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

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.

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.

01-09-2008, 08:03 PM

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.

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


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


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

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.


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.

01-10-2008, 12:04 PM

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

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.


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)

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

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