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And we have liftoff!!

I for one was happy to finally see an American team that didn’t just reek of assholes. Terry was a great bloke to have in front of the cameras and the intimate videos behind the scenes I found quite f

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17 hours ago, MaxHugen said:

It's surprising how much that "fat" mast creates an efficient profile. This is what my interpretation of what the sail profile looks like with 0° AoA, and a camber of 4% which is probably at or near the limit:

image.png.8afdaabc3e082b90e56405f57133d9cb.png

And it still produce a tiny bit of lift! 

CL is 0.297, CD is 0.006, for a L/D ratio of 47.   Zero CL doesn't occur until AoA is past -3°.

I wonder if this is where they're doing some work and maybe ditching the boom?  I know on the 72s that both Oracle and NZ were adding more width on the mast/wing in the front almost daily in the lower section...

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1 hour ago, 4pines said:

I wonder if this is where they're doing some work and maybe ditching the boom?  I know on the 72s that both Oracle and NZ were adding more width on the mast/wing in the front almost daily in the lower section...

I got the impression that both NZ and UK B2’s might have “batten”  booms, one for each skin. Better sail shape control down low and maybe the ability to artificially thicken the foil shape by pushing in and bulging the leeward batten whilst pulling and straightening the windward one?

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54 minutes ago, Stingray~ said:

The amount of mainsail down-low camber they can dial in aboard TR is amazing.. 

Watching Te Rehutai come in yesterday the mainsails get bagged pretty quickly no evidence of any boom just the control device nesting on the rear flight deck once docked mainsails appear reasonably light to man handle. 

Sadly on the cycle home to Poncenby the 140 year old St Stephens Church was well ablaze bugger.

NBCC7GLMEU4WYNU7O4TA7GOTXQ.thumb.jpg.6f14a695c3c2f8c8807ac0f36f1585d0.jpg

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1 hour ago, mikenz2 said:

Sure is... Are these new foils or the same? Been so long I can't remember!

 

P1220189-01.jpeg

P1220160-01.jpeg

Look the same or very close.  Those sure are very large torpedos compared to the other boats.  They most certainly have different modeling results than the other teams or have a different performance target (speed vs stability).

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If they have made some changes to the foils it is very subtle.  This would indicate that they are in the optimization stage and not throwing the ball around.  The other thing is the bulb looks more like a nuclear submarine with them being taller and narrower instead of the other teams going shorter and wide.

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3 hours ago, mikenz2 said:

Sure is... Are these new foils or the same? Been so long I can't remember!

P1220160-01.jpeg

I hadn't appreciated the cross-sectional size of the bulb until your pic put it into perspective!

When we see a good clear side-on pic we should get a fair idea of the foil section.

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13 minutes ago, The_Alchemist said:

If they have made some changes to the foils it is very subtle.  This would indicate that they are in the optimization stage and not throwing the ball around.  The other thing is the bulb looks more like a nuclear submarine with them being taller and narrower instead of the other teams going shorter and wide.

Yes they either very right or very wrong...

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2 hours ago, Ex-yachtie said:

I wondered the same but noticed from @mikenz2s photos that they launch without a boom on the boat, but retrieve with it on the deck. 

It was taking ages to get the mast stepped today, so I'm assuming it as a new rig or it had underdone significant changes. I had to leave before they got any sails out or lowered into the water. They're just sailing back now so I'll go check ;-)

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2 hours ago, Ex-yachtie said:

I wondered the same but noticed from @mikenz2s photos that they launch without a boom on the boat, but retrieve with it on the deck. 

Just think of the reaction in the UK camp if Patriot switches to a boomless mainsail?  That would be just another design feature of their B1 that they changed away from.  But in hindsight, UK’s B1 was not able to control the sail like LR or NZ can.

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3 hours ago, The_Alchemist said:

Seawolf Class stealth attack submarine.

 

Seawolf_class_submarine_1000_0001.thumb.jpg.6f5920af49dd6e6878b41bf871710dd0.jpg

 

I find AM's 'torpedo' approach surprising.

Submarines (and airliner fuselages) are shaped this way in order to make a very strong and light pressure vessel. If they didn't need to handle pressure and just wanted to minimise drag they would definately be another shape - typically a blended wing.

