Richard Lindberg

"Ground loop" is a confusing term. It should really be called a "ground spinout" because it is the same maneuver an automobile negotiates when it spins out of control on slick pavement. Racing cars get into this same predicament even on a dry race course. When an air-plane ground-loops it similarly spins, and will do so on either a wet or dry runway.
 

Ground looping is usually associated with a tail-dragger type of aircraft (one with a tail wheel) because it has a natural tendency to ground loop. Part of its takeoff run is made with its tail elevated, which leaves only the two main landing wheels in contact with the ground. If the plane veers to the right or left during the slow ground-speed phase of its takeoff run, and you are not quick enough with rudder control (or over control) to straighten its run, the plane will ground loop.
If a ground loop occurs, immediately throttle your plane's engine back to idle to stop the skidding circles. A ground loop will not cause a great deal of damage - scraped wing tips, possibly a bent landing gear and/or your own slightly embarrassed ego.
An airplane with a tricycle landing gear (a gear having a nose wheel) has a far less tendency to ground loop than a tail-dragger because three landing gear wheels remain in con-tact with the ground until takeoff: speed is obtained. This does not rule out the possibility of a ground loop, however.
 

The next most probable cause of ground looping is that the engine is installed with more right thrust than needed to counteract the engine's torque, and the plane is actually being pulled into the ground loop. Other causes associated with a tricycle gear are a nose-gear wheel that is not aligned or the failure of one wheel of the main landing gear to rotate freely. In the case of a tail-dragger, one main wheel might be too tight on its axle, which will also contribute to a ground-looping tendency.

 Because tail-draggers are notorious for having a ground-looping tendency, it is advisable to give each of the two main landing wheels a slight toe-in, which helps tremendously to keep the plane headed straight down the runway. "Toe-in" means that the plane's landing gear axles are bent so that the FRONTS of the wheels will be pointing slightly inward, as viewed from below the airplane.
   

Another great help in keeping a tail-dragger from ground looping during its takeoff run is to give a slight amount of up-elevator, to keep the tail wheel in contact with the runway, then GRADUALLY advance the engine's throttle and steer with the plane's tail wheel until a bit of ground speed is reached and the tail is ready to come up. At this point, raise the tail and steer the plane straight down the runway with the plane's rudder.

 Many R/C'ers who are accustomed to flying a plane with a tricycle landing gear, get into the habit of giving their plane's engine an instantaneous burst of full power, then steering the plane down the runway until takeoff speed is reached. This procedure will work for a plane having this type of landing gear. But when these same R/C'ers fly their first taildragger, they quickly come to realize that for such a plane this is a no-no since the plane will react either by lowering its nose into the runway (good-bye propeller) or by ground looping.
Courtesy of Columbia R/C Club, Inc.