Multi-Engine Guide
Chair flying / Drag Demonstration

Drag Demonstration

Feel what each item of drag actually costs on one engine — gear, flaps, a windmilling propeller, and bank angle — so the cleanup items in the engine-failure drill stop being rote and start being urgent.

Guided rehearsal is Premium

Pre-Takeoff Engine-Failure Briefing

  1. Runway, wind, and performance — takeoff distance, accelerate-stop, and single-engine climb for today's density altitude and weight
    Light twins are not required to have a positive single-engine rate of climb at any altitude. Know before you roll whether today's airplane will climb on one.
  2. Speeds: Vr, Vyse (blue line), Vmc (red line), Vsse
  3. Failure before rotation: throttles closed, brakes, stop straight ahead
  4. Failure after liftoff with runway remaining and gear down: close the throttles and land straight ahead
    The landing gear stays selected DOWN as long as there is usable runway or overrun to land on. Gear down means continued takeoff and climb is not recommended.
  5. Failure after liftoff with the gear up and no runway remaining: pitch Vyse, mixtures/props/throttles forward, flaps up, gear up, identify, verify, feather
  6. Climb straight ahead or with shallow turns to at least 400 ft AGL before turning back; obstacles and terrain off the departure end
  7. Who flies, who touches what, and the tolerance for any simulated failure — never below Vsse
    AFH: no engine failure should ever be introduced below Vsse; if none is published, use Vyse.

Setup

  1. Climb to a safe demonstration altitude — at or above 3,000 ft AGL, clearing turns complete
    Nothing in this demonstration should ever be flown below Vsse. Each configuration change here is deliberately costing you performance, so you want altitude to spend.
  2. Establish the baseline: clean, one engine simulated inoperative and zero sideslip, stabilized at Vyse“Baseline — blue line, clean”
    About 2° of bank toward the operating engine with one-third to one-half ball toward it. Note the rate of climb. Every number that follows is compared against this one.
  3. Note field elevation, OAT, and weight — performance here is density-altitude dependent

Execution

  1. Extend the landing gear — hold Vyse, note the change in vertical speed, then retract“Gear down — note the VSI”
    Gear is pure parasite drag added at the worst possible moment. This is why the memory items call for it up.
  2. Extend approach flaps, then full flaps — hold Vyse, note each change, then retract“Flaps — note the VSI”
    On most airplanes full flaps produce more drag than the extended landing gear. That is exactly why the go-around sequence retracts flaps before gear.
  3. Reduce the simulated failed engine from zero thrust to idle so its propeller windmills — note the performance loss“Windmilling prop”
    Zero thrust means power is set on that engine so the drag of its rotating propeller equals that of a stopped feathered propeller. Backing it off to a true windmill is the single biggest item on the list: a propeller windmilling at high RPM in the low blade-angle range can produce parasite drag as great as the parasite drag of the entire airframe. The AFH specifically asks instructors to spend time demonstrating simulated-feathered (zero thrust) versus windmilling performance.
  4. Restore zero thrust and confirm the performance comes back
    This is the whole argument for feathering promptly and for identifying and verifying correctly the first time. If this demonstration is flown with an actual feather instead, plan unfeathering and restart to be completed no lower than 3,000 ft AGL — and remember that repeated feathering and unfeathering is hard on the engine and airframe.
  5. From zero sideslip, roll to wings level with the ball centered — note the climb loss, then return to zero sideslip“Bank angle”
    Wings level with the ball centered requires large rudder toward the operative engine and leaves a moderate sideslip toward the dead engine: climb performance is reduced and Vmc is significantly higher than published, because no horizontal component of lift is helping the rudder. The other incorrect case — ailerons alone, 8–10° of bank toward the operative engine with no rudder — is not demonstrated here; the AFH says instructors should not normally demonstrate it because of the increased risk of loss of control. Only rudder and bank together, about 2° toward the operative engine, produce zero sideslip.

Recovery

  1. Clean up: gear up, flaps up, zero thrust restored, back to zero-sideslip Vyse
  2. Restore symmetrical power and resume normal cruise
  3. Debrief the numbers: rank gear, flaps, windmilling prop, and sideslip by what each one actually cost
    The point is not the specific figures for the day — it is the ordering, and the realization that a marginal single-engine climb is erased by any one of them.

ACS tolerances

  • Airspeed held at Vyse ±5 kt through each configuration change
  • Heading ±10°
  • Never below Vsse
  • Entire demonstration at or above 3,000 ft AGL

Common errors

  • Letting airspeed wander, which contaminates the comparison
  • Chasing altitude instead of holding blue line and reading the VSI
  • Adding drag faster than the airplane can be stabilized and read
  • Treating the day's numbers as the airplane's book performance
  • Forgetting that with a windmilling prop, controllability — not just climb — is degraded