Tailwheel/Tailskid Equipped Glider Oscillations During Launches and Landings

Introduction to Glider Flying > Abnormal and Emergency Procedures > Tailwheel/Tailskid Equipped Glider Oscillations During Launches and Landings

Some two-seat gliders, self-launch gliders, and single-seat gliders have a tailwheel. When loaded and ready for flight, these gliders have the mainwheel and the tail-wheel or tailskid in contact with the ground. In these gliders, the center of gravity is aft of the main wheel(s). Because of this, any upward thrust on the main landing gear tends to pitch the nose of the glider upward unless the tail wheel or tailskid is in contact with the ground and prevents the change in pitch attitude.

Upward thrust on the main landing gear can occur in numerous circumstances. One cause is a bump in the runway surface during takeoff or landing roll. If the resultant pitch-up is vigorous enough, it is likely that the glider will leave the ground momentarily. If air-speed is slow, the elevator control is marginal. As the pilot reacts to the unexpected bounce or launch, overcontrolling the elevator will result in a PIO. [Figure 8-6]

Figure 8-6. Pneumatic tire rebound during hard landing.

Improper landing technique in a tailwheel glider also can lead to upward thrust on the main landing gear and subsequent PIOs. Landing a tailwheel glider in a nose-down attitude, or even in a level pitch attitude, can lead to trouble. If the main wheel contacts the ground before the tailwheel or tailskid, the compression of the pneumatic tire and its inevitable rebound will pro-vide significant upward thrust. The glider nose may pitch up, the angle of attack will increase, and the glider will become airborne. As before, overcontrol of the elevator leads to PIOs.

To prevent this type of PIO, do not allow the glider to settle onto the landing surface with a nose-down atti-tude or with excess airspeed. During the landing flare, hold the glider off a few inches above the ground with gentle backpressure on the control stick as necessary. The speed will decay and the pitch attitude will gradu-ally change to a slightly nose-up pitch attitude. The ideal touchdown is simultaneous gentle contact of main wheel and tailwheel or tailskid. Delaying the touchdown just a small amount results in the tailwheel or tailskid contacting the landing surface an instant before the mainwheel. This type of landing is very acceptable and desirable for almost all tailwheel glid-ers because it makes a rebound into the air very unlikely. Consult the GFM/POH for the glider being flown for further information about recommended pro-cedure for touchdown.