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NOVAAN
Joined: 28 Sep 1994
Posts: 1551
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 Posted: Sat Mar 28, 2020 7:00 pm Post subject: |
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| In golf the ball goes farther when it warm and dry. Humid of foggy air makes a noticeable loss in distance per club |
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cgoudie1
Joined: 10 Apr 2006
Posts: 2599
Location: Killer Sturgeon Cove
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| Posted: Sun Mar 29, 2020 10:42 am Post subject: |
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Yep, let's think this through. H20 has a molecular weight of 18. O2 has
a molecular weight of 32, so for every Oxygen molecule that a water molecule displaces in the equation F=MA the force is reduced by ~ 44%.
H20 Molecules don't displace exactly the same number of oxygen molecules for a given volume of "air", but dry air is still heavier than wet air
(up to the point where it rains). Neither Newton nor I can change the physics for your beliefs. since there are other elements in air ,this considers all other air elements stay equal, and the temperature remains the same.
-Craig
| dllee wrote: | Once again, did you..engineer...think this thru?
Wet air gots h20, which is heavier than pure dry air.
At the same 10 knots, which moves your sail more?
Not talking theory here, just effect in the real world. |
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westender
Joined: 02 Aug 2007
Posts: 1288
Location: Portland / Gorge
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| Posted: Sun Mar 29, 2020 11:52 am Post subject: |
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| So a gallon of O2 weighs more than a gallon of H2O? Yes if it's LOx? How about 40mph of liquid smoke hitting the sail? Water is hard air isn't. |
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dllee
Joined: 03 Jul 2009
Posts: 5329
Location: East Bay
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| Posted: Sun Mar 29, 2020 12:08 pm Post subject: |
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You cannot convince a dedicated engineer that the sky is blue.
Mathematics is finite, and logic or observation has nothing to do with the results. |
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dvCali
Joined: 23 Aug 2007
Posts: 1314
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| Posted: Sun Mar 29, 2020 12:17 pm Post subject: |
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| westender wrote: | | So a gallon of O2 weighs more than a gallon of H2O? Yes if it's LOx? How about 40mph of liquid smoke hitting the sail? Water is hard air isn't. |
The key here is "density". If you, everything being equal, add water molecules to air, the density of the air decreases, and if the density decreases you have less punch in the wind.
The density decreases because the molecular weight of H20 (18 ) is less than the molecular weight of "air" (the air mixture average is 29). If you instead of air add CO2 (molecular weight 42) the density will increase. So yes! Go global warming!!!!!
So humid air has less punch. It IS physics, it is not an opinion. It is possible that people think that humid air has more punch because when it rains, or we have fog, the temperature goes down. And that increases density. Most likely it is just imagination ... |
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dllee
Joined: 03 Jul 2009
Posts: 5329
Location: East Bay
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| Posted: Sun Mar 29, 2020 12:40 pm Post subject: |
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Someone has never windsurfed in Santa Ana winds.
And that is why there exists....people persons...and there exists...engineers. |
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willysp
Joined: 11 Jun 2013
Posts: 32
Location: Seattle, WA
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| Posted: Sun Mar 29, 2020 1:54 pm Post subject: |
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| PeterSS wrote: | | I stumbled across some Pacific NW forum - and these guys all seem to like the Slingshot 76 and 84 Wings..But they seem to use bigger sails..I guess the wind seems very gusty or fickle there? I was going to use the 76 or 84 with my newer 4.6 and 6.0 Sails.. I have an old Retro 7.5 - but that requires the bigger mast, and is much heavier...at my 170lbs..will my Hover122 + 84 wing + 4.6 - 6.0 sails be sufficient to get pumped onto a plane in marginal winds? And yes the hot air is less dense - making the sail less efficient - like a plane taking off at a hot / high airport - requires a loner runway to take off.. The wind here in the summer is Weak, so hoping the bigger Foil under the water helps! Thanks for all the replies thus far. |
You are right, many of the foilers from the Pacific NW forum sail in Lake Washington, which is pretty gusty. I weigh 170 and I use a NX 8.2 for light winds with a formula board and i84 wing. Some are using phantoms 9 and 10 m sails with formula boards and starboard foils. You can see some foilers with big sails and others with smaller sails (everything else being equal). The difference will be the one with bigger sail will pump less and foil through lulls further.
At least that is my theory. And of course, at some point, bigger sail won't give you anything in return. |
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cgoudie1
Joined: 10 Apr 2006
Posts: 2599
Location: Killer Sturgeon Cove
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| Posted: Sun Mar 29, 2020 6:29 pm Post subject: |
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The sky is blue because oxygen resonates at that frequency. It's not magic, it's verified science, but belief, is a whole different arena, and philosophy is only partially my field. I recommend you simply look up what is more dense
water vapor in air or just air in any reference anywhere. Maybe it's a global scientific conspiracy.
Logic (which is a mathematical construct) and observation are what science
is all about.
Without Engineers we'd all be living in caves. But there'd definitely be less
time to ponder things (like physics or the natural world), and some might
prefer less thought. I'm okay with that. You feel free to believe whatever you like.
-Craig
| dllee wrote: | You cannot convince a dedicated engineer that the sky is blue.
Mathematics is finite, and logic or observation has nothing to do with the results. |
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dllee
Joined: 03 Jul 2009
Posts: 5329
Location: East Bay
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| Posted: Sun Mar 29, 2020 6:59 pm Post subject: |
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Yes, it's vital to search the internet for any upcoming questions we might have.
And if the definition says so...it"s a
god given truth, no doubt!
Shut your eyes, don't observe the world. |
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dllee
Joined: 03 Jul 2009
Posts: 5329
Location: East Bay
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| Posted: Sun Mar 29, 2020 7:02 pm Post subject: |
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| And yes, engineers are correct. There is only black or white. |
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