  • ...advantages of the BWB design includes 15–20% increased lift to drag ratio (L/D) due to reduced drag resulting from a 33% lower wetted surface area compared to a conventional tube and wing aircraft

https://www.researchgate.net/publication/292680419_Review_of_evolving_trends_in_blended_wing_body_aircraft_design

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The section between the foil arm and the foil bulb has been replaced on both sides. Foil appears to have less depth/width to it when it attaches to the bulb (could be reflections/optical illusion).

16th November:
1154999354_2020-11-16Starboard.thumb.jpg.c91e1c83b6848749d99efeb3ae93dd41.jpg

6th December:
1826309343_2020-12-06Starboard.thumb.jpg.bbace243924d24e649c15d76d20f6815.jpg

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1 hour ago, mikenz2 said:

The section between the foil arm and the foil bulb has been replaced on both sides. Foil appears to have less depth/width to it when it attaches to the bulb (could be reflections/optical illusion).

16th November:
1154999354_2020-11-16Starboard.thumb.jpg.c91e1c83b6848749d99efeb3ae93dd41.jpg

6th December:
1826309343_2020-12-06Starboard.thumb.jpg.bbace243924d24e649c15d76d20f6815.jpg

That’s a new bulb as well 

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9 hours ago, rh3000 said:

I find AM's 'torpedo' approach surprising.

Submarines (and airliner fuselages) are shaped this way in order to make a very strong and light pressure vessel. If they didn't need to handle pressure and just wanted to minimise drag they would definately be another shape - typically a blended wing.

  • ...advantages of the BWB design includes 15–20% increased lift to drag ratio (L/D) due to reduced drag resulting from a 33% lower wetted surface area compared to a conventional tube and wing aircraft

https://www.researchgate.net/publication/292680419_Review_of_evolving_trends_in_blended_wing_body_aircraft_design

Yes, that submarine is designed to cruise at below 1,000 ft of depth and hull strength is a major design feature.  But it is also designed to travel silently at high speeds which means no cavitation.  The sub reference is more of a "kinda looks like" comment.

Your data is a little misleading.  In those calculations, it compares a conventional plane with 4 under wing hanging jet engines and a tail to the BWB with trailing engines.  The foils do not require those additional appendages that add more drag.  Another issues is the design constraints of the AC rules.  The shape of the blended wing foils need to contain all of the ballast weight may not be optimized for drag.  Also, the bulb and foil design does not need to perform under the same extreme range of speeds as an airplane.

I agree, the BWB should be less drag in an ideal design.  But we have a constrained design space and it needs to perform over a range of conditions (wind speed, waves, stability, acceleration, max lift situations, max RM situations, etc...).  These are all design compromises that feed into the final design.

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30 minutes ago, Sailbydate said:

Pretty smart slog up the harbour by, Luna Rossa 2. She's still my pic for the, Challenger favourite.

The Prada Cup will be some contest.

 AM in strong conditions and secret VMG?
Luna Rosa least errors and slickest manoeuvres?
Ineos low wind quickest onto foils?

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7 hours ago, The_Alchemist said:

Yes, that submarine is designed to cruise at below 1,000 ft of depth and hull strength is a major design feature.  But it is also designed to travel silently at high speeds which means no cavitation.  The sub reference is more of a "kinda looks like" comment.

Your data is a little misleading.  In those calculations, it compares a conventional plane with 4 under wing hanging jet engines and a tail to the BWB with trailing engines.  The foils do not require those additional appendages that add more drag.  Another issues is the design constraints of the AC rules.  The shape of the blended wing foils need to contain all of the ballast weight may not be optimized for drag.  Also, the bulb and foil design does not need to perform under the same extreme range of speeds as an airplane.

I agree, the BWB should be less drag in an ideal design.  But we have a constrained design space and it needs to perform over a range of conditions (wind speed, waves, stability, acceleration, max lift situations, max RM situations, etc...).  These are all design compromises that feed into the final design.

Submarine hulls cavitating? Props and high-speed torpedos sure, but I can't see a submarines needing to worry about cavitation.

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16 hours ago, mikenz2 said:

The section between the foil arm and the foil bulb has been replaced on both sides. Foil appears to have less depth/width to it when it attaches to the bulb (could be reflections/optical illusion).

16th November:
 

6th December:
 

I took your two pic and tried to blend them together.  They are at slightly different angles, but you can see some subtle changes.  The top foil is the new one.

1620587780_Patfoil2020-12-06Starboardcomp.jpg.d8ba62ae9cdf9ad430199c9d277f2cec.jpg

The foil looks like to has been moved slightly forward and lower on the bulb.  They have removed the upward curve where the foil meets the bulb and foils might be narrower.

