Subject: Re:: Re: : Re: : Re: : Re: : Re: [harryproa] Re: Wing Sail Benchmarks
From: "taladorwood@yahoo.com.au [harryproa]"
Date: 1/7/2016, 11:25 PM
To: <harryproa@yahoogroups.com.au>
Reply-to:
harryproa@yahoogroups.com.au

 

Rick, "Yes your maths is wrong.  Meaningless  numbers.


The Cl of 1 combined with wing area of 25sq.m and apparent wind speed of 15kts  gives you the wing lift force.  That has to be resolved into a drive component for the particular point of sail.  At 20 degrees to apparent wind the drive is 315N.  If that is enough to get your 5mph then the power delivered at the hull is 662W (0.89HP) - not much."

Maybe you need to check your numbers, 315N is apx. 4hp not .89HP, I have no idea where you got that 662 W number from except that it may be all your solar power system is capable of producing.

Rick, "With a solar boat design you begin by developing a weight estimate (all the goodies you need or want to carry along with crew) and combine that with a target speed.  That gives a starting point for the hull design."

Well sure, but the hull is probably the easiest part of the design spiral.  Like Leo said, the minimum drag hull is going to be a large longitudinal parabola with an eclipse shape laterally.  Building it though. . .
 
Talador

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Posted by: taladorwood@yahoo.com.au
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