With the solid wing it's so precise in when it is sheeted spilling off wind gust or setting up a system to do so wouldn't be problem the efficiency in the wing make it so. Its doeasn't take large rotational movements to spill of or shake out wind flow only very small movements required.
I see you do understand stalled and not stalled.
That is one of the clearest details of the wing sail that makes it so feasible. Its precision, sailing taken to whole new level. Developing the possibilities with in its boundaries to gain performance and ease of use.
Todd
--- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@...> wrote:
>
> Todd
> I expect the problem many see with the cambered wing is the
> difficulty of finding a really big guy in a really BIG kayak (not
> necessarily red) when in the middle of an ocean. It would be nice
> (or possibly necessary) to have an instant kill switch that depowers
> the rig any time there are too many things to do at once and a gust
> comes along. Better still would be something that inherently
> depowers enough to avoid a full capsize.
>
>
> Rick
> On 06/06/2011, at 3:24 PM, tsstproa wrote:
>
> > Sure it rotates, could be seen either way. Flip just sounds wrong
> > though could be confused with flipping sides from windward to
> > leeward vise versa of the sail its self.
> >
> > Speed of rataion to make shunt has nothing to do with it. Sail
> > position and hull position is the key taking into consideration the
> > wind direction of course.
> >
> > No recovery had the guy with the red kayak retrieve model for me.
> > Gave him 5$ for the effort and the taking up his time...
> >
> > Todd
> >
> > --- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@>
> > wrote:
> > >
> > > Todd
> > > You have to flip the back (concave face) of the wing through the eye
> > > of the wind when shunting if you want to get the best windward
> > > performance from it.
> > >
> > > Your video clearly shows what happens if it is not done faster than
> > > the boat can roll.
> > >
> > > I gather you are able to recover from a roll by using the
> > buoyancy of
> > > your wing? That is something that could be done full scale providing
> > > the roll is always to leeward. I wonder what happens if you roll
> > > with the windward hull down.
> > >
> > >
> > > Rick
> > > On 06/06/2011, at 10:47 AM, tsstproa wrote:
> > >
> > > > What ! What flip There is no flip. The sail is working in both
> > > > directions with out flip the sail! Roll on the power roll off the
> > > > power roll back on the power over roll or rotate and you stall the
> > > > wing.
> > > >
> > > > There are two separate ranges of depower in the sail. First one is
> > > > in the fine tuning after apparent wind builds by over sheeting
> > > > meaning bring current leading edge in even further . Second range
> > > > is heading boat itself up into the wind with out moving sail yet.
> > > > After sail stall and boat speed slows roll sail back to new lead
> > > > edge boat rotates, new stern falling off wind as wing is
> > rotated as
> > > > needed to produce drive force again. It never see wind flat on
> > with
> > > > boat hulls in a compromised position.
> > > >
> > > > You guys just wanna over complicate and speculate cause you truly
> > > > don't understand. When it hits you, you'll know...
> > > >
> > > > Anyone here in my area wanna come give my model a shot. See for
> > > > your self what I'm describing?
> > > >
> > > > I'm money poor and looking for a boat to live on not in a
> > harbor or
> > > > on a mooring to live off the ocean in. Or I'd have one of my
> > models
> > > > built full size already. After all their built full size first in
> > > > my computer then scaled down.
> > > >
> > > > Todd
> > > >
> > > > --- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@>
> > > > wrote:
> > > > >
> > > > > Mike
> > > > > I believe all the issues you raise are valid.
> > > > >
> > > > > The only way I see to make a rigid wing work reliably is with
> > a tail
> > > > > plane or flap.
> > > > >
> > > > > A tail plane can control the lift precisely and will
> > automatically
> > > > > adjust to wind shifts or boat heading.
> > > > >
> > > > > The best wing profile from a performance perspective is
> > cambered as
> > > > > Todd has. To get benefit from this it needs to flip through
> > the wind
> > > > > per your observation. However it is possible to use it in
> > reverse in
> > > > > strong winds where you do not need the maximum lift it is
> > capable of
> > > > > generating to avoid the flip if it is rigid.
> > > > >
> > > > > A 20% thick solid section with a 10% camber will have a
> > higher lift
> > > > > coefficient going to windward than drag coefficient when flat
> > to the
> > > > > wind. So up to the point of being overpowered the force on
> > the sail
> > > > > will be less during the shunt flip than when reaching.
