Flutter cracks the aft fuselage of a Silent 2 Electro in straight flight
The pilot of a Silent 2 Electro was unhurt, but the glider was substantially damaged when it met flutter in straight flight near Giddings. At about 1,460 m MSL and 150 km/h the cockpit began to shake violently from side to side, as though the empennage were twisting; the shaking ran 10 to 15 seconds and stopped once the speed was back to about 111 km/h, after a height loss of some 90 m. The pilot landed back at his departure field without further trouble. Cracks at about ±45° were later found in the aft fuselage, matching the alternating torsion loads flutter produces.
- Straight and level near Giddings: About three hours into a cross-country flight from Waller, the Silent 2 Electro was flying straight and level near Giddings at about 1,460 m MSL and 150 km/h.
- Flutter sets in: The cockpit began to shake violently and noisily from side to side, feeling to the pilot as though the empennage were rocking and twisting.
- Shaking runs 10 to 15 seconds: The speed reached about 167 km/h during the event and the glider lost roughly 90 m of height while the shaking continued.
- Slowing stops the vibration: The shaking ceased once the speed was back to about 111 km/h, and the glider felt controllable again.
- Aft fuselage cracked in torsion: Cracks at about ±45° on both sides, with a longitudinal crack above, were found up to 76 cm forward of the fin. The pilot returned to his departure airfield unhurt.