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#1
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push vs pull vis a vis rudders
This is (presumably) the 'bernouili' bit you
claim is often erroneous. jim, please don't make the mistake of saying that wings lift "because they are round on one side". you can go to any airshow on the planet and see aircraft fly upside down, the round side of the wing towards the ground bernouili had to do with venturi effects and "sounds" scientific to lay ears. a 1st semester aero eng student knows that bernouili does not explain lift. |
#2
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push vs pull vis a vis rudders
JAXAshby wrote in message ... jim, please don't make the mistake of saying that wings lift "because they are round on one side". you can go to any airshow on the planet and see aircraft fly upside down, the round side of the wing towards the ground Of course I won't make that mistake. What made you think I would? I repeat the relevant part of my post: "Any pressure change in a freely flowing fluid will be matched to a change in local fluid speed (barring supersonics, flow breakaway, and the trivial effects of surface viscosity) to conserve energy. This is (presumably) the 'bernouili' bit you claim is often erroneous." I said this in response to your statement that pressure change does not have to be related to a speed change in the circumstances we're talking about. This seemed to me to violate the laws of conservation of energy. It was you who called Bernoulli into it, bless his cotton socks. I quote from your post: "water speed does not have to be equal or greater or less. This can be a bit confusing because "bernoulli" is often -- though erroneously -- given as the reason sails/wings have "lift"." You were here responding to my assumption that if there's a (mean) pressure differential over the rudder, than there will be an allied mean change in fluid speed. Just like an airplane wing creating lift. The fluid speed on the low pressure side will be faster (caveats for supersonic flow etc - we are talking boats). I hope you don't disagree with that. JimB |
#3
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push vs pull vis a vis rudders
jim, airspeed over a wing does not have to faster than airspeed below a wing
for a wing to have lift. "bernoulli" sounds conventiently scientific to explain lift, but it ain't real. Of course I won't make that mistake. What made you think I would? I repeat the relevant part of my post: "Any pressure change in a freely flowing fluid will be matched to a change in local fluid speed (barring supersonics, flow breakaway, and the trivial effects of surface viscosity) to conserve energy. This is (presumably) the 'bernouili' bit you claim is often erroneous." I said this in response to your statement that pressure change does not have to be related to a speed change in the circumstances we're talking about. This seemed to me to violate the laws of conservation of energy. It was you who called Bernoulli into it, bless his cotton socks. I quote from your post: "water speed does not have to be equal or greater or less. This can be a bit confusing because "bernoulli" is often -- though erroneously -- given as the reason sails/wings have "lift"." You were here responding to my assumption that if there's a (mean) pressure differential over the rudder, than there will be an allied mean change in fluid speed. Just like an airplane wing creating lift. The fluid speed on the low pressure side will be faster (caveats for supersonic flow etc - we are talking boats). I hope you don't disagree with that. JimB |
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