Turning flight refers to any maneuver where an aircraft changes its direction or heading while maintaining some form of lift. Unlike straight and level flight, turning involves the generation of a horizontal component of lift, which causes the aircraft to follow a curved path or turning trajectory. This is a fundamental maneuver used during navigation, traffic patterns, and aerobatic or combat scenarios.
1. Basic Concept of Turning Flight
In level turning flight:
- The aircraft is banked at an angle
(phi). - Lift vector is tilted: one component supports weight, the other causes horizontal centripetal acceleration.
- The turn occurs in the horizontal plane.
2. Force Balance in a Level Turn
2.1 Vertical Direction
The vertical component of lift balances weight:
2.2 Horizontal Direction
The horizontal component of lift provides the required centripetal force for turning:
Where:
= Total lift
= Weight
= True airspeed
= Turn radius
3. Load Factor (
)
Load factor is the ratio of lift to weight:
- In a turn, the lift must be greater than weight:
. - Higher bank angles → higher load factors → increased structural stress.
4. Radius and Rate of Turn
4.1 Turn Radius ()
From the horizontal force balance:
- Faster speed → larger radius.
- Steeper bank angle → smaller radius.
4.2 Rate of Turn (
)
Rate of change of heading (in rad/s):
Or in degrees per second:
Where:
= True airspeed in knots
5. Coordinated Turn
In a coordinated turn, there is no side-slip. This requires:
- Correct rudder input.
- Proper balance of lateral and directional forces.
Result: Occupants feel “pressed down” in their seats, not pushed sideways.
6. Effects of Bank Angle
| Bank Angle (φ) | Load Factor (n) | Turn Characteristics |
|---|---|---|
| 0° | 1 | No turn (straight flight) |
| 30° | 1.15 | Gentle turn |
| 45° | 1.41 | Moderate turn |
| 60° | 2.00 | Steep turn (high Gs) |
High load factors can approach structural limits of the aircraft.
7. Energy Considerations
During level turning flight:
- Lift increases to maintain altitude → more induced drag.
- Engine must produce more thrust to maintain speed and altitude.
8. Stall in Turning Flight
Stall speed increases with load factor:
So, as bank angle increases:
- Load factor increases → stall speed increases.
- Steep turns near stall can lead to accelerated stalls.
9. Non-Level Turns
In climbing or descending turns:
- The vertical lift component must also balance the climb/descent component of weight.
- Equations adjust accordingly, but concepts of turn radius and rate remain similar.
10. Summary
| Parameter | Key Equation |
|---|---|
| Load Factor |  |
| Turn Radius |  |
| Rate of Turn |  |
| Stall Speed in Turn |  |
Turning flight requires a balance of lift, bank angle, and thrust. It is an essential maneuver, governed by aerodynamic forces and limitations. Safe and effective turning depends on understanding how bank angle, speed, and load factor interact.
