RIO DE JANEIRO, Brazil – There was plenty of discussion among the race teams back in Perth about how Brazilian rookie Adilson Kindlemann ended up in the Swan River during a training flight. The term ‘wing stall’ was bandied around the Race Airport and it was an accepted fact that this aeronautical phenomenon had contributed to the unfortunate situation, which thankfully saw Kindlemann walk away unscathed.
But for those not used to such terminology, it could be easy to misunderstand the exact meaning of this aviation phrase. Clearly in a wheeled motor vehicle, an engine stall can occur – where the engine stops turning for one reason or another and the vehicle splutters to a halt. Most of us have been there when a foot slips off the clutch and it abruptly engages with the motor, for example. So in general, we can comprehend that type of stalling. Conversely, for those not in the habit of flying aeroplanes, the concept of a wing stalling can bring about much chin rubbing. So where exactly is that engine again… ?
AIR FLOWING OVER THE WING
Ask someone like expert race commentator Steve Jones about this and you’ll receive a thoughtfully crafted explanation of how the pressure of the air above and below a wing differs – and how this is what essentially causes lift. Still with me? Good. He’ll also explain that if you pull the stick back a little too much and move the wing through the air at too great an angle, past the critical angle, the air flowing over the top of the wing, breaks away.
“This is a wing stall,” Jones confirms, giving a very concise and user-friendly explanation for us mere mortals. “Most of the lift ceases immediately and the aircraft stops flying. The drag also increases if this happens. This angle varies from one machine to another depending on the aerofoil section of the wing – how curvy it is.”
GETTING IN A SPIN
It’s not rocket science for anyone with a reasonable grasp of aerodynamics but for anyone new to this, the key thing is to remember that it’s about lift and keeping the airflow attached to the top surface of the wing. All aeroplanes are tested to identify their ‘stall characteristics’ at the prototype stage and many experienced pilots have fallen foul of what’s known in the business as a ‘spin’, where one wing stalls before the other and the aircraft descends like a huge, spinning sycamore seed… Believe it or not, this can form part of compulsory flight training!
This was far from the situation for Kindlemann but all pilots are aware of just how unforgiving an out of control machine can be – and it’s fair to say that the Brazilian rookie won’t want to make the same mistake again. Race pilots can feel this ‘stall’ often just by instinct and with thousands of hours whipping their highly manoeuvrable race planes around all the axes, they usually know how to avoid it. Unfortunately for Kindlemann, he had insufficient height in the track to remedy the situation in time and this is what led to him literally taking an early bath in Perth.
Adilson Kindlemann talks us through the incident in Perth...
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