Flutter

Flutter

While flying with a friend of mine in my hometown in Texas in May 2006, his Kaos experienced flutter and crashed. What is flutter?

Flutter is a phenomenon that occurs when the airflow over the control surfaces of the airplane gets disrupted. This normally happens with the ailerons in radio controlled aircraft but can also happen with the elevators and the rudder.

Alvin’s Kaos was powered by an O.S. .46FX with a Performance Specialties muffler. The airplane was extremely fast! Flutter has an unmistakable sound. It sounds like a loud vibration because that is basically what it is. While looking through the wreckage of Alvin’s plane, the right side elevator was not connected to the horizontal stabilizer. While it is true that the elevator could have pulled loose due to the crash it is more likely that flutter caused the elevator to pull out.

There are a couple of ways to help control flutter. The first and most obvious solution is to make sure the control surfaces are faired smoothly into their respective flying surface. For instance, when you attach an aileron, make sure you sand the back of the wing and the front of the aileron where the air will flow smoothly from the wing over the aileron.

I used to fly an airplane called a Super Duper Joy Stick. The ailerons had a very bad habit of fluttering. To deal with this, several of us that flew the kit attached counterweights to the bottom of the ailerons. This seemed to help. Another thing that may help flutter is to attach a piece of tape or iron on covering across the length of the control surface where it hinges. For example, put a strip of tape lengthwise covering a small portion of the elevator and the horizontal stabilizer. This will help the air flow more smoothly across the control surfaces.

If you hear flutter, immediately pull back on the throttle and up on the elevator to slow the plane down. If you don’t, the plane will disintegrate in a very short time.