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Thread: another thought problem, NOT gun related

  1. #61
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    Quote Originally Posted by FBecigneul View Post
    splain to me the Americas Cup boats doing 29 knots downwind while the wind speed was recorded as 8.8 knots.
    Not hard to find info on this at all. Just a tiny bit of Google Fu effort and the answers are there to see. Seems that they can easily do it but not dead downwind, they must travel in a vector to the wind to do it. Plenty of sailboat website info with the physics explanations out there.

    I get that Al is sometimes annoying to some of you but he's got some ideas and if I look past any potential "annoying" I generally learn something. The wind prop car was very interesting. If you took the time to check it out, followed all the physics and engineering it's a pretty cool thing and the answers are also there to see.

    Oh, the prop car and sailboats seem to me to be two completely different beasts (other than they are both harnessing wind to move) so not sure they should be lumped together for arguing against one or the other.
    Last edited by WSnyder; 08-14-2021 at 05:22 PM.

  2. #62
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    http://www.sailingscuttlebutt.com/20...may-know-ac72/

    If you read down a bit you’ll see they go 1.8 times the speed of the wind and they even reference the silly balloon.
    Last edited by FBecigneul; 08-14-2021 at 07:20 PM.

  3. #63
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    Quote Originally Posted by FBecigneul View Post
    http://www.sailingscuttlebutt.com/20...may-know-ac72/

    If you read down a bit you’ll see they go 1.8 times the speed of the wind and they even reference the silly balloon.
    Ba'daBING!! FBecigneul for the SCORE.....And I just made the balloon up early on! So here we have an article which directly refutes some of the others. As the other articles state, this argument has been going on for decades which is exactly why it's an interesting thought problem.

    At This Point I Must Acknowledge That FBecigneul Is In The Lead

    Off to learn more here

  4. #64
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    Well, I was sorry to burst your balloon.
    NOT
    Last edited by FBecigneul; 08-15-2021 at 02:27 PM.

  5. #65
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    Quote Originally Posted by FBecigneul View Post
    Well, I was sort to burst your balloon.
    NOT
    I didn't say you were RIGHT silly LOL!

    I said you are in the lead with your groupies.....Good Luck

  6. #66
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    Quote Originally Posted by alinwa View Post
    Ba'daBING!! FBecigneul for the SCORE.....And I just made the balloon up early on! So here we have an article which directly refutes some of the others. As the other articles state, this argument has been going on for decades which is exactly why it's an interesting thought problem.

    At This Point I Must Acknowledge That FBecigneul Is In The Lead

    Off to learn more here
    Well Al mby not so fast

    "The boats go directly downwind 1.8 times faster than the wind. So if you let a balloon go as you went around the top mark you would easily beat it to the bottom mark."

    It certainly says that but are they literally traveling directly downwind aka dead downwind? Certainly the boat will beat the balloon to the "mark" but do they actually follow the same path to the same destination? The article doesn't back it up, it just states it. I have found many specifications, calculations and examples showing the different AC boats and the various wind vectors they travel around a course and the speeds they achieve. I find virtually nothing that shows these boats traveling directly in line with true wind. Is that because it is basically faster for these boats to travel at a vector to the true wind? It appears that this is true so maybe that is why I cannot find any numbers showing one of these boats going directly dead downwind? Maybe they are capable of going faster than the wind traveling dead downwind but I haven't found it yet. There are references to the boats slowing way down when aligned with true wind. I found an article where the 1.8 times wind speed calculation for an AC72 boat came from and it was for an early race where that boat averaged 1.8 times wind speed on the course downwind. That boat also averaged 1.6 times wind speed on the upwind portion of the coarse. Does anybody believe that these speeds were dead downwind or dead upwind?

    I'm sure you've seen it but if not someone also built a prop boat that proved out the same thing the prop car did. It was also faster than the wind traveling dead downwind.
    Last edited by WSnyder; 08-16-2021 at 01:57 PM.

  7. #67
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    Beat a dead horse.

  8. #68
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    And as I head for bed, I leave those who get all their knowledge from a book with this thought, Aeronautical engineers find the bumblebee can’t fly.
    How will you keep your balloon from dropping into the water or from rising into obscurity?
    Enough lunacy.

  9. #69
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    Quote Originally Posted by WSnyder View Post
    Well Al mby not so fast

    "The boats go directly downwind 1.8 times faster than the wind. So if you let a balloon go as you went around the top mark you would easily beat it to the bottom mark."

