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#401 floater

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Posted 22 July 2014 - 03:42 PM

I guess it's not certain that four is draggier than three. It's worth keeping in mind that the kink in the dihedral is likely draggier than the straighter anhedral foil.

But what is more interesting - perhaps the ultimate speed of the anhedral is higher?

My WAG is that cavitation may hit the dihedral on the inside of the radius. And because the anhedral has a larger radius - perhaps a greater ultimate speed?

#402 McGyver

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Posted 22 July 2014 - 06:16 PM

One good question is why it took so long for foils to show up on sailboats.  This ferry was in use off Buenos Aires over 40 years ago.

 

 

100_1236.JPG

 

ALISCAFO_TIPO_SIRENA_.jpg



#403 Doug Lord

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Posted 22 July 2014 - 08:13 PM

Monitor was designed and built in the USA in the early 50's-about 60 years ago. At the time it was the most successful sailing hydrofoil ever. It was capable of foiling tacks and gybes and had a unique foil control system using shroud tension among other things. This is the first video I've ever seen of the boat:
More info from foils.org:

11 Jan 98] The following is an extract from a book that I wrote some years ago about hydrofoils. From "Ships That Fly" : MONITOR -- All of Gordon Baker's mechanical genius was not expended on military hydrofoil applications. About 1950 he was interested in using hydrofoils for sailing purposes, having built a three V-foil cat boat with an airplane foil configuration (two foils forward and one aft). This craft attained remarkable speeds while beating into the wind reaching 20 knots. Speed ratios of over 1.5 times the real wind velocity were recorded. However, it had a tendency to "pitch pole" when running before the wind and would go into "irons" when coming about. These undesirable characteristics led Baker, with US Navy backing, to develop the MONITOR, a sloop with two ladder foils forward and a submerged foil aft. The forces of all the stays were fed into a mechanical computer. Based on these inputs, the computer determined and then set, through a linkage system, the appropriate angle of attack on the aft foil for the wind in which the boat was sailing. This solved the problem of pitch-polling and made it possible to come about and stay on the foils. MONITOR first flew in 1955 and a pace boat clocked her at 25 knots. In October of the following year she was paced at 30.4 knots. It was reported that MONITOR attained speed to true wind speed ratios of just over 2.0, and at times unofficial boat speed measurements close to 40 knots were observed. It is interesting to note that the U.S. Navy backing of MONITOR was motivated by its objective to learn more about the foil structural characteristics and construction methods used by Baker. Recommended references: Baker, G.G., "Design of Hydrofoil Boats with Particular Reference to Optimum Conditions for Operating in Waves", Baker Manufacturing Co., Engineering Report No. 248, July 29, 1960. Also, Alexander, Alan F., et al, "Hydrofoil Sailing", Juanita Kalerghi, 51 Welbeck Street, London, 1972. -- John Meyer (jmeyer@erols.com)





#404 Tornado-Cat

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Posted 22 July 2014 - 08:27 PM

^ remember it's not an all or nothing situation, 3 some of the time & 4 some of the time is ok too AFAIK

 

Although I guess you then run into problems with asymmetric boards etc as the rule only allows cant and rake - so perhaps in the end you are stuck with one design philosophy or the other.

Yes, with 4 foils we may see different setting depending on the conditions.

I guess the foil will have 3 positions : full lift, small lift when ww, neutral.



#405 floater

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Posted 23 July 2014 - 04:09 AM



...But physics suggests that the TNZ solution should be faster - because, if you've got a lifting foil beneath your feet - it's got to reduce your righting moment.

All else being equal - bear with me here - having half a TNZ foil in the water beneath two hulls means you are lifting the boat from the centerline....

You're partly correct.  I've been looking into what happens with two boards in the water.  Vertical lift on the windward board does reduce the righting moment.  However, the effect of leeway tends to shift the vertical load more to the leeward foil.  This is more pronounced as the boat flies higher.  Heeling to leeward also shifts load to the leeward foil, but tends to make the boat less stable in heave.  

