Aerodynamic Forces In Flight Manoeuvres Flashcards
What are the four forces that act on the A/C in straight and level flight?
- Lift
- Drag
- Thrust
- Weight
What occurs when the landing gear are lowered on the A/C?
Total drag is increased, which causes speed to decrease, until point where thrust and drag are in equilibrium again.
What occurs in straight and level flight when the flaps are lowered?
- Drag will increase to decrease the speed of the A/C
- An initial increase in lift will occur which must be countered by the pilot to prevent the aircraft climbing. Angle of attack must be reduced.
What is one of the fundamental formula for performance?
Power + Attitude = Performance
What are the forces on the aircraft in a straight and level turn? Draw a diagram.
1) Total Lift
2) Vertical Component of Lift
3) Centripetal force
4) Centrifugal force
5) Resultant Load
6) Weight
What control input is required to maintain level flight in a steep turn?
Elevator
What is the load factor in a 30 deg banked turn?
1.15
What is the load factor in a 60 deg banked turn?
2g
What are the various g forces required at various points in the turn?
- At bottom = 4g
- At side = 3G
- At top = 2g
What should be done to find a constant loop?
- Speed must constant
- G load will vary according to the point in the loop
Describe slipping and skidding?
- Slipping is not enough rudder in the turn
- Skidding is too much rudder in the turn
What is the relationship between weight and CFF in a balanced turn?
Weight and centrifugal force are equal with ball in centre
What is the relationship between weight and centrifugal force in a slipping turn?
Weight is greater than CFF
What is the relationship between weight and centrifugal force in a skidding turn ?
Centrifugal force is greater than weight.
What does an aircraft tend to do in a straight and level turn, climbing and descending turn re. banking tendencies?
- In a S&L turn, aircraft will want to bank into the turn
- In a climbing turn, aircraft will tend to overbank into the turn as the upgoing wing follows a steeper spiral path and will therefore have a reduced AoA, and will generate less lift
- In a descending turn, the inner wing follows a steeper downwards spiral path and will tend to roll out of the turn.
What is the difference between turn rate and turn radius?
- Turn rate refers to the how quickly the aircraft is changing heading in the turn
- Turn radius refers to how much distance is required for the A/C to change heading in a certain direction.
What is the formula for turn radius and ROT?
- Turn radius = KTAS^2 / 11.26*tan(AOB)
- Turn rate = 1091 * Tan (AOB) / KTAS
Does speed have a greater effect on turn radius or turn rate?
Turn radius than on turn rate.
Do turn rate and turn radius depend on weight?
No
What is the relationship between load factor and stall speed?
Stall speed = basic stall speed * sqrt (Load factor).
What is a Rate 1 turn?
Turn rate of 3 deg / s
What is the useful rule to calculated the AoB required for a rate 1 turn at a given speed?
AoB = TAS (IAS at low altitudes) / 10 + 7
What is a maximum rate turn?
A max rate turn is achieved when an aircraft changes direction at the highest possible rate.
What is the formula for max rate turn?
Rate of rotation = 0.5 * (S/W) * rho * V * Cl * sin(AoB)
What are the perfect requirements for a max rate turn?
- Minimum wing loading
- Maximum air density
- Maximum value of the product of speed, angle of bank and AoA
- Sufficient thrust available to maintain the speed mentioned above, with the lift-dependent drag rise with max values of Cl
What can be practically altered to improve the max rate turn?
- Vertical component of thrust, at high AoA
- Combat flaps
- Variable Nozzles
Practically, how close to stall speed is a max rate turn?
Close to stall at high g loading.
What are the three main factors that determine max rate turn performance?
- Clmax
- g limit
- Max power
What speed is the maximum distance between power required and power available?
Max rate of climb (Vy)
Where would max angle of climb (Vx) be?
Max difference between thrust required and thrust available.
Is lift greater than weight in a climb?
No
Is lift greater than weight in a powered descent?
No
At what speed will the aircraft glide at?
Min drag speed to maximize L/D ratio
What is the effect of weight on glide distance?
Doesn’t have an effect, but the heavier aircraft will glide at a higher speed to get to the optimum AoA to maximum L/D.
What will a tailwind/headwind do to glide distance?
- A headwind will reduce glide distance
- A tailwind will increase glide distance.
