Tornado-Cat

Boats and foils comparison

Recommended Posts

Ac50 adopted the bow down attitude generally for downwind, one explanation being that they were set for the upwind, however TNZ was seen sailing upwind with bow down. For the AC75 I don't know if we can see a general attitude yet, but the fans will probably tell the contrary.

Share this post


Link to post
Share on other sites
On 1/19/2020 at 10:25 PM, rh3000 said:

In many ways these foil designs are converging... ETNZ still appears to be the most different...

I don’t understand: in Oracle’s post mortem after AC35, they concluded that a main ETNZ’s winning factor had been the risk (and a huge risk it was, remember the crack that could not be repaired on the one set of light air foils?) they had taked in adopting foils much thinner than the competition ...

Share this post


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

What max beam did you calculate ?

image.png.5456ba96d0de3decb4b35ce324bc5ac4.png

from tip to tip of foils when max extended and max foil tip allowance is 15302 +- the tolerance allowed in the in the foil cant axis pivots which is 2mm each

  • Like 1

Share this post


Link to post
Share on other sites

The interview with Max in the LR threads is very good.  
 

Max said in the interview that all teams will converge to the same foil design.  He also said that once all teams learn how to maneuver the boats, he thinks flat out boat speed will be winner.  He also discusses pre-start maneuvers.

Share this post


Link to post
Share on other sites
48 minutes ago, The_Alchemist said:

Max said in the interview that all teams will converge to the same foil design.  He also said that once all teams learn how to maneuver the boats, he thinks flat out boat speed will be winner. 

Hardly earth shattering insights...

Share this post


Link to post
Share on other sites

ETNZ with no bulb....LR with three on their foils...that will be quite a convergence :blink:

  • Like 1

Share this post


Link to post
Share on other sites

Oh yeah foiling monos are sooooo 2019 ...

Share this post


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

ETNZ with no bulb....LR with three on their foils...that will be quite a convergence :blink:

Convergence doesn’t happen at the start. In fact, being different at the start is kinda a prerequisite for convergence.

Give them long enough and they’ll all end up in the same corner of the rule. 

Share this post


Link to post
Share on other sites
8 hours ago, wind_apparent said:

I’m more interested in these two things right now.  All the AC foil stuff is rehashed.

AB31AD69-285D-45B0-A3EB-2F0BEF87E0AA.jpeg

So the "barbed" nose on the torpedo trips the flow into cavitation that envelopes the whole torpedo to reduce its drag? Is that the basic principle?

Share this post


Link to post
Share on other sites
1 minute ago, wind_apparent said:

Yeah, that how torpedos and to an extent submarines work. Induced cavitation and super cavitation. 

20 years back I sailed with a guy in this field. But things will have moved a long way on in 20 years......

He was super restricted in what he could talk about - but the conundrum that he planted was how they were trying to put unlimited horsepower (nuclear reactor) through a propeller that would need to both apply this horsepower - yet remain stealthy - cavitation was easy to achieve - but kinda gave the Subs position away....... So highly undesirable.

Where are they now with this conundrum - I thought I read that Torpedos are basically "in water" rockets now - but that solution does not apply to the sub.

Share this post


Link to post
Share on other sites

Hunting for Red October eh?

CFB4172B-7B45-48A7-AFAC-AC10D5764EE5.jpeg

Share this post


Link to post
Share on other sites
11 hours ago, Ex-yachtie said:

Hardly earth shattering insights...

Currently 3:1 against that happening, too. Hardly favourable odds, unless he knows torpedoes are training wheels.

Share this post


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

the conundrum that he planted was how they were trying to put unlimited horsepower (nuclear reactor) through a propeller that would need to both apply this horsepower - yet remain stealthy - cavitation was easy to achieve - but kinda gave the Subs position away....... So highly undesirable.

Supercavitating torpedos are a very different thing.

Shkval is the original, its a rocket that runs 200+kt, idea being that it closes range before the victim can get out of the way/shoot a response. (also initial version was nuke...)

