Here's a thought though, Chicken6. When these test pilot chappies arrive at 'best glide' figures, do they actually switch the engine off ? I am assuming you didn't when you did your tests, so there may be a discrepancy there. Anyway I shall watch with interest. I tried it yesterday, by the way, while trying to show a student the effect of flap on the descent, and of course the descent rate seemed to reduce with 10 flap (I think we hit some rising air). Certainly increased with 20 though so she was convinced in the end.