THE IMOCA thread, single/double handed & TOR
- Thread starter Fiji Bitter
- Start date
LeoV
Super Anarchist
jb5
Super Anarchist
Yes its all a trade off for sure. I expect a pretty close field in the VG between the new boats. The field is converging. The skipper should be the deciding factor. At least I hope.
Not expecting much insight from the Artic race though with all the new boats still really in shakedown and setup modes.
carcrash
Super Anarchist
The key to first flight, like for the wright brothers, was sufficient lift to drag.
The key to sustained flight, as needed for VG, is controlled flight. Since automated high rate closed loop control of flight is not allowed (a really, really stupid, unsafe, and expensive decision), then passive closed loop control is required.
The foils that provide the best lift to drag are similar to Charon. However, the good L/D performance is due to the lack of passive closed loop control. So that approach is great for photos and carefully edited videos, but will be a failure in actual ocean racing.
The two approaches that work for passive closed loop control are well known, and have been well known for over a century: ladder foils and V shaped surface piercing foils.
For some lame reason, the designers are ignorant of the century plus of research in this domain, and instead make pretty and expensive carbon structures that just don't work very well in anything like a sustained manner in a realistic seaway.
The key to sustained flight, as needed for VG, is controlled flight. Since automated high rate closed loop control of flight is not allowed (a really, really stupid, unsafe, and expensive decision), then passive closed loop control is required.
The foils that provide the best lift to drag are similar to Charon. However, the good L/D performance is due to the lack of passive closed loop control. So that approach is great for photos and carefully edited videos, but will be a failure in actual ocean racing.
The two approaches that work for passive closed loop control are well known, and have been well known for over a century: ladder foils and V shaped surface piercing foils.
For some lame reason, the designers are ignorant of the century plus of research in this domain, and instead make pretty and expensive carbon structures that just don't work very well in anything like a sustained manner in a realistic seaway.
You keep speaking in dismissive generalities about imoca as if you didn’t see the last VG or the multiple imoca events? Do you think you have a better turnkey design?
carcrash
Super Anarchist
Of course I have seen the previous VG and IMOCA events. But I am an actual engineer. While I am most well known for my software systems, I also personally did the complete design of the Lear Avia Lear Fan, the last airplane Bill Lear developed.
I also did the original implementation of what is now called DSS in 1973-1974, where through first hand experience and many experiments I learned well the tremendous limitations of uncontrolled foils that do not incorporate the proven stability approaches of ladder foils and V shaped surface piercing foils.
T foils with active controls are far, far better than the passively stable approaches that IMOCA mandates. Active controls are much, much cheaper than lots of carbon for big foils. That is what I mean by "stupid" -- its more expensive, less reliable and slower to go the passive approach than using sensors, software, and actuators.
Foiling is not at all new technology. The IMOCA approach utilizes very heavy and very expensive carbon foils and do not provide any semblance of stability. Ladder and V shaped surface piercing foils were originally used with low modulus materials and therefore work with much, much less carbon.
It is like the designers do no trade studies, no research into the rich history of the field.
Long unsupported spans, such as used by Charal, are very heavy. Breaking up the spans with struts that balance the loads, such as are done on both V surface piercing and ladder foils, dramatically reduces load (therefore carbon, cost, and weight), and reduces required foil thickness, therefore decreasing drag and decreasing the drop in pressure that firmly limits the max speed. Exceeding max speed drops pressure below the vapor pressure in water, causing bubbles to form directly from the water (not from the surface), leading to cavitation and high speed crashes.
I also did the original implementation of what is now called DSS in 1973-1974, where through first hand experience and many experiments I learned well the tremendous limitations of uncontrolled foils that do not incorporate the proven stability approaches of ladder foils and V shaped surface piercing foils.
T foils with active controls are far, far better than the passively stable approaches that IMOCA mandates. Active controls are much, much cheaper than lots of carbon for big foils. That is what I mean by "stupid" -- its more expensive, less reliable and slower to go the passive approach than using sensors, software, and actuators.
Foiling is not at all new technology. The IMOCA approach utilizes very heavy and very expensive carbon foils and do not provide any semblance of stability. Ladder and V shaped surface piercing foils were originally used with low modulus materials and therefore work with much, much less carbon.
It is like the designers do no trade studies, no research into the rich history of the field.
Long unsupported spans, such as used by Charal, are very heavy. Breaking up the spans with struts that balance the loads, such as are done on both V surface piercing and ladder foils, dramatically reduces load (therefore carbon, cost, and weight), and reduces required foil thickness, therefore decreasing drag and decreasing the drop in pressure that firmly limits the max speed. Exceeding max speed drops pressure below the vapor pressure in water, causing bubbles to form directly from the water (not from the surface), leading to cavitation and high speed crashes.
The reason why T foils are not allowed because at the time when the rules were being packaged together, as an owner class the intent is not to push design to a level where boats have no development path forward.
Building a sailing imoca autopilot is way more complicated than aviation- I know aviation retirees like to pretend they’re the only ones who went to school - but nautical engineers aren’t idiots. If it were that easy they’d ditch the foils for Stemme glider wings or call up Dassalt for delta wing profiles.
Building a sailing imoca autopilot is way more complicated than aviation- I know aviation retirees like to pretend they’re the only ones who went to school - but nautical engineers aren’t idiots. If it were that easy they’d ditch the foils for Stemme glider wings or call up Dassalt for delta wing profiles.