3 hours ago, Boink said:

So the "barbed" nose on the torpedo trips the flow into cavitation that envelopes the whole torpedo to reduce its drag?

Yep, here's the Shkval nose

As I understand it vents some of the rocket exhaust to help create the bubble & the nose plate can be angled to adjust the bubble shape -> steer.

Shkval_head.jpg

And aft, supposedly the fins were springloaded to skim the inside of the bubble

Shkval_rear.jpg

 

Share this post


Link to post
Share on other sites

they couldnt figure out a guidance system for it ( it lives entirely inside its bubble )

so not so much fire and forget as fire and pray

 

  • Like 1

Share this post


Link to post
Share on other sites

The foil bulbs are a clever method to introduce gases to begin a super cavitation cycle. 

I've been predicting this for months. No one listens :blink:

  • Like 1

Share this post


Link to post
Share on other sites

so what you are saying is completely useless concept for a foiling boat

1: no front nozzle control allowed, only flaps are allowed to be used in AC75,

2: large (unknown) amounts of air are required to be pushed out the front of the foil/bulb ... arnt only hydraulic, electric and mechanical functions allowed in AC75?

3: once an encasing bubble forms you have no directional control (you might need to rely on the ground effect:lol:)

4: is there still a rule that any technology utilised in the cup needs some form of an open patent so not to disadvantage any competitor? or was that just the last cup? seem military secret technology may not be allowed

I just don't see any plausible way it could be used within the rules even if it was available to them

 

Share this post


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

so what you are saying is completely useless concept for a foiling boat

1: no front nozzle control allowed, only flaps are allowed to be used in AC75,

2: large (unknown) amounts of air are required to be pushed out the front of the foil/bulb ... arnt only hydraulic, electric and mechanical functions allowed in AC75?

3: once an encasing bubble forms you have no directional control (you might need to rely on the ground effect:lol:)

4: is there still a rule that any technology utilised in the cup needs some form of an open patent so not to disadvantage any competitor? or was that just the last cup? seem military secret technology may not be allowed

I just don't see any plausible way it could be used within the rules even if it was available to them

 

1 it's not control, it's not using work.

2 it doesn't fit under control systems: Control systems
21.1 The adjustment of control surfaces, where permitted in Rules 15, 16, 19 and 20 must only be controlled
by crew:
(a) by direct contact of the crew on a control surface; or

3 not true, sail rocket did fine. All the torpedoes do fine. Read the most basic premise of super cavitation on wiki.

4. Find me the rule,not my job.

 

 

 

downloadfile.jpg

Share this post


Link to post
Share on other sites

Sail rockets foil ventilated the trailing edge from surface to tip 

it still had water flow over the front and sides 

Share this post


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

1 it's not control, it's not using work.

2 it doesn't fit under control systems: Control systems
21.1 The adjustment of control surfaces, where permitted in Rules 15, 16, 19 and 20 must only be controlled
by crew:
(a) by direct contact of the crew on a control surface; or

3 not true, sail rocket did fine. All the torpedoes do fine. Read the most basic premise of super cavitation on wiki.

4. Find me the rule,not my job.

 

1: looks like control to me (and mentions it in a video)Shkval_head.thumb.jpg.5e16e586b2512d71934d0e5d7b67e8bd.jpg

2: 13.3 Foil systems: (a) shall only comprise mechanical, electrical and hydraulic components,

so my point is they cannot 'pump' air down there with crew power. noting the amount of air in the torp above is taken from one on the inboard rocket exhausts.

3: yea seem great for things that go in straight lines, the torp is a 'fire and pray system'

4: i might be confused with 'commercial products section 8' - I was under the impression there was an early issue with ETNZ getting there AC50 built at southern spars where southern has some building techniques that weren't allowed to be used by other boat builders and therefore weren't allowed to use the techniques ... sorry for assuming the rule was brought over to the latest cup - just found this quote " Because of the tight restrictions on the type of fibre used in the build, Southern were unable to use their most advanced carbon technology. " so guessing it may have been a density issue?

