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View Full Version : i've a question about wings and lift (fluid dynamic mathses!)



BaldieJr
01-09-2008, 07:51 PM
Is there a formula that will calculate lifting force of a long stubby wing?

The wing is somewhere around 20 feet long and 3 inches wide. I'm not sure how to present the "hump", numerically.

This is related to a strange yacht idea. I need to pin down the maths for this thing but don't know where to start.

BaldieJr
01-09-2008, 07:52 PM
To clarify the dimension: the overall wing-span would be 6 inches, tip-to-tip. The wing length (leading edge to trailing edge) is about 20 feet.

Loco-S
01-09-2008, 08:03 PM
http://en.wikipedia.org/wiki/NACA_airfoil

MrMojok
01-09-2008, 08:41 PM
I think you are on the right track Baldie, but if I may offer one suggestion: turn the wings upside down.

Outlaw---
01-10-2008, 05:16 AM
Check out the following link...

http://travel.howstuffworks.com/airplane9.htm

for a simple example of how to calculate lift force if you know the Cl versus angle of attack.

--Outlaw.

DuxCorvan
01-10-2008, 08:31 AM
Working on hydrofoils now, Baldie? http://forums.ubi.com/images/smilies/blink.gif

BaldieJr
01-10-2008, 09:46 AM
i'm trying to solve an old design riddle, which will help me to understand a new design that seems to offend the sensibilities of sailors.

the old design riddle is a boat known as a sharpie. it is capable of exceeding hull speed over long distances. i suspect it has something to do with the hard chines as they present a very long foil when the boat heels over.

the new design riddle is a thing called "chine runners", which appear to invert the chine foil and create lift in opposition to the wind forces.

here is a photo of the chine runners on a very small boat. this thing has no keel at all and can sail in very shallow water.

http://physics.bgsu.edu/~layden/FunStuff/Boats/Matt_Boat/images/2005-05-22/ApplyFiller.jpg

i've some theories i'd like to test but i'd prefer to do it on paper before building a new hull to play with. i suspect that the racing yachtsmen have lost their way, technology-wise.

Covino
01-10-2008, 12:04 PM
http://www.grc.nasa.gov/WWW/K-12/airplane/foil2.html

NASA FoilSim might be a good starting point.

I don't have the browser plugin to run it now but if I recall correctly, you can input wing dimensions/shape, angle of attack, fluid density (air, water, Mars, etc) and it will calculate lift force

BaldieJr
01-10-2008, 03:15 PM
i'm going to have to install windows on a computer sometime so i can play with foilsim. thanks for the link.

here is another shot of a boat with "chine runners". they look like simple foils when the boat is leaning on its side.

http://www.smallsailboats.co.uk/paradox/zero/zero_blocks.jpg

BSS_Goat
01-11-2008, 06:38 AM
I didn't know you built boats.... check out this site. It's not the same boat but they can throw around some ideas.

http://www.southernsportingdesigns.com/forum/viewforum....ba4f77fb3e08da0f1fa4 (http://www.southernsportingdesigns.com/forum/viewforum.php?f=1&sid=161cb9932620ba4f77fb3e08da0f1fa4)

buzzsaw1939
01-11-2008, 06:57 AM
Being an old boat designer, I think I know what your looking for, while healed over in a strong wind it will work as a keel while produceing some lift, to reduce water drag, not a bad idea! http://forums.ubi.com/images/smilies/25.gif

general_kalle
01-11-2008, 07:58 AM
wheres Raaaid?