Quote:
Originally Posted by Crumpp
In the turn, the violent buffet is a double edged sword. There is no such thing as a free lunch especially in physics. In the NACA measured results, encountering the buffet represents a change in available angle of bank. The airplane goes from 78.5 degrees of bank to 60 degrees of bank in one second.
****5G @ 147.73KIAS:
ROT = 1091*tan(78.5) divided by 147.73 KIAS = 36.2 degrees a second
****2G @ 141.647 KIAS:
ROT = 1091*tan(60) divided by 141.647 = 13.34 degrees a second
As a quick ballpark using IAS to get an idea of the scope of the effect on turn performance, we see the rate of turn drop from 36.2 degrees a second to 13.34 degrees a second. That means our time to complete a 360 degree turn changes from 10 seconds to 27 seconds!!!
As the Operating Notes relate, you do not want to turn any airplane in the buffet. Energy cannot be created or destroyed, all the energy that was being used to achieve an instantaneous performance rate of turn of 36.2 degrees a second from our ballpark went to warn the pilot of an impending stall, taking the aircraft right down well inside its sustainable performance envelope of 13.34 degrees a second.
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The Buffet is not a double edged sword. It is easily and immediately recognisable and resolving the issue is equally easy and immediately effective, all you do is ease off the stick until the buffet goes. It is easy to fly on the edge, you 'feel' for the start of the buffet and ease off as applicable, the normal process is to hold it on the edge with gentle movements once you have found the buffet. You don't fly in the buffet, you can fly to the buffet and then its easy to stay outside the vibration
To pull through the buffet would be dangerous, stupid and also difficult to do, the vibration would rattle your teeth and its impossible to miss it. One benefit of using the buffet is that you do this with your head looking out of the cockpit, you don't need to look at any instruments and because it is something you feel it doesn't matter how noisy it is.
I once got caught in a thunder cloud in a strong thermal. Water got into my instruments, the only one I had working was an audio vario that told me by sound if I was climbing and an indication as to how fast I was climbing. To stay in the thermal in the cloud, I had to rely totally on the audio vario and the buffet giving me warning of the stall as I had no idea how fast I was going. By staying on the edge of the stall, flying outside the buffet just feeling for it every now and then, I was able to say in the thermal and ensure that I didn't exceed the Vne.
I say this as it proves that its effective in the most difficult situations