 

Share this post


Link to post
Share on other sites

control yes .. it tips into the stream .. guidance no

it relies ( from memory ) on inertial guidance systems ..so no corrections or updates are used / possible

to explain

it can only try to keep on the course it thinks its on

it can easily do a 360 without knowing it

its why they first thought that the russian sub that went down ( cant recall the name ) had killed itself firing one of these

Share this post


Link to post
Share on other sites
29 minutes ago, wind_apparent said:

this Is a torpedo with wings, and a strut.  Seems to work pretty good.... I’m sure it could be better. 

562D3A7A-E228-4B87-80E2-81AFB4D447DD.jpeg

100% yes 

there are comfortably better and  faster  kite foils out there, LP isn’t a great place to start, sure plenty to improve on but there are 3 year old foils faster than that. 

Share this post


Link to post
Share on other sites
2 hours ago, wind_apparent said:

As far as induced cavitation.... the wind is pretty strong at 35kts.  Who likes hood scoops? #thisguy

E380DE09-9632-41CA-A0D2-7D97EC1BB378.jpeg

I prefer a sleeper to the muscle look.

Share this post


Link to post
Share on other sites
16 minutes ago, wind_apparent said:

I mean. It’s already got pirellis on it. It’s probably a Ferrari 

I had something more like this in mind, actually.

Screen Shot 2020-02-18 at 8.08.40 AM.png

Share this post


Link to post
Share on other sites

if it only had a rotary i'd probably have to go somewhere private for a few minutes

Share this post


Link to post
Share on other sites
6 minutes ago, MR.CLEAN said:

if it only had a rotary i'd probably have to go somewhere private for a few minutes

The Furai did!

Then Top Gear happened to it... another reason I hate those guys

 

Share this post


Link to post
Share on other sites
2 hours ago, wind_apparent said:

Rip

You said it.

Must be a new SA record, congrats.

20200218_111523273.thumb.jpeg.0fb404a24fef9a6675599dc55d952eba.jpeg

Share this post


Link to post
Share on other sites

^ Not AC - so wrong thread, wrong forum

Maybe start a new one somewhere else for those paid to stay out of the AC and compete in handicapped races.

 

  • Like 1

Share this post


Link to post
Share on other sites

I actually think that's pretty interesting, it's rare to get insight into details like this.  I don't like Larry Ellison but I'm not going to shit on interesting sailing.  

The rake angle range seems a lot bigger than  I would have expected, did they get longer rams from the AC days?

  • Like 1

Share this post


Link to post
Share on other sites

They redid a lot of the systems iirc  incl rake for rudders and foils, substituted pumps for some grinders.

Share this post


Link to post
Share on other sites
15 hours ago, nav said:

^ Not AC - so wrong thread, wrong forum

Maybe start a new one somewhere else for those paid to stay out of the AC and compete in handicapped races.

 

Bunch of Olympic medals says you can do both f50 and AC 

Share this post


Link to post
Share on other sites
19 hours ago, nav said:

^ Not AC - so wrong thread, wrong forum

Maybe start a new one somewhere else for those paid to stay out of the AC and compete in handicapped races.

 

True story, take it to the "recycled AC boats forum", where they are still rotating the entire wing for some archaic reason.

Share this post


Link to post
Share on other sites
18 hours ago, RMac said:

I actually think that's pretty interesting, it's rare to get insight into details like this.  I don't like Larry Ellison but I'm not going to shit on interesting sailing.  

The rake angle range seems a lot bigger than  I would have expected, did they get longer rams from the AC days?

Yawn

Share this post


Link to post
Share on other sites

From the AC Facebook page, but I don't agree with their comment.

"Central pod, foredeck extension, dual trenches or a divided cockpit? Whatever you call it, the teams all appear to be on the same page in this area of AC75 . But who did it best with B1 ?"

87189619_2614070932204695_3345779227231256576_o.thumb.jpg.760fb400b4854eebb3aa3bdc0e123b0b.jpg

Share this post


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

From the AC Facebook page, but I don't agree with their comment.

"Central pod, foredeck extension, dual trenches or a divided cockpit? Whatever you call it, the teams all appear to be on the same page in this area of AC75 . But who did it best with B1 ?"