All of the reference lines have been removed which might indicate they are not as concerned about studying the flow anymore.  My guess is that this is basically their race foil, but they will make a major change to the bulb.  I am thinking that current bulbs a cover to hide the ultimate design.

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yup

subs are hugely worried about cavitation

mostly from the props

cavitation = noise ... noise = death

 

looks like the time was spent on internal controls ( lack of much external difference )

still a bit unsteady on her new? outfit

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26 minutes ago, rh3000 said:

My point was more that submarine hulls don't go fast enough to cavitate at the hull.

??? I'm sure its prop cavitation the subs are worried about. That's why the "Toshiba-Kongsberg scandal" happened where the Ruskies got high tech milling machines to build silent props during the Cold War.

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1 hour ago, rh3000 said:

My point was more that submarine hulls don't go fast enough to cavitate at the hull.

There's a cool video on YT where a schoolboy videoed his experiment: a flat round disk being pulled perpendicularly through the water on a thin bit of wire. He clearly demonstrated cavitation occurring at... 10 knots.

This illustrates that water pressure is affected by not just velocity, but also form.

There was a rare mention regarding the latest generation of US subs that they had to address cavitation in "areas other than just the propeller", or something to that effect. As usual, he didn't give much away!  But I suppose it could be virtually any protrusion such as diving planes etc, that might lead to cavitation.

And the real top speed of these subs is almost certainly higher than what they quote.

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3 hours ago, phill_nz said:

yup

subs are hugely worried about cavitation

mostly from the props

cavitation = noise ... noise = death

Is there a rule about refraining from commenting on this UNLESS you’ve seen Red October? I think there should be. 

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2 hours ago, zillafreak said:

??? I'm sure its prop cavitation the subs are worried about. That's why the "Toshiba-Kongsberg scandal" happened where the Ruskies got high tech milling machines to build silent props during the Cold War.

I'm sure the DeVos clan will be happy to send a few of their mercs over to take care of that. 

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2 minutes ago, The_Alchemist said:

AM is using Evinrudes.   TE says they are blowing them up trying to keep up with Patriot.

Actually, almost in spite of myself, I am a bit of a nationalist - and usually root for the USAeans. 

But not the DeVos clan. 

No how . . No way 

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1 minute ago, AJ Oliver said:

Actually, almost in spite of myself, I am a bit of a nationalist - and usually root for the USAeans. 

But not the DeVos clan. 

No how . . No way 

I am rooting for AM and NYYC in spite of the tainted DeVos money.  I try to look at it as rooting for Terry Hutchison and the AC tradition.

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49 minutes ago, Ex-yachtie said:

Is there a rule about refraining from commenting on this UNLESS you’ve seen Red October? I think there should be. 

im not the type to memorize movie scenes so i have no idea of this is or isn't referenced in the red october movie

i spent enough time listening to the never ending pings of a search sonar to learn a little about subs irl ( not a sonarman but a few places have a speaker monitoring them on a frigate )

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4 minutes ago, The_Alchemist said:

  I try to look at it as rooting for Terry Hutchison and the AC tradition.

I'm just imagining that Roger Penske is more involved than he probably actually is.

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5 minutes ago, The_Alchemist said:

I am rooting for AM and NYYC in spite of the tainted DeVos money.  I try to look at it as rooting for Terry Hutchison and the AC tradition.

That is a factor to consider for sure . . 

and actually last time I rooted for the Kiwis vs Larry Ellison 

even though he had some fine people on his team. 

I just have this thing about billionaires 

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12 minutes ago, AJ Oliver said:

Actually, almost in spite of myself, I am a bit of a nationalist - and usually root for the USAeans. 

But not the DeVos clan. 

No how . . No way 

The DeVos clans sins pale in comparison to the baby bombing Emirates.

Go the Handbags.

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13 minutes ago, AJ Oliver said:

 

I just have this thing about billionaires 

Yer watching the wrong sport then dude.

Better that money trickles down to the sailors, builders, shore teams, etc than go to a PAC or stay in their bank account.

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29 minutes ago, phill_nz said:

im not the type to memorize movie scenes so i have no idea of this is or isn't referenced in the red october movie

i spent enough time listening to the never ending pings of a search sonar to learn a little about subs irl ( not a sonarman but a few places have a speaker monitoring them on a frigate )

Dude, you should watch Red October. 

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2 hours ago, Ex-yachtie said:

Is there a rule about refraining from commenting on this UNLESS you’ve seen Red October? I think there should be. 

