Please do this with all your video's. The French are so on point with their design's but all interviews and video's are for many interested but in a language not spoken by many.
I think the second "spar" is there just to make it possible to patent the rig, which would otherwise infringe on prior art (rig designs.) It's a drawback because of the weight and windage.
So after the covering is pulled down, the mast still sticks up, doesn't the round section mast cause more drag than when it is streamlined by the covering? So what is the point of pulling the covering down?
Yes, it's true that an unfaired cylindrical mast (bare pole) will have more drag than a wing shaped mast/wingsail, due to the streamlining provided by the airfoil. Conventional thinking is that there is a risk of the wind catching the sails at an unexpected angle and damaging the boat. With wings that can't move freely, this is a risk. In this case, being able to reef (lower) the sail/wing is desirable, since the mast will have less force than the wing (in the wrong position). For wings that can move freely, if they are uncontrolled, in principle they will orient themselves to the lowest energy position, i.e., point into the wind, and generate minimal (drag and lift) forces. But there is always a risk of the wind shifting faster than the wing can respond, resulting in unwanted forces. That's why being able to drop the sail can be desirable. In that sense, it's a safer and more conservative solution than rigid wingsails.
@@LoanwordEggcorn Yes, most of what you say is true. In most wingsail boats in the past the wing has been allowed to pivot freely controlled by a tail surface behind. In this configuration there is a slight lag between any change in wind direction and the response of the wing. Although this is noticeable it never becomes a problem. I have extensively tested this in both fullsize and model versions. See website www.sailwings.net The Walker series of wingsail boats, where the wing is left up permanently and allowed to weatherock did, they say, tug at their moorings a bit. But presumably it was not a serious problem.
@@peterworsley4699 Thanks much Peter! I liked your earlier wingsail model video with the cam based wing control very much! Didn't realize it was you here. I hope your query gets a response from the video poster. Boat design in general is highly conservative, and mostly for good reason since lives are at risk, which is probably why some designers seek to have a reefable wingsail. I agree with you that in principle the ability to bring down a wingsail quickly is not needed. I suppose the hypothetical problem is a strong wind shift that happens faster than a freely turning wingsail can respond, potentially resulting in unexpected forces in an unwanted direction. For wingsails that are under some kind of rigid/active control, the ability to quickly reef or drop sails may make more sense. I have seen first hand the rigid wingsails of SailGP boats (related to the previous generation America's cup boats, AC50) feather to wind with no problem in order to moor on water, at least in a relatively protected harbor. Question for you: have you considered using a larger aft wing section in your designs, for more of a fully compound wing? I assume that more lift comes from the camber between the wings, since the airfoils are symmetrical.
@@LoanwordEggcorn I think you mean there might be a slot effect between the two surfaces. Short answer - I don't know. There is such a lot of research to do. I have various ideas, but am not always able to test them. Thanks for your appreciation of the cam wing control.
@@peterworsley4699 Yes, slot effect, compound wing, etc., like airplane flaps, is how the previous America's Cup wings worked, for one example. The slot energizes airflow over the back (leeward) side of the (rear) wing (flap) creating more lift and allowing the flow to remain attached at steeper camber/higher overall angle of attack. This creates more lift than a symmetrical airfoil can achieve alone. Downside of slot is more drag, which is why most airplanes only deploy flaps when needed, but they also have highly efficient *asymmetrical* airfoils for cruising speed lift. Boats and aerobatic planes have symmetrical airfoils, since they need to "fly" equally well "upside down". Wingsails gain lift from the camber between the wings of a compound wing. Slot effect is also how a foresail energizes airflow around the back side a mainsail, etc., when going upwind. And vice versa reaching downwind. So any boat that has more then one sail uses slot effect.
You don't need all these complicated computers and motors just to keep the wing at the right angle. It can all be done simply. See website www.sailwings.net
English subtitles are now available.
Please do this with all your video's. The French are so on point with their design's but all interviews and video's are for many interested but in a language not spoken by many.
Très bonne idée. Bon courage et très bonne continuation à vous
Fantastic concept. Is this video available with English subtitles?
