How about this for winging foils and pumping foils - a simple, relatively inexpensive modification to stabilizers to improve performance - free to a good home.
Foils develop more lift with more speed. So if you set up your foil for easy planing (high lift) then it will be draggy at speed and may be prone to broaching. What about varying the angle of attack of the stabilizer while on the move? Further what if it does that automatically?
If the stab can pivot on an axle forward of the centre of lift it can be set with its default position nose down for high lift. What keeps it there is a pad of elastomer at the front. As it goes faster the lift increases rotating it flatter. As it slows the elasomer pushes it back down. When pumping it oscillates from high lift when pushing down, to low lift at the top of the cycle and that's not a bad thing.
Waddaya reckon.
The stab. is an upside down wing, so if the front edge starts out tilted downward for more lift at low speeds, as the speed increases the stab. will want to rotate even more downward. You would need something pushing the front of the stab. upward to reduce the lift as the speed increases, or something on the trailing edge pushing it downward as the speed increases. And both of those would create drag and disrupt the laminar flow of water over the stab. Wasn't Taaroa foils working on an electronic version of an adjustable stab.?
A single 1/8" wide strand of seaweed wrapped around the center front of my stab. (caught between stab. and fuselage in gap created by front stab. shim) disrupted the flow of water enough to affect my ability to get up on the foil!
A fuselage which puts the wing further forward will allow less stab angle/size and for trim to remain constant across a wider speed range. This is why race (but not so much slalom) foils are setup this way.
Downside is slightly worse stall characteristics.
Select to expand quoteSandman1221 said..
The stab. is an upside down wing, so if the front edge starts out tilted downward for more lift at low speeds, as the speed increases the stab. will want to rotate even more downward. You would need something pushing the front of the stab. upward to reduce the lift as the speed increases, or something on the trailing edge pushing it downward as the speed increases. And both of those would create drag and disrupt the laminar flow of water over the stab. Wasn't Taaroa foils working on an electronic version of an adjustable stab.?
A single 1/8" wide strand of seaweed wrapped around the center front of my stab. (caught between stab. and fuselage in gap created by front stab. shim) disrupted the flow of water enough to affect my ability to get up on the foil!
Not if you mount the stab on the top of the fuselage.
Select to expand quotemr love said..Sandman1221 said..
The stab. is an upside down wing, so if the front edge starts out tilted downward for more lift at low speeds, as the speed increases the stab. will want to rotate even more downward. You would need something pushing the front of the stab. upward to reduce the lift as the speed increases, or something on the trailing edge pushing it downward as the speed increases. And both of those would create drag and disrupt the laminar flow of water over the stab. Wasn't Taaroa foils working on an electronic version of an adjustable stab.?
A single 1/8" wide strand of seaweed wrapped around the center front of my stab. (caught between stab. and fuselage in gap created by front stab. shim) disrupted the flow of water enough to affect my ability to get up on the foil!
Not if you mount the stab on the top of the fuselage.
"Not if you mount the stab on the top of the fuselage."
mr love, care to describe in a little more detail what you mean? since when mounting the stab. either on the top, or bottom, of the fuselage the forces on it will be the same, and it functions in the same way. In order to force the wing upward in light winds the leading edge of the stab. has to be tilted downward, and as the speed increases the water pressure on the leading edge of the stab. will increase trying to force in downward even more which in turn forces the front wing upward even more, increasing the risk of breaching. So my original post is correct, you would need something under the leading edge of the stab. to force it upward. Remember the stab. is an inverted wing. It is not like the tail wing of a plane.
Select to expand quoteSandman1221 said..
The stab. is an upside down wing, so if the front edge starts out tilted downward for more lift at low speeds, as the speed increases the stab. will want to rotate even more downward. You would need something pushing the front of the stab. upward to reduce the lift as the speed increases, or something on the trailing edge pushing it downward as the speed increases. And both of those would create drag and disrupt the laminar flow of water over the stab. Wasn't Taaroa foils working on an electronic version of an adjustable stab.?
A single 1/8" wide strand of seaweed wrapped around the center front of my stab. (caught between stab. and fuselage in gap created by front stab. shim) disrupted the flow of water enough to affect my ability to get up on the foil!
No the pivot is in front of the centre of lift. Say the stab has a chord of 90. Then the centre of lift will be about 30 from the leading edge if it's a more or less conventional wing profile. If the pivot is front of that it will pull down with speed. I think it could be done with a minimal effect on drag.
I'm talking of a small mechanical modification to improve the range, not complicated electronics.
