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#1
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On Sat, 04 Sep 2004 23:30:33 GMT, Jim Richardson
wrote: the autoprop turns it's blades, to be parallel to the axis of the shaft, resulting in less drag than in the fwd or reverse direction,. How is that not feathering? I an unfamiliar with the autoprop.If it turns its blades' angle of attack to the near zero angle (actually slightly negative angle) that minimizes drag, then this is said to be a feathering prop. [one realises that a blade's angle varies with distance from the hub, so that the idea of a fixed angle of attack is a slight abstraction] If a prop system allows the blades to fold at the hub in order to minimize drag this is usually described as a folding prop. If a prop system allows the prop blades' angle of attack to vary so as to maximize power transfer at the present water speed, this is said to be a variable pitch prop system. Let me ask Jim specifically (in order to avoid interjections from the lunatic fringe) which of these three types of prop system he would call the Autoprop? Regards Brian Whatcott Altus OK |
#2
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![]() Brian Whatcott wrote: I an unfamiliar with the autoprop.If it turns its blades' angle of attack to the near zero angle (actually slightly negative angle) that minimizes drag, then this is said to be a feathering prop. [one realises that a blade's angle varies with distance from the hub, so that the idea of a fixed angle of attack is a slight abstraction] If a prop system allows the blades to fold at the hub in order to minimize drag this is usually described as a folding prop. If a prop system allows the prop blades' angle of attack to vary so as to maximize power transfer at the present water speed, this is said to be a variable pitch prop system. This may be a description for some. However, in my world, a "variable pitch" prop starts at "zero" pitch (blades 90 deg to a "feathered" position) and to increase speed, pitch is increased. These are also called controllable pitch props and they ( normally ) can not be "feathered". However, it appears from the literature on the autoprop/maxprop, there may be a degree of "variable" to these props ..... I'm mentioning this here, as it does appear there is room for confusion. otn Let me ask Jim specifically (in order to avoid interjections from the lunatic fringe) which of these three types of prop system he would call the Autoprop? Regards Brian Whatcott Altus OK |
#3
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brian, an Auto-Prop fits you definition #3
the autoprop turns it's blades, to be parallel to the axis of the shaft, resulting in less drag than in the fwd or reverse direction,. How is that not feathering? I an unfamiliar with the autoprop.If it turns its blades' angle of attack to the near zero angle (actually slightly negative angle) that minimizes drag, then this is said to be a feathering prop. [one realises that a blade's angle varies with distance from the hub, so that the idea of a fixed angle of attack is a slight abstraction] If a prop system allows the blades to fold at the hub in order to minimize drag this is usually described as a folding prop. If a prop system allows the prop blades' angle of attack to vary so as to maximize power transfer at the present water speed, this is said to be a variable pitch prop system. Let me ask Jim specifically (in order to avoid interjections from the lunatic fringe) which of these three types of prop system he would call the Autoprop? Regards Brian Whatcott Altus OK |
#4
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On Sun, 05 Sep 2004 00:59:49 GMT,
Brian Whatcott wrote: On Sat, 04 Sep 2004 23:30:33 GMT, Jim Richardson wrote: the autoprop turns it's blades, to be parallel to the axis of the shaft, resulting in less drag than in the fwd or reverse direction,. How is that not feathering? I an unfamiliar with the autoprop.If it turns its blades' angle of attack to the near zero angle (actually slightly negative angle) that minimizes drag, then this is said to be a feathering prop. [one realises that a blade's angle varies with distance from the hub, so that the idea of a fixed angle of attack is a slight abstraction] If a prop system allows the blades to fold at the hub in order to minimize drag this is usually described as a folding prop. If a prop system allows the prop blades' angle of attack to vary so as to maximize power transfer at the present water speed, this is said to be a variable pitch prop system. Let me ask Jim specifically (in order to avoid interjections from the lunatic fringe) which of these three types of prop system he would call the Autoprop? Regards I'd say it's either a variable pitch, or simple feathering, since I am unsure from a casual perusal of their website whether the blades are fixed in pitch when set to forward or reverse, or are variable based on rpm. -- Jim Richardson http://www.eskimo.com/~warlock Rule 1: You can't cure stupid |
#5
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![]() Jim Richardson wrote: I'd say it's either a variable pitch, or simple feathering, since I am unsure from a casual perusal of their website whether the blades are fixed in pitch when set to forward or reverse, or are variable based on rpm. From the sites, I get the feeling the pitch is adjustable at installation but fixed from that point on, which would mean it is "feathering", not "variable" (?) otn |
#6
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