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bobstro
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Registered: ‎01-01-2012
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Re: Solar, wind, and human power

DeanGibson wrote:

One interesting thing in one of the articles, was that the 2010 America's Cup used boats with motor-powered winches, and as a result the specifications for the 2013 series was that they be totally human-powered with a crew limit.  So, in a very real sense, the boats are being down-scaled to more "reasonable" standards. 

 

That was one positive takeaway I got from reading the Wired article. If they haven't emphasized the human-powered aspects, the organizers should if this restriction remains for future events. I could see some real-world benfits coming from research into such technologies.

 

In other words, there were limits this year (the sails of the 2010 boats couldn't clear the SF Bay bridge).

 

I mentally interpreted that as the Golden Gate bridge and was about to dive over to YouTube to behold these beasts! :smileyhappy:

 

[...] What I like to see is the technology.  How many of you know that an airplane (with similar building materials) is being tested to fly non-stop around the world, solely on solar power???  That would be a feat in and of itself in the daytime, but this airplane's solar panels will store enough energy to carry the airplane through the night (complete with running lights).

 

I do like to keep up with that sort of development, if only casually (and often from reading Wired, even if Deesy doesn't find it hip.) I recall not so long ago reading about conventionally-powered aircraft going for duration records (and being impressed by how uncomfortable it was for the crew.)

 

You don't find the limits of technology unless you push them (safely).  I was never a fan of Steve Fossett, because I thought he was primarily a risk-taker for the sake of records (I've never admired that), and history proved that two years ago.  The AC72 boats and the solar airplane are (to me) in a different league.

 

Well yeah. You'll be able to buy an AC72 at Walmart soon. :smileyhappy:

The technology-pushing aspects, particulary the human-powered aspects, are interesting. Had it not been for this controversy, I wouldn't have been aware of at least one aspect to the AC races that does interest me. I may not turn into a fan, but if real-world benefits are gained, the sport has redeeming qualities I hadn't appreciated.
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deesy58
Posts: 2,486
Registered: ‎01-22-2012
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Re: Solar, wind, and human power

bobstro wrote:

I suspect there's a large untapped market of Americans just dying to get into catamaran racing at the local lake. They're smart. They've figured this out.

Actually, you're a bit behind the times with this assertion.  The market is not "untapped."  People have been racing sailing catamarans on lakes around the world for a very long time.  Small sailing catamarans were introduced to the world as early as 1961, and the Hobie Cat series of sailing catamarans went on to become the most popular sailing catamarans anywhere: "From 1967 on, the new Hobie Cat Company went on to become the largest manufacturer of small catamarans in the world. In 1967, Alter [the company founder] designed the Hobie 14 Catamaran. Alter wanted to make a boat that could be easily launched into the surf. In 1969, Hobie released the Hobie 16, the most popular catamaran ever and the most competitive catamaran class in the world. Over 135,000 Hobie 16 Cats are sailing around the world."

http://en.wikipedia.org/wiki/Hobie_cat

I have actually seen these boats racing on lakes in the Midwest and on the Great Lakes, and their sailors appeared to be enjoying themselves quite a bit.  Have you gone to your local lake on a weekend and watched any of the boating activities? 

Are you privy to Walmart's sales plans?

Do you believe that one must be privy to WalMart's sales plans in order to believe that it would be unlikely to be able to purchase a multi-million dollar boat in a local store?

(...)

The only reference to winds I see in the 5/10/13 article text is "... In contrast, on the October day that Team Oracle’s AC72 capsized, winds were closer to 25 knots with gusts up to 30." In the 5/9/13 article describing a specific incident, I see "... The wind is blowing at 20 knots and climbing. The AC72 is designed to sail in winds between 5 and 30 knots."

Well, that's what happens when you get your information from a magazine like "Wired."  If you actually watched the races, or if you accessed a copy of the race rules, you might have known that the wind limits were exactly as I stated, and that there was a U.S. Coast Guard officer present on the Committee Boat to make sure that the rules regarding wind were enforced.  What can I say?  You chose to believe a magazine writer over any other source. 

