Are two kite better than one?

You skinny guys won't have this problem but when you weigh 95+ you are normally riding bigger kites. Everyone one knows that bigger kites turn slower for the simply fact they are wider. (It's the same reason you bunch into a ball when doing a summersault. You’re the same weight, but turn faster). Years ago I have seen the foil kite stacked on top of each other a bit like a bi-plane wing. I suppose they were doing it to get more lift/hang time.

Has anyone tried it with bow kites? Say 2 x 8m = A kite that has the lift of a 16m kite but turns like an 8m kite. (Dream on)

Now here is the tricky bit and this comes straight from the calculations used for determining the lift on aeroplane wings. Most people know about the air is travelling faster on the outside of the kite than the inside and this is how we get lift. What the fast moving air does when it meet the slow moving air as it comes off the trailing edge of the kite is create a vortex. Normally called the “Starting Vortex”. This rotating vortex causes air to move in a circular motion around the whole of the kite.

Sailors make use of this phenomenon by putting up a jib and a mainsail. This body of air circulating around each of the sail hits head on in the slot between the main sail and the jib forcing the outer body of air circulating around the main sail to go around the front of the jib. The whole effect of having more air moving over the outside of the jib and the air slowed down on the inside of the jib causes a performance improvement of the jib of up to 50% nathe the expense of the main sail. (Maybe that's why they now make the jibs bigger and the main sails smaller)

So with this in mind maybe the best combination for doubling up bow kites would be to have 6m tuck under the 8m and set back a bit on the same lines.

Wish I had some small kites to try it out. I could have it all wrong but it would be good to get some feed back from the kite manufactures or someone who has tried it.

self landing and self launching will be a biitcch

Hey Crusoe, it sounds like a load of bollocks to me. I think you're thinking a bit too hard. Biplanes have been superceded, as have stacking foil kites. When was the last time you saw one. Bridled kites would make it that much harder again. Imagine the running line of the bridle dragging along the leading edge of the lower kite. It wouldn't work. Your sail dynamic's totally lost me also.The air travels faster around the outside as it has further to travel, this creates a lower pressure on the outside & thus a force on the sail. Your circulating current idea, boy that's a newy on me? The main & jib work well together improving the laminar flow across the sails, but I think you're overcomplicating things. And the arrangement of the kites would be nothing like main & jib.
I'd suggest going back to the basics. A good size efficient board will work your kite a lot harder, and railing hard as you initiate your kite turn (ahead of your own turn) will give you more line tension & a faster kite turn.
What I'm saying is I don't think your 95kg really disadvantages you. We all develop our own styles to suit ourselves. Keep it simple, all you gotta do is have fun.

Hey Crusoe,
Your aerodynamics is pretty much spot on and the biplane effect will help you out. I have flown a double-stacked foil kite on land and it definitely increased the line pull!

Col, the circulation concept has been around before the Wright brothers. The jib/mainsail concept is not about maintaining laminar flow as the the slot actually accelerates the flow (aiding turblulent flow). Laminar flow is not always a good thing. You can get nasty effects with laminar separation bubbles which cause reduced lift and increased drag. The biplane has been superseded because high-aspect ratio (high span and shorter chord) wings are more efficient than two low-aspect ratio wings. But when span (width) affects the turning rate of a kite, then the biplane concept has merit. Particularly when we are not as sensitive to drag, total lift is more influential.

The two kites would turn at the same rate if they are tied together, so would probably turn at the rate of the larger kite?? As for 2x8m kites = 16m kite, it think it might be less efficicient so maybe the same as a 12-14m kite?? Only guessing here.

But agree, launching would be a b%tch!!

Look's like the whole areodynamics class is sitting in!
Maybe there's a bit more to it than sticking a sail up in the air & the wind pushes you along?
Whatthe, you commented on one point that I made. You've stacked foils. What was your experience? I take it you don't do it on water? What do you think of the added difficulty of the front line travelling around the lower kites bridle & it's extension to the upper kite dragging around it's leading edge? Do you agree that in stacking kites there is no interaction as in main/ jib.
Crusoe, I sail with a guy who's 105kg. He's pretty fussy with his choice of gear. He does have very good kite skills & uses a small kite for his size. But boy, there's no way that he's limited by kite turning speed. We all develop our own styles to suit ourselves. Keep it simple, all you gotta do is have fun.

Local chap at Yorkeys a few years back. Definately generated more grunt but difficult to go upwind without the ability to trim the above kite.




Sorry about the size of the picture. I will edit it later when I have a bit more time.

Nice picture Capt. Gumby. Maybe there is hope for the mad idea. I had thought about having the lower kite tucked up closer to the top kite and maybe a 5th string on the lower kite to trim it to the upper kites performance. As far as launching, I suppose it would not be as simple, but I wouldn't write it off until I gave it a ago. I can remember spending up to 20 minutes sometimes trying to relaunch old "C" kites years ago (pre2003) and I hope I never ever see another 2 string kite again in my life and I'm not talking about 'Trainer Kites"

Yes, I know I had my hopes up getting 16M grunt out of 2 x 8m but why set the goal post too low.

Thanks Boxburg. Those pictures tell me heaps. Not much wind (no white caps) no other kites in the air and plenty on the beach. Maybe this idea is worth pursuing. It would be great if I could get some feed back from the guys who were actually doing it. Find out how they got on with launching and landing plus grunt and turning.

Thanks for the positive feed back Ian. Maybe the guys with the R&D money might get interested in the idea if they saw a wider market for them. It seems fairly clear that stacking kites gives more grunt. Maybe the way to go is to have something that is designed to attach to the underside of any kite so that it could be used by any rider. It would be like an optional extra you buy for that particular kite. The idea being that this optional extra just expands the wind range that the kite would perform in. (notably the lower end) Heavier riders may use them to reduce the kite size and lighter riders may use them to enable them to fly in lighter conditions. A lot of guys have at least 2 kites so why not have one kite with this add on smaller kite to give you more grunt.

Went out for a kite yesterday and the wind was only just making 15. I pulled out the Hindenburg and had two hours of fun while the rest of the guys with their smaller kites packed up and sat on the beach. There was enough wind to fly their kites but only down wind. If they had one of these add on kites to give them more grunt, they may have also been out on the water.

Instead of stacking kites, I reckon changing boards - if you can find flat shallow water, try a skimboard. I could stay upwind in about 7-8 knots with my 14m Rhino 05 and a nemo skimmer. (90kgs)

Col, the stacked kite i flew was only a two-line kite (about 7 years ago!) so no experience with bridles and extra lines to relate. I think the kites were both about 2.5m2. We didn't take it on the water, but my mate tried to rollerblade behind them.

The setup was the same as the kites shown in this video: