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June 11, 2006
OSTIV Lectures - day three
We began the third day of the Congress with Gerhard Waibel´s presentation of his paper “Development of OSTIV Airworthiness Standards Traced in OSTIV-Publications.” In dealing with the new regulatory agency, EASA, the certification of both lighter and heavier gliders than we are now flying, must break new ground. Gerhard parallels this situation to the situation in the early 1950´s and, by looking at the early OSTIV publications, he traced how the existing airworthiness standards evolved. It is clear that this rich history provides us with excellent guidance for the future.
Christoph Kensche presented “Damage Detection of Fatigue-Loaded CFRP-Components” co-authored by Rodolfo Aoki and Dieter Oppel. This paper discussed a proposed method of satisfying the lifetime certification procedure using simplified load and fatigue tests. In addition, the use of non-destructive testing techniques were explored, which are of value for identifying failures in composite structures without cutting into or even destroying the structure.
The next paper was “Investigation of the Glider Load Spectra” by Miroslaw Rodzewicz. In this paper the load spectrum of a glider was measured throughout its various phases of flight, including cruise, thermal, wave, and aerobatic flight. The spectral analysis of these data allows the cumulated number of load changes to be extrapolated. This is of great value for the simplifying the fatigue testing and certification of sailplane structures.
Hugh Browning then presented an important paper, “Safe Winch Launches”, intended to reduce the number of fatal and serious accidents during winch launching. This paper explored the role of stall during rotation in these accidents and found that it significantly increased with the rate of rotation. Thus, it was recommanded that high rates of pitch rotation should be delayed until sufficient airspeed is obtained. In addition, it was noted that half the serious accidents were due to power failure close to the ground (less than 100 feet). In this situation, the importance of getting the nose down quickly cannot be over-emphasized, and waiting for a specified airspeed at a specified altitude, say 50 feet, before steepening the climb can save lives. Finally, pushing over too quickly can be dangerous. The important details are contained in the paper, which should be considered by all interested in reducing winch-launching accidents.
Ian Oldaker then presented his paper “The Canadian Safety Management Programme”. Ian gave an overview of efforts taken in Canada to improve their gliding safety in an efficient and cost-effective manner. In particular, this program emphasizes an interaction with clubs, such that every member becomes invested in improving safety. This is an extremely interesting approach which puts the club into position to improve their own safety programs through self assessment.
The last presentation of the day was given by Bart Berendsen, co-authored by Loek Boermans: “Improvement of an Artificial Stall Warning System for Sailplanes”. This paper dealt with an improved stall warning device. The system uses static pressure measurements at two points in the side of the fuselage nose to give an angle-of-attack indication that is independent of wing loading and yaw angle. Flight tests proved that the system works at wings level stall, wings level slip, coordinated turn, skidding turn, landinggear extended, speedbrakes extended and high speed stall, independent of wing loading.
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