    It certainly says that but are they literally traveling directly downwind aka dead downwind? Certainly the boat will beat the balloon to the "mark" but do they actually follow the same path to the same destination? The article doesn't back it up, it just states it. I have found many specifications, calculations and examples showing the different AC boats and the various wind vectors they travel around a course and the speeds they achieve. I find virtually nothing that shows these boats traveling directly in line with true wind. Is that because it is basically faster for these boats to travel at a vector to the true wind? It appears that this is true so maybe that is why I cannot find any numbers showing one of these boats going directly dead downwind? Maybe they are capable of going faster than the wind traveling dead downwind but I haven't found it yet. There are references to the boats slowing way down when aligned with true wind. I found an article where the 1.8 times wind speed calculation for an AC72 boat came from and it was for an early race where that boat averaged 1.8 times wind speed on the course downwind. That boat also averaged 1.6 times wind speed on the upwind portion of the coarse. Does anybody believe that these speeds were dead downwind or dead upwind?

    I'm sure you've seen it but if not someone also built a prop boat that proved out the same thing the prop car did. It was also faster than the wind traveling dead downwind.



    So gratifying to see someone actually THINK about this!!

    Thank You

    I can't even understand these folks who get all fluffed up skirts instead of thinking all while assuming someone else is an idiot.

    It is my considered opinion that all the boat proponents are saying "yeahhh, we can BEAT that balloon hands down"..... to some imaginary "finish line" on the water. AT which point they'll also be two miles away! Mebbeso them folks who watch The Cup on the teevee figure there's a line-striper guy out there making lines. 'Minds me of Tom and Huckleberry on their balloon trip where Huck sez "We CAIN'T be over Kaintucky!! Kaintucky is RED on the map and I din't see no line!" to alla' you'se watching the Cup Race with all them coolio grid lines just picture that there balloon running hey-diddle-diddle right down the middle......

    THIS is exactly why I bring up "tacking" in earlier posts..... And I acknowledge that FBecigneul "_may_ be right....IF, and only if an iceboat can tack wikkid enough to chase that balloon down. I was a poor kid. Ain't never sailed, ain't never HAD no iceboat, ice FISHIN' was the extent of my adventurings and I hadda' dig a lot of worms to buy my first ice auger....


    but POOR don't mean DUMB


  10. #70
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    A short course on racing a sailboat. First, the shortest distant between two points is called the rhumb line. So, if you can hold your speed on the rhumb line it is the course to be taken. When jibing and going downwind the rhumb line is easy enough to hold. It is when heading into the wind that the newer AC and the twelve meter yacht have it over “lesser” boats. The 12 meters will hold speed at close to 10 degrees off the wind. The new AC boats with their wings instead of sail can hold speed at closer to 2 degrees off the wind and they can tack at a moments notice. We’re chasing a balloon downwind, well you are, and so we can hit top speed directly downwind even in a conventional blow boat. The main is trimmed to where is is exposed to the downwind element and feeds the excess positive pressure wind into the spinnaker. The negative pressure on the downwind side of the main is used and multiplies the wind for its own use. Even without a spinnaker and using a Genoa headsail the same principle exists. The main catches and uses wind and feeds the excess into the “Jenny”. I can’t make it any simpler than that. It’s simple multiplication that dooms your balloon.

  11. #71
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    Quote Originally Posted by FBecigneul View Post
    A short course on racing a sailboat. First, the shortest distant between two points is called the rhumb line. So, if you can hold your speed on the rhumb line it is the course to be taken. When jibing and going downwind the rhumb line is easy enough to hold. It is when heading into the wind that the newer AC and the twelve meter yacht have it over “lesser” boats. The 12 meters will hold speed at close to 10 degrees off the wind. The new AC boats with their wings instead of sail can hold speed at closer to 2 degrees off the wind and they can tack at a moments notice. We’re chasing a balloon downwind, well you are, and so we can hit top speed directly downwind even in a conventional blow boat. The main is trimmed to where is is exposed to the downwind element and feeds the excess positive pressure wind into the spinnaker. The negative pressure on the downwind side of the main is used and multiplies the wind for its own use. Even without a spinnaker and using a Genoa headsail the same principle exists. The main catches and uses wind and feeds the excess into the “Jenny”. I can’t make it any simpler than that. It’s simple multiplication that dooms your balloon.
    Nice explanation, thank you

  12. #72
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    To be clear, this DOES NOT mean that I believe in "wind multiplying sails" as described.


    TANSTAAFL


    But that I appreciate adult conversation using supported arguments.

  13. #73
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    Quote Originally Posted by alinwa View Post


    So gratifying to see someone actually THINK about this!!

    Thank You

    I can't even understand these folks who get all fluffed up skirts instead of thinking all while assuming someone else is an idiot.
    Furthering my education via reading and attempting to understand new things

    Going deeper into the AC boat rabbit hole.

