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Dimples On Model Aircraft Could Greatly Extend Range
Have they tried dimples on radio controlled aircraft? The size and
speed could designed around the magic Reynolds number = 100,000 where the coefficient of drag drops precipitously. Dimpling could vastly extent the range of large and slow as well as small and fast radio controlled aircraft. A competitive cyclist is the right size and speed for Nre = 100,000 so dimple suits can work. Same for golf balls. Nre = 100,000 for widebodies going 0.5 knots so dimples won't work except on the runway. From fluid mechanics the Reynolds number is the ratio of inertial forces/viscous forces. N re = Diameter X velocity X density of fluid/viscosity of fluid. Bret Cahill |
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Dimples On Model Aircraft Could Greatly Extend Range
"Bret Cahill" wrote in message ... Have they tried dimples on radio controlled aircraft? The size and speed could designed around the magic Reynolds number = 100,000 where the coefficient of drag drops precipitously. Dimpling could vastly extent the range of large and slow as well as small and fast radio controlled aircraft. A competitive cyclist is the right size and speed for Nre = 100,000 so dimple suits can work. Same for golf balls. Nre = 100,000 for widebodies going 0.5 knots so dimples won't work except on the runway. From fluid mechanics the Reynolds number is the ratio of inertial forces/viscous forces. N re = Diameter X velocity X density of fluid/viscosity of fluid. Bret Cahill We competitive cyclists use dimples already on our disk wheels. And some skinsuits incorporate them. But they don't look like the dimples on a golf ball. They are shaped differently and they are shallow. Check out Zipp disk wheel dimples he http://www.zipp.com/wheels/detail.php?ID=33 Over a 40K ITT this rear wheel can give you a 30-40 second advantage over smooth disk wheels. -- Gregory Hall |
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Dimples On Model Aircraft Could Greatly Extend Range
Have they tried dimples on radio controlled aircraft? � The size and
speed could designed around the magic Reynolds number = 100,000 where the coefficient of drag drops precipitously. Dimpling could vastly extent the range of large and slow as well as small and fast radio controlled aircraft. A competitive cyclist is the right size and speed for Nre = 100,000 so dimple suits can work. �Same for golf balls. Nre = 100,000 for widebodies going 0.5 knots so dimples won't work except on the runway. From fluid mechanics the Reynolds number is the ratio of inertial forces/viscous forces. N re = Diameter X velocity X density of fluid/viscosity of fluid. Bret Cahill We competitive cyclists use dimples already on our disk wheels. And some skinsuits incorporate them. But they don't look like the dimples on a golf ball. They are shaped differently and they are shallow. Check out Zipp disk wheel dimples hehttp://www.zipp.com/wheels/detail.php?ID=33 Over a 40K ITT this rear wheel can give you a 30-40 second advantage over smooth disk wheels. A model plane about the size of a cyclist would benefit most from dimples if it only went cycling speeds, 20 - 25 knots. Smaller aircraft would need to be designed to go faster inverse with size. A golf ball sized aircraft would have to go 200 mph for dimples to work. Bret Cahill |
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Dimples On Model Aircraft Could Greatly Extend Range
wrote in message ... Have they tried dimples on radio controlled aircraft? ? The size and speed could designed around the magic Reynolds number = 100,000 where the coefficient of drag drops precipitously. Dimpling could vastly extent the range of large and slow as well as small and fast radio controlled aircraft. A competitive cyclist is the right size and speed for Nre = 100,000 so dimple suits can work. ?Same for golf balls. Nre = 100,000 for widebodies going 0.5 knots so dimples won't work except on the runway. From fluid mechanics the Reynolds number is the ratio of inertial forces/viscous forces. N re = Diameter X velocity X density of fluid/viscosity of fluid. Bret Cahill We competitive cyclists use dimples already on our disk wheels. And some skinsuits incorporate them. But they don't look like the dimples on a golf ball. They are shaped differently and they are shallow. Check out Zipp disk wheel dimples hehttp://www.zipp.com/wheels/detail.php?ID=33 Over a 40K ITT this rear wheel can give you a 30-40 second advantage over smooth disk wheels. \ A model plane about the size of a cyclist would benefit most from \ dimples if it only went cycling speeds, 20 - 25 knots. \ \ Smaller aircraft would need to be designed to go faster inverse with \ size. \ \ A golf ball sized aircraft would have to go 200 mph for dimples to \ work. I wonder if anybody has thought of putting the appropriate dimples on the surface of propellers? Seems like reducing drag there would increase RPM and reduce HP required. A bicycle wheel spins much faster than 20-25 knots apparent to the air it interfaces with. At 30 knots, for example, the surface of the wheel might be moving closer to 100 knots apparent to the wind. -- Gregory Hall |
