Subject: Re: [harryproa] Re: steering with delta COE-CLR
From: Rick Willoughby
Date: 6/9/2011, 7:35 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

 

Ben

The self regulating wing overcomes the feedback aspect.  

Thrust vectoring is OK at low speed; not as effective as a rudder once speed increases.

A friend steered his pedal boat by curving the flex shaft to either side.  He could steer as well at slow speed as he could at high speed but it was not as effective as a rudder at high speed.  It also required quite a lot of force to curve the shaft so his linkage was heavy.  He proved it could be done but has since gone back to the dipping rudders.

The lack of rudder could be more of a problem than you think.  For example my dipping rudders take a bit of getting used to in a following sea because the back of the boat is apt to slide down the wave in a broaching motion.  I learnt to anticipate this such that I insert a bit of blade if I think it is going to happen.  It is also linked to the problem I have with the V14 boat that tends to flop roll when in a following sea. The stabilisers are in the middle of the boat and the boat will suspend from the ends leaving the stabilisers enough above the water that the list is close to capsize before the stabiliser is loaded.  I have to move my weight or turn into the list  to stay upright.   

The V15 design has stabilisers further aft and there is no rocker in the stern.  This certainly reduces the problem.

As in a windsurfer I think it would take a lot of practice to steer the boat well.  There will probably be issues in a shunt for example.  There would also be problems when you are running trying to create a steering moment.  Even if you say you will only reach downwind you need to be able to recover from the situation where the sail thrust and boat drag are directly in line.  

If you have a rudder the only requirement to steer is boat motion.  You do not need drive.  Think about the situation coasting into a beach.

Rick
On 10/06/2011, at 8:53 AM, bjarthur123 wrote:

 

thanks for the informative reply.

instability would not be a problem with this method of steering if combined with your wing w/ tail flap, correct? if it auto-adjusts to keep its AOA constant, there would be no positive feedback loop when turning, if i understand things correctly. would this solve your seaway concerns too?

steering without sails up, i was thinking either paddle for a small boat, as arto suggested, or engine vectoring on a larger one. would that not work? did you ever consider thrust vectoring on your peddle boats instead of the dipping rudders??

you make it seem as if the adjustment in COE and CLR need only be quite small. do you think it would be enough, with a fixed mast, to just rotate the leeboard fore and aft? or would it need to be slid on rails??

ben

> It will produce a lot of turning moment. These are the biggest
> forces on the boat so separating them small amounts creates huge
> moments. It works well with windsurfers but takes practice.
>
> One of the potential issues is instability. If the mast is moved
> forward to bear away the angle of attack increases and it will drive
> more unless it is near stall. It could be like balancing a marble on
> a ball - that is my experience with windsurfers as I was often wet.
> There is never equilibrium.
>
> Then there is the situation of a seaway
> where the CoE and CoP will be shifting about both longitudinally and
> laterally creating different moments. This is the main requirement
> for rudders so the boat can hold a course as not all things can be
> accommodated by the main elements.
>
> I tried steering with two wings on a model boat years ago without any
> success but that is less positive than shifting a sail relative to a
> board.
>
> You may also need means to steer when the sail is down.
>
> Connecting the sail and board on a common beam that could be tilted
> fore and aft would probably be the simplest to engineer.


Rick Willoughby
03 9796 2415
0419 104 821

__._,_.___
Recent Activity:
Visit Your Group
.

__,_._,___