> > > > >
> > > > > Also for a large range of true wind an easily driven proa
> > will gain
> > > > > apparent wind speed. So this increases the drive when moving
> > > > > compared with the overturning load during the sail flip.
> > > > >
> > > > > A non-cambered wing can be fitted with a flap to achieve the
> > same
> > > > > result as a cambered wing. It will not automatically adjust
> > to wind
> > > > > shift but it can be depowered by releasing the sheet.
> > > > >
> > > > > If you are after a real easy to handle rig then maybe a Flettner
> > > > > rotor would be of interest:
> > > > > http://www.rotorboat.com/videonotes.html
> > > > > These get very high lift coefficients compared with typical foil
> > > > > shape - Cl of 5 or 6. A shunt would simply involve changing the
> > > > > direction of rotation. The ratio of Cd when not rotating to
> > best Cl
> > > > > when rotating is about 10 times. If it had a tail section
> > that could
> > > > > be deployed in heavy wind the Cd could be reduced even more.
> > They
> > > > > are easily depowered by reducing the speed of rotation.
> > > > >
> > > > > Rick
> > > > > On 06/06/2011, at 9:02 AM, Mike Crawford wrote:
> > > > >
> > > > > >
> > > > > > I's possible that I'm missing something.
> > > > > >
> > > > > > Could you show me how to stall a square/elliptical rig, and
> > leave
> > > > > > it stalled for a few minutes, even if the wind direction
> > > > changes or
> > > > > > the boat drifts? That would do a lot to help me see the
> > safety of
> > > > > > the rig, and should be easily demonstrated on a model if it's
> > > > > > possible.
> > > > > >
> > > > > > I've flow four-line kites since the 1990's, so I'm familiar
> > with
> > > > > > how they power and depower. My favorite thing is to use the
> > kites
> > > > > > on a flat beach during low tide, flying along on a three-
> > wheeled
> > > > > > kite buggy. Great fun. That said, I've never been able to just
> > > > > > leave my kite alone while I get up to pee.
> > > > > >
> > > > > > There's also the worry of the momentary shock loading of the
> > > > > > system during a shunt as the wing turns from one side to
> > another.
> > > > > > Your "Planning Proa squared" appears to demonstrate this
> > issue,
> > > > > > with the windward hull popping off the water momentarily
> > during
> > > > > > many of the shunts. Get hit with a gust at the same time,
> > and the
> > > > > > boat is gone.
> > > > > >
> > > > > > Which is not to say it's a bad rig. Your tests have clearly
> > > > > > shown how fast it can be. I just personally have an issue
> > putting
> > > > > > this on a boat with a stove, fuel, water, head, and
> > passengers.
> > > > > >
> > > > > > ---
> > > > > >
> > > > > > This is actually one big reason that I'm planning on a proa in
> > > > > > the first place.
> > > > > >
> > > > > > If I dump my current catamaran in water less than 30' deep, it
> > > > > > will likely cost me between two and six thousand dollars to
> > > > replace
> > > > > > the equipment that could get damaged. I love having a boat
> > with an
> > > > > > SA/D over 50, but it does worry me when pushing the boat. That
> > > > > > kind of cost figure for a capsize tends to lead to white
> > knuckles
> > > > > > when flying a hull. Especially if I'm at an angle where
> > dumping
> > > > > > the sheets will actually increase the heeling moment,
> > leading to a
> > > > > > knockdown or pitchpole.
> > > > > >
> > > > > > So it's my dream to get a boat of similar speed, but with
> > greater
> > > > > > righting moment and longer waterline, and a more powerful
> > rig that
> > > > > > I can always just depower by letting go. Up to this point, you
> > > > > > wouldn't think that fast and safe could go together with
> > the same
> > > > > > boat. But a WTW proa, or catprao, can be an impressive design.
> > > > > >
> > > > > > - Mike
> > > > > >
> > > > > >
> > > > > >
> > > > > > tsstproa wrote:
> > > > > >
> > > > > >>
> > > > > >> When you stall a foil there is no load. Thats reason why
> > planes
> > > > > >> fall out of the sky Or Kites fall back into the windwindow.
> > > > > >>
> > > > > >> The key is the no load and when and how to achieve it and
> > when
> > > > and
> > > > > >> how to bring it back on with out the sudden snap. 4/5 line
> > Kites
> > > > > >> do this by controling the leading edge and adjusting aoa
> > with the
> > > > > >> back line pulling in or out accordingly. If you don't have
> > the
> > > > > >> experience its harder to imagine the possiblity.