The writer said it couldn't be turned off. Can it? It can be adjusted certainly. Do they not attempt to transition as quickly as possible? I'm sure he used dramatic language, but isn't that one of the challenges of these new boats?

Like the [constant speed] propeller on an airplane or the rotor on a helicopter, the wing on a sailing catamaran can be adjusted to provide no thrust at all, allowing the boats to come to a dead stop in the water.

Of course, if you had watched any of the races, you would have known that

Pardon my ignorance, but I thought the big wing sail was the exciting new technology, and the one that introduced many of the new challenges.

Solid wings have been around since, at least, the previous America's Cup races.  Both the Oracle boat and the New Zealand boat had wings that were almost identical.  The size and shapes of the cloth sails, however, were a bit different.  The teams also did not always choose to use the same types of cloth sails as part of their strategies.  It made a difference in the outcome of the races. 

If you saw a single picture of any of the AC72 racing yachts, you would have seen that they contained a two-part, adjustable wing, and at least one, or sometimes two, cloth sails. 

(...)

From what I'm reading lately, it appears there will be a net win for the City, but a much more modest one than was originally hyped. Roust can probably give us a better view from the ground. However, had there not been the spectacular comeback, my understanding is that it could have been a significant loss. Is a comeback of such monumental proportions going to required for these events to turn a profit for the hosting city?

There were a very good many fans from New Zealand present in San Francisco cheering for their team.  It appeared that there were many thousands of fans lining the shores, and at America's Cup Park, and those fans, presumably, had to eat and sleep while they were in San Francisco.  Just because one local doesn't like Larry Ellison, and doesn't believe that the races benefited the area, does not make it so. 

No, I'm not deriding anybody. I'm pointing out that I find commonality in the sports I don't like (big dollar-driven, technology-focused events such as yacht and NASCAR racing), versus purely technology/science (e.g. mars landing) or athlete-focused (e.g. hockey) events. I'm glad others enjoy the big-money sports, so long as it doesn't waste my taxes.

You are implying that baseball, hockey, football and basketball are not "big-money" sports when in fact, they are.  When was the last time you checked into the salaries of some of these professional athletes?  Where do you believe that money comes from?  I'm guessing that none of the sailors on either of the America's Cup finalists will ever make as much in their entire lives as some American athletes make in a single year. 

(...)

If you could guarantee a nail-biting comeback from an 8:1 deficit every time, I think you could count on those crowds. I don't know if the crowds late in the series would have appeared otherwise. From what I've read, turnout was significantly lower early on.

Actually, the crowds looked largest on the first weekend of racing.  Later, when many people had to return to work, the crowds thinned out.  Also, many of the New Zealand fans had to return home.  Virtually nobody believed that Oracle Team USA could recover from their deficit and win the Cup, so I doubt that it had anything to do with the crowds until the last day of racing, when the race became a "sudden death" event for both teams. 

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bobstro
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Registered: ‎01-01-2012
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Money power

[ Edited ]
deesy58 wrote:

Actually, you're a bit behind the times with this assertion.  The market is not "untapped."  People have been racing sailing catamarans on lakes around the world for a very long time. 

 

Thank you for making my case.

 

[...] Do you believe that one must be privy to WalMart's sales plans in order to believe that it would be unlikely to be able to purchase a multi-million dollar boat in a local store?

 

Aren't you being a bit elitist to think that the average American wouldn't relish the opportunity to race an AC72 on Golden Pond?


[...] Well, that's what happens when you get your information from a magazine like "Wired."  If you actually watched the races, or if you accessed a copy of the race rules, you might have known that the wind limits were exactly as I stated, and that there was a U.S. Coast Guard officer present on the Committee Boat to make sure that the rules regarding wind were enforced.  What can I say?  You chose to believe a magazine writer over any other source. 

