The Medium Level Turn

British Young Pilots · Flying Training · Module FT-9.1

Content:

Lean to turn

Watch a cyclist go round a bend: they lean into it. An aeroplane turns the same way. It does not steer like a car. It banks: one wing goes down, the other goes up, and round it goes.

A medium level turn is a gentle lean of 30 degrees or less, staying at the same height, with the power left alone.

Try it now: stand up, arms out like wings. Tip your left arm down a little and your right arm up. That is about 30 degrees, and you are turning left.

Source: Pooleys Vol 1 (15th ed.) p.141.

The tilted lift pulls you round

Banking tilts the lift. The sideways part pulls the aeroplane round. The upward part is now too small, so ease back on the stick for a little more lift. Tap the steps in order.

Source: Pooleys Vol 1 (15th ed.) p.141–142 and p.150.

What a medium level turn is

Exercise 9a. A medium level turn is flown at a constant height, with a medium angle of bank (30° or less), at constant power and in balance. Later in training come climbing turns, descending turns, rate 1 turns and steep turns (45° of bank or more).

The forces: banking tilts the lift, and its horizontal part is the turning force (the centripetal force). Nothing opposes that force, so the aeroplane is no longer in equilibrium and is pulled into the turn. More bank gives more turning force. Tilting the lift also shrinks its vertical part, so you add back pressure as you bank: a higher angle of attack, more total lift, and the vertical part balances the weight again.

Source: Pooleys Vol 1 (15th ed.) p.141–142.

Flying the turn: four moves

  • Look out. Look the way you are going to turn first, then the other way, then sweep your eyes back across. Pick a landmark to finish on.
  • Roll. Stick to the side to bank, with a touch of rudder on the same side so the ball stays in the middle.
  • Back pressure. Ease the stick back a little so the nose does not drop.
  • Keep looking. Outside first, then the nose against the horizon, then a quick peek at the dials.

Pilots call that last one LAI: Lookout, Attitude, Instruments. Say the four moves out loud together.

Source: Pooleys Vol 1 (15th ed.) p.147, p.149 and p.151.

What changes in the turn

  • Nose attitude is higher than in straight and level flight, because of the back pressure. It is right when the aeroplane neither gains nor loses height.
  • Airspeed falls a little, usually about 5 knots: more lift means more induced drag. Accept it.
  • Stalling speed rises: about 7% higher at 30° of bank. At normal speeds there is still a safe margin.
  • The aeroplane tends to overbank: the outer wing travels faster and makes extra lift. Simply hold the bank you want with the ailerons.

Judge the bank against the natural horizon and confirm it on the AI (attitude indicator). In a side-by-side cockpit the nose looks higher against the horizon in a left turn than in a right turn, seen from the left seat.

Source: Pooleys Vol 1 (15th ed.) p.142–143 and p.147.

Stopping the turn

Remember the landmark you picked? Just before the nose reaches it, start to roll out, because the aeroplane keeps turning until the wings are level.

  • Roll the wings level with the stick, with a touch of rudder the same way.
  • Relax the back pressure, or the aeroplane will climb.
  • Look out again, especially where the raised wing was hiding the sky.

Too early or too late? No problem: tidy up the heading and the height afterwards. On the sim, call out your landmark before you start.

Source: Pooleys Vol 1 (15th ed.) p.148–151.

Balance: keep the ball in the middle

While the aeroplane is rolling, aileron drag (adverse yaw) swings the nose away from the roll. Counter it with rudder pressure in the direction of the roll, both rolling in and rolling out; the extra pressure comes off once the turn is steady. After that the ball tells you the balance: ball out to the right, more right rudder, and the same on the left.

SLIPPING BALANCED SKIDDING ball on the low side more right rudder ball in the centre comfortable in your seat ball thrown outside too much right rudder All three show a turn to the RIGHT

Source: Pooleys Vol 1 (15th ed.) p.144–145 and p.149.

Flying the manoeuvre

  • Before entry: at the height and airspeed you want (altimeter steady, VSI at zero), in trim. Look out: into the turn, then opposite and behind, then scan back. Pick a reference point to roll out on.
  • Entry: roll on bank with aileron, balance with same-side rudder, add back pressure to hold height.
  • In the turn: bank with ailerons, balance with rudder, height with elevator. Gaining height: more bank or lower the nose. Losing height: less bank or raise the nose. Work the LAI cycle.
  • Roll out: start about 10° before the reference point. Roll off bank, balance with rudder, gradually release the back pressure. Look out again.

Do not trim in the turn: it is a transient manoeuvre. On the panel the DI shows the heading changing while the altimeter stays put.

STRETCHWhy start the roll-out before the reference point, and what happens to the height if you forget to release the back pressure?

Source: Pooleys Vol 1 (15th ed.) p.147–151.

Technical: turning performance and rate 1

Turning performance has two measures: the rate of heading change and the radius of the turn. At a constant airspeed, a steeper bank gives a higher rate and a smaller radius. At a constant bank angle, a lower airspeed does the same.

A rate 1 turn changes heading at 3° per second: 180° in one minute, 360° in two (the "2 MIN" marking on many turn coordinators). It is the standard rate used in instrument flying. The bank needed depends on speed. Rule of thumb with the ASI in knots: airspeed divided by 10, plus 7. At 90 knots that is 9 + 7 = 16° of bank. With an ASI in miles per hour, add 5 instead of 7. Confirm on the turn coordinator, or with the heading indicator and a clock.

Stall speed in the turn rises with the load factor: the wings carry extra load at a higher angle of attack, so the stalling angle is met at a higher speed (about 7% higher at 30° of bank).

Source: Pooleys Vol 1 (15th ed.) p.142 and p.145–146.

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Turn sorter

One pilot action at a time: does it belong to ENTERING the turn, being IN the turn, or ROLLING OUT? Tap to sort it.