Tornado-Cat

Boats and foils comparison

Recommended Posts

3 minutes ago, Tornado-Cat said:

Different foils too.

yysw268053.jpg.92f53e3c19934ee5920c0c6f53a65bf5.jpg

Rocket pods? Maybe to help with flow at the tips of the flaps? But then why only on the bottom?

T joints on the bulb look dirty, shouldn't they be filleted?

Share this post


Link to post
Share on other sites

So, I see a shit load of drag going on, on two of the foil versions above.

The torpedoes 'may' be more stable - but are they faster? Not likely.

Share this post


Link to post
Share on other sites
2 minutes ago, Sailbydate said:

So, I see a shit load of drag going on, on two of the foil versions above.

The torpedoes 'may' be more stable - but are they faster? Not likely.

We don't know whether the torpedo is for better hydro drag or to play with the mass within the rule.

Share this post


Link to post
Share on other sites

I think we need both new boats with the rig up before we can really have this conversation in full.

But I actually think the answer lies in the weather on any given day, ETNZ really look to have targetted the light stuff hard and I feel AM are at the other end with LR somewhere in between, although those foil pods are just odd and don't even look real, are we sure they are not just for show!

Share this post


Link to post
Share on other sites
5 minutes ago, Boybland said:

I think we need both new boats with the rig up before we can really have this conversation in full.

But I actually think the answer lies in the weather on any given day, ETNZ really look to have targetted the light stuff hard and I feel AM are at the other end with LR somewhere in between, although those foil pods are just odd and don't even look real, are we sure they are not just for show!

For the pleasure of speculation, if I was willing to foils as soon as possible, I would chose:

- Orca for flat water

- Sardine for little chops

- Flipper for waves

Now, at speed and foiling, I think I would prefer the Orca hoping to get a small air cushion between hull and water.

 

Share this post


Link to post
Share on other sites
13 minutes ago, Tornado-Cat said:

I would prefer the Orca hoping to get a small air cushion between hull and water.

I think you're naive to think there will be any sort of ground effects or hovercraft like effects for Defiant. Their shape is purely conceived for minimal drag through the air whilst up on the foils. It's going to go splat when she comes down off the foils, and be way more sticky with her large wetted area than the other two. In marginal conditions Defiant will be the last boat to rise, and the worst performer in any contact with a chop.

To me, Te Aihe still looks the most advanced design of the three we've seen so far.

  • Like 3

Share this post


Link to post
Share on other sites
1 hour ago, RobG said:

Rocket pods? Maybe to help with flow at the tips of the flaps? But then why only on the bottom?

T joints on the bulb look dirty, shouldn't they be filleted?

I think the answer is no. You want maximum space for flow to pass between or you accelerate the flow and increase cavitation issues. 

Share this post


Link to post
Share on other sites
55 minutes ago, Tornado-Cat said:

We don't know whether the torpedo is for better hydro drag or to play with the mass within the rule.

I think it is for drag. The rule definitions seem to preclude the pod from inclusion in the mass modification calc, or at best an interpretation is required. Someone posted they felt the definitions section where this argument logically derives is normative, but the rule does not state that it is normative, and I don't think we can assume. 

Share this post


Link to post
Share on other sites

I'll throw my thought out there...

Bulb foils are the high speed foils, non-bulb foils are the low speed foils.

Think of it like moth foils, heavy air foils are far smaller in surface area and wouldn't have room for ballast, therefor the weight is distributed in a bulb at the joint.

Light air foils are far larger in surface area and have the volume inside to spread out the ballast internally without the bulb.

Sheer size of the foils is a dead-give-away to me, TNZ's foils appear to be 4x the area of both LR and AM and of a thicker cord. 

If I have some time I will model them up, just need some good front/rear/side images of all sets to get even mildly accurate shapes and volumes etc.

  • Like 2

Share this post


Link to post
Share on other sites
6 minutes ago, darth reapius said:

Bulb foils are the high speed foils, non-bulb foils are the low speed foils.

I think you could be right. Te Aihe's foils definitely look to have more surface area. More lift for lower wind ranges. What are the rules for foil changes in the cup match? 

Share this post


Link to post
Share on other sites
57 minutes ago, Horn Rock said:

I think you're naive to think there will be any sort of ground effects or hovercraft like effects.

 

That is what I thought at the beginning, we tried concave with sailboards years ago and it did not work. However these boats will sail over 40 kts, have you put your hand outside of a car at 80 km per hour ? it lifts, and the boat is a bit more larger than a hand. I don't say the boat won't crash, I think a few cm of air cushion above water can make the difference. Remains to be seen though.

