Example board · Aviation

Stalls and load factor

A revision board made in MySummaries for CPL theory, shown as the app shows it in study mode. Updated 30 September 2026.

Highlights: the idea a number to know what to do, or the formula a trap

CPL Theory / Stalls and load factorStudy

AerodynamicsStalls and load factor12 sections · 3 columns

Bank, load factor and the turn

Bank	Load factor, 1/cos φ	Stall speed, × √n	A 50 kt stall becomes	Rate of turn at 100 kt	Radius at 100 kt
0°	1.00	—	50 kt	—	straight
15°	1.04	+2%	51 kt	2.9°/s	1,007 m
30°	1.15	+7%	54 kt	6.3°/s	467 m
45°	1.41	+19%	59 kt	10.9°/s	270 m
60°	2.00	+41%	71 kt	18.9°/s	156 m
75°	3.86	+97%	98 kt	40.8°/s	72 m

The stall

• A wing stalls at its critical angle of attack, not at a speed
• Past it the flow separates over the top and lift falls away
• Any airspeed, any attitude, any weight
• $L = C_L \cdot \tfrac12 \rho V^2 S$: at the stall $C_L$ is at its maximum, so more lift needs more speed
• On the chart: $C_{L\max}$ at about 20°, then the drop

Where the wing stalls first

• The root, ideally, so the ailerons keep working through the stall
• Rectangular: root first. Tapered or swept: tip first
• Washout: less incidence at the tip, so the root reaches critical first
• Stall strips at the root; slots or slats near the tips

The warnings

• Buffet: the separated flow shakes the airframe
• The stall warner, a horn or a light, a few knots before the stall
• Soft controls, a high nose attitude, a decaying airspeed
• Ice on the wing: it can stall before the warner sounds

Spin or spiral dive?

• Spin: stalled, the airspeed low and steady, the rotation steady
• Spiral dive: not stalled, the airspeed and g climbing fast
• Spin recovery: PARE, power idle, ailerons neutral, rudder opposite, elevator forward
• Spiral recovery: power off, roll the wings level, then ease out of the dive

Lift, drag and the stall

The stalls you practise

• Power-off: the approach, flap and gear down, low and slow
• Power-on: the climb-out at full power; propeller yaw makes a wing drop likely
• Accelerated: above $V_S$, in a steep turn or an abrupt pull-up
• Cross-control: a skid, rudder into the turn and aileron against it
• Elevator trim: a go-around with nose-up trim set; full power pitches the nose up
• Secondary: pulling out of a recovery before flying speed is back

Recovery and traps

• Unload first: lower the angle of attack, then level the wings, then power
• Skidding base-to-final turn: the inside wing stalls first, a spin entry
• A level 75° turn pulls 3.86 g: past a normal-category airframe's 3.8 g
• The arcs are 1 g stall speeds: in a turn the stall comes sooner

What else moves the stall speed

• Weight: 10% lighter, about 5% lower ($V_S \propto \sqrt{W}$)
• Flap: lower, from a higher $C_{L\max}$, but it stalls at a smaller angle
• Forward CG: higher, since the wing also carries the tail's down-force
• Ice or frost: higher, and at a smaller angle of attack
• Altitude: about the same indicated airspeed; the true airspeed is higher

In a level turn

• Coordinated and level: n = 1/cos φ, and $V_{S,\text{turn}} = V_S\sqrt{n}$
• 60° of bank: 2.00 g, and a stall 41% faster
• 30° costs only 7%; 45°, 19%
• Rate one, 3°/s, is a full circle in 2 minutes: bank ≈ TAS/10 + 7 (100 kt: 17°, exactly 15°)
• Rate and radius depend on bank and TAS alone: weight changes neither
• More bank, more back pressure: the angle of attack creeps towards critical

On the ASI

• Bottom of the white arc, $V_{S0}$: the stall in landing configuration
• Bottom of the green arc, $V_{S1}$: the stall clean
• Top of the white arc, $V_{FE}$: the most with flap extended
• Red line, $V_{NE}$

Manoeuvring speed

• $V_A$: full, abrupt control stalls the wing before it overstresses the airframe
• $V_A = V_S\sqrt{n_{\text{limit}}}$: at +3.8 g, 1.95 times $V_S$
• Limit loads: normal +3.8/−1.52 g, utility +4.4/−1.76 g, aerobatic +6.0/−3.0 g
• Lighter means lower: $V_A$ falls with weight

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