I wonder if what appears to be more entrainment (water running up the foil - as opposed to the usual meaning of air being pulled down) on the u-shaped foils spoils their lift with crossflow. That aside, she looks happiest on the third set of foils.
Yes we have pondered what is going on with the water running up the foils, which is why I tried out fences on one set but the difference was insignificant. We also agree with you that the third set (standard kinked foils, thicker section) were performing the best
Hi Queenslander. Not so easy to move the foils fore and aft. That is why i was trying a forward raked set of foils but I need to improve their shape. Need to find the balance between maximum position as far forward as possible for stability when foiling Vs the ability to tack without having to do a 3-point turn
v foils are good because no matter how fast you can go they wont have enough lift to breach the surface as the lift area reduces with speed and the semi vertical nature of them is better for side force, however they drag more with opposing forces. Perhaps instead a hybrid with a small (to be determined flat surface (parallel to water surface), NOT large enough to lift the boat out of the water at any concevable speed then the balance of the lift generated by a Half V form , reducing the drag and lifting the boat up wind at the same time by making the half V component shaped to lift in the up wind direction? When a foil gets one chord length from the surface the drag doubles so hopefully you can make the smallish flat component deep enough to make a really fast setup. Then there is foil shape like H005 Eppler etc . even a flat bottomed foil is quite effective , just 0.5 deg of AOA up at the nose to compensate for it not being a full foil shape. I love the new video format with your explanations , its twice as good to view imo.
Thanks for your comments Wayne - I'll try to include more narrative in future, but video editing is not my strong point! I agree with you about the hybrid concept, and the U foils were in fact my first attempt at a hybrid, and I have already started to make a former for a set extremely similar to the shape you have suggested - a small flat section at the bottom of a smaller V component. But the geometry will be a difficult issue to sort out as the boat is sometimes foiling on about just 4cm of V foil. Does not take much to get it flying when its moving fast, and the danger is that ANY flat section could be too much! Lots to learn yet
perhaps altering your foil thickness is the key to that issue, then more foil in the water would be required to generate lift. There is obviously more drag when more is in the water but that seems like a worthy one to try.
oh and the vertical component of the hybrid could be a symmetrical (traditional ) keel which would limit the drag on one half of the foil so it wouldn't matter as much how deep the rest of the Half V was and would keep the small horizontal component deep enough that it was never one chord length from the surface
to lift a human we are running 800cm2 aprox 100kg at 15kmph , 1500cm2 will lift at 10kmph . with water 800 times as dense as air , these wings really pack a surprising punch eh? You can actually feel the increased drag under foot as to near the surface within one chord length too. To determine lift an arm rotating with your foil attached in a pool could work , with just a spring to push against the arm , calibrated by known loads , and an oring pushed up a rod to hold the maximum deflection measurement. A little like motorbike front forks where you find your max deflection by how far the oring was moved on the fork e.g. max travel. Once you have known baselines you can test relative to known results with out much fuss. Apart from horrible vibrations, bent bits of flat SS may be easier to rapidly trial, for human foils we used flat 4mm alloy sheet , it actually worked ok , but you probably only need 2mm or less in ss , thinner the better. Look out baking trays , haha.
Hello George. I use a standard mainsail for the light airs (attached to the last with just string every 20mm or so), but all the smaller rigs generally have a pocket luff mainsail. The pocket is up to 100mm deep and the mast just sits inside the pocket. The idea of the pocket is to give an improved aerodynamic shape behind the mast. It is a compromise on a solid wing. Rgds
Utterly lubberly !!! Thank you for posting all your vids Captain. I am inspired to get up out of my wheelchair and go sailing again ! xxxxx
I like the talking about the idea. It would be cool if you talk about the movements and analyse them
Point taken - will try to be more informative next time, but video editing is not my strong point!
Very cool, it looks fast.
I wonder if what appears to be more entrainment (water running up the foil - as opposed to the usual meaning of air being pulled down) on the u-shaped foils spoils their lift with crossflow. That aside, she looks happiest on the third set of foils.