I've always been a proponent of an unlimited submarine AC class. The US might have a wee bit of an advantage, I guess...

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13 hours ago, The_Alchemist said:

It all depends on which snapshot you look at, I think they are in the same stance as before.

883212107_ScreenShot2020-12-06at11_42_27AM.thumb.jpg.71ca19ae5710c139d14e617bc23fb8d5.jpg2113679842_ScreenShot2020-12-06at11_43_39AM.thumb.png.898e39ad3e540646831ef505d7a878d8.png

That is one mean looking boat!

Uh oh! Someone's broken out the dreaded yellow lines!

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I wouldn't be surprised if AM surprised the challengers. She's been on the water the longest, always looks stable and seems to tack and gybe well. Of the challengers they are the least in your face going about their business quietly. Whilst her hull doesn't appear as extreme as the others it still looks like a very fast boat. Only 10 days now until we see some racing. Who knows what the future holds?

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4 hours ago, zillafreak said:

??? I'm sure its prop cavitation the subs are worried about. That's why the "Toshiba-Kongsberg scandal" happened where the Ruskies got high tech milling machines to build silent props during the Cold War.

yeah I know.. my point is, it's not the hull shape that is staving cavitation, it's the prop shape.. we are going well off piste here from my original assertion that a nuclear sub tube shape isn't optimal for best drag, lowest cavitation shape... :D

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3 hours ago, MaxHugen said:

There's a cool video on YT where a schoolboy videoed his experiment: a flat round disk being pulled perpendicularly through the water on a thin bit of wire. He clearly demonstrated cavitation occurring at... 10 knots.

This illustrates that water pressure is affected by not just velocity, but also form.

There was a rare mention regarding the latest generation of US subs that they had to address cavitation in "areas other than just the propeller", or something to that effect. As usual, he didn't give much away!  But I suppose it could be virtually any protrusion such as diving planes etc, that might lead to cavitation.

And the real top speed of these subs is almost certainly higher than what they quote.

yeah we are way off piste... :D

My original assertion was simple - subs are dead round much more because of pressure vessel needs than a rounded cylinder actually being a perfect drag shape, especially with needing to create lift surfaces.

The idea that a submarine is a good analogy for optimal foil shape is a misapprehension. 

I still stand by that assertion. :D

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4 minutes ago, rh3000 said:

yeah we are way off piste... :D

My original assertion was simple - subs are dead round much more because of pressure vessel needs than a rounded cylinder actually being a perfect drag shape, especially with needing to create lift surfaces.

The idea that a submarine is a good analogy for optimal foil shape is a misapprehension. 

I still stand by that assertion. :D

Agreed.    Now, back to AC75s...   ;)

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26 minutes ago, terrafirma said:

I wouldn't be surprised if AM surprised the challengers. She's been on the water the longest, always looks stable and seems to tack and gybe well. Of the challengers they are the least in your face going about their business quietly. Whilst her hull doesn't appear as extreme as the others it still looks like a very fast boat. Only 10 days now until we see some racing. Who knows what the future holds?

Yeah, you'd have to offer me rather good odds to bet against them. But as you said, "only 10 days now".

( "Are we there yet? Are we there yet? Are we there yet? Are we there yet? Are we  ........" )

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9 hours ago, Ex-yachtie said:

Dude, you should watch Red October. 

No you shouldn't. It's just a piece of Cold War hysterical propaganda. 

The USSR was never really much of a threat at all. 

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10 hours ago, AJ Oliver said:

That is a factor to consider for sure . . 

and actually last time I rooted for the Kiwis vs Larry Ellison 

even though he had some fine people on his team. 

I just have this thing about billionaires 

Well, then you better find another sport because the AC is the sport of billionaires!  ha ha...  

Just look at it as that the team is fleecing the billionaire out of their money and putting it to use entertaining you.

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8 hours ago, rh3000 said:

yeah we are way off piste... :D

My original assertion was simple - subs are dead round much more because of pressure vessel needs than a rounded cylinder actually being a perfect drag shape, especially with needing to create lift surfaces.

The idea that a submarine is a good analogy for optimal foil shape is a misapprehension. 

I still stand by that assertion. :D

hey, I agree and I was the one that posted the sub pic....   round also gives the least amount of surface area per volume (of course drag may be affected by the ratio of leading edge area vs other area...., etc...).  I just saw a sub when I first saw that picture of the foils. 

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