Share this post


Link to post
Share on other sites
15 minutes ago, Horn Rock said:

I think you could be right. Te Aihe's foils definitely look to have more surface area. More lift for lower wind ranges. What are the rules for foil changes in the cup match? 

I think this is broadly right darth reapius, except that in addition to high-speed low-speed the tradeoff between takeoff speed and top speed is a factor too that teams have to weigh, looking at their predicted modes around the race course in different scenarios. 

  • Like 1

Share this post


Link to post
Share on other sites

Let me throw out another idea about the torpedo or bulb foils in use by AM and LR.  When these boats are foiling, the foils will be just below the surface of the water.  The torpedo/bulb could give some bulbous bow effect or be similar to a swath hull.  As such, it may reduce the drag of the foil arm in the water.  I suspect that the foil arm may not be long enough to get the same wave cancelation effect, but at the speeds these boats will be going it may be a factor.  Add that to the versatility of "foil modifications" with the 80/20 rule, improved control of the RM (weight in one spot) and some possible super cavitation effects.   And to think, I haven't been drinking...

Share this post


Link to post
Share on other sites
2 hours ago, Tornado-Cat said:

have you put your hand outside of a car at 80 km per hour ? it lifts,

To really get lift (like a wing) the underside would need to be dead flat to generate pressure differential. Their hull is still quite round which leads me to believe it's more about drag reduction than lift. Also, at speed they're getting enough lift from the foils, so lift generated by the hull would not seem necessary.

  • Like 1

Share this post


Link to post
Share on other sites
3 minutes ago, Horn Rock said:

To really get lift (like a wing) the underside would need to be dead flat to generate pressure differential. Their hull is still quite round which leads me to believe it's more about drag reduction than lift. Also, at speed they're getting enough lift from the foils, so lift generated by the hull would not seem necessary.

Everyone's talking about the kiwi bulge like it's meant for reducing drag during touchdowns, but what if the flatness of Defiant's hull is meant for windward-heel touch downs? Of course I have no idea how anyone plans to sail these monsters, but based off of my limited experience sailing foiling multis, the boat sails faster with the windward hull in the water and the leeward foil working than with leeward heel. If the AM guys have calculated for this, they could just be anticipating the fact that the big ol keel hanging off the side is going to drop the windward chine before the boat falls off the foils, which would only give them contact with the water on that much more round yet still defined chine. If NZ does end up dropping to windward, they're probably making contact with the water on their hump as well as their much softer windward chine, doubling the amount of boat they would be dragging through the water. In addition, trying to modulate the cant of the windward foil to lift during a fall would most likely just slow the boat down even more due to the sheer amount of lift required to reverse the downwards acceleration of the massive ball of lead hanging 20 feet off the side of the boat. Maybe embracing the fall is the better option. By no means am I an expert on hydrodynamics, so these are just my raw thoughts.

Of course, I don't happen work for airbus either, so I have basically no clue how they could have factored ground effect in, but it seems to me like the boundary layer in more disturbed water would be so thin or nonexistent that trying to gain aerodynamic lift from having a flat bottom is more or less pointless. 

Now these points could be totally moot, and USA 2 could look exactly like NZ 2, or even NZ1 for that matter. Then everyone on this forum is screwed.

Guess we'll find out just how wrong we all are off Sardinia in a few months' time. 

  • Like 1

Share this post


Link to post
Share on other sites
6 minutes ago, josh_bartoszuk1 said:

what if the flatness of Defiant's hull is meant for windward-heel touch downs?

Kinda like doing an edge touch? Interesting idea, but from what we've seen these boats seem to come down with a flat attitude. There does seem to be some heel - either way - whilst flying, but yeah, coming down with a significant heel might lead to some unintended consequences - as in capsizes - as well as requiring  very precise control between the main, helm and foils.

Share this post


Link to post
Share on other sites
3 hours ago, buckdouger said:

I think it is for drag. The rule definitions seem to preclude the pod from inclusion in the mass modification calc, or at best an interpretation is required. 

Definitions aren't normative when there is a rule that is explicit. Rule 13.2 (c) defines the bulb as part of the "foil wing":

13.2 For the purposes of Rules 5 and 10:
(a) a foil does not include the metal foil arm head, fasteners attaching the foil arm head to the foil arm, any foil arm drum, or any other components inside the hull IGES that are disconnected from a foil when it is removed from the yacht;
(b) except for parts of foil systems, any material that does not move relative to a foil flap must be part of that foil flap; and
(c) except for the foil arm stock, foil flaps and foil systems, any material within the region described in Rule 13.4 must be part of the foil wing.