Ahstom
Member
The energical cost should also be considered... If the number of active surface is tripled, so is the consumption (roughly) of the auto pilot. Given that the class is moving towards the objectif of limiting/banning the use of fossile fuel, I don't think that an active control of the lifting surface is a thing that we will see...
jb5
Super Anarchist
https://mailchi.mp/tipandshaft/n215paul-meilhat-un-bon-moment-pour-faire-passer-des-messages-podcast-morgan-lagravire?e=9a497c6fa7
Paul Meilhat interview on the link in French. IMOCA RDR winner. Still looking for 'several' million euros for his TOR/RDR/VG (2024) campaign. Seems to have leads but nothing is set and the sponsorship field has of course probably changed significantly. Talks a lot about the need to reduce costs in IMOCA, but doesn't mention the TOR in this regard, to make it sustainable and points to Francis Joyon as a great example.
Nothing really about the TOR beyond the funding question mark. Of course if the TOR slips a year I would think his focus would move to RDR/VG only. He's still very active in the IMOCA GA.
I feel sorry for the guy. True talent on the sidelines along with some other notables as well of course.
A few quotes:
"today it is very difficult to sell projects for several million euros , this is not a period conducive to decisions. It is to be expected that the share of the cake will be much more limited in the years to come"
"Everyone is aware that it has to be cheaper and that we have to do things in a smarter and more united way between us, within the classes but also between the classes."
"A year ago, you would still have found it difficult to pass sustainability rules at the GA; Today, things have changed a little, but it is not yet everyone's overall priority . In general, the solution is also in the overall reduction of costs: it means moving a little less, having less logistics, not sending teams and containers everywhere, not doing X pairs of foils and X sails, etc. This is where we have to work. A guy like Francis Joyon, with his strap-on annex on his trampoline, still shows that we can do it . When he goes to the four corners of the world, he has very very little logistics. Perhaps we must return to the racing model as it existed at the beginning. When I see the great film Mor Bihan by Nicolas Raynaud on the Whitbread des Glandos, I am a bit nostalgic for that time. The guys went around the world without logistics, just with their boat, everyone managed and there was a lot of help. I find that we have lost a lot of this spirit of solidarity, which exists in Mini. Today, we operate in silos, each team is a little closed in on itself, because the pressure and the stakes have risen, we have lost a bit of this community side, contacts with amateurs. As a kid, I remember that all professional skippers ended up on races like the Spi Ouest-France, whereas now we don't cross paths much ."
Paul Meilhat interview on the link in French. IMOCA RDR winner. Still looking for 'several' million euros for his TOR/RDR/VG (2024) campaign. Seems to have leads but nothing is set and the sponsorship field has of course probably changed significantly. Talks a lot about the need to reduce costs in IMOCA, but doesn't mention the TOR in this regard, to make it sustainable and points to Francis Joyon as a great example.
Nothing really about the TOR beyond the funding question mark. Of course if the TOR slips a year I would think his focus would move to RDR/VG only. He's still very active in the IMOCA GA.
I feel sorry for the guy. True talent on the sidelines along with some other notables as well of course.
A few quotes:
"today it is very difficult to sell projects for several million euros , this is not a period conducive to decisions. It is to be expected that the share of the cake will be much more limited in the years to come"
"Everyone is aware that it has to be cheaper and that we have to do things in a smarter and more united way between us, within the classes but also between the classes."
"A year ago, you would still have found it difficult to pass sustainability rules at the GA; Today, things have changed a little, but it is not yet everyone's overall priority . In general, the solution is also in the overall reduction of costs: it means moving a little less, having less logistics, not sending teams and containers everywhere, not doing X pairs of foils and X sails, etc. This is where we have to work. A guy like Francis Joyon, with his strap-on annex on his trampoline, still shows that we can do it . When he goes to the four corners of the world, he has very very little logistics. Perhaps we must return to the racing model as it existed at the beginning. When I see the great film Mor Bihan by Nicolas Raynaud on the Whitbread des Glandos, I am a bit nostalgic for that time. The guys went around the world without logistics, just with their boat, everyone managed and there was a lot of help. I find that we have lost a lot of this spirit of solidarity, which exists in Mini. Today, we operate in silos, each team is a little closed in on itself, because the pressure and the stakes have risen, we have lost a bit of this community side, contacts with amateurs. As a kid, I remember that all professional skippers ended up on races like the Spi Ouest-France, whereas now we don't cross paths much ."
jb5
Super Anarchist
[No message]
Yep - and there’s no fail safe here. Break a T foil system in a foiling system designed with that in mind and you’re not sailing anywhere stable with that foil.
Also I think it is kind of rich re criticizing nautical/imoca design while pushing for more complexity and unproven concepts and banking that expert opinion on... the Lear product that never delivered despite massive interest and orders because.... of complicated gearbox and composite manufacturing that wasn’t there yet. Shrug.
Sailbydate
Super Anarchist
No semblance of stability? I think you should stick to airplanes!
And I wonder why it is that airplanes ditched biplanes with struts and nice lightweight wing structures for monoplanes and heavy spars? Drag might possibly have something to do with it no? Every strut to break up a span will produce drag, and most likely it is another surface piercing item to cause more drag, and of course it has a weight overhead as well, particularly if in compression which it will be.
And these sort of boats are never about top speed - that's irrelevant. Sustained high averages are the thing under as many conditions as possible, and the Vendee has its own fairly well delimited predominant weather and sea patterns to deal with.
Imoca rules and the logic behind them has always been a Gallic mystery, but that's what they are and that's what they have to work with.
jb5
Super Anarchist
G. Lebec / Charal
jb5
Super Anarchist
72 hours sail for BP