    AC72's and Apparent Wind: https://www.youtube.com/watch?v=VAmUcRdqhjU From the video: AC boats are now so fast "in effect everything is upwind" "we are basically sailing upwind all of the time" due to apparent wind. Very cool concept (apparent wind) and a bit of a mind bender to start.

    From the Apparent Wind wiki:

    Implications on sailing speeds

    In sailboat racing, and especially in speed sailing, apparent wind is a vital factor, when determining the points of sail a sailboat can effectively travel in. A vessel traveling at increasing speed relative to the prevailing wind will encounter the wind driving the sail at a decreasing angle and increasing velocity. Eventually, the increased drag and diminished degree of efficiency of a sail at extremely low angles will cause a loss of accelerating force. This constitutes the main limitation to the speed of wind-driven vessels and vehicles.[citation needed]

    Windsurfers and certain types of boats are able to sail faster than the true wind. These include fast multihulls and some planing monohulls. Ice-sailors and land-sailors also usually fall into this category, because of their relatively low amount of drag or friction.[citation needed]

    In the foiling AC72 America's cup catamarans, the boats sail through the water at up to double the environmental wind strength. The effect of this is to radically change the apparent wind direction when sailing "downwind". In these boats the forward speed is so great that the apparent wind is always forward—at an angle that varies between 2 and 4 degrees to the wing sail. This means that AC72's are effectively tacking downwind, although at a greater angle than the normal 45-degree upwind angle, usually between 50 and 70 degrees.
    Last edited by WSnyder; 08-18-2021 at 06:14 PM.

  14. #74
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    Quote Originally Posted by WSnyder View Post
    Furthering my education via reading and attempting to understand new things
    .......
    In the foiling AC72 America's cup catamarans, the boats sail through the water at up to double the environmental wind strength. The effect of this is to radically change the apparent wind direction when sailing "downwind". In these boats the forward speed is so great that the apparent wind is always forward—at an angle that varies between 2 and 4 degrees to the wing sail. This means that AC72's are effectively tacking downwind, although at a greater angle than the normal 45-degree upwind angle, usually between 50 and 70 degrees.
    Me too. But in the end, the salient point is that there's nothing "new" under the sun, and physics.

    Fast boats have been running across the wind forever and from watching a modern cup even the angles haven't changed all that much.

    zig


    zag


    zig


    zag


    If ways had been found which allow one to hew closer to the wind, it seems we'd see them. All this talk about pressure differentials and multiplication and apparent VS actual and reminds me of other discussions where because the descriptors include these phrases it's then assumed they're new or relevant when in fact they're included only because there's no better way to describe the action...... In simple fact, when a leaf tumbles downwind it's because it has "positive pressure" on one side and "negative pressure" on the other but the talk of MULTIPLYING or somehow using the wind twice is where the physics falls apart, where the physics professor took the bet.


    Which he DID by the way..... and I'm sure even that rube of a professor had heard of boats going "faster than the wind"......

    To "multiply" the wind one must present a mechanism which does so. Re-direction does not multiply, re-direction of the wind is just a way to modify direction, like moving money through different accts or transactions to clean it. This action changes the direction and character of the money but it doesn't make money. Only a banana republic government can actually "make" money which of course then acts to drag down the system, just like in a boat.

    The prop machine I linked in the op actually throws a new motive action into the mix which makes it DDFTTW. It could not be made to work on water or on ice. It cannot be made "more efficient" nor "faster" through tacking......And the salient point is that the dangling windflags actually reverse direction! the machine actually IS going Directly Downwind Faster Than The Wind! It uses the wind to generate enough velocity to experience a headwind!

    And it shows a mechanism which produces that velocity. Not magic, not reuse nor multiplying of force, a mechanism which uses a previously unused motive mechanism and puts it to good use.

    The only "new" mechanisms presented in a Cup race are lowered drag due to foiling, lighter components due to availability of slightly higher strength composites, mainly cf and to a small extent computer modeling to test theoretical gains in a controlled environment. Actually SAILING and winning is still guts and seat-of-the-pants

  15. #75
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    Those who know sailing will tell you it’s not just a question of whose is the faster or fastest boat in the race but who crosses the finish line first. All that tacking and jibing serves more than one purpose. You tack or jibe to stay closer to the rhumb line but also to get the upper hand on the other boats. You may also cut across the other boat in the starboard quarter to get them to back off or change course because you have right of way. Boats change course because they think they can catch a wind or current change before the others. All the while remember it’s a gentleman’s sport.

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