 

You don't think they all have a variation of a "central pod, foredeck extension, dual trench or a divided cockpit"?

Tell me, which one doesn't?

Share this post


Link to post
Share on other sites

Please excuse my ignorance, but do any of you nerds know which boat seems to have the set up with the most lift? 

Splashdowns on these things seem to happen almost exclusively during the foil transition.  As the sailworld article suggested, when the opposing foil is lifted and represents minimal lift and plenty of drag. If the boat is set up with low drag, low lift foils, then it amplifies this.  It seems to make sense that with this low drag setup, more lift needs to be generated through this transition phase, to counteract the lack of lift and increased drag of the other foil, and this is best achieved by altering the boats pitch, and changing the foil angle of attack.  A low drag form at zero yaw generally aquires relatively more drag and lift as its angle of attack is changed.  It also means greater deceleration.  Is the nose down aspect of some boats perhaps a result of tuning the foils and hull so as to maintain the desired lift v drag equation when they have to bring the bow up to generate enough angle of attack and subsequently lift, to compensate for the relative lack of lift in the foils when travelling in a straight line?  It seems risky, too much bow up and you simultaniously get massive aero drag and lift at the same time as massive hydro drag and lift.  Boat goes up, foil stalls, SPLASH! 

Theres been a bunch of times weve seen Te Aihe fang into a tack, take off, stall, and crash down.  Haven't really seen it from anyone else.  Either their control systems are poo, which given their advantage last round, I doubt, or.... I reckon TNZ is running a super fast low drag setup, but right on the edge of what they can wrestle into constancy.  

But I legit know shit about boats, only bicycle aero, so roast me if its deserved

 

 

 

  • Like 2

Share this post


Link to post
Share on other sites

Well that's an interesting analysis on some of what we have been seeing, it would even gel with their 'let's throw the ball out as far as possible' line, but there are lots of other possible explanations too so.......time will tell maybe

Share this post


Link to post
Share on other sites

Nick says endplating the hull to the water double wingspan?  Seems to suggest it is quite important!

Maybe we will see hulls with bulge at the bottom? Like ETNZ and LR?

Share this post


Link to post
Share on other sites

the biggest thing i got from the interviews was

almost all theories postulated here were .... wrong

end plating under the hull .. couldn't happen nope .. nothing to do with it ... wrong

best displacement hulls LR NZ .. nope wrong

best aero hulls usa fracs ... nope wrong

hydro drag way more important .. nope wrong its 50 / 50

 

  • Like 3

Share this post


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

the biggest thing i got from the interviews was

almost all theories postulated here were .... wrong

end plating under the hull .. couldn't happen nope .. nothing to do with it ... wrong

best displacement hulls LR NZ .. nope wrong

best aero hulls usa fracs ... nope wrong

hydro drag way more important .. nope wrong its 50 / 50

 

What do those guys know...

Share this post


Link to post
Share on other sites

if the eggspurts here are to be believed

not much .. and most of that will be wrong as well

Share this post


Link to post
Share on other sites
2 hours ago, phill_nz said:

the biggest thing i got from the interviews was

almost all theories postulated here were .... wrong

end plating under the hull .. couldn't happen nope .. nothing to do with it ... wrong

best displacement hulls LR NZ .. nope wrong

best aero hulls usa fracs ... nope wrong

hydro drag way more important .. nope wrong its 50 / 50

Accurately measuring foils from photographs..........nope wrong.

  • Like 1

Share this post


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

Accurately measuring foils from photographs..........nope wrong.