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Dimples On Model Aircraft Could Greatly Extend Range
Have they tried dimples on radio controlled aircraft? ? The size and
speed could designed around the magic Reynolds number = 100,000 where the coefficient of drag drops precipitously. Dimpling could vastly extent the range of large and slow as well as small and fast radio controlled aircraft. A competitive cyclist is the right size and speed for Nre = 100,000 so dimple suits can work. ?Same for golf balls. Nre = 100,000 for widebodies going 0.5 knots so dimples won't work except on the runway. From fluid mechanics the Reynolds number is the ratio of inertial forces/viscous forces. N re = Diameter X velocity X density of fluid/viscosity of fluid. Bret Cahill We competitive cyclists use dimples already on our disk wheels. And some skinsuits incorporate them. But they don't look like the dimples on a golf ball. They are shaped differently and they are shallow. Check out Zipp disk wheel dimples hehttp://www.zipp.com/wheels/detail.php?ID=33 Over a 40K ITT this rear wheel can give you a 30-40 second advantage over smooth disk wheels. \ A model plane about the size of a cyclist would benefit most from \ dimples if it only went cycling speeds, 20 - 25 knots. \ \ Smaller aircraft would need to be designed to go faster inverse with \ size. \ \ A golf ball sized aircraft would have to go 200 mph for dimples to \ work. I wonder if anybody has thought of putting the appropriate dimples on the surface of propellers? Seems like reducing drag there would increase RPM and reduce HP required. I'm not certain dimples would make much difference in a well designed airfoil wing or prop or fusalage. Maybe something that had an awkward shape, i. e., a strut, would benefit the most. I may recant. A golf ball goes 4 times further with dimples but a golf ball isn't aerodynamic in the first place. A bicycle wheel spins much faster than 20-25 knots apparent to the air it interfaces with. At 30 knots, for example, the surface of the wheel might be moving closer to 100 knots apparent to the wind. It's just double the speed of the hub. Bret Cahill |
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Dimples On Model Aircraft Could Greatly Extend Range
In rec.aviation.marketplace Gregory Hall wrote:
I wonder if anybody has thought of putting the appropriate dimples on the surface of propellers? Seems like reducing drag there would increase RPM and reduce HP required. While reducing drag would be a goal, fixed propeller systems are designed to keep the tip velocity under mach 1. For constant speed props, the RPM is whatever you set it to, again under mach 1. -- Jim Pennino Remove .spam.sux to reply. |
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Dimples On Model Aircraft Could Greatly Extend Range
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Dimples On Model Aircraft Could Greatly Extend Range
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Dimples On Model Aircraft Could Greatly Extend Range
On Nov 4, 4:26*pm, "daestrom"
wrote: wrote: In rec.aviation.marketplace Gregory Hall wrote: I wonder if anybody has thought of putting the appropriate dimples on the surface of propellers? Seems like reducing drag there would increase RPM and reduce HP required. While reducing drag would be a goal, fixed propeller systems are designed to keep the tip velocity under mach 1. For constant speed props, the RPM is whatever you set it to, again under mach 1. True, but reducing Hp requirements would still be an advantage. There's an outfit that markets a perforated tape for propeller leading edges. The perfs act like dimples. They claim performance improvements with their stuff, of course. See http://www.dimpletape.com/ Dan |
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Dimples On Model Aircraft Could Greatly Extend Range
In rec.aviation.marketplace daestrom wrote:
wrote: In rec.aviation.marketplace Gregory Hall wrote: I wonder if anybody has thought of putting the appropriate dimples on the surface of propellers? Seems like reducing drag there would increase RPM and reduce HP required. While reducing drag would be a goal, fixed propeller systems are designed to keep the tip velocity under mach 1. For constant speed props, the RPM is whatever you set it to, again under mach 1. True, but reducing Hp requirements would still be an advantage. What part of "While reducing drag would be a goal," did you not understand? -- Jim Pennino Remove .spam.sux to reply. |
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