Now it is. (In case you havent come back)
C'est bon! Aller! Aller! Aller!
I think the second "spar" is there just to make it possible to patent the rig, which would otherwise infringe on prior art (rig designs.) It's a drawback because of the weight and windage.
Magnifique projet. Malheureusement, pas encore prêt d'arriver ...
So after the covering is pulled down, the mast still sticks up, doesn't the round section mast cause more drag than when it is streamlined by the covering? So what is the point of pulling the covering down?
Yes, it's true that an unfaired cylindrical mast (bare pole) will have more drag than a wing shaped mast/wingsail, due to the streamlining provided by the airfoil.
Conventional thinking is that there is a risk of the wind catching the sails at an unexpected angle and damaging the boat. With wings that can't move freely, this is a risk. In this case, being able to reef (lower) the sail/wing is desirable, since the mast will have less force than the wing (in the wrong position).
For wings that can move freely, if they are uncontrolled, in principle they will orient themselves to the lowest energy position, i.e., point into the wind, and generate minimal (drag and lift) forces. But there is always a risk of the wind shifting faster than the wing can respond, resulting in unwanted forces.
That's why being able to drop the sail can be desirable. In that sense, it's a safer and more conservative solution than rigid wingsails.
@@LoanwordEggcorn Yes, most of what you say is true. In most wingsail boats in the past the wing has been allowed to pivot freely controlled by a tail surface behind. In this configuration there is a slight lag between any change in wind direction and the response of the wing. Although this is noticeable it never becomes a problem. I have extensively tested this in both fullsize and model versions. See website www.sailwings.net The Walker series of wingsail boats, where the wing is left up permanently and allowed to weatherock did, they say, tug at their moorings a bit. But presumably it was not a serious problem.
@@peterworsley4699 Thanks much Peter! I liked your earlier wingsail model video with the cam based wing control very much! Didn't realize it was you here.
I hope your query gets a response from the video poster.
Boat design in general is highly conservative, and mostly for good reason since lives are at risk, which is probably why some designers seek to have a reefable wingsail.
I agree with you that in principle the ability to bring down a wingsail quickly is not needed.
I suppose the hypothetical problem is a strong wind shift that happens faster than a freely turning wingsail can respond, potentially resulting in unexpected forces in an unwanted direction.
For wingsails that are under some kind of rigid/active control, the ability to quickly reef or drop sails may make more sense.
I have seen first hand the rigid wingsails of SailGP boats (related to the previous generation America's cup boats, AC50) feather to wind with no problem in order to moor on water, at least in a relatively protected harbor.
Question for you: have you considered using a larger aft wing section in your designs, for more of a fully compound wing? I assume that more lift comes from the camber between the wings, since the airfoils are symmetrical.
@@LoanwordEggcorn I think you mean there might be a slot effect between the two surfaces. Short answer - I don't know. There is such a lot of research to do. I have various ideas, but am not always able to test them. Thanks for your appreciation of the cam wing control.
@@peterworsley4699 Yes, slot effect, compound wing, etc., like airplane flaps, is how the previous America's Cup wings worked, for one example.
The slot energizes airflow over the back (leeward) side of the (rear) wing (flap) creating more lift and allowing the flow to remain attached at steeper camber/higher overall angle of attack. This creates more lift than a symmetrical airfoil can achieve alone.
Downside of slot is more drag, which is why most airplanes only deploy flaps when needed, but they also have highly efficient *asymmetrical* airfoils for cruising speed lift.
Boats and aerobatic planes have symmetrical airfoils, since they need to "fly" equally well "upside down". Wingsails gain lift from the camber between the wings of a compound wing.
Slot effect is also how a foresail energizes airflow around the back side a mainsail, etc., when going upwind. And vice versa reaching downwind. So any boat that has more then one sail uses slot effect.
Why French no audience ?
Nous sommes pauvres! nous n'avons pas encore internet partout à haut débit
Non sérieusement, nous le voyons en ce moment à Bordeaux et il est magnifique quand il passe sous le pont Delmas!
You don't need all these complicated computers and motors just to keep the wing at the right angle. It can all be done simply.
See website www.sailwings.net