 

Nothing you have written contradicts the article that you are taking issue with. If you'd quit trying to turn this into a critique of Wired magazine and stick to the facts, you'd see that what you took issue with wasn't actually written. I'm sure you wish that's what had been written. Perhaps that's what you thought was written. But I don't see any such thing  actually stated in the article. Have I missed something?

 

The article describes the limits of the boats. It does not say that they'd be racing in those conditions in the AC races. You are taking issue with something not stated in the article, at least not that I'm seeing.


[...] Like the [constant speed] propeller on an airplane or the rotor on a helicopter, the wing on a sailing catamaran can be adjusted to provide no thrust at all, allowing the boats to come to a dead stop in the water.

 

But it's always there, and thus can't be turned "off". That was the point made in the article. The author was making the point that the crew must have experience with the wing, and that it's not like traditional sailing. I do not believe that is incorrect.

[...] If you saw a single picture of any of the AC72 racing yachts, you would have seen that they contained a two-part, adjustable wing, and at least one, or sometimes two, cloth sails. 

 

I've seen the pictures and videos. There was this really interesting article in Wired magazine that had them, in fact. You should look at that article. It has pictures and everything.

[...] There were a very good many fans from New Zealand present in San Francisco cheering for their team.  It appeared that there were many thousands of fans lining the shores, and at America's Cup Park, and those fans, presumably, had to eat and sleep while they were in San Francisco.  Just because one local doesn't like Larry Ellison, and doesn't believe that the races benefited the area, does not make it so. 

 

Unlike sponsor Louis Vuitton, the City of SF wasn't entitled to any guarantees. One article cited an estimate of $22M to the City to hold the races for things like police protection. I understand the final tallies won't be available until November, but even recent articles seem to indicate "... As of Sept. 18, according to Cup organizers, the gates had drawn just 700,000 of the 2 million anticipated attendees. Ellison and his team had raised $16.5 million of the $20 million needed to offset the city’s costs (with a reported $14 million going toward the reimbursement), and broadcasts were drawing about 1 million viewers domestically, which meant that the Cup was failing to deliver on virtually all of its promises. "

 

I'm sure there were fans there, and I've read that they may have made a modest profit, but I'm wondering if the end result and the exciting end will be enough to make another city consider getting involved. If SF indeed managed only a modest profit, is hosting an AC event a prudent use of taxpayer funds?

[...] You are implying that baseball, hockey, football and basketball are not "big-money" sports when in fact, they are. 

 

I implied nothing of the sort, Deesy. You have a tendency to put the words you wish someone said into their mouths, then argue that issue. I wrote specifically that I "... don't like big dollar-driven, technology-focused events." I like technology events. I like big-dollar sports (some). But men in machines don't appeal to me as a sporting event. Hey, good on ya if you do, but if I'm asked as a taxpayer if I approve gambling on such outcomes, I'll vote NO.

 

[...] Actually, the crowds looked largest on the first weekend of racing.  Later, when many people had to return to work, the crowds thinned out.  Also, many of the New Zealand fans had to return home.  Virtually nobody believed that Oracle Team USA could recover from their deficit and win the Cup, so I doubt that it had anything to do with the crowds until the last day of racing, when the race became a "sudden death" event for both teams. 

The size of the crowds on any given day don't matter in the end. Did the city make or lose money for hosting the event? Was the city given any guarantees to reduce the risk of not recovering public monies spent?
Was it worth it for the taxpayers of SF? I hope so. Tourism and sports can be huge revenue generators for cities and governments, and bring a lot of employment and other benefits in. I'd far rather see even something like AC racing than Casinos in my town. I just hope it actually was a winner for the City, and not just a promoter's empty promises.
DeanGibson
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Registered: ‎04-12-2011

"Angle of attack" is not a Karate move

[ Edited ]

Without getting into the whole of this long discussion, adjusting the speed of a sailboat, whether one with conventional sails or rigid wings, is trivial (or at least trivial enough that no one will allow you out on the water without knowing how).  No one wants sailboats heading back into the marina without being able to control their speed quite well.  While I'm sure a lot of sailboat owners return to the marina using a tiny outboard motor, it's not necessary.