When flying at a medium height (say, 300 - 500 mm) the righting moment isn't altogether different from a hull with straight boards, since the straight boards also reduce righting moment.

 The details change with the foil configuration, but the trends seem to be similar over a wide range of foil configurations (C, J, L).
 
One interesting thing with two boards is anhedral is stabilizing - at least within the restrictions of the A Class rule.  
 
The righting moment picture could be changed drastically with some simple board controls.  Port tack, neutral, starboard tack, switched as the crew moves across.  
Why do straight boards also reduce righting moment?

#406 Doug Lord

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Posted 23 July 2014 - 12:25 PM

Check this sketch out: with four boards down, and flying the windward hull, the windward foil has a small component of force acting to reduce righting moment:

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#407 floater

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Posted 23 July 2014 - 02:04 PM

Thank you. Good. For some reason I failed to put the heel back on for conventional sailing mode.

One thing about the foilers - none of them like to heel to leeward.

#408 Doug Lord

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Posted 23 July 2014 - 02:45 PM

Thank you. Good. For some reason I failed to put the heel back on for conventional sailing mode.

One thing about the foilers - none of them like to heel to leeward.

 

I don't know about that-the Flying Phantom and GC32 are frequently photographed with a small "normal" angle of heel. With Veal Heal the Moth unloads the dgrbd and gains up to around 40% more RM-but it doesn't work so well on multies.

 

Phantom pix Phantom International, GC 32 pix macca:

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#409 macca

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Posted 24 July 2014 - 07:02 AM

We can sail with leeward heel. But for sure it's faster with windward heel... A lot faster.

#410 darth reapius

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Posted 24 July 2014 - 08:36 AM

Does that change upwind and downwind at all Macca? And would it be to do with having less windward rudder in the water... Just less wetted surface area...



#411 edouard

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Posted 24 July 2014 - 08:57 AM

One good question is why it took so long for foils to show up on sailboats.  This ferry was in use off Buenos Aires over 40 years ago.

 

Because controlling the speed is much easier with an engine than with sails. Since sails (or a wing) can't provide power on demand, the control of the foils to provide a given lift at all time is much more complex than on a power boat. There is also the problem of lateral stability with sail powered craft, something you don't have to deal with (or hardly) on a power boat.



#412 Chris 249

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Posted 24 July 2014 - 09:48 AM

One good question is why it took so long for foils to show up on sailboats.  This ferry was in use off Buenos Aires over 40 years ago.

 

It didn't take so long.

 

Dave Keiper's cruising tri Williwaw was fully flying in the ocean in the late '60s. The video of the boat in action are shocking - the hull and rig looks extremely crude, about as efficient as an early Piver, but the boat smoked when foiling fast.

 

Small cats like Icarus and Mayfly were foiling at Weymouth Speed Week in the '70s, and there were many other foilers at such events.

 

Tabarly's tri Paul Ricard was using foils, adjusted by a pivoting main beam, when it was launched in '79 and other tris such as VSD were fitted with them for some time. The 26m (85' IIRC) tri Charles Heidsick was designed to semi-fly using foils and the ground effect of the beam. 

 

Moths were, IIRC, foiling in the '60s in trials; there's blurry pics on Moth sites of a scow foiling on (IIRC) Port Philip Bay in Australia in that era, with further details about the experiment. Windsurfers were photographed foiling about '77, for example in the Churchulla (sp) Bros book. There was also foiling Mistral M1 at my local beach around '83 and there are pics of Harken stock foils being used and advertised for sale on the original Windsurfer around the same time. And as Doug has pointed out, Monitor was there in the '50s.

 

With the technology of the day, though, boats were normally too heavy to make foiling effective around a course. Creating sails that were powerful enough to lift a boat onto foils but could then stay flat enough when the apparent wind increased would have been impossible, too.

 

You can add in the fact that popular craft tend to be simple, tough, cheap and perform well in light winds, which are not easy things to achieve on a foiler.

