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#1
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Here you go... wing keels
http://www.vacantisw.com/foildesign.htm
actual intelligent discussion of keel design, the various factors influencing how keels work, and a very clear explanation of the Reynolds number. I suggest that certain people read it very very studiously to find the answer as to whether wing keels lift the boat. Yes or no? DSK |
#2
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Here you go... wing keels
DSK wrote: http://www.vacantisw.com/foildesign.htm actual intelligent discussion of keel design, the various factors influencing how keels work, and a very clear explanation of the Reynolds number. I suggest that certain people read it very very studiously to find the answer as to whether wing keels lift the boat. Yes or no? DSK Someone think at 8 kt a lead wing is going to provide lift? Would both side of the wing provide equal lift on a heel? Wouldent that cause the boat to heel more? I know nothing about winged keels. I just thought it was a better way to put weight down low and keeping a shallow draft. Sorta like thoses boats that have two keels. Joe |
#3
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Here you go... wing keels
Doug,
Your article by Vacanti talks volumes of LIFT. You should be able to answer your own question. Does all the LIFT describe in the article LIFT the boat? Of course not. Does it help increase Speed? Maybe. Maybe Not. Doug, I've spent a life time in the Oil refinery measuring liquid flows. Orifice Plates designed using Reynold numbers You and Vacanti have not made mention of the large "Gray Area" of the Reynolds # between laminar flow and turbulent flow. It is right in this area that our keels live. You also ignored the "Newtonian" factor and just talked Reynolds and Bernoulli. Let us not forget that each created lifting force has a equal and opposite force. It is important to identify these forces. A wind tunnel isn't necessary for the speeds we are dealing with. A level of water, in the bath tub and shaker of talcum powder on the surface of the water will show these actions and how they are shedded. A "Wing Keel" works but in needs motion to make it work. Motion thru the water. In a "Drifter" a straight fin will outperform it but as motion increase it will increase its effect and yes it will be more effective. I think I've said enough for an Old Beached Sailor. I'll back out of this discussion http://community.webtv.net/tassail/ThomPage |
#4
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Here you go... wing keels
Thom Stewart wrote:
Doug, Your article by Vacanti talks volumes of LIFT. You should be able to answer your own question. Does all the LIFT describe in the article LIFT the boat? That's why I used the word "up" Doug, I've spent a life time in the Oil refinery measuring liquid flows. Orifice Plates designed using Reynold numbers You and Vacanti have not made mention of the large "Gray Area" of the Reynolds # between laminar flow and turbulent flow. Actually it does. Almost all foils will have at least a small section of laminar flow, some rather odd foils are designed to work almost entirely in laminar flow... even odder ones with none. Ever seen a super-cavitating prop? You also ignored the "Newtonian" factor and just talked Reynolds and Bernoulli. Actually, I didn't. I didn't write that web page ... Let us not forget that each created lifting force has a equal and opposite force. It is important to identify these forces. Forces are not always equal & opposite, though. If they were, nothing could ever move. For example, the force exerted by the wind on the sails heels the boat & drives it forward. The boat goes faster *until* it creates enough drag to equal the drive. At that point, forces are equal. Have you worked on control systems that cycled or hunted? An example of how difficult it can be to get forces to equalize smoothly? Fresh Breezes- Doug King |
#5
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Here you go... wing keels
Yes Doug,
--------------------------------------------- Have you worked on control systems that cycled or hunted? An example of how difficult it can be to get forces to equalize smoothly? ------------------------------------------------- That is why PB, Reset, & Dev have been added to those systems http://community.webtv.net/tassail/ThomPage |
#6
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Here you go... wing keels
Thom Stewart wrote:
Yes Doug, --------------------------------------------- Have you worked on control systems that cycled or hunted? An example of how difficult it can be to get forces to equalize smoothly? ------------------------------------------------- That is why PB, Reset, & Dev have been added to those systems Proportional Band also known as Gain Reset rate can be a very effective way of stopping the system from hunting, but can also be over done so that the system is either too fast or too slow... ask Bobsprit which, after all I've been busted for talking gibberish. Get him to explain what Dev stands for and what it does too. I'd like to read that myself. Regards Doug King |