Where rule 5 is "Component limits and modifications" and figure 13.1 associated with Rule 13.4 includes essentially everything beyond the end of the arm that isn't explicitly excluded by 13.2 (i.e. the flaps and foil systems) as part of the foil.

I don't know how the change allowance is applied though. Can any of the 6 "foil wings" be modified by up to 20% mass? In that case, those with a bulb can effectively have 12 wings if they remanufacture their 6 existing foils into 6 new foils.

  • Like 1

Share this post


Link to post
Share on other sites

On the foil bulbs, the mass has to go somewhere. Maybe the bulb solution is a lead bulb and carbon foils, whilst the no bulb option is full tungsten steel foils to get the density up throughout and avoid the extra volume of lead by distributing the denser material throughout. Expensive solution 

Share this post


Link to post
Share on other sites
5 hours ago, RobG said:

Rocket pods? Maybe to help with flow at the tips of the flaps? But then why only on the bottom?...

My guess is they house actuators of some kind.

  • Like 2

Share this post


Link to post
Share on other sites
17 minutes ago, Basiliscus said:

My guess is they house actuators of some kind.

I respectfully say, what an un elegant solution when they have managed no gap hinges. The big bulb might be good place for hiding the needed bits and bobs?

Share this post


Link to post
Share on other sites
7 hours ago, Tornado-Cat said:

For the pleasure of speculation, if I was willing to foils as soon as possible, I would chose:

- Orca for flat water

- Sardine for little chops

- Flipper for waves

Now, at speed and foiling, I think I would prefer the Orca hoping to get a small air cushion between hull and water.

Playing the speculation game as well...

In displacement mode, I choose Sardine
In fully foiling mode, Orca
In foiling mode with short contact with water, Flipper

About the various foils we have seen, it might be dictated by which stage of their program they are in. Let's not forget AM and LR had surrogates to get time testing the concept. ETNZ didn't and might want to start foiling in less wind and maybe not achieve as high speed with the first boat and set of foils. All 3 should cover most sailing conditions and speed for design input into next boat (maybe ETNZ lacking a bit for supercavitation if those torpedo are addressing that).

Looks like all teams are well into the game right now and love the different designs approach. We are just missing more weta27 in US, Italy and UK...

  • Like 1

Share this post


Link to post
Share on other sites

for getting onto foils first I choose flipper

for top speed I choose Orca

for VMG I choose flipper

for displacement mode VMG under flipper take off speed I choose sardine

For maneuverability in Displacement mode under flipper take off speed I choose Orca

Share this post


Link to post
Share on other sites
1 hour ago, barfy said:

I respectfully say, what an un elegant solution when they have managed no gap hinges. The big bulb might be good place for hiding the needed bits and bobs?

If you only have an actuator in the bulb, that's a long stretch of tube/rod to accurately control the torque at the far end of the flap. If there's an actuator at both ends, the torque issue is halved (in my simplistic view).

Share this post


Link to post
Share on other sites

ok just to throw another parameter in

 

for takeoff distance

flipper

flamingo

flopper

i have not yet seen

boudicas revenge

Share this post


Link to post
Share on other sites
7 hours ago, Sailbydate said:

So, I see a shit load of drag going on, on two of the foil versions above.

The torpedoes 'may' be more stable - but are they faster? Not likely.

we all learned last cup that stability on foils is faster than just straight "speed"

Share this post


Link to post
Share on other sites

They sure look like airplane wing actuators in miniature. Are there any actual flaps visible? can you deform a whole foil surface by stressing it with such a device, so no separate flap? . Angles required aren't huge. At least we get to wildly speculate since they're visible. 

Share this post


Link to post
Share on other sites
7 hours ago, Horn Rock said:

To really get lift (like a wing) the underside would need to be dead flat to generate pressure differential. Their hull is still quite round which leads me to believe it's more about drag reduction than lift. Also, at speed they're getting enough lift from the foils, so lift generated by the hull would not seem necessary.

Turn it upside down. AM’s hull shape is remarkably wing shaped, just upside down producing downforce instead of lift. That downforce increases righting moment, thus increasing power. 
 

That’s all just my theory. 

Share this post


Link to post
Share on other sites
16 hours ago, Tornado-Cat said:

We don't know whether the torpedo is for better hydro drag or to play with the mass within the rule.

If it's the later, and teams have done it to experiment with their wings, I really do wonder how much learning can be done using the torpedo foils.  If the intent is to give flexibility in the design of the wings, and one day you revert to an ETNZ style foil, can those lessons really be applied once the bulb is removed?

