i think i have worked it out...

maybe you are right and all of the sailmakers, professional windsurfers, speed record holders etc have been wrong all these years.

or

maybe aerodynamics do make a difference with the performance of a foil.

Beaglebuddy said...

Victor B said...

Beaglebuddy said...

According to that logic the "lift" would pull you directly downwind.

No it doesn't.

I'm simply saying have a look at a wing and a cammed sail and do some research.

I'm not saying I am an expert. My reply was expressing a general opinion in relation to cam vs no cams.

If you want to get down to tin tacs speak to a sail designer. I was simply providing an opinion and an analogy to explain it.

No animosity or 'trolling' on my part. See ya.

I'm not getting the analogy between a sail and an airplane wing, the wind is coming from 90 degrees different direction and the sail is angled 90 degrees different to the horizon.
Sure some wind is approaching the sail from the front like an airplane wing but that is a result of the propulsion wind from the other direction.
An airplane wing does not have all the wind pressure coming straight upward from the ground towards the sky.

It's not really an analogy as such, both the sail and wing have the same design principle. Any air moving past the sail / wing will create a difference In pressure from one side to the other as the air has to travel further around the curved side. The sail will be forced to move due tothe difference in pressure. You will harness that energy to drive your craft in the direction you need to move.

Check the pic of vando in the slalom board post, link below) shows a nice profile of the sail / wing in motion.
www.seabreeze.com.au/forums/post.asp?method=ReplyQuote&REPLY_ID=1064504&TOPIC_ID=100368&FORUM_ID=8

..... both the sail and wing have the same design principle. Any air moving past the sail / wing will create a difference In pressure from one side to the other as the air has to travel further around the curved side. The sail will be forced to move due tothe difference in pressure....

I have never understood how this pressure difference can explain why an aircraft can fly upside down, if anyone knows the answer please let us know

powersloshin said...

..... both the sail and wing have the same design principle. Any air moving past the sail / wing will create a difference In pressure from one side to the other as the air has to travel further around the curved side. The sail will be forced to move due tothe difference in pressure....

I have never understood how this pressure difference can explain why an aircraft can fly upside down, if anyone knows the answer please let us know

from xkcd.com


amasci.com/wing/airfoil.html
www.cam.ac.uk/research/news/how-wings-really-work

this may help.

powersloshin said...

..... both the sail and wing have the same design principle. Any air moving past the sail / wing will create a difference In pressure from one side to the other as the air has to travel further around the curved side. The sail will be forced to move due tothe difference in pressure....

I have never understood how this pressure difference can explain why an aircraft can fly upside down, if anyone knows the answer please let us know

Increased angle of attack,not an efficient use of the foil but will still provide lift. Try sticking your hand out the car window and increase and decrease the angle of attack ,more lift/less lift with a poor foil (Hand dependant)

Well I've never tried it, but I can imagine it would be awfully twitchy. angle of attack is going to be very critical, too much = instant stall, too little = not enough lift, and there's probably only a degree or so between the 2.
I wouldn't like having to rely on it, stuck downwind somewhere.

It depends on what point of view your looking from but from what I can see the evidence points to the greater the number of cams in a sail is directly proportional to the greater profit margins achieved from selling them.

cammd said...

It depends on what point of view your looking from but from what I can see the evidence points to the greater the number of cams in a sail is directly proportional to the greater profit margins achieved from selling them.

I dont think you have thought through that statement... so let me expand your knowledge.

Lets break down the differences between a freeride sail and a race sail:
- there is about a 10x increase in complexity when designing a CAM'ed sail
- carbon battons vs fibreglass
- CAM's
- higher skin tension in CAM'ed, requires better materials
- more material... ie: usually bigger sail sizes
- you dont sell as many CAM'ed vs RAF, eg 1:10 to 1:50
- you have to give away about a quarter of them to your sponsored riders, with another quarter getting them at-cost
- RAF designs haven't changed much over the years, while CAM'ed have changed dramatically

I think you will find that the only reason brand develop race sails, is to win races... for publicity for the brand.

Matt, you forgot the R&D costs race sails vs wave sails. Race sails way more complex and way more hrs burned getting them right.

powersloshin said...

..... both the sail and wing have the same design principle. Any air moving past the sail / wing will create a difference In pressure from one side to the other as the air has to travel further around the curved side. The sail will be forced to move due tothe difference in pressure....

I have never understood how this pressure difference can explain why an aircraft can fly upside down, if anyone knows the answer please let us know

Most of the lift is from plain old angle of attack/force. Think paper airplane.

The rest of the lift comes from viscosity. Air is like a liquid, a bit sticky, kinda. The curve over the top of a wing lifts the sticky stream of air upwards, and the wing with it.

Also magnets.

What I like about windsurfing: I'm always sailing upwind. It's magic.

byronmc said...

Now you have a cambered sail you will never look back. As stated non cam is like a hybrid 3 cylinder electric compaired to the V8 of a cambered sail. It will be faster more stable and easier to sail "when theres wind". negative not many slightly heavier but generaly cambered sails have beter masts that are lighter which outways this.
Enjoy the new ride and do some PBs.

Great profile shot! Hows the foot going? You haven't missed much!