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PostPosted: Mon Jun 24, 2002 2:46 am 
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KITEBOARDING SCENARIOS #3

Uplift Lofting

You are an experienced kiteboarder and are flying a 15 m, four line inflatable with onshore 18 to 22 kt winds. You just launched your kite and are dragging along the sand waiting for your friends to launch. Your kite comes within 20 ft. (6 m), of the windward face of a six story building as you are dragging along. The next thing you know you are being dragged out of control towards the building at speed with your kite rapidly flying towards vertical or the zenith the closer you come to the building. You think you are going to be dragged into the side of the building when you suddenly are lofted free of the ground. You rapidly rise up off the ground until you are about 20 ft. (6 m) high. You start to panic, fail to control the kite, stall it and fall into the sand along the base of the building. You suffer some broken ribs, a concussion, cuts and bruises. You are not wearing a helmet or impact vest.

What should you do?

1. How to avoid the problem in the first place.

a. Once you launch go offshore without delay. NEVER fly a full sized traction kiteboarding kite on land for any longer than strictly necessary. Wait beyond 300 ft. (100 m) from shore, if you need to wait or delay launching.
b. Avoid onshore wind conditions. If you do fly in them be extra cautious.
c. Never allow your kite to come close, 50 to 100 ft. (15 to 30 m) of the windward face of a vertical surface (cliffs, buildings, dense trees, hills, walls, etc.), in onshore winds. If it looks like you are coming within that distance be prepared to activate your kite depowering leash rapidly.
d. Always wear adequate protective gear, helmet, impact vest, gloves, etc.

2. How to deal with the problem if it is too late to avoid it.

a. Once you are being dragged towards the building activate your depowering leash immediately.
b. Test your leash periodically and inspect it frequently to improve the chances for proper performance.
c. If you are lofted continue to fly the kite at all costs. Your chances of coming through uninjured at this point are not good but may be aided by the following.
d. If you maintain kite control you may glide out of the slipstream and be able to land, hard but potentially with minimal injury.
e. If necessary steer lightly to the left or right to glide out of the standing pressure wave generated by the face of the building. Once you start to fall you have left the slip stream but continue to fly out.
f. Be ready to depower your kite just before impact to disable the kite from dragging your into further problems should you hit hard and lose control.

3. KSI accounts, if any, that are related.

(http://groups.yahoo.com/group/kitesurf/ ... g%20Safety%
20Information/)

41. Incident # 6 02 1
19. Incident # 1 02 1
7. Incident # 5 01 1

Comments: Uplift lofting could be a relatively common problem considering the frequency of vertical surfaces near launches and onshore wind conditions. The winds don’t have to be very high to create such an incident. Twenty knots, perhaps even less could do it. With today’s larger kites and higher wind speeds flying up the windward face of the surface relative to the onshore wind speed, causing uplifting lofting is easy to do. You only need to come close enough. How close is close, that is hard to say. One hundred feet is a good practical distance to shoot for. So, you stall a kite on launch and you are dragged downwind, you carve a turn too near shore and let your kite go over the uplift zone, you bust a jump near shore and get dragged downwind, etc. It is easy to do, remember in kiteboarding “distance is your friendâ€


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PostPosted: Mon Jun 24, 2002 3:04 pm 
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I just heard about a incident in South Africa that gives another example of uplift lofting. It is described at:

http://www.kitesurfers.co.nz/newsdetails.aspx#newsitem1

and soon will appear in the KSI.

I have been talking with hanggliders this morning about condo soaring. That is when the glider works down to in front of the condo and then rides the standing pressure wave up to above roof level. Many of our larger kites have similar or even greater areas than hanggliders.

I am still collecting information but it seems that these guys can pickup enough lift to go above roof level about 70 ft. (about 20 m), or MORE to windward from the face of the buildings. Also, they can soar in as little as 18 mph or about 16 kts.

So, that means that in moderate wind letting your kite come inside 100 ft. may be dangerous. In stronger winds even coming within 100 ft. may be too close. This includes not only buildings but anything else that will bump winds up including walls, even low ones, hills, dense trees, certainly cliffs and other vertical surfaces.