 

The fact that offshore boats were foiling decades ago proves that foiling trickled UP to the America's Cup, like most technologies did.



#413 edouard

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Posted 24 July 2014 - 10:07 AM

One good question is why it took so long for foils to show up on sailboats.  This ferry was in use off Buenos Aires over 40 years ago.

 

It didn't take so long.

 

Dave Keiper's cruising tri Williwaw was fully flying in the ocean in the late '60s. The video of the boat in action are shocking - the hull and rig looks extremely crude, about as efficient as an early Piver, but the boat smoked when foiling fast.

 

Small cats like Icarus and Mayfly were foiling at Weymouth Speed Week in the '70s, and there were many other foilers at such events.

 

Tabarly's tri Paul Ricard was using foils, adjusted by a pivoting main beam, when it was launched in '79 and other tris such as VSD were fitted with them for some time. The 26m (85' IIRC) tri Charles Heidsick was designed to semi-fly using foils and the ground effect of the beam. 

 

Moths were, IIRC, foiling in the '60s in trials; there's blurry pics on Moth sites of a scow foiling on (IIRC) Port Philip Bay in Australia in that era, with further details about the experiment. Windsurfers were photographed foiling about '77, for example in the Churchulla (sp) Bros book. There was also foiling Mistral M1 at my local beach around '83 and there are pics of Harken stock foils being used and advertised for sale on the original Windsurfer around the same time. And as Doug has pointed out, Monitor was there in the '50s.

 

With the technology of the day, though, boats were normally too heavy to make foiling effective around a course. Creating sails that were powerful enough to lift a boat onto foils but could then stay flat enough when the apparent wind increased would have been impossible, too.

 

You can add in the fact that popular craft tend to be simple, tough, cheap and perform well in light winds, which are not easy things to achieve on a foiler.

 

The fact that offshore boats were foiling decades ago proves that foiling trickled UP to the America's Cup, like most technologies did.

 

Actually the first foiling power boats such as the HD-4 (http://en.wikipedia.org/wiki/HD-4) date back to the 1910s. So it did take a while to move to sail boats, and a while longer again for commercial implementation such as the foiling fairies McGyver was referring to.



#414 nav

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Posted 24 July 2014 - 10:44 AM

Stolen from the FP

 

This has been threatened for some time - glad to see someone made it a reality.

Now wait for the video...

 

soft-cell-1-1024x866.jpg

 

 

More here... http://www.google.de...ved=0CHYQrQMwGg

 

softwing_2.jpg

 

softwing_1.jpg

 

 

Same idea from last year - Swiss?



#415 macca

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Posted 24 July 2014 - 11:04 AM

Does that change upwind and downwind at all Macca? And would it be to do with having less windward rudder in the water... Just less wetted surface area...


It's more of an advantage when sailing upwind, we have pretty long foils so we can achieve a fair bit of heel. Our draft is 2.3m and the new AC62 is 2.7m IIRC. So for us to have useful windward heel is easier to achieve then it will be on the new AC boats.

It works in the same way as the moth, rig over the top gives lift, RM increases as well. Plus the foil geometry in the water changes so that the main shaft is entering the water at a more vertical angle and the tip is immersed deeper and at a more horizontal angle. This reduces leeway, increases efficiency (less of a surface piercing lifting effect from the main shaft and the tip is in cleaner water) and there is surprisingly no loss of heave stability. So it's all wins when you get the mode rolling.

#416 edouard

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Posted 24 July 2014 - 12:07 PM

Same idea from last year - Swiss?

 

SoftWing is indeed a Swiss company (http://soft-wing.ch/) but the original designer is Hugues de Turckheim.



#417 Chris 249

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Posted 24 July 2014 - 12:31 PM

Hughes from Tiga? Wow... he was a fun and innovative guy in windsurfing.