 

Of course, this assumes that the downside of all that flexibility is that the torpedo style foils are greater drag, which they appear to be.

Share this post


Link to post
Share on other sites
39 minutes ago, Ex-yachtie said:

If it's the later, and teams have done it to experiment with their wings, I really do wonder how much learning can be done using the torpedo foils.  If the intent is to give flexibility in the design of the wings, and one day you revert to an ETNZ style foil, can those lessons really be applied once the bulb is removed?

 

Of course, this assumes that the downside of all that flexibility is that the torpedo style foils are greater drag, which they appear to be.

Don't be so fast to say that the torpedo design has more drag.  The long wing foils of NZ have a very long leading edge and surface area that all creates drag.  The Torpedo is one large mass, but it is efficient in the amount of drag it creates (less surface area for a given mass).  There has to be more surface area in a pair of long wings than in a torpedo and two small wings.  Also, The long wings of the NZ foils may create too much lift and thus have to be adjusted (flaps, angle, etc...) to keep the boat stable as they sail.  The increased drag for the adjustments and longer foils can really slow the boat down.  If NZ doesn't have a VMG trick (like the last cup), they may get up quickly but be hunted down by AM.

Share this post


Link to post
Share on other sites
10 hours ago, RobG said:

If you only have an actuator in the bulb, that's a long stretch of tube/rod to accurately control the torque at the far end of the flap. If there's an actuator at both ends, the torque issue is halved (in my simplistic view).

True that. Perhaps some deformation trailing off the flap angle towards the tip would be ok. There is mention of deformation in the rule, but would be hard to measure in the water I reckon.

Just can't see carrying all that drag for an external actuator when none of the boats so far, including mini moon, have had to go that route. They look look cool tho.

Share this post


Link to post
Share on other sites

 

9 hours ago, minimumfuss said:

They sure look like airplane wing actuators in miniature. Are there any actual flaps visible? can you deform a whole foil surface by stressing it with such a device, so no separate flap? . Angles required aren't huge. At least we get to wildly speculate since they're visible. 

That was my thought as well.  Similar to what someone else said, a single actuator in the bulb would result in a lot of twist/deflection as you get further away.  The second actuator would allow better control of the foil twist.

 

Share this post


Link to post
Share on other sites
10 hours ago, RobG said:

If you only have an actuator in the bulb, that's a long stretch of tube/rod to accurately control the torque at the far end of the flap. If there's an actuator at both ends, the torque issue is halved (in my simplistic view).

Maybe the sharklets house actuators for flaps along those tip-ups?

Share this post


Link to post
Share on other sites
11 minutes ago, Stingray~ said:

Maybe the sharklets house actuators for flaps along those tip-ups?

Maybe its a weight balance to prevent/ensure correct twist of the foil? are they even allowed dynamic control of the foil? Thought it was just the arm.

Share this post


Link to post
Share on other sites
9 minutes ago, luminary said:

Maybe its a weight balance to prevent/ensure correct twist of the foil? are they even allowed dynamic control of the foil? Thought it was just the arm.

They do design their own (fixed) fairings for the trailing edge of the foil arms but they will actively tune the trailing edge flaps of the foil wings. 

The tip-ups on Sardine’s wings will surely need to have flaps in order to stay in tune along with the rest of the wing; one of the purposes for the sharklets could be to house actuators for flaps along that section of the wing?

Share this post


Link to post
Share on other sites
4 minutes ago, luminary said:

Maybe its a weight balance to prevent/ensure correct twist of the foil? are they even allowed dynamic control of the foil? Thought it was just the arm.

15.5 Through a foil flap’s range of rotation angles and twists, a foil flap cross-section shall not significantly
deform except as permitted in Rules 15.4, 15.8 and 15.9, or as a result of external forces.

15.8 A foil flap may contact a foil wing, and in the absence of external forces, and at any cross-section and
rotation angle, either may cause deformation in the other in a single zone covering not more than 20% of
the local chord length. Outside this zone, neither shall cause deformation in the other.

15.9 Connections between sections of a foil flap are exempt from Rules 13.9, 15.4 and 15.5, providing such
connections span a combined total of no more than 10% of the span of a foil wing, where the span is
measured along the rondure.

looks like some deformation allowed between different sections of flap, maybe that's the flap that some noticed near the wing root.

Share this post


Link to post
Share on other sites
27 minutes ago, barfy said:

either may cause deformation in the other in a single zone covering not more than 20% of
the local chord length.

Almost reads like ‘bending’ or controlled morphing is allowed between the wing and the flap, within those limits. 