Yes we have pondered what is going on with the water running up the foils, which is why I tried out fences on one set but the difference was insignificant. We also agree with you that the third set (standard kinked foils, thicker section) were performing the best
Awesome work 👌🏻👌🏻
Thanks Ken!
Love your work. I’m an Aclass sailor. Are you thinking about experimenting with the position of the dagger boards relative to the mast ?
Hi Queenslander. Not so easy to move the foils fore and aft. That is why i was trying a forward raked set of foils but I need to improve their shape. Need to find the balance between maximum position as far forward as possible for stability when foiling Vs the ability to tack without having to do a 3-point turn
v foils are good because no matter how fast you can go they wont have enough lift to breach the surface as the lift area reduces with speed and the semi vertical nature of them is better for side force, however they drag more with opposing forces. Perhaps instead a hybrid with a small (to be determined flat surface (parallel to water surface), NOT large enough to lift the boat out of the water at any concevable speed then the balance of the lift generated by a Half V form , reducing the drag and lifting the boat up wind at the same time by making the half V component shaped to lift in the up wind direction? When a foil gets one chord length from the surface the drag doubles so hopefully you can make the smallish flat component deep enough to make a really fast setup. Then there is foil shape like H005 Eppler etc . even a flat bottomed foil is quite effective , just 0.5 deg of AOA up at the nose to compensate for it not being a full foil shape. I love the new video format with your explanations , its twice as good to view imo.
Thanks for your comments Wayne - I'll try to include more narrative in future, but video editing is not my strong point! I agree with you about the hybrid concept, and the U foils were in fact my first attempt at a hybrid, and I have already started to make a former for a set extremely similar to the shape you have suggested - a small flat section at the bottom of a smaller V component. But the geometry will be a difficult issue to sort out as the boat is sometimes foiling on about just 4cm of V foil. Does not take much to get it flying when its moving fast, and the danger is that ANY flat section could be too much! Lots to learn yet
perhaps altering your foil thickness is the key to that issue, then more foil in the water would be required to generate lift. There is obviously more drag when more is in the water but that seems like a worthy one to try.
Currently we are making the top part of the V thicker than don at the tip. Need a tame tank-test facility and someone who can make 3D printed foils!
oh and the vertical component of the hybrid could be a symmetrical (traditional ) keel which would limit the drag on one half of the foil so it wouldn't matter as much how deep the rest of the Half V was and would keep the small horizontal component deep enough that it was never one chord length from the surface
to lift a human we are running 800cm2 aprox 100kg at 15kmph , 1500cm2 will lift at 10kmph . with water 800 times as dense as air , these wings really pack a surprising punch eh? You can actually feel the increased drag under foot as to near the surface within one chord length too. To determine lift an arm rotating with your foil attached in a pool could work , with just a spring to push against the arm , calibrated by known loads , and an oring pushed up a rod to hold the maximum deflection measurement. A little like motorbike front forks where you find your max deflection by how far the oring was moved on the fork e.g. max travel. Once you have known baselines you can test relative to known results with out much fuss. Apart from horrible vibrations, bent bits of flat SS may be easier to rapidly trial, for human foils we used flat 4mm alloy sheet , it actually worked ok , but you probably only need 2mm or less in ss , thinner the better. Look out baking trays , haha.
what ar
e the dimensions of this boat? mast high, boat width and length as well as weigh
thank you!
Hello Justin. This is a Mini40 class multihull. 122cm long, 122cm wide. The luff of the mainsail is 170cm and the weight is about 3kg when sailing
I do not know if you are monitoring this anymore but my question is what is the type of mainsail you are running?
Hello George. I use a standard mainsail for the light airs (attached to the last with just string every 20mm or so), but all the smaller rigs generally have a pocket luff mainsail. The pocket is up to 100mm deep and the mast just sits inside the pocket. The idea of the pocket is to give an improved aerodynamic shape behind the mast. It is a compromise on a solid wing. Rgds
@@PerthMini40man Thank you.
Good
Music unnecessary, too loud. Thank you for posting.
It hides the noise of the gas boats running on the lake. You can always turn the volume down
PerthMini40man I wanted to hear what you had to say.
interesting
v irritating moozak. YOYOY ??