If only someone could design and manufacture something like this

https://connect.hexagongeosystems.com/BLK3D-construction-UK?&utm_medium=paidsearch&utm_source=google&utm_campaign=UK-BX_EN_2019_BLK3D_building_construction&utm_content=message4&gclid=EAIaIQobChMIv4nYprmF6AIVhbTtCh2_lALtEAAYASAAEgKZg_D_BwE

Share this post


Link to post
Share on other sites

as a guess it needs hard corners and straight lines .. thickness on deliberately non reflective gentle compound curves might be a little beyond its capabilities

Share this post


Link to post
Share on other sites
20 minutes ago, enigmatically2 said:

If only someone could design and manufacture something like this

It's an off the shelf device so you could just go out and buy it. Being a Leica it probably costs an arm and a leg. However as Phil alludes to, this device is for measuring straight lines in a construction environment, not the subtle curves of a T-foil. Professional-grade accuracy..... Whatever that means - I couldn't find any numbers on that site, but as Martin Fisher says - 1mm can mean the difference between a good and a bad foil.

Share this post


Link to post
Share on other sites

It doesn't take much to discover it costs under £500.

Accurate photogrammetry requires features in the images for the software to correlate and determine parallax between different images. It also needs a calibrated lens and pretty high–end software. Digital mapping applications have been doing it for over 30 years, Google maps is a more recent example. The same technology can be applied to images of any object.

  • Like 1

Share this post


Link to post
Share on other sites

I know its off the shelf device. I was being sarcastic.

That is a relatively cheap portable example of the genre. Other more accurate devices exist. If you can get shots at the right angles then the thickness and curves are no problem..

Other products just use software based on DSLR images. 

There are various constraints, but nothing unsurmountable.

Accuracy is dependent on a number of features. But is certainly accurate enough for these purposes as they can then feed the design into their models to see the expected performance

 

Share this post


Link to post
Share on other sites
On 2/16/2020 at 6:27 AM, Lickindip said:

image.png.5456ba96d0de3decb4b35ce324bc5ac4.png

from tip to tip of foils when max extended and max foil tip allowance is 15302 +- the tolerance allowed in the in the foil cant axis pivots which is 2mm each

A foil can't be at the very top or bottom of the allowed area unless it has no flaps (or if at the top they only go down and if at the bottom they only go up).

The entire foil, with the flaps at their extremes, must fit in the area.

Share this post


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

Nick says endplating the hull to the water double wingspan?  Seems to suggest it is quite important!

Maybe we will see hulls with bulge at the bottom? Like ETNZ and LR?

Yeah was fascinating...

Shirley's podcast is worth about a years worth of conjecture on here...

Hopefully the objective, cerebral and real perspectives shared by the four designers puts to bed some of the innuendo and scuttlebut that a few trolls like to peddle in :-)

  • Like 4

Share this post


Link to post
Share on other sites

Yet not a single mention of ground effect either .. where have they all gone wrong ;-)  

Share this post


Link to post
Share on other sites
12 hours ago, Kiwing said:

Nick says endplating the hull to the water double wingspan?  Seems to suggest it is quite important!

Not quite. Perfect endplating of an airfoil doubles the aspect ratio vs. no endplating at all , no news there.  But mainsail seal on boat deck already achieves a good portion of endplating, narrow hull/water air gap further improves it, although still “not perfect”- the question is by how much

Share this post


Link to post
Share on other sites
On 1/27/2020 at 11:04 AM, nav said:

.......... presumably any gap under the keel must lead to less than 'perfect root seal'? 

So how to quantify that. What is the equivalent aspect ratio with a 5cm gap, 20cm, 50cm etc etc?

That will tell us if it's a/ significant enough to chase and b/ realistically achievable in a racing situation

 

Share this post


Link to post
Share on other sites

Interesting to hear that AM was obsessed with just getting a simple to sail B1 on the water as fast as possible.  They really took a hit from the delays on the foil arms!  They took shortcuts on the design in order to begin building as soon as possible, but lost that sailing time and were already locked into building their first hull.  There designer said that further design refinements were planned to be made on B2.  That would explain the “simple” design solutions they have on B1 that everyone has been talking about.

  • Like 1

Share this post


Link to post
Share on other sites
18 hours ago, Priscilla said:

This is what happens when you get experts involved.

DF445860-638C-46C8-8F8F-74C9BDFDCF66.jpeg.813008144edfedbc0a66d8d5b1edef3c.jpeg

Well, that'll never work for starters.... can't even foil...