 

It's simply adjusting the "angle of attack".  In aviation, most traditional instructors teach using the angle of attack as the primary means of controlling aircraft speed in most circumstances.  There are some that teach that power controls airspeed, but that can lead to accidents like the recent one at KSFO:  Maintaining airspeed was left to the auto-throttle function, which apparently wasn't enabled.  Oops.

 

In aviation, since maintaining a constant (vertical) lift is normally essential, increasing the angle of attack allows the airplane (or glider) to maintain the same lift at a lower airspeed, regardless of the power available.  Most airplanes decrease their airspeed when making a landing approach;  most sailpanes (gliders) increase their airspeed for landing.

 

In a sailboat, the lift is normally horizontal, and you simply align the sail/wing with the wind to create a zero angle of attack:  this normally results in zero lift, allowing the sailboat to not only come to a stop, but to soon drift downwind.  Therefore, a little bit of lift can be used to keep the boat without any gain or loss into the wind.  Unfortunately, this usually results in some drift to the side, but this can be effectively offset if necessary by continuously tacking. Beginner stuff, as I recall.

 

At any rate, a constant wind for sailboats is considered a positive thing.

 

Watching the speed control (and the quick acceleration) of the AC72 boats prior to the starting line, was fascinating.  When New Zealand was penalized in race 17, it had to come to a stop for the penalty.  It seemed to be able to do this quickly, without much effort.

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deesy58
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Re: "Angle of attack" is not a Karate move

All exactly correct, Dean!

 

Have you thought about a second career writing for Wired magazine?  :smileywink:

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bobstro
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Re: "Angle of attack" is not a Karate move

He certainly doesn't have as many issues reading it.

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bobstro
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Re: "Angle of attack" is not a Karate move

[ Edited ]

Dean, I wanted to get a good night's rest before responding. US Air, National car and my hotel seem to have conspired against me this week...

 

You wrote " ... Without getting into the whole of this long discussion, adjusting the speed of a sailboat, whether one with conventional sails or rigid wings, is trivia. [...] It's simply adjusting the "angle of attack [...] In a sailboat, the lift is normally horizontal, and you simply align the sail/wing with the wind to create a zero angle of attack:  this normally results in zero lift, allowing the sailboat to not only come to a stop, but to soon drift downwind.". " I believe you are describing how a fixed sail craft is controlled under general circumstances for maneuvering and stopping. Is that correct?

 

While Deesy would like to make this an arguement about the magazine, I found actually reading the Wired article informative. I think Deesy is taking issue with this paragraph (emphasis mine): "... Turning from an upwind heading to a downwind heading is a basic maneuver in a conventional sailboat. “If you ever got into trouble,” Spithill says, “you would just pull the sails down.” But on a wingsailed catamaran, that’s not possible. Because of the AC72′s very power and efficiency, the boat’s design is its own worst enemy when it has to turn and sail square to the wind. With no way to switch a wingsail off, there’s only one way to get through the death zone: as quickly as possible.

 

While the use of "death zone" sounds like a bit of overwrought hyperbole, it's not a term of the author's invention. I have found many references to it when specifically describing the complexity of changing heading from upwind to downwind in a high-performance craft such as the AC72 and racing skiffs.

 

I noticed that the Wired article described the circumstances under which Artemis crewman Simpson was killed almost exactly elsewhere: "... the boat was steering into position to put the wind at its back - "bearing away" in yachting parlance. It's a tricky maneuver, a 180-degree turn known as "the zone of death," because the boats may accelerate out of control, while shifting from upwind to downwind." Eerily, it appears that the Wired article was released on the day he was actually killed.

 

The challenge doesn't seem to be unique to the AC72 craft, but the sheer size and complexity of those boats makes it more of a challenge. To my uneducated eye, it appears that both the Oracle and Artemis boats were lost in almost exactly the same circumstances. The level of coordination among crew required to execute these maneuvers seems very high.