#418 edouard

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Posted 24 July 2014 - 12:33 PM

Hughes from Tiga? Wow... he was a fun and innovative guy in windsurfing.

 

Yup.



#419 floater

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Posted 24 July 2014 - 06:03 PM


Does that change upwind and downwind at all Macca? And would it be to do with having less windward rudder in the water... Just less wetted surface area...

It's more of an advantage when sailing upwind, we have pretty long foils so we can achieve a fair bit of heel. Our draft is 2.3m and the new AC62 is 2.7m IIRC. So for us to have useful windward heel is easier to achieve then it will be on the new AC boats.

It works in the same way as the moth, rig over the top gives lift, RM increases as well. Plus the foil geometry in the water changes so that the main shaft is entering the water at a more vertical angle and the tip is immersed deeper and at a more horizontal angle. This reduces leeway, increases efficiency (less of a surface piercing lifting effect from the main shaft and the tip is in cleaner water) and there is surprisingly no loss of heave stability. So it's all wins when you get the mode rolling.
given no loss in heave control with a windward heel - one might imagine taking a bit of the kink out of the vertical.

The GC foil might be okay with a bit more L, and a little less V. And become a little bit quicker.

#420 nav

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Posted 24 July 2014 - 07:15 PM

Does that change upwind and downwind at all Macca? And would it be to do with having less windward rudder in the water... Just less wetted surface area...


It's more of an advantage when sailing upwind, we have pretty long foils so we can achieve a fair bit of heel. Our draft is 2.3m and the new AC62 is 2.7m IIRC. So for us to have useful windward heel is easier to achieve then it will be on the new AC boats.

It works in the same way as the moth, rig over the top gives lift, RM increases as well. Plus the foil geometry in the water changes so that the main shaft is entering the water at a more vertical angle and the tip is immersed deeper and at a more horizontal angle. This reduces leeway, increases efficiency (less of a surface piercing lifting effect from the main shaft and the tip is in cleaner water) and there is surprisingly no loss of heave stability. So it's all wins when you get the mode rolling.

 

 

...taken from this?

 

11.4 The maximum dimension of any daggerboard shall be 5.000 m in any direction, measured
    along a straight line.

 

That's the only relevant* dimension I see ATM - or is it hidden elsewhere?

 

Wouldn't it be nice if they got away from the mono nomenclature finally , 'daggerboard'! Pfft...

 

* draught and board length obviously not the same thing, but related



#421 Catatonic

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Posted 24 July 2014 - 07:48 PM

Wouldn't it be nice if they got away from the mono nomenclature finally , 'daggerboard'! Pfft...


Yeah it should be daggerboards...

#422 floater

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Posted 25 July 2014 - 01:14 AM

A Class with TNZ foils:

Attached File  image.jpg   186.88K   10 downloads

http://www.carbonicb...ng-way.html?m=1

#423 Doug Lord

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Posted 25 July 2014 - 02:23 AM

The only trimaran of any size currently sailing(as far as I know) with a version of TNZ's UptiP foils on the amas-my scale test model 5.5'LOA,6.7' Beam, lots of sail:
More here http://www.boatdesig...-36058-107.html and in the Radio Control Multihulls thread in the Multihulls forum


click for a spectacular view--

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#424 floater

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Posted 25 July 2014 - 02:34 AM

^^
Sorry - should have said TNZ'ish foils. The straight dagger gives them a decidedly non-TNZ'ish look.

^
Cool stuff Doug - but is that a wand dangling off the main hull?

#425 Doug Lord

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Posted 25 July 2014 - 01:03 PM

Thanks-the main foil is wand controlled with dual wands so one is always in the water when she's heeled. The idea is that the foils allow the boat to fly the main hull/whole boat in light air when it wouldn't fly due to wind pressure alone.The breeze in this pictures was measured with a Davis Wind Meter at 5mph(not knots!). That allows the boat to be very wide which gives tremendous RM as the wind picks up. The ama foils worked extraordinarily well validating the whole i-flap concept. They were inspired by TNZ,designed by me, with the major difference of the "i-flap":

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#426 ~Stingray~

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Posted 29 July 2014 - 01:39 PM

fun piece, at http://www.sail-worl...-the-Cup/124989

--

On the final day of the Moth Worlds, Beau Outteridge caught up with two America's Cup helmsmen: Chris Draper (Luna Rossa Challenge) and Nathan Outteridge (Artemis Racing). 

