Symmetrical boards producing very little lift so there's not as much disruption from change aoa and reversing flow change. Knife like Pointy leading edges with high tapered camber will though on a symmetrical board. Lots to be fudged there too...
In the clip from 4:00-4:40
http://www.youtube.com/watch?v=996oaTUYa0UThe bow is doing exactly what I was looking for. See the rise while sailing to windward when the wind backs off just a little.
4:30 in, The future in flying proas The leaping shunt. Better be strap in for that. If playstation can be made to with stand leap over 20 foot waves Why not a leaping proa shunt WHOA HOOOOO .....
Todd
--- In
harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@...> wrote:
>
> Todd
> It seems the rudder is not working as hard as you would expect. It
> has attached flow more often because it is operating in a narrower
> range. Really noticeable when you shunt.
>
> Am interested in a big persons view of this as well if you have one.
>
> This is half of the cambered section I proposed for the dagger
> board. Needs to be mirrored to get fore/aft symmetry. It would be
> similar size to what you currently have.
> 
>
> Rick
> On 13/06/2011, at 8:43 AM, tsstproa wrote:
>
> > Here's the shot of board shapes and a little first person view
> > sailing with three boards, then two.
> >
http://www.youtube.com/watch?v=996oaTUYa0U> > Todd
> >
> > --- In
harryproa@yahoogroups.com.au, "tsstproa" <bitme1234@> wrote:
> > >
> > >
> > > The model seemed slower but more stiff with more directional
> > stability sailed higher to windward but not much more. The
> > advantage I see would be in lower true windspeeds at least thats
> > where I seen the difference. There's alot of fudge that still can
> > be done I know. A high aspect lifting foil to windward might be an
> > idea. The foil my be adding lift already when heeling is develope
> > or with enough side load and slight aoa change. Controling the
> > leeboards aoa with
another servo to test and putting on the smaller
> > boards. The boards have a full rounded not square or blunt leading
> > edge the camber is symmetrical fore to aft and Leeside to Windward
> > side. I'll knife the edges out and see what happeneds . I think the
> > sheeting effect may have to do more with trim of each board for
> > course sailed. I put the camer facing the other board and sse if
> > the same effect is happening.
> > >
> > > The course sailed is limited to shore line and outer water depth
> > keeping the model close so I don't lose it. I can tack up the beach
> > on a starboard course with out a problem except sailing the model
> > from leeward side is difficult to see the sail trim at that angle
> > and at a greater distance. So broad reaching to run to stay away
> > from the beach and then sailing as
close as possible to the wind
> > back up the beach even then the sometimes the shore tends to get in
> > the way.
> > > To me the location and its side/offshore winds seems perfect for
> > testing different points of sail with out getting to fare away from
> > the shore.
> > >
> > > Model pitching is very small. Its the immersion of entire hull
> > when beating vs when broad reaching is what I would like to try and
> > over come. Fore to aft pitch is very stable. All but the most
> > extreme wind shifts or turn outs from a shunting, boat will heel
> > before diving its nose.
> > >
> > > Todd
> > >
> > >
> > >
> > > --- In
harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@>
> > wrote:
> > > >
> > > > Todd
> > > > How did it go with the dagger board?
> > > >
> > > > The bow down trim is mostly related to the amount of drag and how
> > > > high up the CoE is.
> > > >
> > > > I cannot tell if the rudders are cambered. Even so they seem to
> > have
> > > > squarish edges. It may be just shadow, Any abrupt change in
> > section
> > > > shape will lead to flow separation and the water sheeting.
> > > >
> > > > A cambered dagger board will reduce the drag. Having the sail set
> > > > close to and over a flat deck will reduce drag. These things will
> > > > help bring the leading
bow up. Adding more rocker on the lw hull
> > > > could be counter productive but it is worth a try. You could also
> > > > try more width in the ends ie larger entry angle. I would go for
> > > > more width before trying more rocker. Making the ww hull with
> > say V
> > > > with 10 to 20 degree deadrise might reduce drag on it as it lifts.
> > > > This is the best way to reduce wetted surface as this hull as it
> > > > unloads rather than going for too much rocker.
> > > >
> > > > If you add a lot of rocker to the ww hull the water will stay
> > > > attached on the underside of the trailing end and get lifted up.
> > > > This will help with bow up but increases wetted surface.
> > > >
> > > > That fact that you can get this model to sail well suggests
> >
that it
> > > > will sail really well in full scale but it is still at a size
> > where
> > > > other factors like surface tension come into play. I cannot
> > > > reliably model a small scale boat like this. It would need to be
> > > > about 2m long to get more representative performance results of
> > full
> > > > scale.