It is pretty hard to make out any ‘hinge’ existing between the wings and the flaps in the foils that LR launched with.

Share this post


Link to post
Share on other sites
4 hours ago, Herfy said:

looks like the flat bottom didn't stick to the water like some are saying

If that's the inspiration for Defiant's hull design, they're in big trouble Herfy.

  • Like 1

Share this post


Link to post
Share on other sites
5 hours ago, Herfy said:

Don't be so fast to say that the torpedo design has more drag.  The long wing foils of NZ have a very long leading edge and surface area that all creates drag.  The Torpedo is one large mass, but it is efficient in the amount of drag it creates (less surface area for a given mass).  There has to be more surface area in a pair of long wings than in a torpedo and two small wings.  Also, The long wings of the NZ foils may create too much lift and thus have to be adjusted (flaps, angle, etc...) to keep the boat stable as they sail.  The increased drag for the adjustments and longer foils can really slow the boat down.  If NZ doesn't have a VMG trick (like the last cup), they may get up quickly but be hunted down by AM.

I don’t think ETNZ’s foils are much longer than LR’s. 

Share this post


Link to post
Share on other sites

Boats are so different that I predict we will have the most important distance between first and second in the AC history.

The best teams now are taking high resolution photos of each team, make 3 D models and test it in their simulator. A the same time they try to figure out the polar of each B1.

At this game the defender has 3 months advance for B2 and may already know the wind limits that should be announced December 20th 2019 ("match conditions").

The competitor with the best concept out of the box or able to wait for this time and with the means to copy and improve the best present concept should win.... with a distance.

 

Share this post


Link to post
Share on other sites

But still a simulator and not real life, so I think we are on the same page.... 

“What we were seeing in the wind tunnel and what we were seeing on the track was a very different situation,” he explained. “It took until after [the 2014 Hungarian Grand Prix] to actually get everyone to agree and understand that there were big correlation issues, and they made some really good work after that, they understood it and 2015 was much better.”

“There’s a lot of correlation issues, yeah,” he said. “The rest is downforce, also, and it’s not really good in terms of pure numbers. But the biggest issues [are] correlation – behaviour on track versus wind tunnel.

“If you believe wind tunnel and everything, it’s all good and it’s all getting better. If you believe the lap time and feeling and what we’re measuring on track… not so much. So that’s what we’re really trying to analyse at the minute: what’s really the problem, and [what’s] causing the correlation issue?”

https://www.formula1.com/en/latest/article.grosjean-2019-haas-problems-remind-me-of-2014-lotus.7ui4ZHzppAALAJfqUhuZyr.html

 

Who do you think has s better grip on wind tunnel and simulation, F1 or AC?

 

Share this post


Link to post
Share on other sites

This is where I think that Orca would have an advantage with a flat hull, she would rebound instead of crashing. Notice that it confirms what I said, that a crash would put Flipper on the side  (as when they crashed on the foils first time out). (photo credit weta27)

 

 

Capture.PNG

Share this post


Link to post
Share on other sites
1 hour ago, Tornado-Cat said:

This is where I think that Orca would have an advantage with a flat hull, she would rebound instead of crashing. Notice that it confirms what I said, that a crash would put Flipper on the side  (as when they crashed on the foils first time out). (photo credit weta27)

 

 

Capture.PNG

C'mon, TC. As you saw, Flipper popped right back up and carried on. We've seen nothing even close to an Orca crash land (similar to Flippers) so what do you base your assumptions/conclusions on? Wishful thinking? I'm not buying it. 

  • Like 3

Share this post


Link to post
Share on other sites
1 hour ago, Tornado-Cat said:

This is where I think that Orca would have an advantage with a flat hull, she would rebound instead of crashing. Notice that it confirms what I said, that a crash would put Flipper on the side  (as when they crashed on the foils first time out). (photo credit weta27)

 

 

Capture.PNG

You wouldn't think a flat bottom would grip the largest area of water causing it to stick the most?

I would have thought TNZ would be the best for bounce-back and AM would be the worst...

  • Like 2

Share this post


Link to post
Share on other sites

Feels good to come back to this thread and see they have put the wrap back on RB1 (first post), best for us all if TC doesn't update that one.

 

  • Like 2

Share this post


Link to post
Share on other sites
9 hours ago, DHFiend said:

 

Who do you think has s better grip on wind tunnel and simulation, F1 or AC?

