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- Feb 11, 2013
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This subject may have been beat to death a thousand times, but darned if I can find any definitive guidance.
In the Seneca II with its TSIO-360 Continental engines, I want to see if the aircraft will perform better (burn less fuel) at cruise with the props pulled back. I've had this in the back of my mind, but reading Bob Gardner's multi engine book, he talks about it also, but probably not in direct reference to this airplane type. The benefits of lower turning seem to promote less engine wear, and less fuel flow. I have cruised at 2200, but no lower, at 28" -25" in economy cruise settings. At some point, the engine will lug just like stepping on the gas in a car in 5th gear at 30 mph. But if I'm just easing along with 28" or less and 1900, I wonder what stresses will be placed on the engine not otherwise happening? And of course, Lindbergh's high MAP and low rpm for increased fuel economy seems appropriate. The POH says do not run between 2000-2200 rpm over 32" and the tachs have that as the yellow zone. But it does not prohibit operation in the caution zone - just above 32", so I suppose Lindbergh's high MAP would not be good on the engine for whatever reason in those ranges. But it does not say you cannot go back into the green range BELOW 2000 rpm - getting us back into Lindbergh territory. Now I understand why some logicians developed the term 'circular reasoning' - when you're dealing with propeller rpms, its all circular that's for sure. Any actual experiences appreciated, regardless of engine type.
In the Seneca II with its TSIO-360 Continental engines, I want to see if the aircraft will perform better (burn less fuel) at cruise with the props pulled back. I've had this in the back of my mind, but reading Bob Gardner's multi engine book, he talks about it also, but probably not in direct reference to this airplane type. The benefits of lower turning seem to promote less engine wear, and less fuel flow. I have cruised at 2200, but no lower, at 28" -25" in economy cruise settings. At some point, the engine will lug just like stepping on the gas in a car in 5th gear at 30 mph. But if I'm just easing along with 28" or less and 1900, I wonder what stresses will be placed on the engine not otherwise happening? And of course, Lindbergh's high MAP and low rpm for increased fuel economy seems appropriate. The POH says do not run between 2000-2200 rpm over 32" and the tachs have that as the yellow zone. But it does not prohibit operation in the caution zone - just above 32", so I suppose Lindbergh's high MAP would not be good on the engine for whatever reason in those ranges. But it does not say you cannot go back into the green range BELOW 2000 rpm - getting us back into Lindbergh territory. Now I understand why some logicians developed the term 'circular reasoning' - when you're dealing with propeller rpms, its all circular that's for sure. Any actual experiences appreciated, regardless of engine type.
