Multi-Engine Aerodynamics

Saturday, May 06, 2023 at 07:43 PM ET

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Why Twins Are Trickier Than Singles Studying the image above should provide some insights into the fundamental physics and aerodynamics of conventional twin-engine airplanes. Obviously, when one engine is turning and the other is “burning,” asymmetric thrust is one result. (Others include losing 50 percent of the airplane’s power, and something like 80 percent of its performance.) Maintaining heading, if not climb performance, requires finding a pitch, yaw and roll attitude presenting the least drag and offering the most thrust. I liken it to balancing the airplane on the head of a pin. — J.B.

Key Takeaways:

The article strongly advocates for "chair flying" and continuous mental rehearsal as crucial practices for pilots, especially for mastering complex and critical maneuvers like multi-engine engine failure on takeoff.
It details the essential "Identify, Verify, Feather" sequence for managing engine failures and emphasizes understanding minimum control speed (Vmc) to prevent dangerous Vmc rollovers at low airspeeds.
Maintaining multi-engine proficiency requires constant practice and a deep comprehension of unique aerodynamic challenges like yaw, critical engine effects, and increased systems complexity, beyond mere legal requirements.

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I’m a big believer in “chair flying.” The best chair is the pilot’s seat of the aircraft you’re learning, with the engine or engines stopped and external electrical power. As a helicopter student, I spent many happy hours sitting in the hangared Robinson, practicing autorotations, a maneuver I found really difficult. Hold your hand like this. Look here. Now look here. Move your hand here. That kind of thing. The maneuver got a lot easier after chair-flying it.

Developing those motor skills and hand/eye coordination doesn’t have to be done while the engines are running, however. Even professional baseball players use tees to practice hitting balls pitched to certain locations.