 

I think Adrian Newey has a good grip and is working in both.  That is why I am so intrigued with the thinking behind Ineos

Share this post


Link to post
Share on other sites
9 hours ago, Sailbydate said:

C'mon, TC. As you saw, Flipper popped right back up and carried on. We've seen nothing even close to an Orca crash land (similar to Flippers) so what do you base your assumptions/conclusions on? Wishful thinking? I'm not buying it. 

Well, we have two flat boats, one "rounded belly" and one light V, so will see soon. W'll see who is right but it will be a key component of the winning boat.

Ever did water skying, sailed a sailboard ? if you jump and want to rebound on, what do you want a rounded hull under your foot or a flat ?

Share this post


Link to post
Share on other sites

I think top side Britannia is quite similar philosophy to Te Aihe, but more extreme. The flares to where the crew are go higher and go up sooner. It will be interesting once Britannia has it's rig on to see how well hat tessellates with the hull. Both Te Aihe and Britannia have the crew, and related equipment pushed right far forward, with crew members next to teh mast and over the foils.  Again, INEOS maybe more extreme in that regard.

Underneath Lunna Rossa and Te Aihe both have the central bulge / skeg.  But, still quite different. Te Aihe looks more about wetted area when not foiling and Lunna Rossa looks more about leeway. Then just looking at the cradles you can see Defiant and Britannia both have the very flat bottoms, carrying a lot of the width forward of the mast too. But, again, Britannia looks the more extreme example judging by the pivot points for the foil arms. 

Foils... all the three later launches and the 3 with test boats have gone for bulbs. Rules hole or just a more efficient way to get mass and righting moment than distribute it along a long foil you don't need? Interesting little fences and strips on the Lunna Rossa and Britannia foils. 

Share this post


Link to post
Share on other sites

One thing is certain.... those foils are so different, that someone got it right, and someone got it wrong for sure.

Share this post


Link to post
Share on other sites
21 minutes ago, dachopper said:

One thing is certain.... those foils are so different, that someone got it right, and someone got it wrong for sure.

Well, let us think about it.  

The three teams that used a test boat all started out with foils similar to the NZ foils on the test boats (minor changes in tips, etc).  

All three of those teams have now launched their B1 and are now using foils with bulbs/torpedos foils.  

I think that it is very significant that all of the teams that have sailed this boat design have progressed away from the NZ type foils.

 

Another point, is that those three have basically built flat bottom boats (LR added a keel, but still mostly flat) whereas NZ a "stepped V" type of hull.

 

So NZ is the major outliner in the foils and the hull bottom.  Either their simulator is predicting something the other didn't see, or they have missed out by not sailing a test boat.  We will see...

Share this post


Link to post
Share on other sites

We should find out when B2s are launched (or when B1s go head-to-head in competition).

Share this post


Link to post
Share on other sites

It is like the Brits designer said in the video.  You start with an idea that you think will work and then you keep tweaking it until you "optimize" that design space.  If you start down the wrong design path you may never know about a better path.  And as NZ has stated, the cup may have already been won, or at least some may have already been eliminated.

Share this post


Link to post
Share on other sites

OK I speculate that ;

the flat bottoms aim at a planning transition to lift off

that the others aim at a Moth heal to lift off

Wow that is really sticking my neck out!!

Share this post


Link to post
Share on other sites

Recall finals race 2 in the last cup - ETNZ took off sailed into a hole, Oracle caught up a 500m deficit on two short upbeat legs only to muck up a gyre and fall back 500m in one gibe 

straight line sped - getting up and staying up on foils all come into it but iat what level of priority given the much more variable conditions in Auckland - including tide

can”t wait for two to line up in anger

  • Like 1

Share this post


Link to post
Share on other sites

Interesting how both boats have pretty much exactly the same bottom, Manta being a bit wider than Orca. I think that both  try to use the "ricochet" effect.

71667118_2472989032976573_4598336371013189632_n.jpg.569d2b28ee73e081c2378f8e9b45d661.jpg.e98dd8499227fe5de99b9195215e041c.jpg

EP-190929660.jpg.4e7f378d0c0c3474f1c0284a1d07236e.jpg

yysw268269.jpg

  • Like 1

Share this post


Link to post
Share on other sites

Flipper has the biggest distance between the foil and the bottom of the hull, Manta the shorter, and the difference is not small. Two different concepts.1567803522_69_The-boat-was-named-Te-Aihe.thumb.jpg.e9e5feefe6f78f0f5cb4103362601d66.jpg

Capture.PNG

  • Like 1

Share this post


Link to post
Share on other sites

Component Rule Quantity Change allowance
Hull surfaces Open 2 y 0% & 25% area
Foil arms Supplied 4 -
Foil arm trailing edges Open 6 20% mass
Foil wings Open 6 20% mass
Foil flaps Open 20 20% mass
FCSs Supplied 2 -
Rudder uppers Open 4 20% mass
Rudder lowers Open 4 20% mass
Mast tubes Specified 3 20% mass
Supplied rigging sets Supplied 3 -
Mainsails Open *10 25% area
Headsails Open *29 25% area
yWith reference to the Protocol, a Competitor may modify one of its hulls but not the other.
*See Rule 5.11.

