The_Alchemist
Super Anarchist
I added some NASA info in the “boats and foils comparison” thread.
Recon diary
- Thread starter Mozzy Sails
- Start date
Kenny Dumas
Super Anarchist
Maybe they’re measuring just how much drag you actually get from dipping a foil, instead of just saying it’s bad ? Especially relevant with the larger foil option
Kiwing
Super Anarchist
Maybe they are evaluating the windward heal drag of the foil?
shebeen
Super Anarchist
I doubt that would be a anything close to a net benefit, would be very hard to achieve and would pop out too easily.
Maybe AC38 in a AC75 V3 could have twin rudders to get the F50 effect
enigmatically2
Super Anarchist
Comment on Sailworld site for ETNZ on their vanilla AC40 yesterday:
"Very good synchronisation between main and Jib leach twist control."
So we know that INEOS have added the jib car to adjust jib sheeting angle, but I have not seen anything on the AC40s (or if so don't remember it). How are they controlling jib twist/leech?
"Very good synchronisation between main and Jib leach twist control."
So we know that INEOS have added the jib car to adjust jib sheeting angle, but I have not seen anything on the AC40s (or if so don't remember it). How are they controlling jib twist/leech?
enigmatically2
Super Anarchist
I've been thinking more about the windward foil in the water thing that @Mozzy Sails was talking about in his most recent video.
1) I think he is absolutely correct in his assertions for the AC40. That boat has to be a race boat in its own right, unlike the LR and Ineos LEQ12s
2) I also agree that LR have gone for the more "obvious" scaling solution
3) Where I differ a bit is that I think Ineos have done changed the foil arms to accomplish 2 things
a) to get the leeward foil at the same depth as they will be on the new AC75s so that the data they get is not so much cleaner but more representative in terms of the wave action on those foils
b) to get the RM scaled. As Mozzy correctly says these boats (or at least the AC40 and probably the others) are relatively compared to the scaled AC 75. That means to get the correct RM the arms need to be shorter in their lateral projection
To accomplish those you need quite different foil arm shapes. That has the negative of the windward one trailing more. There are always going to be compromises.
One other aspect of that compromise is that the Ineos solution will have much lower inertial momentum about the leeward foil as a centre of rotation. That would make it much less stable than the other LEQ12 (which all have a much lower rotational inertia than the AC75s). So we would expect Ineos to be skittish and less stable than the others - which it does appear to be.
Having a lower RM might also mean that they can utilise less lateral force, so they may need smaller or flatter sails than the other LEQ12s. I don't know whether we have any evidence for the former, but would be hard to compare to get an accurate comparison of the latter.
All these things mean (as I have said before) that speed comparisons are irrelevant. This is all about gathering data.
Its also worth noting that larger foils also (partially) invalidates the advantage of the old Ac75s being used for testing because they are scaled. The new foils, with their larger span will give more RM to AC75s. In the AC37 race boats that will be counteracted by the reduced weight, but on the old boats if they will either mismatch on weight or on RM, they cannot match both until new style foils are used (from the final race allowance).
Always compromises and balance
1) I think he is absolutely correct in his assertions for the AC40. That boat has to be a race boat in its own right, unlike the LR and Ineos LEQ12s
2) I also agree that LR have gone for the more "obvious" scaling solution
3) Where I differ a bit is that I think Ineos have done changed the foil arms to accomplish 2 things
a) to get the leeward foil at the same depth as they will be on the new AC75s so that the data they get is not so much cleaner but more representative in terms of the wave action on those foils
b) to get the RM scaled. As Mozzy correctly says these boats (or at least the AC40 and probably the others) are relatively compared to the scaled AC 75. That means to get the correct RM the arms need to be shorter in their lateral projection
To accomplish those you need quite different foil arm shapes. That has the negative of the windward one trailing more. There are always going to be compromises.
