Thanks for the off list replies. I have received reports of 7 instances from instructors and pilots alike. Not a huge number, but then this may indicate that this is a quite isolated problem.
My experience were similar to others and also similar to the situations described by Drek Piggott in "Sub Gravity Sensations and Gliding Accidents". The trainee coped with demonstrations of gentle stalls and nose high stalls, although I did note a tendency for the trainee to hold the nose down and allowing the airspeed to increase excessively, but this was not an uncommon finding with trainees when introduced to stalls. Hence I was not expecting any problem. When I handed over to him and talked him through a nose high stall (i.e. Patter went along the lines of "Raise the nose above the horizon, keep it there by keeping the stick coming back, feel the pre stall buffet, note the nose dropping despite having full back stick, recover..."). During recovery, the trainee then eased the stick forward, but then as the aircraft nosed over more (we were now un-stalled by this stage), the trainee then suddenly put the stick to the front stop. The trainee was with head arched back almost looking at me upside down! By the time I caught it (a combination of the surprise factor plus reaction time), we had gone past vertical (dust was stuck to the canopy, I was hard up against my shoulder straps). The trainee pilot did not let go of the stick even after I told him to. I had to do a high speed, high G pull out (I was careful not to use excessive control inputs because we were above Vmax manoeuvring). Airspeed got close to Vne, no flutter occurred. After stabilising into a safe flying attitude, I did a control check and deemed that all was fine. I again demonstrated gentle stalls to the trainee and then he did some recoveries himself with me talking him through. I then did a post-brief on the ground; the pilot didn't know what had happened when he bunted the nose over and was at a loss to explain. Some notes I received: If the aircraft is almost inverted after nosing over, consideration of a roll out to recovery may be needed, because pulling through from inverted runs the risk of overspeed. This point is made in the book "The Handbook of Glider Aerobatics" by Peter Mallinson. http://www.amazon.com/Handbook-Glider-Aerobatics-Peter-Mallinson/dp/1840371102 To summarise: Negative (reduced) G sensitivity is a rarely reported problem, with subtle warning signs, but a dramatic (often surprising and rapidly deteriorating) presentation with potentially catastrophic results. With repeated and graded exposure to reduced G situations as well as an explanation of what is happening, most (if not all) affected pilots will learn to tolerate reduced G. M.T. _______________________________________________ Aus-soaring mailing list Aus-soaring@lists.internode.on.net To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