> > > >
> > > > Rick
> > > > On 12/06/2011, at 6:12 AM, tsstproa wrote:
> > > >
> > > > > Second video much better wind on a higher tide. Higher tide
> > allows
> > > > > me wider sailing ground with out getting into deep water or
> > running
> > > > > ashore.
> > > > >
> > > > > First half at normal spedd second half in super slow motion and
> > > > > back
to normal speed towards end.
> > > > >
> > > > >
http://www.youtube.com/watch?v=DCxMexef2_0> > > > >
> > > > > Second test last night winds were stronger. New sail linkage
> > giving
> > > > > me more throw and a little more positive control. Also did a
> > three
> > > > > board test. Simple connection out to leeward side of leehull On
> > > > > board camera quit working before I tested model with the
> > third board.
> > > > >
> > > > > The water sheeting effect on rear board I think is in part what
> > > > > your saying Rick but also from what I'm seeing it looks like
> > high
> > > > > side loads put on the unweighted board? Notice
ride height
> > when its
> > > > > the front board vs when its the rear board. Is this the
> > effect of
> > > > > having an extremely low draft with an extremely light model.
> > > > > Nothing pressing down on rear end of boat at speed?
> > > > >
> > > > > Even so I'm thinking a new leehull 30''square 0r 2.5'' square
> > for
> > > > > the model 36'' long hull, maybe with a little deeper rocker
> > just to
> > > > > keep the bottom of stem just off the water.
> > > > >
> > > > > Todd
> > > > >
> > > > > --- In
harryproa@yahoogroups.com.au, Rick Willoughby
<rickwill@>
> > > > > wrote:
> > > > > >
> > > > > > Todd
> > > > > > You can mount it roughly in line with your rudders.
> > > > > >
> > > > > > The camera showing the rudder in your video is handy. It
> > looks like
> > > > > > the one in shot has a blunt leading edge and the flow
> > detaches to
> > > > > > form a sheet. I am very interested to see a similar shot of
> > the keel
> > > > > > you make. If you make the edges with a small radius the
> > flow should
> > > > > > stick to them without forming the sheet. The flow attaches
> > better at
> > > > > > higher Reynolds number so it will improve as you increase
> > the scale
> > > > > >
and increase the speed.
> > > > > >
> > > > > > Gardner and I were discussing different ways to support the
> > loads
> > > > > > from the board and we came up with the idea of a brace from
> > his
> > > > > > cockpit to a the dagger board. Your loads on the model are
> > not big
> > > > > > enough to need this detail but this solution makes it
> > simpler to
> > > > > > support a full scale dagger board that has the ability to
> > pivot up.
> > > > > >
> > > > > > Rick
> > > > > > On 11/06/2011, at 10:42 AM, tsstproa wrote:
> > > > > >
> > > > > > > Thanks Rick, I pick up something locally. Swann thumb
> > camera.
> > > > > > >
> >
> > > > >
http://www.youtube.com/watch?v=wWRXllhPiag> > > > > > >
> > > > > > > Pretty happy with performance of model. The rocker
> > leeward hull
> > > > > > > might need to be alittle deeper. Might want to widen both
> > hulls a
> > > > > > > tad or at least windward hull to maybe 22''wide.
> > > > > > >
> > > > > > > All the mods you mention would seem to benefit for sure
> > but add to
> > > > > > > complicating the build. For now just simple box hull
> > formsm with
> > > > > > > low free board.
> > > > > > >
> > > > > > > I havn't added the center dagger board yet. The boat
with
> > "out"
> > > > > > > boards had lots of bite. Just adding the center with the
> > two end
> > > > > > > boards just isn't appealing to me but I will do it never
> > the less.
> > > > > > > Where do you want it in line with the two inboard or
> > outboard of
> > > > > > > leehull or in hull?
> > > > > > >
> > > > > > > Todd
> > > > > > >
> > > > > > > --- In
harryproa@yahoogroups.com.au, Rick Willoughby
> > <rickwill@>
> > > > > > > wrote:
> > > > > > > >
> > > > > >
> > The board does not need much rounding on the edges
> > because it
> > > > > is not
> > > > > > > > working through a range of angles like the rudders.
> > > > > > > >
> > > > > > > > I have been working on a 12% thick section with a 4%
> > camber.
> > > > > So the
> > > > > > > > leeward face is still slightly convex; not flat.