Share this post


Link to post
Share on other sites

Share this post


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

Interesting to hear that AM was obsessed with just getting a simple to sail B1 on the water as fast as possible.  They really took a hit from the delays on the foil arms!  They took shortcuts on the design in order to begin building as soon as possible, but lost that sailing time and were already locked into building their first hull.  There designer said that further design refinements were planned to be made on B2.  That would explain the “simple” design solutions they have on B1 that everyone has been talking about.

That can’t be right. TH said they were shit hot. 

  • Like 1

Share this post


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

Links not working. HELP!

Curious.  Links seem to be fine here...  I'm listening to the first podcast now.

Share this post


Link to post
Share on other sites

for sure they have thrown a lot of light on the subject

must be why the trolls havnt been seen

Share this post


Link to post
Share on other sites

Interesting that according to Martin Fischer, LR and ETNZ chose the design "together". Both design teams worked very closely together to not only choose the boat, but also write the Class Rule. So for all Patrizio's concerns he raised about the Kiwi's choosing a boat that was too complex, it sounds like he has his own design team to blame as much as he does the Kiwi team.

Share this post


Link to post
Share on other sites

What’s the name of the podcast? The links don’t work for me. 

Share this post


Link to post
Share on other sites

Excellent and interesting podcasts. Some thoughts

1) if the hustle was purely about endplating, why has no one just gone for a simple skeg. There is more to it than that

2) if the teams can only get less than 1 it more as someone said, they will all be close. That means sailing skills will be important which I am glad of

3) I hope it doesn't come down to someone guessing the weather and thus right foils

4) AMS conventional boom (which I like) seems to just have been a desire for simplicity on B1. Ah well. Still no explanation of Ineos' solution

5) would like to know more of what is in those top-section of masts 

Share this post


Link to post
Share on other sites
37 minutes ago, enigmatically2 said:

Excellent and interesting podcasts. Some thoughts

1) if the hustle was purely about endplating, why has no one just gone for a simple skeg. There is more to it than that

2) if the teams can only get less than 1 it more as someone said, they will all be close. That means sailing skills will be important which I am glad of

3) I hope it doesn't come down to someone guessing the weather and thus right foils

4) AMS conventional boom (which I like) seems to just have been a desire for simplicity on B1. Ah well. Still no explanation of Ineos' solution

5) would like to know more of what is in those top-section of masts 

Certainly guessing the right foils might be very important (in particular if the wind is on the foiling limit).

 

I also find the top section of the mast interesting. Would it be allowed with a horizontal top section (like the end of some airplane wings)?

Share this post


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

Interesting that according to Martin Fischer, LR and ETNZ chose the design "together". Both design teams worked very closely together to not only choose the boat, but also write the Class Rule. So for all Patrizio's concerns he raised about the Kiwi's choosing a boat that was too complex, it sounds like he has his own design team to blame as much as he does the Kiwi team.

Just because you were a contributor, doesn’t mean you agree with the original design concept.  Being a member of a team means you give your best to help the team succeed even if you think it went in the wrong direction.

As you pointed out, LR and NZ had several months head start in the design of their B1’s over the other teams.

Share this post


Link to post
Share on other sites
5 hours ago, enigmatically2 said:

Excellent and interesting podcasts. Some thoughts

1) if the hustle was purely about endplating, why has no one just gone for a simple skeg. There is more to it than that

2) if the teams can only get less than 1 it more as someone said, they will all be close. That means sailing skills will be important which I am glad of

3) I hope it doesn't come down to someone guessing the weather and thus right foils

4) AMS conventional boom (which I like) seems to just have been a desire for simplicity on B1. Ah well. Still no explanation of Ineos' solution

5) would like to know more of what is in those top-section of masts 

I also wonder why we haven’t seen AM test a simple skeg like extension to see if it makes a difference.  They could make a strip and just stick it to the hull and then remove it.   The last video does show Defiant foiling real close to the water, maybe they are close enough to get enough end plating.  I think the AM designer said there were different ways to accomplish this end plating.