One other aspect of that compromise is that the Ineos solution will have much lower inertial momentum about the leeward foil as a centre of rotation. That would make it much less stable than the other LEQ12 (which all have a much lower rotational inertia than the AC75s). So we would expect Ineos to be skittish and less stable than the others - which it does appear to be.
Having a lower RM might also mean that they can utilise less lateral force, so they may need smaller or flatter sails than the other LEQ12s. I don't know whether we have any evidence for the former, but would be hard to compare to get an accurate comparison of the latter.
All these things mean (as I have said before) that speed comparisons are irrelevant. This is all about gathering data.
Its also worth noting that larger foils also (partially) invalidates the advantage of the old Ac75s being used for testing because they are scaled. The new foils, with their larger span will give more RM to AC75s. In the AC37 race boats that will be counteracted by the reduced weight, but on the old boats if they will either mismatch on weight or on RM, they cannot match both until new style foils are used (from the final race allowance).
Always compromises and balance
Forourselves
Super Anarchist
nav
Super Anarchist
- 14,090
- 592
Wow a lot of theories there.....
FCS and foil arms are 2 separate things obviously
The arms/foil position is such a fundamental part of the design of this class that suggesting a change is possible now is almost Oracle-esque
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enigmatically2
Super Anarchist
So outstanding questions/investigations that I can recall to watch out for, Mozzy to ask if he gets chance etc
1) why did Ineos go for the different foil arm length/shape resulting in windward foil dragging
2) what is the mysterious other control alluded to be LR in their lower main area (and do others have anything similar)
3) what is the purpose of the holes (if they are holes) on LR foil flaps
4) controls on mast base
5) what is purpose of the complex Ineos traveller system
6) how are teams putting the main ram horizontally allowing for traveller movement. Assumed in one case as this centre track, not sure in the other
Anything I've missed
1) why did Ineos go for the different foil arm length/shape resulting in windward foil dragging
2) what is the mysterious other control alluded to be LR in their lower main area (and do others have anything similar)
3) what is the purpose of the holes (if they are holes) on LR foil flaps
4) controls on mast base
5) what is purpose of the complex Ineos traveller system
6) how are teams putting the main ram horizontally allowing for traveller movement. Assumed in one case as this centre track, not sure in the other
Anything I've missed
captainSackSparrow
New member
Continuing from the windward foil dipping in the water conversation...
This is assuming they care about the windward foil dipping in the water and the effect this has on speed. Could they be more interested in loads, sail control, foil flex, and the orbital action of waves on foils.
OR they were banking on being able to use the tow mast to collect data, and therefore control the ride height more accurately within the thinner margin (i.e. high enough for windward foil out of water) of their different foil arms.
This is assuming they care about the windward foil dipping in the water and the effect this has on speed. Could they be more interested in loads, sail control, foil flex, and the orbital action of waves on foils.
OR they were banking on being able to use the tow mast to collect data, and therefore control the ride height more accurately within the thinner margin (i.e. high enough for windward foil out of water) of their different foil arms.
buckdouger
Anarchist
- 859
- 378
I think there continue to be questions about ETNZ flaps, the curvature, the very smooth upper surface and materials.
I had a thought that maybe some teams with AC40s may first reverse engineer what they get before putting it back together to sail as it's the best clue as to how ETNZ approaches controls etc and it's unlikely they'd have deliberately come up with obscure other ways of designing things even if they saved their best ideas for their big boat.
buckdouger
Anarchist
- 859
- 378
See my post above.. maybe they are studying it
nav
Super Anarchist
- 14,090
- 592
No. The spec for the FCS is to released, not 'changed'. And that has nothing to do with the arm dimensions which you fantasize are to be changed at this late stage
It is soon after here. "On the 1st of March the Foil Cant system specification will be posted. And it may be that this is possible from a rules legality perspective but it's outside the technical capability of the one-design foil cant system. And we'll know more when the Rule comes out."
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yourbiggestfan
New member
Bow fell of it when it arrived I heard...
Looking for all the hidded data transponders and microphones the Kiwis installed during the build...
