PoF Flashcards
Parasite drag =
Skin friction drag + form drag + interference drag
Profile drag =
Skin friction drag + form drag
Skin friction drag =
Airflow causing friction over the wing
What worsens skin friction drag
Wing contamination
Form drag =
Pressure differential between leading & trailing edge (pressure at leading edge higher than trailing)
Aerodynamic force of high to low PG acts against direction of flight
Is Q (IAS) proportional to form drag
Yes
What happens to form drag when:
1) AOA increases?
2) Vortex generators are installed?
1) form drag increases
2) form drag decreases
How to minimise parasite drag? (4)
- Streamlining
- Incorporating fillets & fairings
- Using laminar flow wing sections
- Minimising frontal area
Induced drag =
Span-wise flow causing wing tip vortices
Higher CL or lower IAS affects Induced drag how?
Stronger wing tip vortices
What do wing tip vortices cause?
Stronger downwash = rearward inclined wing lift = greater induced drag
What happens to induced drag when:
1) lift increases?
2) weight increases?
3) load factor (g) increases?
4) speed increases?
5) aspect ratio increases?
1) induced drag increases
2) induced drag increases
3) induced drag increases
4) induced drag decreases
5) induced drag decreases
What is the CDi equation?
CDi = CL² ÷ AR
How to minimise induced drag? (3)
- High AR
- Tapered wing Planform with wing twist & span-wise camber variation
- Using end plates, tip-tanks, winglets or tip shaping
Gravity =
9.81 m/s²
Is air density proportional to TAS?
No (inversely proportional)
What happens to air density when:
1) Temp. increases?
2) Static pressure increases?
3) Humidity increases?
4) Alt. increases?
1) air density decreases
2) air density increases
3) air density decreases
4) air density decreases
A plane is rolling right, which aileron is down?
Left aileron down
What camber does the horizontal stabiliser have?
Negative
1 metre = how many ft?
3.28ft
How many ft in a statue mile?
5280ft
How many ft in a NM?
6080ft
How many kts per m/s?
2
How to calculate °Kelvin?
°C + 273
How to calculate °F?
(⁹/⁵ × °C) + 32
How many lbs in a kg?
2.205
What is the sweep angle?
Angle between the 25% chord line & the line perpendicular to the root chord
What happens when entering ground effect?
- Lift increases
- Induced drag decreases
- Tailplane æ modified so that less downforce is created = pitch down moment
- ASI & altimeter under-read
Where is the AC on a wing?
¼ chord position at < Mach 0.4
Taper ratio =
Tip chord ÷ root chord
Mean geometric chord =
Wing area ÷ wing span
Aspect ratio =
Wing span ² ÷ wing area
Lift equation?
L = ½ p V² S CL
Lift equation where CL is sought?
CL = L ÷ (½ p V² S)
Dynamic pressure=
½ p V²
What is the relationship between IAS & dynamic pressure?
IAS is proportional to √dynamic pressure
CLMAX =
1 ÷ Vs²
VS1g (new) =
VS1g (old) × √(new weight ÷ old weight)
New VA ÷ old VA =
√CL old ÷ CL new
What’s the relationship between new and old load factors (n) and old and new speeds (V)
N(new) ÷ n(old) proportional to V²new ÷ V²old
Load factor (n) =
Lift ÷ Weight
n∆ =
Vnew² ÷ Vold²
Bernoulli’s theorem =
P + ½ p V² = K
Pressure + kinetic energy (dynamic pressure) = constant
Pressure (Pa) =
Force (N) ÷ Area (m²)
Lift & drag depend on? (4)
- AoA
- Aerofoil thickness & camber
- Air density
- Velocity
What is the best L/D ratio known as?
Optimum AoA
Will a change of weight in a given config. change L/D max?
No
An AoA other than optimum AoA will cause what with regards to the L/D ratio?
More drag for lift required
Mach No. =
TAS ÷ LSS
LSS =
38.96 × √absokute temp. (K)
Thrust =
T = D + W sin(gamma)
D = drag, W = weight, Gamma = angle between weight & opposite to lift in a climb
Limit load factors:
1) CS-25?
2) Normal CS-23?
3) Utility CS-23?
4) Aerobatic CS-23?
1) -1g to +2.5g
2) -1.52g to +3.8g
3) -1.76g to +4.4g
4) -3g to +6g