Share this post


Link to post
Share on other sites

So now I see the reason for the large bulb. Unlimited number of wings can be used if <20% total wing weight. ETNZ doesn't have that option.

Consequently, the boat’s overall center of gravity is low for low-speed handling. Teams are only allowed to build six wings, but are allowed to change up to 20 percent of the wing weight. Three of the four teams have elected to integrate bulbs into their wing designs. It’s conceivable that 80 percent of the wing weight is in these bulbs, which would allow the three teams to plug multiple wing designs into these same bulbs without them counting toward the six-wing limit.

Share this post


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

Just because you were a contributor, doesn’t mean you agree with the original design concept.  Being a member of a team means you give your best to help the team succeed even if you think it went in the wrong direction.

As you pointed out, LR and NZ had several months head start in the design of their B1’s over the other teams.

They withdrew from the last cup when they didn't agree with the concept of a 50ft Cat.

Share this post


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

Teams are only allowed to build six wings, but are allowed to change up to 20 percent of the wing weight.

only 6 foils that must all stay within 20% of the original launch foils

 

Foil wings Open 6 20% mass

For components listed in Rule 5.1 that have a “Change allowance” mass percentage:
(a)
(b)
5.11
When such a component is first declared according to Rule 5.5, 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.
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 component; and
(ii) a common portion of at least 80% of the mass of the original component must remain un-
modified and must match all declared versions of the component.
(c) The portion of mass of a component that matches another version of that component is determined
by aligning the unmodified portion of the original and modified components and determining the
mass of all regions where the material substance remains unmodified and in the same place in both
versions of the component.

 

it does allow them to make more radical changes within the 20% allowance

Share this post


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

Just because you were a contributor, doesn’t mean you agree with the original design concept.  Being a member of a team means you give your best to help the team succeed even if you think it went in the wrong direction.

As you pointed out, LR and NZ had several months head start in the design of their B1’s over the other teams.

They are the challenger of record and signed the protocol. I think that counts as agreeing with the design concept.

Share this post


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

only 6 foils that must all stay within 20% of the original launch foils

 

Foil wings Open 6 20% mass

For components listed in Rule 5.1 that have a “Change allowance” mass percentage:
(a)
(b)
5.11
When such a component is first declared according to Rule 5.5, 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.
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 component; and
(ii) a common portion of at least 80% of the mass of the original component must remain un-
modified and must match all declared versions of the component.
(c) The portion of mass of a component that matches another version of that component is determined
by aligning the unmodified portion of the original and modified components and determining the
mass of all regions where the material substance remains unmodified and in the same place in both
versions of the component.

 

it does allow them to make more radical changes within the 20% allowance

I think that’s what he said.

Share this post


Link to post
Share on other sites
2 hours ago, zillafreak said:

It’s conceivable that 80 percent of the wing weight is in these bulbs, which would allow the three teams to plug multiple wing designs into these same bulbs without them counting toward the six-wing limit.

yeh i quoted the wrong bit

read it with that bit instead

 

Share this post


Link to post
Share on other sites

Interesting thing is that the designers of the bulbed foil wings say the bulbs are just there to get the mass up, as they choose tiny foils - nothing to do with interchangeability as suggested here....

  • Like 2

Share this post


Link to post
Share on other sites

There doesn't seem to be any point in having a bulb just to give you the option of trying out multiple tips if a foil with no bulbs is faster. All you're doing is wasting time and money.

I think ETNZ have nailed it ..... Use the hawk to develop the foils, whilst Flipper is in transit. Am I correct in saying that there's no limit on how many foils they can use on the test boats? The arms onthe hawk appear to be much closer in design and size to the race boat size than we've seen on the other test boats so I would have thought any data gathered would be much more meaningful and could be applied to the big boats foils with a high level of confidence.                                                      

     I guess the other teams did some foil development on their  test boats as well, but they've not been reported as being out recently so that's obviously stopped.

Share this post


Link to post
Share on other sites

They can change 20% of their existing main foils as well.

Quite enough to dramatically change there performance!

Share this post


Link to post
Share on other sites