 

When a component is first declared according to Rule 5.5 that has an “Change allowance” mass percentage
in Rule 5.1:
(a) The Competitor must declare to the Measurement Committee:
(i) a component mass;
(ii) an IGES file of an exterior component shape; and
(iii) construction drawings showing the internal structure of the component.
(b) At all times when that component is installed on an AC75 Class Yacht with that yacht afloat:
(i) at least 80% of the mass of the component must match the original declared component;
and
(ii) at least 80% of the mass of the original declared component must match the component.
(c) The percentage of mass by which two versions of a component match is determined by aligning the
unmodified portion of the original and modified component, then identifying all regions where the
original and modified component differ, including:
(i) surface geometry, where a surface is present; and
(ii) material specification, e.g. fibre type, fibre orientation, ply sequence, resin type. Where
repairs are permitted by Rule 5.15, material specification need not be identical, as long as
it is equivalent to the satisfaction of the Measurement Committee; e.g. dry fibre may be
substituted for an equivalent pre-preg fibre, or two plies of 150 g may be substituted for one
ply of 300 g.
The percentage of mass by which two components match is then the mass of all regions where
geometry and construction is identical, as a percentage of the total component mass.
(d) In determining whether two regions of a component match, the Measurement Committee may
make an allowance for unintended distortion of a component during manufacture, as long as in
any local region the two regions of the component can be matched, and the position of one region
relative to an adjacent region has not changed at all.
5.14 For components with a “Change allowance” mass percentage, it is permitted to declare a hypothetical
“original component” which must comply with the relevant rules for that component type, but is not required
to be identical to the component when it is first installed and afloat. In this case, the hypothetical
component declaration becomes the “original component”, and the component as first launched and subsequently
modified must have corresponding declarations, which must satisfy the permitted changes with
respect to the hypothetical “original component”.

 

 

or to put it another way

it looks like etnz has missed a trick with the foil design

all their eggs are irretrievably in the one basket

not that the basket is defiantly in the wrong area .. just that its a basket that has much less leeway for change

i still think different weather and sea conditions will favour different boats .. and will probably more control the final outcome of the series

 

 

Share this post


Link to post
Share on other sites
8 minutes ago, phill_nz said:

or to put it another way

it looks like etnz has missed a trick with the foil design

all their eggs are irretrievably in the one basket

not that the basket is defiantly in the wrong area .. just that its a basket that has much less leeway for change

i still think different weather and sea conditions will favour different boats .. and will probably more control the final outcome of the series

 

 

Either that, or they know what they’re doing, as they demonstrated in AC35 and they’ve committed to something that has less flexibility but more speed. 

  • Like 1

Share this post


Link to post
Share on other sites
1 hour ago, Tornado-Cat said:

The 4 foilsCapture.thumb.PNG.9202d00ee6bfe488f8a0dbac8aafadc3.PNGCapture2.thumb.PNG.9851944d194e1eb7090ea186a6f8c072.PNG.e1bac18921da4eb9aa310c4d34ce9e2c.PNG

yysw268053.jpg.92f53e3c19934ee5920c0c6f53a65bf5.jpg.39b9deb028e7102c641eb0ba96844f81.jpg.8297639a48966ca684b79b5e27e0341e.jpg

 

Capture.PNG

That is exactly what us couch sailors need. Side-by-side photos of the four launched boats... foils, hulls, wings... thank you so much. 

  • Like 1

Share this post


Link to post
Share on other sites
19 minutes ago, phill_nz said:

not that the basket is defiantly in the wrong area .. just that its a basket that has much less leeway for change

 

8 minutes ago, Ex-yachtie said:

Either that, or they know what they’re doing, as they demonstrated in AC35 and they’ve committed to something that has less flexibility but more speed. 

yehh .. thats what that bit says

Share this post


Link to post
Share on other sites
7 minutes ago, phill_nz said:

 

yehh .. thats what that bit says

Which would be fine if your post wasn’t based on the premise that “ETNZ has missed a trick”. Whilst you’re suggesting they’ve failed to identify opportunity, I’m saying they understand the opportunities available and have the  knowledge to pursue the right one.