Check out this video where they discuss the relevance of the Moth Class to the America's Cup. 



#427 Sailbydate

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Posted 29 July 2014 - 08:22 PM

fun piece, at http://www.sail-worl...-the-Cup/124989

--

On the final day of the Moth Worlds, Beau Outteridge caught up with two America's Cup helmsmen: Chris Draper (Luna Rossa Challenge) and Nathan Outteridge (Artemis Racing). 

Check out this video where they discuss the relevance of the Moth Class to the America's Cup. 

Interesting. Noted NO's comment about staying abreast of any new foiling techniques in the moth.



#428 nav

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Posted 29 July 2014 - 09:48 PM

^ Nicely done.

 

Still on message; "We love the AC, don't care where"

 

An incestuous world though, Larry's son, Nathan's brother.....



#429 Koukel

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Posted 04 August 2014 - 04:39 PM

Last year there was a lot of discussion about using the windward foils on the AC72s to pull down or give positive righting moment, due to flex or sagging of the windward ama.  Did that discussion go away when we learned the forward / backward "pitch" of the foils was being adjusted?  Also, do the smaller catamarans using both foils, maybe just the As, use the windward foil for righting moment or entirely for lifting?

 

Just curious if there is a consensus and I missed it.

 

Koukel 



#430 nav

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Posted 04 August 2014 - 05:15 PM

^ Those who insisted that spaghetti boats and foils were compatible mostly saw the error of their ways either when OB2 was rebuilt in the image of NZB1, or later when the designers admitted as much.

 

Augmenting righting moment utilizing the windward foil was disallowed under the AC72 class rule (with a few exceptions) and is again disallowed under the AC62 rule (with similar exceptions).

 

Questions above as to whether the 62 might use 4 foils to lift in some/all circumstances.



#431 SimonN

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Posted 04 August 2014 - 09:23 PM

Last year there was a lot of discussion about using the windward foils on the AC72s to pull down or give positive righting moment, due to flex or sagging of the windward ama.  Did that discussion go away when we learned the forward / backward "pitch" of the foils was being adjusted?  Also, do the smaller catamarans using both foils, maybe just the As, use the windward foil for righting moment or entirely for lifting?

 

Just curious if there is a consensus and I missed it.

 

Koukel 

It's still early days in the A's, but to date, only a few have experimented with using the windward foil for righting moment but the general view is that with the foils we currently have, it doesn't. At the moment, it seems that there are 2 modes people find work. First, there is both foils set to lift. This works particularly well in marginal conditions to get the boat foiling. It seems like the loss of righting moment due to the lift of the windward board is more than offset by the gains from early foiling. I also believe that at this point, going downhill also benefits from lift on both foils because it helps stabilizes ride height and heel and you don't need as much righting moment anyway. Upwind, everything suggests that having the windward foil set a neutral in most conditions is the best way forward, but this may change if we get foiling upwind better than we are.



#432 ~Stingray~

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Posted 04 August 2014 - 09:31 PM

Basiliscus suggested here somewhere that at AC72 scale, negative attack on the WW foil to achieve RM would be simply too dangerous even it it were allowed.

#433 Koukel

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Posted 05 August 2014 - 02:55 AM

Basiliscus suggested here somewhere that at AC72 scale, negative attack on the WW foil to achieve RM would be simply too dangerous even it it were allowed.

Me too.

 

Koukel



#434 bluesea

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Posted 06 August 2014 - 12:41 AM

These (not necessarily this one) existed before the foiling Moth.

 

2diCW58l.jpg






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