Posted: Thu Jul 14, 2011 9:22 am Post subject: Avoid Area Curve
Hi, while teaching my trainees about the avoid area curve or the deadman's curve as it was known, i got an interesting doubt for which i could not get a satisfactory answer... hope you guys can help...
for a alouette helicopter (single engined) below the knee of the curve, at 100 feet of height the safe speed is 46kts but as you go higher, at 200 ft 46kts is within the unsafe region. How is it that with more height in hand we are still unsafe? during the discussion here... the most popular opinion seemed to be that it has got to do something with the crashworthiness of the aircraft????
The reason for this, I think, Is because at 100 ft the potential energy is lower than at 200ft! but even if you have a gain of altitude at 200 ft it is not enough to gain Rotor RPM witch is, with the speed, the most important factor to consider in auto rotation. Regarding speed, 200ft is not enough to gain speed without increasing dramatically your vertical descent. So you are higher at the same speed but you can't actually use this energy appropriately so the crash will be worst.
Yes it is related with the crashwhortiness of the aircraft!
Sorry for my english writhing It is my second language!
hope this can help!
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