Only time will tell. 

Share this post


Link to post
Share on other sites
4 minutes ago, Ex-yachtie said:

Which would be fine if your post wasn’t based on the premise that “ETNZ has missed a trick”. Whilst you’re suggesting they’ve failed to identify opportunity, I’m saying they understand the opportunities available and have the  knowledge to pursue the right one.

 

yes .. i should have written MAY have

Share this post


Link to post
Share on other sites
2 hours ago, Tornado-Cat said:

Flipper has the biggest distance between the foil and the bottom of the hull, Manta the shorter, and the difference is not small. Two different concepts.

Both boats have exactly the same distance from the foil pivot to the water line and centre line, the same foil max draught and the same max hull beam and foil beam.

So your point appears to be that the boat with the narrower waterline has the greater draft for the same displaced volume. Have a star!

Only one of the four boats is approaching the limits of the rules in this regard (minimum required second moment of area).

Share this post


Link to post
Share on other sites
1 hour ago, phill_nz said:

o put it another way

it looks like etnz has missed a trick with the foil design

all their eggs are irretrievably in the one basket

not that the basket is defiantly in the wrong area .. just that its a basket that has much less leeway for change

i still think different weather and sea conditions will favour different boats .. and will probably more control the final outcome of the series

Now, if you went the "way of the bulb", for your 20 % of change to have more omff, doesn't that make you a slave to the bulb forever more? Isn't that a big corner to end up in?

Share this post


Link to post
Share on other sites
1 hour ago, Varan said:

Flat bottomed girls make the foiling (or semi-foiling) world go 'round.

Get on your bikes & ride! Whoops, scratch that, not allowed, carry on.

  • Like 2

Share this post


Link to post
Share on other sites
10 minutes ago, barfy said:

Now, if you went the "way of the bulb", for your 20 % of change to have more omff, doesn't that make you a slave to the bulb forever more? Isn't that a big corner to end up in?

Nah you have 4 more,  It's just to test some ideas?

Share this post


Link to post
Share on other sites
1 hour ago, Varan said:

That is exactly what us couch sailors need. Side-by-side photos of the four launched boats... foils, hulls, wings... thank you so much. 

 

2 hours ago, Tornado-Cat said:

The 4 foilsCapture.thumb.PNG.9202d00ee6bfe488f8a0dbac8aafadc3.PNGCapture2.thumb.PNG.9851944d194e1eb7090ea186a6f8c072.PNG.e1bac18921da4eb9aa310c4d34ce9e2c.PNG

yysw268053.jpg.92f53e3c19934ee5920c0c6f53a65bf5.jpg.39b9deb028e7102c641eb0ba96844f81.jpg.8297639a48966ca684b79b5e27e0341e.jpg

 

Capture.PNG

Obviously kiwis odd man out with no bulb. Maybe holding back with a top secret version? Did they find some flaw with bulb design?

My guess is they did not want to "give away" the bulb issue early on, like not foiling too early (oops), but everyone else figured it out. Time will tell

Share this post


Link to post
Share on other sites
1 hour ago, Ex-yachtie said:

Which would be fine if your post wasn’t based on the premise that “ETNZ has missed a trick”. Whilst you’re suggesting they’ve failed to identify opportunity, I’m saying they understand the opportunities available and have the  knowledge to pursue the right one.

Only time will tell. 

 I am only pointing out that all of the other teams have already tested the type of foils on NZ (minus some wing tips).  They have ALL gone to the bulb type.  

NZ may have simulated something on that foil type that the others have not seen in calculations or testing, but I would doubt it.  

Every pre-release AC75 design drawing and promotional efforts show the NZ type of foils.  Do you really think that ALL three of the other teams missed some iteration of that foil type?  UK spent at least 90,000 man hours into just the design of their B1.

 

lr mini moon.jpg

t5.jpg

UK T5 2.jpg

mule.png

mule American-Magic-Flying.jpg

Share this post


Link to post
Share on other sites
12 minutes ago, zillafreak said:

 

Obviously kiwis odd man out with no bulb. Maybe holding back with a top secret version? Did they find some flaw with bulb design?

My guess is they did not want to "give away" the bulb issue early on, like not foiling too early (oops), but everyone else figured it out. Time will tell

That is ridiculous.  They can only make 6 foils and 2 are supposed to be just decoys?  Yea, right, go with that if you want....

Share this post


Link to post
Share on other sites
11 minutes ago, Herfy said:

UK spent at least 90,000 man hours into just the design of their B1.

90,000 man hours humanity will never get back!

Share this post


Link to post
Share on other sites