RCU Forums - View Single Post - Lost an Engine (and Lived to Tell About It)

12-01-2005 | 11:21 PM

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William Robison

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From: Mary Esther, Florida, FL

RE: Lost an Engine (and Lived to Tell About It)

JPro:

Quote:

...but he swears that using rudder with an engine out on a twin model is suicide. Right or wrong?

He could not be any more wrong. Models have to answer to the same aerodynamic "Laws" that larger twins do, it's just the Reynolds' numbers that are different.

Remember the ailerons effectively change the AOA of the wing. When you try to correct for a dead engine with ailerons you go to "Negative" incidence on the side with the engine running, and the prop wash ensures continuing airflow over the wing. The up aileron pushes the wing down, that wing panel still works normally. But on the other side... that aileron goes down, in effect increasing the incidence and therefore the AOA. Along with this we've lost the prop wash on that side, and unless your air speed is 'way up the wing panel with the dead engine will stall. Immediate spin, and unless you're high you will not recover before you have an unplanned landing.

Proper use of the rudder has saved many a war bird twin with a dead engine. I have never heard of the ailerons doing the same, but some planes like the Twinstar fly so well on a single engine that the error wont kill your plane.

Rudder use will make the difference between a plane that will fly again and a pile of sticks, shattered fiberglass, and crushed foam.

Hope my aerodynamics lesson wasn't over the top, but I wanted you to understand WHY the aileron was the wrong control for an engine out.

Bill.

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