 

Correct if I'm wrong, Dean, but I also understand that there's no "fly by wire" computer control on these vessels, and that everyting is now done manually, including the winches that you mentioned previously, as well as this coordination between crew for complex manuevers. Is that correct?

 

To be clear, I think the complexity of the boats winnows down potential competitors. I don't think it's an argument against a city sponsoring an event. Racing has always been a risky business, and I doubt the sense of danger would have dissuaded Simpson any more than risk would have dissuaded a Gee Bee racer pilot in my grandfather's day. If young crew members want to put themselves in danger, I don't feel compelled to stop them. I applaud their courage, even if I fear for their bloodline. So long as they don't put the public at risk and don't ask me to pay for their hobby, I'm all for it. While I might raise an eyebrow over my city sponsoring a demolition derby, these are events that advance the state of technology, and are something to be proud of.

 

I've enjoyed reading Patrick O'Brian's "Aubrey" series enough to appreciate the old sailing ships. I recall that coming about could also be perilous on sailing ships, but for different reasons. If I'm not mistaken, a poorly executed move could find the full sails square to the wind head-on, resulting in broken masts. Interesting to read that the wind square into the sails at speed is still a tricky maneuver, but due to altogether different physics.

 

Other articles about the AC72 boats, while not so focused on the big wing, are nonetheless interesting. This one had some interesting tidbits I'd not appreciated before: "... For the hydrofoil boats, called foilers, the fluid mechanics of lift is paramount. It differs from the lift of airplanes in that there is a free surface (water) very close to the foils, whereas an airplane lifts in nearly an infinite fluid (air). Lift in the presence of a free surface is the new field of fluid mechanics for foiling boats. In an ordinary boat, there is lift in the form of side force generated to counterbalance the side force of the sails. However, most of the lifting surface of an ordinary sailboat (the downward-projecting centerboard) is further from the free surface than is the case with a foiler, on which most of the underwater appendage is horizontal and close to the free surface." I'm not clear on whether the hydrofoil is the same as the daggerboards on these boats. I was expecting to see more of an underwater "wing", but they don't appear to be overly large horizontal surfaces.

 

With my son now active duty in the Navy, I'm now even more interested in bigger ships. I know a lot of the new planned littoral combat ships make use of hydrofoils.

 

In reading these articles (yes, including the Wired articles, Deesy), I've gained an increased appreciation for these craft, even if not the event or organizers. Not enough to make me watch the races live, but I'm more likely to read up on the craft and technologies themselves now. I may read about it in Wired, Discover or PopSci though. Hope that's OK, Deesy!

 

I don't think the decision of whether to host an event should be affected by such risks (within reason), but I do think hosting cities need to make sure it's ultimately a "good thing" for the taxpaying citizenry when laying out taxpayer money. Raising public awareness of the events helps with that, so I suppose they've been successful in reaching me with this press.

 

 

 

 

 

 

 

 

DeanGibson
Posts: 2,248
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Re: "Angle of attack" is not a Karate move

[ Edited ]

Before getting into any of the details, the Wikipedia article on sailing ( http://en.wikipedia.org/wiki/Sailing ) and the embedded links, give a far more accurate (and detailed) explanation of sailing than I ever could.  That having been said, there is only on really dangerous maneuver in pleasure sailing (assuming one can swim and wears a lifejacket):  that of (intentionally, or otherwise due to inattention to changes in relative wind direction) changing from a port jibe to a starboard jibe or vice versa.  In such a case, if you do not haul in the sail (reducing speed) before allowing the wind to change direction over the stern, the sail and its boom can suddenly swing from one side of the boat to the other with great force, injuring anyone on the boat in its path (see helicopter note below).

 

For all other sailing conditions, simply letting the sail out (eg, your article's "It’s not like a keel boat or even a dinghy where you just ease the sheets and turn.") works well in most circumstances.

