Twin Engine

Posted on | April 6, 2009 | 1 Comment

Twin Engine

Why do you own a twin engine, light aircraft?

My first light twins were bought for my air charter service. When I finally got around to my first 421, I realized what great twins Cessna built. I got to where I compared them to Piper, and felt the Piper Navajo was a Chevrolet to the Cessna 421's Cadillac. The kind of flying I do didn't really warrant the pressurization, so I when I stumbled onto the 411, I finally had the perfect plane for me. It will take me over a thousand miles non-stop at an economical cruise of 230 mph. Where the 421 burns around 40 gallons per hour, the 411 pulls back to a little less than 35. You can fill the tanks with 200 gallons, the seats with average sized people, close the door and go. I have managed to lose an engine a couple of times due to clogged fuel lines, and after cleaning up the engine, set the rudder trim to compensate for the dead engine and continued on to an airport with maintenance facilities, no sweat. Don't let the taxi speed fall off too much, though. She's a bear to taxi on one engine. I guess the best answer is that I feel totally comfortable, totally at home in her left seat.

Someone said, in reference to the Cessna 337, something about Lycoming engines. I thought the Skymaster had Continentals.

Twin-engine Polo

What are the left-turning tendencies in a conventional twin-engine airplane?

Actually most twins don't have counter rotating props.

The torque of the engine causes a left rolling tendency. For each and every action, there is an equal and opposite reaction. As viewed from the cockpit, the crankshaft on an American-made engine rotates clockwise. The opposite reaction is for the airframe to roll to the left.

The propeller propels air currents around and about the airframe in a clockwise direction (as viewed from the rear). The airstream strikes the left side of the vertical stabilizer and rudder, yawing the nose of the airplane to the left.

Gyroscopic precession from the rotation of the crankshaft and propeller causes the airplane to yaw to the left.

In nose high attitudes, a left-turning tendency results from the fact that the descending propeller blade takes a bigger bite out of the air than does the ascending blade, which is on the left. This P-factor adds to the left-turning tendency when the airplane is in a nose-high attitude.

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