wing due to airflow having less time to flow on sharp
Where does ice form on propellers + how much does it reduce performance as a percentage
Forms near roots up to 20% reduction in performance - anything else is due to icing elsewhere
Frost vs Ice on CL max reduction and V speeds
Frost has a smaller reduction on both than Ice
How will contamination impact climb performance
Skin friction and form drag increase
Thrust increases to balance drag
Ice can double total drag
Unable to climb/accelerate
Pre flight icing practices
Inspect/clean all critical surface
T/O before holdover time
If expires de ice and anti ice needed again
Tailplane icing
More susceptible to icing on tailplane (sharper LE)
Slow speed flight - more downwash increase angle of attack at tailplane. Seperation bubbles reducing down force produce by tailplane
Pitch trimming becomes less effective and elevator buffet
If complete stall nose will pitch down uncontrollably
Extending flaps with tailplane icing
Increases wings downwash which makes separation bubble extend further aft reducing aerodynamic performance
Tailplane recovery
Reduce flaps to pre config
Pull back on control column
Don’t increase thrust
Heavy rain in regards to contamination
Large accumulation
Increase skin friction drag and reduce energy in boundary layer
Stalling AOA decrease + VS increases
More thrust needed to overcome loss of momentum
Repainting
Increase weight therefore drag
Low altitude threats
Thunderstorms
Microbursts
Turbulence
Wake turbulence
Icing