> > > > > >>
> > > > > >> http://www.youtube.com/watch?v=LrezrEfQj68
> > > > > >>
> > > > > >> Todd
> > > > > >>
> > > > > >> --- In harryproa@yahoogroups.com.au, Mike Crawford <mcrawf@>
> > > > > >> wrote:
> > > > > >> >
> > > > > >> >
> > > > > >> > The Maltese Falcon is most impressive.
> > > > > >> >
> > > > > >> > However, the rig worries me because there's no easy way to
> > > > > >> depower it,
> > > > > >> > and keep it depowered without attention/effort, if you're
> > > > not on
> > > > > >> a mega
> > > > > >> > yacht.
> > > > > >> >
> > > > > >> > The Falcon is an extremely heavy monohull with full
> > electronic
> > > > > >> control
> > > > > >> > of those sails. Need less power? Push a button, and motors
> > > > roll the
> > > > > >> > sails in between the fixed arms. If things get hairy,
> > the boat
> > > > > >> is heavy
> > > > > >> > enough and strong enough to hang on until the sails are in.
> > > > While
> > > > > >> > sailing, electronics will also keep the sails at an optimum
> > > > > >> angle to the
> > > > > >> > wind.
> > > > > >> >
> > > > > >> > Assuming a proa won't have those features, I'd have to say
> > > > this is
> > > > > >> > more of a racing rig, to be used only by those who really
> > > > know what
> > > > > >> > they're doing, and are prepared to capsize, than on a boat
> > > > where
> > > > > >> you
> > > > > >> > might go cruising, or on a single or dual-handed
> > distance race.
> > > > > >> >
> > > > > >> > Presenting that full face of the sail to the wind during a
> > > > tack or
> > > > > >> > shunt is a problem. On a small boat, or a model, it
> > might be
> > > > fun
> > > > > >> to pop
> > > > > >> > the windward hull out of the water during a shunt, and
> > then to
> > > > > >> zoom off
> > > > > >> > at the amazing speeds the dynarig is capable of. But
> > what if
> > > > > >> you're on
> > > > > >> > a large boat that's not easily rightable after a capsize,
> > > > > >> perhaps in
> > > > > >> > high seas with gusty winds? That could be a disaster
> > waiting to
> > > > > >> happen,
> > > > > >> > particularly if there's only one person to handle the sail.
> > > > > >> >
> > > > > >> > Reefing the sail in those same high seas and gusty winds
> > could
> > > > > >> also be
> > > > > >> > a problem. With an easy rig, una rig, or junk rig, you can
> > > > let the
> > > > > >> > sheets out, the sail will weathercock, and you can take
> > your
> > > > > >> time while
> > > > > >> > reefing, getting a drink, peeing, or tending to an
> > injury or
> > > > > >> equipment
> > > > > >> > failure. For as long as you want. On the other hand, the
> > > > square rig
> > > > > >> > won't stay weathercocked in one direction, and stands the
> > > > chance of
> > > > > >> > presenting the full face of the sail to the wind, even
> > if for a
> > > > > >> short
> > > > > >> > period of time.
> > > > > >> >
> > > > > >> > Even if the boat does not capsize, shock-loading components
> > > > to that
> > > > > >> > level isn't a recipe for equipment longevity.//
> > > > > >> >
> > > > > >> > Again, I think the square/dynarig would be great fun on a
> > > > 20'-er in
> > > > > >> > warm waters (or with wetsuits), where you could play
> > with the
> > > > > >> boat like
> > > > > >> > a Hobie, flying a hull, and righting the boat if things
> > don't
> > > > > >> work out.
> > > > > >> > But I couldn't imagine putting that sort of stress on a
> > > > > >> lightweight proa
> > > > > >> > in the 30' to 50' range. Putting a boat that size on its
> > > > side is
> > > > > >> a bad
> > > > > >> > day, no matter what happens afterwards.
> > > > > >> >
> > > > > >> > - Mike
> > > > > >> >
> > > > > >>
> > > > > >
> > > > > >
> > > > >
> > > > > Rick Willoughby
> > > > > rickwill@
> > > > > 03 9796 2415
> > > > > 0419 104 821
> > > > >
> > > >
> > > >
> > >
> > > Rick Willoughby
> > > rickwill@
> > > 03 9796 2415
> > > 0419 104 821
> > >
> >
> >
>
> Rick Willoughby
> rickwill@...
> 03 9796 2415
> 0419 104 821
>