On 4/25/07, Rolf wrote: > The Griffon engine caused a number of accidental deaths for Spit pilots. > There are three factors which induce significant "unconventional" forces > on a propeller-driven plane that few 'civilians' know about. P-Factor, > Spiral Propwash, and Torque unwind.... Russell, Your description of the factors involved are good, but you missed one. There are *four* "turning" factors that affect most light propeller-driven aircraft. You forgot about gyroscopic precession. The tendency for a gyroscope (propeller) to react to a force input by imparting a force 90 degrees from the input force. Pulling back on the stick (yoke) for takeoff imparts a vertical force on the prop which is turned in most aircraft into a left yawing force. During initial training in most typical aircraft with a prop that is turning clockwise (as viewed from the pilot's seat), all four of these forces are all introduced by the instructor as "left-turning tendencies", and we all learn to stomp pretty aggressively on the right rudder during the takeoff roll. Later, after the pilot has a grasp of these fundamentals, the instructor will discuss that that factors change significantly in an aircraft with a counter-clockwise turning prop. You're correct that pilots must think about and correct this "almost automatic" foot movement when transitioning to different aircraft. The counter-clockwise engine is but one example. Long-time instructors working their way up the food chain to turbines also have a tendency to push on that right rudder pedal automatically, when it's not needed... which can be pretty entertaining to watch until the person corrects their learned behavior. In addition, multi-engine students learn about the "critical engine" in aircraft with multiple props that turn the same way. In most twin designs, one specific engine in a twin engine aircraft (usually the right engine) will create more adverse effects on yaw and aircraft controllability than the other. http://en.wikipedia.org/wiki/Critical_engine Some twin-engine designs try to eliminate the "critical engine" scenario by mounting counter-rotating engines on each wing. Bottom line - it's up to the pilot to know and fly their aircraft. Nate -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist