Questions for Quad Riders ........
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questions for quad riders
Somewhat intresting thread. Is boost more a feeling than fact? If you compare the size of a sail to the boat it propels. Fins on a board are either
very efficient or HMMM? Dare I say.
Rovings? cause lift where?
Havent heard of a flow machine that can replicate the movement of water
on the face of a wave or the interaction of fin and board at all angles of attack. Would be intresting if someone did. Then all this would be data and proven with numbers and computers. Would shapers and fin makers be craftsmen or engineers.
very efficient or HMMM? Dare I say.
Rovings? cause lift where?
Havent heard of a flow machine that can replicate the movement of water
on the face of a wave or the interaction of fin and board at all angles of attack. Would be intresting if someone did. Then all this would be data and proven with numbers and computers. Would shapers and fin makers be craftsmen or engineers.
- Kauaikneelo
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ITS LIKE PUTTING YOUR FLAT HAND OUT THE WINDOW OF A CAR. THE AIR IS MOVING AT A CONSTANT RATE (SPEED OF CAR OR FACE OF A
WAVE) WHEN YOU MOVE YOUR HAND, YOU CAN FEEL WHEN PRESSURE WOULD CAUSE THRUST OR SPEED UP FEELING. SAME WITH SURFING
NOW PUT TWO FIN SHAPED HANDS SIDE BY SIDE AND SEE WHAT CAN HAPPEN - MAYBE A WHOLE NEW CONCEPT
WAVE) WHEN YOU MOVE YOUR HAND, YOU CAN FEEL WHEN PRESSURE WOULD CAUSE THRUST OR SPEED UP FEELING. SAME WITH SURFING
NOW PUT TWO FIN SHAPED HANDS SIDE BY SIDE AND SEE WHAT CAN HAPPEN - MAYBE A WHOLE NEW CONCEPT
Aloha from the Kingdom of Atooi
Hannya
w regards to the "lift"
this is part of the conclusion:
KAUAIKNEELO
getting interesting
cheers
w regards to the "lift"
this is part of the conclusion:
my italicsThe work has shown that the presence of fillets can decrease the overall drag of the fin, even though the viscous drag is increased due to the added surface area, the smoothing of the sharp edges between the fin and the board causes pressure distributions to be spread over a larger area.
However, this decrease in drag is restricted to double-foiled fins such as the middle fin, and there is very little noticeable difference when fillets are added to the side fins, possible due to the fact that the whole inside edge is flat, so the effect on drag of filleting the base is less pronounced than for a double foiled fin (middle fin).
However, even for the middle fin the total drag decrease is so marginal that it is unlikely to be noticed in practise, even by expert surfers, but the fillets do create a substantial increase in vertical lift, which may partially explain the more buoyant, lighter feel to glassed-on fins, and
their preference in use by surfers on the professional circuit.
KAUAIKNEELO
getting interesting
cheers
questions for quad riders
Thanks Zorro
Ive never heard the fillets called roving I didnt know what component was being refered to. Most modern fighter jets use blended wing technology not only for stealth but increased lift, less drag as stated. just read on another site one reason pros use glass on fins while in the islands is for strength. I thought the primary purpose of fillets were for strength due to increased surface mating area without digging into the foam. I believe that was one method of fin installation way back.
I maybe wrong but what some are refering to and Im not sure the spellings right is bernoulli's principle or law how a wing creates lift. The air going over the top of the wing slows down due to the curve on the upper surface while the bottom surface being straight the air continues at normal speed. Creating a high pressure area on the bottom of the wing and low pressure area on the top of the wing making lift. Thrust is a different story i think now i have to look it up
If hydrodynamics and aerodynamics are the same then the fin thats foiled on one side will try to turn to the low pressure foiled side of the fin.
I liked that Idea when I got my first twinfin fish around 1973.
We'll figure it out some how. Swell due tomorrow?
Ive never heard the fillets called roving I didnt know what component was being refered to. Most modern fighter jets use blended wing technology not only for stealth but increased lift, less drag as stated. just read on another site one reason pros use glass on fins while in the islands is for strength. I thought the primary purpose of fillets were for strength due to increased surface mating area without digging into the foam. I believe that was one method of fin installation way back.
I maybe wrong but what some are refering to and Im not sure the spellings right is bernoulli's principle or law how a wing creates lift. The air going over the top of the wing slows down due to the curve on the upper surface while the bottom surface being straight the air continues at normal speed. Creating a high pressure area on the bottom of the wing and low pressure area on the top of the wing making lift. Thrust is a different story i think now i have to look it up
If hydrodynamics and aerodynamics are the same then the fin thats foiled on one side will try to turn to the low pressure foiled side of the fin.
I liked that Idea when I got my first twinfin fish around 1973.
We'll figure it out some how. Swell due tomorrow?
- Smokin Rock
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Hy Hannya
calling on bernoulli (or a venturi) to explain something is frought with danger. Many a bloody battle has been fought and lost/not lost on the subject, here and on swaylocks
but it does exist in real life
in a big west wind the lee side windows of my house are sucked outwards
or Mr Bernouilli's wig:
album_showpage.php?pic_id=1389
mind you the wind could be getting under the wig
same way as in an toed in fin, the water could be hitting outside edge causing a turning moment
or in a wing angled slightly up, the air could be hitting the underneath, giving lift
and in a bonzer, there could be just more water sent off the tail area of the board, giving more thrust
or the rocker of a board, whether the board is foiled or not, will cause a turning moment because of the water hitting the rail nose lift from the bottom (Stand in waist deep water, put the board on edge and push it forward - presto, the board turns )
Ler
I thought I was obtuse. I haven't ridden a quad since tuesday.
calling on bernoulli (or a venturi) to explain something is frought with danger. Many a bloody battle has been fought and lost/not lost on the subject, here and on swaylocks
but it does exist in real life
in a big west wind the lee side windows of my house are sucked outwards
or Mr Bernouilli's wig:
album_showpage.php?pic_id=1389
mind you the wind could be getting under the wig
same way as in an toed in fin, the water could be hitting outside edge causing a turning moment
or in a wing angled slightly up, the air could be hitting the underneath, giving lift
and in a bonzer, there could be just more water sent off the tail area of the board, giving more thrust
or the rocker of a board, whether the board is foiled or not, will cause a turning moment because of the water hitting the rail nose lift from the bottom (Stand in waist deep water, put the board on edge and push it forward - presto, the board turns )
Ler
I thought I was obtuse. I haven't ridden a quad since tuesday.
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- Legend (Contribution King!)
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"From Q and A with the New York Times"
Q. How can a plane fly upside down? Why doesn't the shape of the wings force the plane downward?
unless of course more water was striking the rear of the outside edge the fin
or that the placement of the fin near the rail created a turning force that greatly outweighed the force generated by the toe in.
anyone familar with "ground effect" (pelicans flying over the ocean surface?)
Q. How can a plane fly upside down? Why doesn't the shape of the wings force the plane downward?
Oddly enough, with the AOA on a toed in fin you might expect the board to turn in the other direction to what it does ie towards the stringer (or would you? )
A. The wing shape is designed to create relatively lower pressure above the wing as it meets the oncoming airstream, according to the Fort Worth Division of the General Dynamics Corporation in Fort Worth, Tex., and the key word is relatively.
If you hold a piece of paper at the bottom edge, let it flop away from you and blow hard across it, the paper rises, company spokesmen explained, because you have created lower pressure above the curved surface it forms. The same thing would work upside down, because the pressure differential would still exist. The question is how to get it to work for you rather than against you.
According to Joe Bill Dryden, senior experimental test pilot for General Dynamics, many factors affect flying ability, but one key to flying upside down is attaining the right angle of attack, one of the major contributors to lift.
Loosely speaking, he said, the angle of attack is the angle at which the wind is coming at the plane. If you draw a line from the leading edge to the trailing edge of the wing's airfoil, or cross section, it must always form a small angle toward the direction at which the wind approaches the plane.
"Upside down, if you do nothing, the airplane wants to fall to the ground," he said. "But if you push the plane so it is at the same angle as right side up, you develop enough lift so the plane flies upside down."
The pilot feels his way to that angle. When sufficient lift is achieved, Mr. Dryden said, "the airplane doesn't know if it is flying upside down or not."
The Pitt Special, a biplane made especially for acrobatics, has a symmetrical airfoil that presents exactly the same profile to the oncoming airstream both top and bottom, to make flying upside down easier, Mr. Dryden said. The plane also has oil and fuel systems designed for the gravitational condition of flying upside down, a limiting factor for other planes. A jumbo passenger jet, for example, could perhaps fly upside down only 15 or 20 seconds before its internal systems would be disrupted.
unless of course more water was striking the rear of the outside edge the fin
or that the placement of the fin near the rail created a turning force that greatly outweighed the force generated by the toe in.
anyone familar with "ground effect" (pelicans flying over the ocean surface?)
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I have 3 boards that have no toe - in and they are quadfish.They ride like the keel fish but hold better and you don't have to setup your turns nearly as much.....very fast boards also. The fins are smaller and narrow base and are dead straight with no cant at all. I am taking them to G land with me soon...