 

That works really well on a simple boat with full sail articulation (freedom of movement).  If your sail (or wing) articulation is restricted (for performance or other reasons), you are going to require increased skill in certain maneuvers.  To see an example of the article's concern about the "death zone", watch (my YouTube link) the Oracle boat's turn from upwind (leg 3) to downwind (leg 4) in the final race.  Done well (as in this case), it is a spectacular maneuver.

 

A similar situation occurs in helicopters:  One of the really good proficiency maneuvers in a helicopter is, while hovering into the wind over a fixed spot on the ground, to make a 360 pivot at a constant rate of turn, while remaining over the fixed spot at a constant altitude.  Aside from the necessity of varying power as you pivot due to the changes in wind forces, and the need to continually change the tilt of the rotor disk, when the tail of the helicopter passes through the 180 degree point, it tends to whip the helicopter into a rapid turn (just like in the jibing sailboat), which must immediately be countered by a quick reaction on the pedals.  Quite fun actually, when you get the hang of it, and a good test of understanding the helicopter and the wind.

 

A final comment re your quote "For the hydrofoil boats, called foilers, the fluid mechanics of lift is paramount. It differs from the lift of airplanes in that there is a free surface (water) very close to the foils, whereas an airplane lifts in nearly an infinite fluid (air)."

 

In airplanes and sailplanes, this is true in cruise flight.  However, it is NOT TRUE in landings (which tend to be an important part of flying).  When an airplane or sailplane is closer to the ground than about one wingspan, the proximity of the ground (called "ground effect") causes "induced" drag (the predominant portion of drag when landing) to drop to as little as 10% of its normal value.  Sailplanes in particular make regular use of this:  a sailplane that finds itself a bit short of its path to a desired landing spot, should (non-intuitively) dive to the surface, skimming the surface of the ground about two to three feet up.  This can extend its gliding range by up to a mile or so.

 

As far as the size of the underwater foil / wing:  Stick you hand our your car window at a slight incline, and note the speed at which the relative wind exerts some noticeable upward force on you hand (probably about 25MPH).  Now do the same thing, moving your hand through the water in a filled bathtub at about one MPH.  Lift is (roughly) proportional to:

 

  1. The density of the fluid (water is about 800x dense as air at sea level),
  2. the angle of attack,
  3. the area of the lifting surface, and
  4. the square of the speed.
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deesy58
Posts: 2,486
Registered: ‎01-22-2012
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Re: "Angle of attack" is not a Karate move

I believe that the incident in the races where the New Zealand boat came very close to capsizing was when both boats were jibing. 

 

Just as an observation, not all sailboats have a boom.  Most small sailboats, for example, have no boom.  The sails are held by ropes (lines).  The jib and gennaker sails on the America's Cup yachts were similarly rigged, and you could see the sails switching from one side of the wing (mast) to the other during jibes and tacks. 

 

What pilot has not found out about ground effect while trying to make a landing? 

 

Do you have a sailplane rating? 

 

Just wondered. 

 

DeanGibson
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Re: "Angle of attack" is not a Karate move


deesy58 wrote:

I believe that the incident in the races where the New Zealand boat came very close to capsizing was when both boats were jibing. 

 

Just as an observation, not all sailboats have a boom.  Most small sailboats, for example, have no boom.  The sails are held by ropes (lines).  The jib and gennaker sails on the America's Cup yachts were similarly rigged, and you could see the sails switching from one side of the wing (mast) to the other during jibes and tacks. 

...

 

Do you have a sailplane rating? 

 

 




  • Airplane single and multi-engine land:  Airline Transport level
  • Airplane single engine sea:  Commercial level
  • Glider (sailplane): Commercial level
  • Helicopter: Commercial level

 

I was under the impression that most traditional sailboats had a boom:  http://en.wikipedia.org/wiki/Boom_%28sailing%29 (fourth sentence).

 

The one incident where I saw the New Zealand boat almost capsize, was upwind (tacking) in the finals w/ Oracle, but I think your observation is otherwise correct.

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