I suspect that many of the more powerful lofting incidents were made a bit worse by ridge lift or uplift lofting when the kite was lifted up by this standing pressure wave during the flight of the kiteboarder.

Remember, kiteboarding IS NOT AS EASY AS IT LOOKS, particularly if things go wrong. You need to know a great deal, practice good safety procedures, have safety gear and use sound judgment to reduce the chance of serious incidents and accidents if things go wrong.

Rick Iossi


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PostPosted: Mon Jun 24, 2002 8:55 pm 
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Here is a post dealing with this thread that appeared on ikitesurf.com.

As a hang glider pilot I can certainly verify all this and more. Hang gliders tend to range from 10 to 22 sq-meters (22 meters is a huge - tandem hang glider). We sore ridge lift in well below 18 mph. On Marina Beach in the S.F. Bay area (CA), we launch directly off the beach - not from the top of a ridge. We then soar the ridge which varies from 5 to 50 feet high along its several mile length.

There are three ways I know of to get very significant lift withouth the obvious ridge.

1) thermals - much less prevalent at beach sites than kitesurfers believe - but not non-existent.

2)Wind shears (we can soar 2000' high in standing shears at Ft. Funston on only a 175' ridge). This is a common occurance. The same is true at Marina on almost no ridge. We tend to fly ridge sites at the beach, but the ridge is NOT needed to provide this type of lift.

3) Gradient. This one is bizzare. When the wind hits the beach after traveling unimpeded over the water it slows down along the ground - creating a gradient. This can actually create a "virtual ridge". This helps to explain how we soar straight off the beach at Marina in relatively low winds (sometimes below 10mph in larger gliders).

Paragliders can fly up to 17,999' altitude legally (and do so) traveling hundreds of miles at best. Look at your kite and see if it looks significantly differnt in size or shape from a paraglider.

Good luck, good sailing, and be careful.

Rick Cavallaro


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PostPosted: Tue Jun 25, 2002 7:01 am 
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Very interesting stuff, Rick. Thanks for taking the time to share all of this detailed info with us. We can all learn from this information and knowledge is power.

The comparisons to hang gliders and paragliders is compelling. Perhaps this is a morbid question but, do you have data on the yearly average number of fatalities and/or serious accidents in these or other extreme sports? Surely this information is out there and it may be of some help in gaining perspective on where our sport may be headed in regard to accidental deaths.

John


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PostPosted: Tue Jun 25, 2002 11:19 am 
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Hello John,

You are so right. There is a lot to be learned by looking at the sports of hang gliding and paragliding with regard to kiteboarding. They are all weather dependent sports. They all have the potential to cause injury although kiteboarding exceeds the potential of the other two activities in the potential risk to bystanders.

Kiteboarding is not as easy as it looks. The same can be said about hang gliding, paragliding or even flying an airplane. In some ways you can be brought up to speed rapidly but not with adequate knowledge and training to see you through necessarily when things go bad.

Here are some references that may help to add perspective:

Tables 2 and 3 in this reference provide some interesting accident statistics including a comparison to other sports.

birch.eecs.lehigh.edu/wghgc/newsletters/ 2000/WG-FEB00.DOC

Paragliding Accident Summary for 2000
http://www.ushga.org/article16.asp

I had the link to the USHGA accident database but am trouble with the search engines locating it again. I will post it once I find it.

Rick Iossi


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PostPosted: Tue Jun 25, 2002 5:17 pm 
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I just talked to the guy that taught me to hang glide at Miami Hang Gliding. He used to condo soar a great deal until the residents put a stop to it.

He passed on the following comments.

1. There is minimal uplift directly in front of the vertical surface until you get above the roof or ridge level due to wind gradient effects.

2. They would go condo soaring in as little as 15 mph up to around 20 mph.

3. They would sometimes rise to 800 ft. above roof level.

So, if your kite is above the level of the vertical surface you may be lifted. If you are already in a jump and your kite falls into the lift ban caused by the vertical surface you will increase the amount of lift and travel. This happened to Dimitri in Hatteras recently above a tree line.

So, from this it MAY be ok to come within 100 ft. of 15 story buildings or higher. Anything lower than that you are at risk particularly in higher winds. If you are jumping when your kite moves into the lift ban, you could really go flying.

Rick Iossi


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