Yes a weed trap could be a nuisance.
Select to expand quoteGasHazard said..Sandman1221 said..
The stab. is an upside down wing, so if the front edge starts out tilted downward for more lift at low speeds, as the speed increases the stab. will want to rotate even more downward. You would need something pushing the front of the stab. upward to reduce the lift as the speed increases, or something on the trailing edge pushing it downward as the speed increases. And both of those would create drag and disrupt the laminar flow of water over the stab. Wasn't Taaroa foils working on an electronic version of an adjustable stab.?
A single 1/8" wide strand of seaweed wrapped around the center front of my stab. (caught between stab. and fuselage in gap created by front stab. shim) disrupted the flow of water enough to affect my ability to get up on the foil!
No the pivot is in front of the centre of lift. Say the stab has a chord of 90. Then the centre of lift will be about 30 from the leading edge if it's a more or less conventional wing profile. If the pivot is front of that it will pull down with speed. I think it could be done with a minimal effect on drag.
I'm talking of a small mechanical modification to improve the range, not complicated electronics.
Yes a weed trap could be a nuisance.
Well that is what Taaroa foils was working on, but not any more, only conventional foils on their website now.
But a diagram of what you are thinking of would be helpful, a picture is worth a 100 words!
Select to expand quoteSandman1221 said..mr love said..Sandman1221 said..
The stab. is an upside down wing, so if the front edge starts out tilted downward for more lift at low speeds, as the speed increases the stab. will want to rotate even more downward. You would need something pushing the front of the stab. upward to reduce the lift as the speed increases, or something on the trailing edge pushing it downward as the speed increases. And both of those would create drag and disrupt the laminar flow of water over the stab. Wasn't Taaroa foils working on an electronic version of an adjustable stab.?
A single 1/8" wide strand of seaweed wrapped around the center front of my stab. (caught between stab. and fuselage in gap created by front stab. shim) disrupted the flow of water enough to affect my ability to get up on the foil!
Not if you mount the stab on the top of the fuselage.
"Not if you mount the stab on the top of the fuselage."
mr love, care to describe in a little more detail what you mean? since when mounting the stab. either on the top, or bottom, of the fuselage the forces on it will be the same, and it functions in the same way. In order to force the wing upward in light winds the leading edge of the stab. has to be tilted downward, and as the speed increases the water pressure on the leading edge of the stab. will increase trying to force in downward even more which in turn forces the front wing upward even more, increasing the risk of breaching. So my original post is correct, you would need something under the leading edge of the stab. to force it upward. Remember the stab. is an inverted wing. It is not like the tail wing of a plane.
If the stab sits on top of the fuselage and you want to decrease lift the TE of the stab can tilt down to flatten off the AOA. So if it pivoted at the LE then the water pressure would want to push the TE down if it were working against some sort of spring. As the water pressure decreased at slower speeds it would get pushed up again and increase lift. All great in theory but to calibrate some sort of spring loaded hinging device would be a nightmare.
Select to expand quotemr love said..Sandman1221 said..mr love said..Sandman1221 said..
The stab. is an upside down wing, so if the front edge starts out tilted downward for more lift at low speeds, as the speed increases the stab. will want to rotate even more downward. You would need something pushing the front of the stab. upward to reduce the lift as the speed increases, or something on the trailing edge pushing it downward as the speed increases. And both of those would create drag and disrupt the laminar flow of water over the stab. Wasn't Taaroa foils working on an electronic version of an adjustable stab.?
A single 1/8" wide strand of seaweed wrapped around the center front of my stab. (caught between stab. and fuselage in gap created by front stab. shim) disrupted the flow of water enough to affect my ability to get up on the foil!
Not if you mount the stab on the top of the fuselage.
"Not if you mount the stab on the top of the fuselage."
mr love, care to describe in a little more detail what you mean? since when mounting the stab. either on the top, or bottom, of the fuselage the forces on it will be the same, and it functions in the same way. In order to force the wing upward in light winds the leading edge of the stab. has to be tilted downward, and as the speed increases the water pressure on the leading edge of the stab. will increase trying to force in downward even more which in turn forces the front wing upward even more, increasing the risk of breaching. So my original post is correct, you would need something under the leading edge of the stab. to force it upward. Remember the stab. is an inverted wing. It is not like the tail wing of a plane.
If the stab sits on top of the fuselage and you want to decrease lift the TE of the stab can tilt down to flatten off the AOA. So if it pivoted at the LE then the water pressure would want to push the TE down if it were working against some sort of spring. As the water pressure decreased at slower speeds it would get pushed up again and increase lift. All great in theory but to calibrate some sort of spring loaded hinging device would be a nightmare.
Without a diagram, it really is difficult to talk about it. But all the same, I can see what you mean, I think! Taaroa had to be doing something similar with an electromechanical device.
But I think the problem with using a purely mechanical device like a spring is that let's say you are heading hard upwind and then suddenly turn down wind, the pressure on the stab. tail would decrease instantly causing the stab. leading edge to rotate down increasing lift and causing a breach. Same thing when doing a foiling gybe. Would be very difficult to use a foil that does that, like riding a bull or roller coaster ride.
Select to expand quoteSandman1221 said..mr love said..Sandman1221 said..mr love said..Sandman1221 said..
The stab. is an upside down wing, so if the front edge starts out tilted downward for more lift at low speeds, as the speed increases the stab. will want to rotate even more downward. You would need something pushing the front of the stab. upward to reduce the lift as the speed increases, or something on the trailing edge pushing it downward as the speed increases. And both of those would create drag and disrupt the laminar flow of water over the stab. Wasn't Taaroa foils working on an electronic version of an adjustable stab.?
A single 1/8" wide strand of seaweed wrapped around the center front of my stab. (caught between stab. and fuselage in gap created by front stab. shim) disrupted the flow of water enough to affect my ability to get up on the foil!
Not if you mount the stab on the top of the fuselage.
"Not if you mount the stab on the top of the fuselage."
mr love, care to describe in a little more detail what you mean? since when mounting the stab. either on the top, or bottom, of the fuselage the forces on it will be the same, and it functions in the same way. In order to force the wing upward in light winds the leading edge of the stab. has to be tilted downward, and as the speed increases the water pressure on the leading edge of the stab. will increase trying to force in downward even more which in turn forces the front wing upward even more, increasing the risk of breaching. So my original post is correct, you would need something under the leading edge of the stab. to force it upward. Remember the stab. is an inverted wing. It is not like the tail wing of a plane.
If the stab sits on top of the fuselage and you want to decrease lift the TE of the stab can tilt down to flatten off the AOA. So if it pivoted at the LE then the water pressure would want to push the TE down if it were working against some sort of spring. As the water pressure decreased at slower speeds it would get pushed up again and increase lift. All great in theory but to calibrate some sort of spring loaded hinging device would be a nightmare.
Without a diagram, it really is difficult to talk about it. But all the same, I can see what you mean, I think! Taaroa had to be doing something similar with an electromechanical device.
But I think the problem with using a purely mechanical device like a spring is that let's say you are heading hard upwind and then suddenly turn down wind, the pressure on the stab. tail would decrease instantly causing the stab. leading edge to rotate down increasing lift and causing a breach. Same thing when doing a foiling gybe. Would be very difficult to use a foil that does that, like riding a bull or roller coaster ride.
Yep, agree..calibration would be so difficult........maybe something for the speed records as they are sailing a pretty constant angle
Who remembers the fins from a few years back (maybe 15 ) that had a hing in the middle so as you pushed hard upwind it would fold in and creat more lift and as you went of wind the pressure would decrease and it would flaten of
Maybe this could work like ailerons ?
This reminds me of when Corvette experimented with electromagnetic wheel shocks, they worked great on a speed bump going 70 mph, just a wump sound, but in more difficult conditions they got overloaded. Probably why Taaroa gave up on their adjustable foil.
Select to expand quoteSandman1221 said..
This reminds me of when Corvette experimented with electromagnetic wheel shocks, they worked great on a speed bump going 70 mph, just a wump sound, but in more difficult conditions they got overloaded. Probably why Taaroa gave up on their adjustable foil.
GM and Ford are still using it (MagneRide).
Select to expand quoteWillyWind said..Sandman1221 said..
This reminds me of when Corvette experimented with electromagnetic wheel shocks, they worked great on a speed bump going 70 mph, just a wump sound, but in more difficult conditions they got overloaded. Probably why Taaroa gave up on their adjustable foil.
GM and Ford are still using it (MagneRide).
I think MagneRide is different it uses a fluid just like regular shocks, but that fluid flow is controlled magnetically because it contains magnetic particles, so there are no moving parts. What Corvette was testing was an electromechanical shock absorber that literally lifted the wheel up over a speed bump and then lowered the wheel back down so that there was no impact between wheel and speed bump to give a perfectly smooth ride.