> > > > > > > >
> > > > > > > > You should be able to shift area from the current
> > rudders to the
> > > > > > > > board so total blade area is not much more than you
> > have now.
> > > > > > > >
> > > > > > > > Something that might be useful for producing hands free
> > video
> > >
> > is a
> > > > > > > > little camera like this:
> > > > > > > >
http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?> > > > > > > idProduct=10093
> > > > > > > > It could be mounted on the boat to give a close up view of
> > > > > things.
> > > > > > > > They will hold about 45 minutes of recording. You can edit
> > > > > the good
> > > > > > > > bits into a smaller clip.
> > > > > > > >
> > > > > > > > Rick
> > > > > > > > On 07/06/2011, at 9:26 AM, tsstproa wrote:
> > > > > > > >
> > > > > > > > > Yeah thats next
I remember your discussion on toyote.
> > > > > > > > >
> > > > > > > > > Todd
> > > > > > > > >
> > > > > > > > > --- In
harryproa@yahoogroups.com.au, Rick Willoughby
> > > > > <rickwill@>
> > > > > > > > > wrote:
> > > > > > > > > >
> > > > > > > > > > Todd
> > > > > > > > > > You should test a dagger board in the middle of the
> > hull
> > > > > with
> > > > > > > the
> > > > > > > > > two
> > > > > > > > >
> small rudders. Give the board a slight camber so it is
> > > > > > > lifting to
> > > > > > > > > > windward.
> > > > > > > > > >
> > > > > > > > > > Another observation I mentioned with the drive test
> > is that
> > > > > > > the boat
> > > > > > > > > > crabbed sideways quite easily. A decent dagger
> > board would
> > > > > > > prevent
> > > > > > > > > > this.
> > > > > > > > > >
> > > > > > > > > > Rick
> > > > > > > > > > On 07/06/2011, at 6:09 AM, tsstproa wrote:
> > > > > > > > > >
> > > > > > > > > > > Development of Proa
Squared along with boards
> > tested.
> > > > > > > > > > >
> > > > > > > > > > >
http://www.youtube.com/watch?v=DG1LuSq_CLg> > > > > > > > > > >
> > > > > > > > > > > In the video the proa squared free sailing version
> > > > > worked fine
> > > > > > > > > with
> > > > > > > > > > > the single 4 1/2 sq inch with about 3- 3 1/2
> > sqinches
> > > > > of board
> > > > > > > > > > > submerged. It actually tending to bear off the
> > wind more
> > > > > > > than I
> > > > > > > > > > > expected with this
single board down. So the
> > bigger boards
> > > > > > > where
> > > > > > > > > > > not tested in single board down configuration. I
> > > > > proceeded in
> > > > > > > > > using
> > > > > > > > > > > the two of the smallest boards for two board down
> > sailing.
> > > > > > > What I
> > > > > > > > > > > experienced was heavy weather helm no matter how
> > hard over
> > > > > > > boards
> > > > > > > > > > > were held over they were over powered by the sail
> > the
> > > > > model
> > > > > > > was
> > > > > > > > > > > uncontrollable shunting, sailing in a straight
line
> > > > > > > etc...Lots of
> > > > > > > > > > > finesse required and even then very frustrating.
> > So I
> > > > > > > jumped up to
> > > > > > > > > > > the second 1 1/4''x 5'' larger retangular board
> > wha la
> > > > > great
> > > > > > > > > > > success balanced sailing and shunting just a
> > touch of
> > > > > > > weather helm
> > > > > > > > > > > coming out of a shunt . On on the hard though
> > hands free
> > > > > > > sailing
> > > > > > > > > > > straight.
> > > > > > > > > > >
> > > > > > > > > > > With this design of craft shunting
happens so
> > fast the
> > > > > > > > > advantage of
> > > > > > > > > > > leaving both boards down is quit significant
> > maintaining
> > > > > > > control
> > > > > > > > > > > and predictability allows me to sail faster not the
> > > > > other way
> > > > > > > > > > > around fight helm to maintain control.
> > > > > > > > > > >
> > > > > > > > > > > enjoy
> > > > > > > > > > > Todd
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > >
> > > 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
> > > > > >
> > > > >
> > > > >
> > > >
> > > > Rick Willoughby
> > > > rickwill@
> > > > 03 9796 2415
> > > > 0419 104 821
> > > >
> > >
> >
> >
>
> Rick Willoughby
> rickwill@...
> 03 9796 2415
> 0419 104 821
>