The Ground LoopThe ground loop is when the tail of the aircraft loses directional stability and rotates about the horizontal axis of the aircraft. This leads the tail to want to spin around the nose of the aircraft as it is disturbed from a straight line. When this happens, the momentum will carry aircraft partway or potentially all the way around until the tail of the aircraft is headed in the direction that the aircraft nose was originally aimed if no correction is made. In many cases, the momentum will cause a wing to dip and may cause a wing strike on the outside of the ground loop, leading to a cart wheeling effect in which the other wing will be caused to strike as well. As the ground-loop happens, directional control is lost and the aircraft will frequently travel off the runway surface and be subjected to the potential hazards that exist off the runway such as lights, ditches, or unimproved surfaces. There can be no doubt that this can cause damage that may range from minor to very severe and is something that no pilot would choose to do. To avoid ground looping an aircraft the pilot will need to be able to maintain proper rudder control at all times, even through what most tricycle gear pilots will consider a moderate or slow taxi. Tailwheel aircraft have the ability to ground loop to some extent at virtually any speed of travel above stopped, the speed simply controls how much momentum will be available when the aircraft ground loops. This momentum will determine how far or bad the ground loop will become if it is encountered. It is for this reason that the pilot should taxi slowly, perform landings that will allow for appropriate stopping and get themselves to a controllable taxi speed as soon as possible when landing. In consideration of this, the pilot should be cautious to not over-brake. When braking the aircraft, if it is not applied smoothly and one side is favored, the aircraft will have a tendency to veer to the side that more brake is applied. Once the tail is disturbed from straight travel, it will take greater rudder and brake pressure on the opposite side to bring the aircraft back to straight. It should be noted here that overcorrection can lead to a fishtailing effect that will gradually worsen and lead to a position where the pilot no longer has enough rudder or brake control to stop the developing ground loop. Crosswind landings are the time when most pilots are at the greatest susceptibility to ground looping the aircraft. Rudder control is vitally important during these operations. At times, a quick jab on a brake will help keep the aircraft headed straight if the pilot finds that the nose is starting to veer one direction of the other, but in general, if the pilot is not able to maintain directional stability with the rudder down the runway, they are probably in a crosswind that is too strong for their aircraft and are subjecting themselves unnecessarily to a greater ground loop potential. Tailwheel aircraft are very safe aircraft to fly and the potential for ground loop should not scare people away from flying them, but a strong understanding of the physics behind a ground loop should be developed. This will need to include an understanding of the dynamics of aircraft stability, rudder and brake control, and how the pilot should recognize a developing situation and react to it appropriately. In most aircraft, depending on the position of the aircraft or how far the ground loop has developed, a couple of options are available for the pilot. If the ground loop is occurring upon touchdown or slightly after, the best option will be to apply full power, steer the aircraft with the rudders, and go-around. A safe go-around is always better than a bad landing. If the ground loop has developed further, the pilot is no longer able to directionally control the aircraft, or a go-around is not possible, the pilot should immediately retard the throttle to idle and control the aircraft to the best of their ability using rudders and brakes to bring the aircraft to a stop. While doing so, the pilot should keep the stick/yoke all the way back to keep the tail of the aircraft on the ground and the nose up. This will keep the angle of attach high so the aircraft will have a decreased potential for becoming airborne again and additionally will minimize the potential for prop strike as the aircraft travels through the ground loop. |
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| Dodgen Aircraft • 740 Grand Street • Allegan, MI 49010 • Allegan: (269) 673-4157 • info@dodgenaircraft.com | |||||||||
