Wow, Rita now Cat. 5 (165 mph)

[DeanDavis]

Jason,

I think I will be passing wind tonight, lots of wind I hope. Are you sure you don't want to make it? You can always stay upwind of me.

Dean

[Kenny]

Hey Dean,

I don't want to pour water on your physics lesson. However, in your first illustration, you did not take into account that you don't need a photo or post it note. Your body becomes a sail in wind that strong.

Okay, here is a silly question for you. Let's say you had sustained and consistent wind (never happens, but for the sake of illustration). How strong would it have to be so that you could go out with a board (no sail or kite) and ride around using your body as a sail? I know it will never happen, but it makes me smile just thinking about some crazy trying it as a hurricane comes marching into shore.

Kenny

[RickHeninger]

Kenny,

It would all depend on the square of the length of your bottom lip... Once you went down, re-launching would be tough. You'd have to yank on your 5th line... Facing the wind, open your mouth allowing the wind to lift you back up to get your body out of the water enough to start planing again... I have no idea...

However, Dean, Craig, Jim, etc... That is cool considering no friction. In fact, I think that if you take the limit of that function with ZERO friction, you'd reach infinite speed. the x-component would increase to infinity as the y-component remained constant... Similar concept to a water skier crossing the wake perfectly perpendicular to boat, impossible phisically but theoretically if the water skier cut so hard as to reduce the y-component or forward component to ZERO, he'd have to be tending toward infinite speed. Man, that is faster than Finian! One more example, pulling a rope secured on one end with a weight in the middle so that there is NO SAG AT ALL... You have to pull infinitely hard. Use the trig function and vectors and take limit and force tends towards infinity... If I remember right... Layne I know you are itching to post on this one!

[huck]

Yes if you stuck your sail in the ground then the force would change as the square of the wind speed but you don't do that you use that force to propel you across the water. As you do that you increase the resultant wind speed across your sail. Lets assume that the winds are 20 mph and you are riding 20 mph (my guess is that is possible). The resultant wind speed over the sail is now 28 mph and your force is now a function of 28^2 and not 20^2. You are extracting power from the wind more efficiently.

To make the numbers more confusing, the apparent wind on a kite is not only the result of board speed, but also the speed of the kite moving back and forth or looping.(we all know the power burst generated by kite loops)

The ability to generate apparent wind from a standstill is what gets kitere planing in such light wind.

Using the above example:
-Riding in 20mph wind with kite parked, the kite sees wind of 28mph.
-Steer the kite up and down, the kite sees wind of >28mph
-The look of terror on your face when you accidently put your kite into a loop and superman, uncontrolled towared your car parked on the beach...priceless.



Brian

[DeanDavis]

You guys are addicts or fanatics or something, it’s awesome. When I wrote the original Rita post I was just amazed at the thought of that much wind but I really didn’t know if anyone else would find it interesting (or care the least). But by the number of views and the replies I guess others did find it interesting and it sparked lots of interesting conversations. Ever since I started kiteboarding I found this group of people awesome, friendly, and supportive. It is most definitely a part of why I love the sport (unlike the bad taste left in my mouth from the surfing crowd in Cali). But as far as the interest and knowledge on the engineering/physics side I figured I was somewhat of an oddity but you guys are all over that stuff (especially you wind surfers). I think that is awesome and pretty darn amazing*. I have never run into a surfer who wanted to discuss the physics of riding a wave (I bet most have never even given it a thought) or a skier who wanted to talk about the energy dissipated in a quick stop let alone one who actually understands that stuff.

Anyway it’s all good and someday I’ll need to hook up with some of you to have these cleaver conversations (calculator in hand), preferably after a ripping session in front of a cold one.

*Is that because there are an unusual number of engineers out there wind riding or is it because this sport is so damn amazing that we need to learn as much as we can about it?

[Fred Gruendell]

Call me a nerd... I actually read that whole thread... AND LIKED IT... Great topic Dean.

I was in Fort Walton Beach, Fl. for Rita. The hotel I was staying in was on the beach on the gulf. Of course Rita came ashore far to the west of us, but it was amazing what that much wind over that large of an area can do. The normally flat gulf was pitching up impressive waves. The surfers came out and got some, but only after it dropped a couple of notches.

I had to work all week and missed the wild wind. I finally did get to sail on Sunday and the wind had pretty much died off. It was nice to sail in 6.0 conditions with 86 degree water temps.

Having not actually been through a hurricane, I have no first hand appreciation for the energy, but I could see the evidence of Ivan and Dennis still all around. I can only sympathize with the survivors of Katrina.

[Craig Goudie]

Ya big nerd!

-Craig

Call me a nerd... I actually read that whole thread... AND LIKED IT... Great topic Dean.

[watch23]

Is everything like this these days?:lol: