ISASI seminar2012, August 27-31 2012, Baltimore, USA
Authors John Stoop, Jan de Kroes
Lund University, Delft University of Technology
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Title: The stall shield, from serendipity to innovation
Over the decades, stall –and in particular deep stall- has been a fundamental hazard in flying fixed wing aircraft as demonstrated by crashes, with the Trident and other T-tail configured designs. Recent crashes, like AF447 and TK1951, have demonstrated that stall is still an inherent hazard with potentially fatal consequences.
Due to the application of advanced pro-active flight envelopes protection designs, stall has become a rare phenomenon. Pilots in commercial aviation do no longer acquire basic stall recovery skills , but stall still emerges during final approach, enroute and climbing to cruise altitude. During operational practices, safety balanced against other business values in an efficiency-thoroughness trade off. This reduces safety from a strategic value at a business continuity level to an operational constraint.
In contrast to military aircraft, for commercial aircraft pilots, applying thrust vectoring is beyond their skills and experience, while a canard wing configuration also has its limitations.
This contribution introduces and discusses an innovative design for stall recovery, the stall shield. The stall shield introduces additional, dedicated aerodynamic forces to regain control over the aircraft, instead of manipulating existing and already compromised lift and thrust forces by adding control surfaces at the nose and tail of the aircraft during stall conditions.
This stall shield might also serve as a new safety assessment tool in aircraft design by assessing stall characteristics in the conceptual design phase and providing training opportunities for pilots in stall recovery. Powerful avionics will facilitate automated recovery and simulator training for using this stall shield.
The introduction of the stall shield is not only as an example of how serendipity through accident investigations may disclose recurrence of critical modes of operandi in aircraft stability and control, but also how aerospace engineers and designers can apply this knowledge to develop innovative solutions.