POF Flashcards
Stall speed highest when CG is?
Forward (due to tailplane countering lift to keep aircraft level)
Minimum Control speeds highest when CG is?
Aft (due to shorter rudder moment arm)
How does thrust affect stall speed?
Because at a stall (high AoA) a component of thrust is acting with lift, removing this will cause the stall speed to increase. Published stall speeds are determined with zero thrust normally.
What’s a pushover?
Lower than 1.0 Load Factor. Stall speed decreases
Buffer Margin _____ during a constant IAS descent?
Increases (Mach No becomes smaller)
Forward CG - What Happens to Stick Force?
Increases due to increased stability
Equation VA based on VS => ___ x _____
Va => Vs x sq.rt(n load factor)
Transport Aircraft - Positive load factor with flaps extended
+2.0g
Transport Aircraft - Positive load factor clean
+2.5g
Load Factor in bank = ___ / ____
Load Factor = 1 / Cos(Angle of bank)
Radius of turn from Velocity
TAS2(in m/s)
g (9.81) x Tan(Angle of bank)
Stall speed Vs related to weight
Vs = sq.rt(Weight)
Weight = Lift
Load factor with change of speed
Change in g x (new speed / old speed)
Va based on load factor and Vs
Va = Vs x sq.rt(Load Factor)
When does Shock Stall occur?
When CL is at max
Positive Load factor for Light Aircraft
+3.8g
Positive Load factor for Light Utility Aircraft
+4.4g
Taper ratio is …
Taper ration = Tip Chord to Root Chord
(It’s always less than 1)
When a propeller has icing it’s efficiency drops by … %
20%
Ideal Gas - Density / Pressure / Temp Equation
Gas Constant (C) = Pressure
(rho x T (K))
Coefficient of Induced Drag (CDI) = ____
CDI = CL2
Aspect Ratio Calculation
AR = Wing Span2
Wing Area
Wingspan : Mean Geometric Chord
The Continuity Equation is
K = Area x Density x Velocity
What happens at an Expansion Wave?
Compressed air expands…
- Decrease in pressure
- Decrease in density
- Decrease in temperature
- Increase in velocity
Positively cambered aerofoil at zero lift produces ______ pitching moment
Nose down
Where is wing sweep angle measured?
Angle st 25% chord line to lateral axis
What do Fowler Flaps do? (position / camber)
Move aft increase S, and also increase camber
When the CG is at the Neutral point what happens
Neutral Longitudinal Stability!
Wing Loading is
Aircraft Weight
Wing Area
Power is ____ x _____
Power = Force x Velocity
Rate of doing work
Drag Divergence Mach against MCRIT
Higher than MCRIT
Sweptback wings behave like…
Thinner wings
Dutch roll occurs with what stability?
Strong Lateral
Weak Directional
Mean Geometric Chord
Wing Area
Wing Span
Main funciton of Trailing Edge Flaps?
Increase CLMAX
Differences at Shockwave
Temp - Up
Density - Up
Pressure - Up
Velocity - Down
Opposite behind expansive wave
Where is VRA situated on Manoeuvre Envelope?
Between Va and Vc
Max Gusts on Gust envelope diagram
25ft/sec at Vd
50ft/sec at Vc
66ft/sec at Vb (design speed for max gust intensity)
Gust Load Factor Equation
Change in Load Factor x (New Speed/Old speed)
Stall speed for given Vs multiple
Stall Load Factor= Given Vs value2
Prop Efficiency is
Usable Prop Power THP (Thust x TAS)
Shaft Power EHP (Torque x RPM)
How do you increase Power Absorption of Prop?
Increase Diameter
Increase Solidity
(Reduces efficiency)
(Limited by tip speed / clearance)
Examples of artificial control force generation
Spring Feel (no relationship to actual Q)
Bob Weight
Q-Feel
Gear Change (usually on rudder)
Aperiodic Means (and example)
No oscillating - Spiral Dive - Where Strong Directional stability and Weak Lateral Stability exists
Ice on Leading Edge may increase VTH by (%)
40-50%
TAS at 40,000 compared to MSA
TAS Doubled
Aerobatic Aircraft max Load Factor
6g
Circumference of Circle based on Radius
C = 2 x pi x R
Skidding / Slipping - Ball and Corrective action
Ball will be towards circular path
Skidding (nose inwards) / Slipping (nose outside)
Correct by rudder (kick the ball)
Or increase bank angle in opposite direction to ball