#7
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Here you go... wing keels;`OT Control
Doug,
I think you have Reset & Deviative mixed up but maybe not. Proportional Band limits the amount of response to the original Off Set or a proportional amount. PB will keep cycling down but has a tendancy to "Droop" Not return to its original value. RESET will make additional correction to return to original point but with a new correction force. Deviative (Like Pepper) needs to be added carefully. It is a ampilifier of the original off set. It forces the PB to a greater correction force. Doug, that is a rather quick and dirty explaination. If you want more contact me off line http://community.webtv.net/tassail/ThomPage |
#8
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Here you go... wing keels;`OT Control
"Thom Stewart" wrote in message
... Doug, I think you have Reset & Deviative mixed up but maybe not. Proportional Band limits the amount of response to the original Off Set or a proportional amount. PB will keep cycling down but has a tendancy to "Droop" Not return to its original value. RESET will make additional correction to return to original point but with a new correction force. Deviative (Like Pepper) needs to be added carefully. It is a ampilifier of the original off set. It forces the PB to a greater correction force. Doug, that is a rather quick and dirty explaination. If you want more contact me off line Thom, you just reminded me of an old Croydon boy I worked at LBH with. He was a carpenter but when things were slow in his area, he'd be my helper with the HVAC controls. We had lots of pneumatics. We later converted the controls to digital but left the pneumatic actuators in place (to save some cash). When I left LBH and went to Rohm and Haas, he went to a local school district for a job. He reported back to me that they wanted to know if he knew anything about troubleshooting and calibrating pneumatic controls. He said, "I can usually play with the settings enough to get them working." That was not the answer they wanted to hear! Needless to say, he didn't get the job. Scout |
#9
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Here you go... wing keels;`OT Control
Scout wrote:
Thom, you just reminded me of an old Croydon boy I worked at LBH with. He was a carpenter but when things were slow in his area, he'd be my helper with the HVAC controls. Cool... he already had a hammer .... We had lots of pneumatics. We later converted the controls to digital but left the pneumatic actuators in place (to save some cash). Everybody did that. Saved cash plus the first & second generation digitally controlled linear actuators sucked. The ones they make now are pretty good but don't trust their power ratings or their power consumption specs. The funny thing is that a lot of people justified the switch in order to save on LP air system & compressor maintenance. ... When I left LBH and went to Rohm and Haas, he went to a local school district for a job. He reported back to me that they wanted to know if he knew anything about troubleshooting and calibrating pneumatic controls. He said, "I can usually play with the settings enough to get them working." That was not the answer they wanted to hear! Needless to say, he didn't get the job. That's where better test-taking skills would have made the difference. If he'd tossed around a lot of words like "setpoint" and "proportional band" he'd have been all set. Regards Doug King |
#10
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Here you go... wing keels;`OT Control
"DSK" wrote in message
.. . Scout wrote: Thom, you just reminded me of an old Croydon boy I worked at LBH with. He was a carpenter but when things were slow in his area, he'd be my helper with the HVAC controls. Cool... he already had a hammer .... We had lots of pneumatics. We later converted the controls to digital but left the pneumatic actuators in place (to save some cash). Everybody did that. Saved cash plus the first & second generation digitally controlled linear actuators sucked. The ones they make now are pretty good but don't trust their power ratings or their power consumption specs. The funny thing is that a lot of people justified the switch in order to save on LP air system & compressor maintenance. ... When I left LBH and went to Rohm and Haas, he went to a local school district for a job. He reported back to me that they wanted to know if he knew anything about troubleshooting and calibrating pneumatic controls. He said, "I can usually play with the settings enough to get them working." That was not the answer they wanted to hear! Needless to say, he didn't get the job. That's where better test-taking skills would have made the difference. If he'd tossed around a lot of words like "setpoint" and "proportional band" he'd have been all set. True! He probably shouldn't have mentioned kerf when discussing cut-in and cut-out setpoints. Scout |
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